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Evaluation of Significance of Bacteria in Larval Development ofCochliomyia macellaria (Diptera Calliphoridae)Author(s) Aqeel Ahmad Alberto Broce Ludek ZurekSource Journal of Medical Entomology 43(6)1129-1133 2006Published By Entomological Society of AmericaDOI httpdxdoiorg1016030022-2585(2006)43[1129EOSOBI]20CO2URL httpwwwbiooneorgdoifull1016030022-258528200629435B11293AEOSOBI5D20CO3B2

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DEVELOPMENT LIFE HISTORY

Evaluation of Significance of Bacteria in Larval Development ofCochliomyia macellaria (Diptera Calliphoridae)

AQEEL AHMAD ALBERTO BROCE AND LUDEK ZUREK1

Department of Entomology Kansas State University Manhattan KS 66506

J Med Entomol 43(6) 1129ETH1133 (2006)

ABSTRACT Bacteria were isolated and identiTHORNed from the digestive tract of the secondary screw-worm Cochliomyia macellaria (F) (Diptera Calliphoridae) and their role in the larval developmentof this insect was assessed in laboratory bioassays The analysis of 16S rDNA sequences revealed thatthe bacterial isolates represented four species Providencia sp Escherichia coliO157H7 (Escherich)Enterococcus faecalis (Orla-Jensen) and Ochrobactrum sp (Holmes) Developmental assays demon-strated thatCmacellaria larvae are able to develop on a sterile blood agar and no bacteria are requiredto complete larval development Indeed developmental times were shorter and survival rates of Cmacellaria on a sterile blood agar and the modiTHORNed Harris rearing diet were greater compared withthat on the blood agar inoculated with individual and mixed bacterial isolates The cultures ofOchrobactrum sp and E faecalis supported larval development to a signiTHORNcantly greater extent thanthose of Providencia sp and E coliO157H7 The presence of bacteria in newly emergedCmacellariaadults also was assessed and revealed that the bacteria in the gut of larvae can survive pupation andcolonize the gut of adult szligies This study shows that development of larvae of Cmacellaria does notdepend on bacteria and that some bacterial isolates negatively impact larval development

KEY WORDS szligies bacteria larval development Cochliomyia macellaria

Larvae of szligies in families Muscidae Calliphoridae(blow szligies) and Sarcophagidae (szligesh szligies) typicallydevelop in decaying organic matter such as animalfecesmanure carrion and food wastetrash contain-ing a large and diverse bacterial community (Spiller1964 DOtildeAmato et al 1980 Mullen and Durden 2002)Studies assessing the importance of bacteria in thelarval development of these szligies have focused primar-ily on Muscidae and have suggested a close evolution-ary relationship between bacteria and szligies Bacteriaplay a critical role in the larval development of houseszligies Musca domestica L (Schmidtmann and Martin1992 Zurek et al 2000) stable szligiesStomoxys calcitrans(L) (Lysyk et al 1999 Romero et al 2006) face szligiesMusca autumnalis De Geer (Hollis et al 1985) andhorn szligiesHematobia irritans (L) (Perotti et al 2001)In contrast much less information is available for Cal-liphoridae and Sarcophagidae Studies on blow szligiesand bacteria have focused primarily on the role ofbacteria in the oviposition behavior of the screwwormCochliomyia hominivorax (Coquerel) (Devaney et al1973 Eddy et al 1975 Bromel et al 1983 Chaudhuryet al 2002) and the blow szligy Lucilia cuprina (Wiede-mann) (Emmens and Murray 1983) In addition lar-vae of blow szligies in general possess antibacterial prop-erties and have been used for maggot debridementtherapyNtildetreatment of human bacterial skin infec-

tions with larvae of calliphorid szligies (Sherman et al2000 Mumcuoglu et al 2001) The most frequentlystudied blow szligy species from this perspective includeLucilia sericata (Meigen) Calliphora vicina (Rob-ineau-Desvoidy) and Phormia regina (Meigen)(Sherman et al 2000 Mumcuoglu et al 2001 Kerridgeet al 2005) C vicina larvae can digest bacteria in themidgut (Greenberg 1968) however to our knowl-edge no studies have assessed the signiTHORNcance of bac-teria in the larval development of blow szligies

The secondary screwworm Cochliomyia macellaria(F) (Diptera Calliphoridae) is an insect of sanitaryand forensic importance (Baumgartner and Green-berg 1985 Byrd and Butler 1996 Maldonado and Cen-teno 2003) Larvae of this szligy species typically developin carrion but they also can cause facultative myia-sisNtildeinfestation of wounds of animals and people butoften after the invasion by primary myiasis-causingszligies (Mullen and Durden 2002) C macellaria larvaefeed on necrotic tissues but they also may invadehealthy tissues (Broce 1985)

Details on the length of development of the imma-ture stages of the secondary screwworm have beenwell documented in several studies (Laake et al 1936Greenberg and Szyska 1984 Greenberg 1991 Byrdand Butler 1996) however information on the role ofbacteria in the development of secondary screwwormlarvae is lacking1 Corresponding author e-mail lzurekksuedu

0022-2585061129ETH1133$04000 2006 Entomological Society of America

Because larvae of the secondary screwworm typi-cally develop in a highly septic habitat bacteria playan important role in the oviposition of blow szligies andthe midgut of blow szligy larvae provides conditions forbacterial digestion we hypothesized that the bacteriaplay an important role in nutrition and larval devel-opment of this insect The objective of this study wasto assess the signiTHORNcance of bacteria isolated from thedigestive tract of the secondary screwworm in thelarval development of this species

Materials and Methods

Isolation of Bacteria Bacteria were isolated fromthe surface sterilized (Zurek et al 2000) second instarsof C macellaria obtained from a laboratory colonystarted with specimens collected in Manhattan KSLarvae are reared on an artiTHORNcial medium (modiTHORNedafter Harris et al 1985) containing powdered eggpowdered milk citrated bovine blood and a supera-bsorbent polymer (G-400 Waterlock Grain Process-ing Corp Muscatine IA) Adults are fed sugar waterand the larval medium ad libitum (as protein source)and kept at 25 2C 70 10 RH and a photoperiodof 186 (LD) h

For the isolation of bacteria 10 individual secondinstars were surface sterilized with 005 sodium hy-pochlorite and 70 ethanol (Zurek at al 2000) andindividually homogenized in 1 ml of sterile phosphate-buffered saline (PBS) pH 72 (MP Biomedicals Es-chwege Germany) Samples were serially diluted inPBS and 34 l of each dilution was drop-plated intriplicates onto two broad-spectrum microbial mediatrypticase soy broth agar (TSBA) (Difco Detroit MI)and bovine blood agar (BBA) (BBL Sparks MD) andonto two selective and differentiating media MacCo-nkey agar (MAC) (Difco) and modiTHORNed Enterococcusagar (mENT) (BBL) Plates were incubated aerobi-cally at 28C (TSBA and BBA) and 37C (MAC andmENT) for up to 48 h Morphologically distinct singlecolonieswere subculturedonTSBA incubatedat 28Cfor 48 h and stored at 4CIdentification of Bacteria The isolates were pre-

screened by phenotypic tests including Gram stain-ing catalase (using 3 hydrogen peroxide) oxidase(BBL) and indole test (BBL) The genomic DNA ofselected isolates was extracted from 24-h-old culturesby using a DNeasy tissue kit according to the manu-

facturerOtildes instructions (QIAGEN Valencia CA) The16S rDNA was ampliTHORNed by polymerase chain reaction(PCR) by using the universal eubacterial primers UF5AGA GTT TGA TYM TGGC 3 (position 8ETH23) andUR 5 GYT ACC TTG TTA CGA CTT (position 1492)(Barbieri et al 2001) PuriTHORNed genomic DNA (10 ng)was used as a template for PCR The master mix con-tained 100 nM each primer 400 M dNTPs 3 mMMgCl2 and 05 U ofTaqpolymerase (all from PromegaMadison WI) in the THORNnal volume of 25 l AmpliTHORN-cation was conducted using a Peltier thermal cycler(MJ Research Watertown MA) with the programdescribed previously (Romero et al 2006) PCR prod-ucts were puriTHORNed using the GFX PCR DNA and gelband puriTHORNcation kit (GE Healthcare Little ChalfontBuckinghamshire United Kingdom) and visualizedunder UV light on a 10 agarose gel (Fisher FairLawn NJ) with 005 of ethidium bromide

Partial 16S rDNA sequences (1400 bp) were de-termined by an Applied Biosystems 3730xl (AppliedBiosystems Foster City CA) at the University of Cal-ifornia Riverside Core Instrumentation Facility (Riv-erside CA) by using the same eubacterial universalprimers used for PCR The sequences were comparedwith the sequences in the National Center for Bio-technology Information GenBank database by usingBLAST (Altschul et al 1990) Sequences were man-ually aligned and edited with CodonCode Alignerversion 134 (CodonCode Corporation DedhamMA)Developmental Bioassays Bovine blood agar was

used as a base medium for C macellaria larval devel-opmental assays DeTHORNbrinated cattle blood was asep-tically added to the Columbia agar base (BBL) to aTHORNnal concentration of 5 Approximately 8 ml of bloodagar was dispensed into sterile plastic petri plates (60by 15 mm) and allowed to solidify Blood agar plateswere inoculated by individual bacterial isolates bystreaking a single colony and used immediately for thebioassays

Fly eggs were obtained from the C macellaria lab-oratory colony surface sterilized (Zurek et al 2000)and two eggs were transferred with a sterile camelOtildes-hair brush onto each medium plate The treatmentsconsisted of the blood agar plates with individual iso-lates as well as the mixture of all isolates (Table 1)Sterile blood agar and standard szligy rearing mediumwere used as negative control and positive control

Table 1 Developmental characteristics (mean SEM) of C macellaria on blood agar in the presenceabsence of selected bacteria(all media inoculated with the total 98 eggs)

TreatmentPupation

()Length of thelarva stage (d)

Pupal wt(mg)

Length of thepupa stage (d)

Development toadult stage ()

Adult wt(mg)

Sterile blood agar 8878ab 783 041c 2820 122ab 436 017bc 7449b 1911 132aStandard rearing medium 9490a 773 009c 2925 106a 453 008bc 8673a 1978 123aProvidencia sp 1735c 978 072a 2548 116b 462 009bc 1429c 1523 052bE coli O157H7 3571c 913 020ab 2662 181ab 429 017c 3143c 1752 028aE faecalis 7551b 821 043bc 2688 075ab 449 016bc 6939b 1939 031aOchrobactrum sp 8163b 843 050bc 2740 086ab 469 011ab 7245b 1866 075aBacterial mixture 2755c 930 011ab 2465 132b 500 000a 2245c 1530 120b

Means within a column followed by the same letter are not signiTHORNcantly different (P 005 PROC GLM LSMEANS SAS Institute 2003)

1130 JOURNAL OF MEDICAL ENTOMOLOGY Vol 43 no 6

respectively In total 49 plates and 98 eggs were usedfor each treatment in four bioassays (9 10 10 and 20plates in each bioassay respectively)

Plates were incubated at 28C and monitored dailyfor larval mortality until pupation The length of larvaldevelopment (egg hatching to pupation) larval sur-vival and pupal duration were recorded Pupae weregently removed using a sterile camelOtildes-hair brush andweighed within 24 h of pupation followed by surfacesterilization (as described above) and placed individ-ually in sterile plastic petri plates (60 by 15 mm)Emerged adults from all treatments were weighedwithin 12ETH24 h of emergence surface sterilized (asdescribedabove)homogenized in1mlofPBS seriallydiluted and drop-plated onto TSBA to determine thediversity and concentration of bacteria in the digestivetract Plates were incubated at 28C for 48 h andcolony-forming units (CFU) counted Voucher spec-imens of C macellaria were submitted to the KansasState University Museum of Entomological and PrairieArthropod Research Department of EntomologyManhattan KS (voucher no 183)Data Analysis Data for the duration of larval de-

velopment pupal weight pupal duration adult bodyweight and bacterial counts were analyzed using one-way analysis of variance (ANOVA) and means werecompared using the least-squares means (LSMEANS)procedure (P 005) of a general linear model (PROCGLM) (SAS Institute 2003)

Data for the proportion () of larvae that reachedpupation and proportion that survived to the adultstage were transformed by the arcsine square root[arcsine ( pupation100)] or [arcsine ( adultemergence100)] to stabilize error variance and an-alyzed using ANOVA Means were compared by theLSMEANS test (P 005) of PROC GLM (SAS In-stitute 2003) Although all tests of signiTHORNcance werebased on the transformed data the untransformeddata on the proportion of larvae that reached pupation() and proportion () that survived to adult stageare reported

Results

Identification of BacteriaThe analysis of 16S rDNAsequences revealed that our isolates represented fourspecies Providencia spp (99 identity withAM040495)Escherichia coliO157H7 (99 identity toAY513502) Enterococcus faecalis (99 identity withAY850358) and Ochrobactrum sp (99 withAF028733) Results of the phenotypic tests were inagreement with the identiTHORNcation by 16S rDNA anal-ysisDevelopmentalAssaysCmacellaria larvae success-

fully developed on a sterile blood agar (no bacteria)(Table 1) Overall a signiTHORNcantly greater proportionof szligy larvae reached the pupal stage when kept on asterile blood agar (888) and C macellaria rearingmedium (949) than on any other medium (F 1426 df 6 21P 00001) However the proportion

of pupation on sterile blood agar did not differ signif-icantly from that on blood agar inoculated withOchrobactrum sp (816) andE faecalis (755) (Ta-ble 1) A signiTHORNcantly lower proportion of pupationwas observed on the blood agar inoculated withE coliO157H7 (357) Providencia sp (174) and thebacterial mixture (276) compared with that of allother treatments (Table 1)

The length of larval development varied signiTHORN-cantly among treatments (F 369 df 6 21 P 00115) (Table 1) The longest larval developmentaltime (98 07 d) was observed on the blood agarinoculated with Providencia sp and that was signiTHORN-cantly different from all other treatments except thatfrom the blood agar inoculated with E coli O157H7(91 02 d) and the bacterial mixture (93 01 d)Larval development was faster on the sterile bloodagar and C macellaria rearing medium than on anyother media (Table 1)

The pupal weight from different media varied butit was not signiTHORNcantly different among treatments(F 166 df 6 21 P 01795) The lightest pupaewere recovered from the blood agar inoculated withthe bacterial mixture (247 13 mg) and Providenciasp (255 12 mg) The length of the pupal stagevaried signiTHORNcantly among treatments (F 356 df 6 21P00137)The longestpupalduration(5d)wasrecorded from the blood agar inoculated with thebacterial mixture

The proportion of larvae that developed to the adultstagevaried signiTHORNcantlyamong treatments(F1101df 6 21 P 00001) (Table 1) The highest adultemergence was recorded from the standard rearingmedium (867) followed by the sterile blood agar(745) blood agar inoculated withOchrobactrum sp(725) and E faecalis (694) A signiTHORNcantly lowerproportion of adult emergence was recorded on theblood agar with Providencia sp and the blood agarwith the bacterial mixture compared with that of allother treatments (Table 1) Fresh adult body weightdiffered signiTHORNcantly among treatments (F 446 df 6 21 P 00046) The lightest adults were recoveredfrom the blood agar inoculated with Providencia sp(152 05 mg) and the bacterial mixture (153 12mg) and these values were signiTHORNcantly different fromthat of all other treatments (Table 1)

Bacteria were detected in newly emerged C ma-cellaria adults that were fed as larvae on bacteria Thesterile blood agar treatment was excluded from theanalysis because no bacteria were detected in any ofthe newly emerged C macellaria The prevalence ofbacteria in newly emerged adults ranged from 574 to909 (Table 2) The bacterial counts from C macel-laria adults that developed as larvae on the standardrearing medium and the blood agar inoculated withthe bacterial mixture together were signiTHORNcantlygreater than those fed on blood agar inoculated withindividual bacteria (F 2405 df 5 18 P 00001) The bacterial counts ranged from 51 103 to35 105 CFU per szligy (Table 2)

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1131

Discussion

Studies addressing the signiTHORNcance of bacteria in thedevelopment of immature stages of muscoid szligies in-cluding house szligies (Schmidtmann and Martin 1992Zurek et al 2000) stable szligies (Lysyk et al 1999 Ro-mero et al 2006) horn szligies (Perotti et al 2001) andface szligies (Hollis et al 1985) have shown that larvae ofthese szligies fail to develop in a sterile substrate dem-onstrating their dependence on live bacterial cellsThe principle of this symbiosis is unknown it is pos-sible that larvae require bacteria as a direct source ofnutrients andor as a source of nutritional supple-ments (eg vitamins) (Espinosa-Fuentes and Terra1987) Bacteria also may contribute to szligy develop-ment by breaking down nutrients in organic substratesmaking them more suitable for larval digestion ab-sorption and metabolism (Zurek et al 2000) It hasbeen reported that larval survival and development ofmuscoid szligies vary greatly depending on the bacterialspecies (Lysyk et al 1999 Zurek et al 2000 Perotti etal 2001 Romero et al 2006) Interestingly the bac-teria that support larval development of stable szligiesalso stimulate oviposition of gravid females (Romeroat al 2006)

Our bioassays using artiTHORNcial media demonstratedthatCmacellaria larvae are able to develop on a sterileblood agar and no bacteria are required to completelarval development Furthermore development andsurvival of C macellaria larvae on the sterile bloodagar and standard C macellaria rearing medium weregreater compared with that of all other treatmentswith bacterial isolates This is in stark contrast to re-sults of similar developmental studies with muscoid szligylarvae showing strict dependence on live bacteria Cmacellaria larvae are able to develop without bacteriaindeed some bacterial isolates (eg Providencia spand E coli O157H7) negatively inszliguenced the larvaldevelopment These bacteria may produce toxic com-pounds andor compete for the nutrients andor makethe conditions in the medium unsuitable for szligy de-velopment The growth and metabolism of bacteria onthe blood agar may cause break down of hemoglobinpH changes andor production of compounds thatlimit or inhibit larval development (Schmidtmann andMartin 1992) The reason for the poor development of

C macellaria larvae in the presence of Providencia spand E coli O157H7 is unknown Zurek et al (2000)also reported no larval growth of M domestica withProvidencia rettgeri (Haddley Elkins amp Caldwell) andProvidencia stuarti (Ewing) Likewise Rochon et al(2004) found that stable szligy larvae and pupae had lowsurvival when fed onE coli alone They suggested thatstable szligy larvae cannot digestE coli and therefore usethe cells as a food source In our study larval survivalof C macellaria on blood agar inoculated with Efaecalis and Ochrobactrum sp was comparable withthat of larvae on sterile blood agar AlthoughOchrobacter spp occur in human clinical specimens(Holt et al 1994) no pathogenicity was reported toinsects including Galleria mellonella (L) and Spo-doptera littoralis (Boisduval) (Babic et al 2000) Be-cause C macellaria larvae could not develop on theblood agar with the mixture of all four bacterial iso-lates it is likely that one or more of these isolates wassomehow inhibiting the larval development (thegrowth of all four isolates on the blood agar was com-parable)

Although bacteria are not required for the devel-opment of C macellaria larvae it is possible that theyplay a role in oviposition attraction of this szligy to po-tential developmental habitats such as carrion andwounds of animals andor nutrition of adult szligies Bac-teria andor bacterially derived volatile compoundsplay a role as oviposition stimulants for gravid szligiesincluding the blow szligies C hominovorax (Devaney etal 1973 Eddy et al 1975 Bromel et al 1983Chaudhury et al 2002) and L cuprina (Emmens andMurray 1983) and the muscoid stable szligy (Romero etal 2006)

The presence of bacteria in newly emerged C ma-cellaria adults fed as larvae on bacteria shows thatbacteria in the gut of larvae can survive pupation andcolonize the gut of adult insects The high concentra-tion of bacteria associated with individual szligies is animportant factor in potential transmission of humanand animal pathogens by these szligies Urban and Broce(1998) reportedM domestica and C macellaria as themost important vectors of potentially pathogenic bac-teria in dog kennels in Kansas

In conclusion this study shows that development oflarvae of C macellaria does not depend on bacterialcells In contrast some bacterial isolates negativelyimpact the szligy development

Acknowledgments

We thank Kent E Hampton for technical assistance and JWhitworth for reviewing the manuscript This article is con-tribution 06-290-J of the Kansas Agricultural ExperimentStation

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Table 2 Prevalence and concentration of bacteria associatedwith C macellaria adults that fed as larvae on blood agar withselected bacteria

TreatmentPrevalence

no positivetotal ()Concn

(CFUszligy)

Sterile blood agar 073 (0) NAStandard rearing medium 7285 (847) 35 105aProvidencia sp 914 (643) 51 103bE coli O157H7 2131 (677) 28 104bE faecalis 3968 (574) 11 104bOchrobactrum sp 2471 (662) 27 104bBacterial mixture 2022 (909) 35 105a

Means within a column followed by the same letter are not signif-icantly different (P 005 PROC GLM LSMEANS SAS Institute2003) NA not applicable

1132 JOURNAL OF MEDICAL ENTOMOLOGY Vol 43 no 6

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DrsquoAmatoLA FWKnappDLDahlman 1980 Survivalof the face szligy in feces from cattle fed alfalfa hay or graindiets effect of fermentation and microbial changes En-viron Entomol 9 557ETH560

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Received 3 April 2006 accepted 17 July 2006

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1133

Because larvae of the secondary screwworm typi-cally develop in a highly septic habitat bacteria playan important role in the oviposition of blow szligies andthe midgut of blow szligy larvae provides conditions forbacterial digestion we hypothesized that the bacteriaplay an important role in nutrition and larval devel-opment of this insect The objective of this study wasto assess the signiTHORNcance of bacteria isolated from thedigestive tract of the secondary screwworm in thelarval development of this species

Materials and Methods

Isolation of Bacteria Bacteria were isolated fromthe surface sterilized (Zurek et al 2000) second instarsof C macellaria obtained from a laboratory colonystarted with specimens collected in Manhattan KSLarvae are reared on an artiTHORNcial medium (modiTHORNedafter Harris et al 1985) containing powdered eggpowdered milk citrated bovine blood and a supera-bsorbent polymer (G-400 Waterlock Grain Process-ing Corp Muscatine IA) Adults are fed sugar waterand the larval medium ad libitum (as protein source)and kept at 25 2C 70 10 RH and a photoperiodof 186 (LD) h

For the isolation of bacteria 10 individual secondinstars were surface sterilized with 005 sodium hy-pochlorite and 70 ethanol (Zurek at al 2000) andindividually homogenized in 1 ml of sterile phosphate-buffered saline (PBS) pH 72 (MP Biomedicals Es-chwege Germany) Samples were serially diluted inPBS and 34 l of each dilution was drop-plated intriplicates onto two broad-spectrum microbial mediatrypticase soy broth agar (TSBA) (Difco Detroit MI)and bovine blood agar (BBA) (BBL Sparks MD) andonto two selective and differentiating media MacCo-nkey agar (MAC) (Difco) and modiTHORNed Enterococcusagar (mENT) (BBL) Plates were incubated aerobi-cally at 28C (TSBA and BBA) and 37C (MAC andmENT) for up to 48 h Morphologically distinct singlecolonieswere subculturedonTSBA incubatedat 28Cfor 48 h and stored at 4CIdentification of Bacteria The isolates were pre-

screened by phenotypic tests including Gram stain-ing catalase (using 3 hydrogen peroxide) oxidase(BBL) and indole test (BBL) The genomic DNA ofselected isolates was extracted from 24-h-old culturesby using a DNeasy tissue kit according to the manu-

facturerOtildes instructions (QIAGEN Valencia CA) The16S rDNA was ampliTHORNed by polymerase chain reaction(PCR) by using the universal eubacterial primers UF5AGA GTT TGA TYM TGGC 3 (position 8ETH23) andUR 5 GYT ACC TTG TTA CGA CTT (position 1492)(Barbieri et al 2001) PuriTHORNed genomic DNA (10 ng)was used as a template for PCR The master mix con-tained 100 nM each primer 400 M dNTPs 3 mMMgCl2 and 05 U ofTaqpolymerase (all from PromegaMadison WI) in the THORNnal volume of 25 l AmpliTHORN-cation was conducted using a Peltier thermal cycler(MJ Research Watertown MA) with the programdescribed previously (Romero et al 2006) PCR prod-ucts were puriTHORNed using the GFX PCR DNA and gelband puriTHORNcation kit (GE Healthcare Little ChalfontBuckinghamshire United Kingdom) and visualizedunder UV light on a 10 agarose gel (Fisher FairLawn NJ) with 005 of ethidium bromide

Partial 16S rDNA sequences (1400 bp) were de-termined by an Applied Biosystems 3730xl (AppliedBiosystems Foster City CA) at the University of Cal-ifornia Riverside Core Instrumentation Facility (Riv-erside CA) by using the same eubacterial universalprimers used for PCR The sequences were comparedwith the sequences in the National Center for Bio-technology Information GenBank database by usingBLAST (Altschul et al 1990) Sequences were man-ually aligned and edited with CodonCode Alignerversion 134 (CodonCode Corporation DedhamMA)Developmental Bioassays Bovine blood agar was

used as a base medium for C macellaria larval devel-opmental assays DeTHORNbrinated cattle blood was asep-tically added to the Columbia agar base (BBL) to aTHORNnal concentration of 5 Approximately 8 ml of bloodagar was dispensed into sterile plastic petri plates (60by 15 mm) and allowed to solidify Blood agar plateswere inoculated by individual bacterial isolates bystreaking a single colony and used immediately for thebioassays

Fly eggs were obtained from the C macellaria lab-oratory colony surface sterilized (Zurek et al 2000)and two eggs were transferred with a sterile camelOtildes-hair brush onto each medium plate The treatmentsconsisted of the blood agar plates with individual iso-lates as well as the mixture of all isolates (Table 1)Sterile blood agar and standard szligy rearing mediumwere used as negative control and positive control

Table 1 Developmental characteristics (mean SEM) of C macellaria on blood agar in the presenceabsence of selected bacteria(all media inoculated with the total 98 eggs)

TreatmentPupation

()Length of thelarva stage (d)

Pupal wt(mg)

Length of thepupa stage (d)

Development toadult stage ()

Adult wt(mg)

Sterile blood agar 8878ab 783 041c 2820 122ab 436 017bc 7449b 1911 132aStandard rearing medium 9490a 773 009c 2925 106a 453 008bc 8673a 1978 123aProvidencia sp 1735c 978 072a 2548 116b 462 009bc 1429c 1523 052bE coli O157H7 3571c 913 020ab 2662 181ab 429 017c 3143c 1752 028aE faecalis 7551b 821 043bc 2688 075ab 449 016bc 6939b 1939 031aOchrobactrum sp 8163b 843 050bc 2740 086ab 469 011ab 7245b 1866 075aBacterial mixture 2755c 930 011ab 2465 132b 500 000a 2245c 1530 120b

Means within a column followed by the same letter are not signiTHORNcantly different (P 005 PROC GLM LSMEANS SAS Institute 2003)

1130 JOURNAL OF MEDICAL ENTOMOLOGY Vol 43 no 6

respectively In total 49 plates and 98 eggs were usedfor each treatment in four bioassays (9 10 10 and 20plates in each bioassay respectively)

Plates were incubated at 28C and monitored dailyfor larval mortality until pupation The length of larvaldevelopment (egg hatching to pupation) larval sur-vival and pupal duration were recorded Pupae weregently removed using a sterile camelOtildes-hair brush andweighed within 24 h of pupation followed by surfacesterilization (as described above) and placed individ-ually in sterile plastic petri plates (60 by 15 mm)Emerged adults from all treatments were weighedwithin 12ETH24 h of emergence surface sterilized (asdescribedabove)homogenized in1mlofPBS seriallydiluted and drop-plated onto TSBA to determine thediversity and concentration of bacteria in the digestivetract Plates were incubated at 28C for 48 h andcolony-forming units (CFU) counted Voucher spec-imens of C macellaria were submitted to the KansasState University Museum of Entomological and PrairieArthropod Research Department of EntomologyManhattan KS (voucher no 183)Data Analysis Data for the duration of larval de-

velopment pupal weight pupal duration adult bodyweight and bacterial counts were analyzed using one-way analysis of variance (ANOVA) and means werecompared using the least-squares means (LSMEANS)procedure (P 005) of a general linear model (PROCGLM) (SAS Institute 2003)

Data for the proportion () of larvae that reachedpupation and proportion that survived to the adultstage were transformed by the arcsine square root[arcsine ( pupation100)] or [arcsine ( adultemergence100)] to stabilize error variance and an-alyzed using ANOVA Means were compared by theLSMEANS test (P 005) of PROC GLM (SAS In-stitute 2003) Although all tests of signiTHORNcance werebased on the transformed data the untransformeddata on the proportion of larvae that reached pupation() and proportion () that survived to adult stageare reported

Results

Identification of BacteriaThe analysis of 16S rDNAsequences revealed that our isolates represented fourspecies Providencia spp (99 identity withAM040495)Escherichia coliO157H7 (99 identity toAY513502) Enterococcus faecalis (99 identity withAY850358) and Ochrobactrum sp (99 withAF028733) Results of the phenotypic tests were inagreement with the identiTHORNcation by 16S rDNA anal-ysisDevelopmentalAssaysCmacellaria larvae success-

fully developed on a sterile blood agar (no bacteria)(Table 1) Overall a signiTHORNcantly greater proportionof szligy larvae reached the pupal stage when kept on asterile blood agar (888) and C macellaria rearingmedium (949) than on any other medium (F 1426 df 6 21P 00001) However the proportion

of pupation on sterile blood agar did not differ signif-icantly from that on blood agar inoculated withOchrobactrum sp (816) andE faecalis (755) (Ta-ble 1) A signiTHORNcantly lower proportion of pupationwas observed on the blood agar inoculated withE coliO157H7 (357) Providencia sp (174) and thebacterial mixture (276) compared with that of allother treatments (Table 1)

The length of larval development varied signiTHORN-cantly among treatments (F 369 df 6 21 P 00115) (Table 1) The longest larval developmentaltime (98 07 d) was observed on the blood agarinoculated with Providencia sp and that was signiTHORN-cantly different from all other treatments except thatfrom the blood agar inoculated with E coli O157H7(91 02 d) and the bacterial mixture (93 01 d)Larval development was faster on the sterile bloodagar and C macellaria rearing medium than on anyother media (Table 1)

The pupal weight from different media varied butit was not signiTHORNcantly different among treatments(F 166 df 6 21 P 01795) The lightest pupaewere recovered from the blood agar inoculated withthe bacterial mixture (247 13 mg) and Providenciasp (255 12 mg) The length of the pupal stagevaried signiTHORNcantly among treatments (F 356 df 6 21P00137)The longestpupalduration(5d)wasrecorded from the blood agar inoculated with thebacterial mixture

The proportion of larvae that developed to the adultstagevaried signiTHORNcantlyamong treatments(F1101df 6 21 P 00001) (Table 1) The highest adultemergence was recorded from the standard rearingmedium (867) followed by the sterile blood agar(745) blood agar inoculated withOchrobactrum sp(725) and E faecalis (694) A signiTHORNcantly lowerproportion of adult emergence was recorded on theblood agar with Providencia sp and the blood agarwith the bacterial mixture compared with that of allother treatments (Table 1) Fresh adult body weightdiffered signiTHORNcantly among treatments (F 446 df 6 21 P 00046) The lightest adults were recoveredfrom the blood agar inoculated with Providencia sp(152 05 mg) and the bacterial mixture (153 12mg) and these values were signiTHORNcantly different fromthat of all other treatments (Table 1)

Bacteria were detected in newly emerged C ma-cellaria adults that were fed as larvae on bacteria Thesterile blood agar treatment was excluded from theanalysis because no bacteria were detected in any ofthe newly emerged C macellaria The prevalence ofbacteria in newly emerged adults ranged from 574 to909 (Table 2) The bacterial counts from C macel-laria adults that developed as larvae on the standardrearing medium and the blood agar inoculated withthe bacterial mixture together were signiTHORNcantlygreater than those fed on blood agar inoculated withindividual bacteria (F 2405 df 5 18 P 00001) The bacterial counts ranged from 51 103 to35 105 CFU per szligy (Table 2)

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1131

Discussion

Studies addressing the signiTHORNcance of bacteria in thedevelopment of immature stages of muscoid szligies in-cluding house szligies (Schmidtmann and Martin 1992Zurek et al 2000) stable szligies (Lysyk et al 1999 Ro-mero et al 2006) horn szligies (Perotti et al 2001) andface szligies (Hollis et al 1985) have shown that larvae ofthese szligies fail to develop in a sterile substrate dem-onstrating their dependence on live bacterial cellsThe principle of this symbiosis is unknown it is pos-sible that larvae require bacteria as a direct source ofnutrients andor as a source of nutritional supple-ments (eg vitamins) (Espinosa-Fuentes and Terra1987) Bacteria also may contribute to szligy develop-ment by breaking down nutrients in organic substratesmaking them more suitable for larval digestion ab-sorption and metabolism (Zurek et al 2000) It hasbeen reported that larval survival and development ofmuscoid szligies vary greatly depending on the bacterialspecies (Lysyk et al 1999 Zurek et al 2000 Perotti etal 2001 Romero et al 2006) Interestingly the bac-teria that support larval development of stable szligiesalso stimulate oviposition of gravid females (Romeroat al 2006)

Our bioassays using artiTHORNcial media demonstratedthatCmacellaria larvae are able to develop on a sterileblood agar and no bacteria are required to completelarval development Furthermore development andsurvival of C macellaria larvae on the sterile bloodagar and standard C macellaria rearing medium weregreater compared with that of all other treatmentswith bacterial isolates This is in stark contrast to re-sults of similar developmental studies with muscoid szligylarvae showing strict dependence on live bacteria Cmacellaria larvae are able to develop without bacteriaindeed some bacterial isolates (eg Providencia spand E coli O157H7) negatively inszliguenced the larvaldevelopment These bacteria may produce toxic com-pounds andor compete for the nutrients andor makethe conditions in the medium unsuitable for szligy de-velopment The growth and metabolism of bacteria onthe blood agar may cause break down of hemoglobinpH changes andor production of compounds thatlimit or inhibit larval development (Schmidtmann andMartin 1992) The reason for the poor development of

C macellaria larvae in the presence of Providencia spand E coli O157H7 is unknown Zurek et al (2000)also reported no larval growth of M domestica withProvidencia rettgeri (Haddley Elkins amp Caldwell) andProvidencia stuarti (Ewing) Likewise Rochon et al(2004) found that stable szligy larvae and pupae had lowsurvival when fed onE coli alone They suggested thatstable szligy larvae cannot digestE coli and therefore usethe cells as a food source In our study larval survivalof C macellaria on blood agar inoculated with Efaecalis and Ochrobactrum sp was comparable withthat of larvae on sterile blood agar AlthoughOchrobacter spp occur in human clinical specimens(Holt et al 1994) no pathogenicity was reported toinsects including Galleria mellonella (L) and Spo-doptera littoralis (Boisduval) (Babic et al 2000) Be-cause C macellaria larvae could not develop on theblood agar with the mixture of all four bacterial iso-lates it is likely that one or more of these isolates wassomehow inhibiting the larval development (thegrowth of all four isolates on the blood agar was com-parable)

Although bacteria are not required for the devel-opment of C macellaria larvae it is possible that theyplay a role in oviposition attraction of this szligy to po-tential developmental habitats such as carrion andwounds of animals andor nutrition of adult szligies Bac-teria andor bacterially derived volatile compoundsplay a role as oviposition stimulants for gravid szligiesincluding the blow szligies C hominovorax (Devaney etal 1973 Eddy et al 1975 Bromel et al 1983Chaudhury et al 2002) and L cuprina (Emmens andMurray 1983) and the muscoid stable szligy (Romero etal 2006)

The presence of bacteria in newly emerged C ma-cellaria adults fed as larvae on bacteria shows thatbacteria in the gut of larvae can survive pupation andcolonize the gut of adult insects The high concentra-tion of bacteria associated with individual szligies is animportant factor in potential transmission of humanand animal pathogens by these szligies Urban and Broce(1998) reportedM domestica and C macellaria as themost important vectors of potentially pathogenic bac-teria in dog kennels in Kansas

In conclusion this study shows that development oflarvae of C macellaria does not depend on bacterialcells In contrast some bacterial isolates negativelyimpact the szligy development

Acknowledgments

We thank Kent E Hampton for technical assistance and JWhitworth for reviewing the manuscript This article is con-tribution 06-290-J of the Kansas Agricultural ExperimentStation

References Cited

Altschul S F W Gish W Miller E W Myers and D JLipman 1990 Basic local alignment search tool J MolBiol 215 403ETH410

Table 2 Prevalence and concentration of bacteria associatedwith C macellaria adults that fed as larvae on blood agar withselected bacteria

TreatmentPrevalence

no positivetotal ()Concn

(CFUszligy)

Sterile blood agar 073 (0) NAStandard rearing medium 7285 (847) 35 105aProvidencia sp 914 (643) 51 103bE coli O157H7 2131 (677) 28 104bE faecalis 3968 (574) 11 104bOchrobactrum sp 2471 (662) 27 104bBacterial mixture 2022 (909) 35 105a

Means within a column followed by the same letter are not signif-icantly different (P 005 PROC GLM LSMEANS SAS Institute2003) NA not applicable

1132 JOURNAL OF MEDICAL ENTOMOLOGY Vol 43 no 6

Babic I M F Saux E Giraud and N Boemare 2000Occurrence of natural dixenic associations between thesymbiont Photorhabdus luminescens and bacteria relatedto Ochrobactrum spp in tropical entomopathogenic Het-erorhabditis spp (Nematoda Rhabditida) Microbiology146 709ETH718

Barbieri E B J Paster D Hughes L Zurek D P MoserA Teske and M L Sogin 2001 Phylogenetic charac-terization of epibiotic bacteria in the accessory nidamen-tal gland and egg of the squidLoligo pealei (CephalopodaLoliginidae) Environ Microbiol 3 151ETH167

Baumgartner D L and B Greenberg 1985 Distributionand medical ecology of the blow szligies (Diptera Callipho-ridae) of Peru Ann Entomol Soc Am 78 565ETH587

Broce A B 1985 Myiasis-producing szligies pp 83ETH100 InR E Williams R D Hall A B Broce and P J Scholl[eds] Livestock Entomology Wiley New York

Bromel M F M Duh G R Erdmann L Hammack andG Gassner 1983 Bacteria associated with the screw-worm szligy Cochliomyia hominivorax (Coquerel) and theirmetabolites Endocytobiology 2 791ETH800

Byrd J H and J F Butler 1996 Effects of temperature onCochliomyia macellaria (Diptera Calliphoridae) devel-opment J Med Entomol 33 901ETH905

Chaudhury M F J B Welch and L A Alvarez 2002Responses of fertile and sterile screwworm (Diptera Cal-liphoridae) szligies to bovine blood inoculated with bacteriaoriginating from screwworm-infested animal woundsJ Med Entomol 39 130ETH134

DrsquoAmatoLA FWKnappDLDahlman 1980 Survivalof the face szligy in feces from cattle fed alfalfa hay or graindiets effect of fermentation and microbial changes En-viron Entomol 9 557ETH560

DeVaney J A G W Eddy E M Ellis and R HarringtonJr 1973 Attractancy of inoculated and incubated bo-vine blood fractions to screwworm szligies (Diptera Calli-phoridae) role of bacteria J Med Entomol 10 591ETH595

Eddy G W J A Devaney and B D Handke 1975 Re-sponse of the adult screwworm (Diptera Calliphoridae)to bacteria-inoculated and incubated bovine blood inolfactometer and oviposition test J Med Entomol 12379ETH381

Emmens R and M Murray 1983 Bacterial odors as ovi-position stimulants for Lucilia cuprina (Wiedemann)(Diptera Calliphoridae) the Australian sheep blowszligyBull Entomol Res 73 411ETH416

Espinosa-Fuentes F P and W R Terra 1987 Physiolog-ical adaptations for digesting bacteria Water szliguxes anddistribution of digestive enzymes inMusca domestica lar-val midgut Insect Biochem 17 809ETH817

GreenbergB 1968 Model for destruction of bacteria in themidgut of blow szligy maggots J Med Entomol 5 31ETH38

Greenberg B andM L Szyska 1984 Immature stages andbiology of THORNfteen species of Peruvian Calliphoridae(Diptera) Ann Entomol Soc Am 77 488ETH517

Greenberg B 1991 Flies as forensic indicators J Med En-tomol 28 565ETH577

Harris R L E F Gersabeck C Corso and O H Graham1985 Screwworm larval production on gelled mediaSouthwest Entomol 10 253ETH256

Hollis J H F W Knapp and K A Dawson 1985 Inszligu-ence of bacteria within bovine feces on the developmentof the face szligy (Diptera Muscidae) Environ Entomol 14568ETH571

Holt J H N R Krieg PHA Sneath J T Staley and S TWilliams [eds] 1994 BergeyOtildes manual of determinativebacteriology Williams amp Wilkins Baltimore MD

Kerridge A H Lappin-Scott and J R Stevens 2005 An-tibacterial properties of larval secretions of the blowszligyLucilia sericata Med Vet Entomol 19 333ETH337

Laake EW E C Cushing andH E Parish 1936 Biologyof the primary screwworm szligy Cochliomyia americanaand a comparison of its stages with those ofC macellariaUS Dep Agric Tech Bull 500

Lysyk T J L Kalischuk-Tymensen L B Selinger R CLancaster LWever andK-J Cheng 1999 Rearing sta-ble szligies larvae (Diptera Muscidae) on an egg yolk me-dium J Med Entomol 36 382ETH388

Maldonado M A and N Centeno 2003 Quantifying thepotential pathogens transmission of the blowszligies(Diptera Calliphoridae) Mem Inst Oswaldo Cruz 98213ETH216

Mullen G and L Durden [eds] 2002 Medical and veter-inary entomology Academic San Diego CA

Mumcuoglu K Y J Miller M Mumcuoglu M Friger andMTarshis 2001 Destruction of bacteria in the digestivetract of the maggot of Lucilia sericata (Diptera Callipho-ridae) J Med Entomol 38 161ETH166

Perotti M A T J Lysyk L D Kalischuk-Tymensen L JYanke and L B Selinger 2001 Growth and survival ofimmature Haematobia irritans (Diptera Muscidae) is in-szliguenced by bacteria isolated from cattle manure andconspeciTHORNc larvae J Med Entomol 38 180ETH187

RochonK T J Lysyk andLB Selinger 2004 Persistenceof Eschericha coli in immature house szligy and stable szligy(Diptera Muscidae) in relation to larval growth andsurvival J Med Entomol 41 1082ETH1089

Romero A A Broce and L Zurek 2006 Role of bacteriain oviposition behavior and larval development of stableszligies Med Vet Entomol 20 115ETH121

SAS Institute 2003 SAS OnlineDoc 91 SAS Institute CaryNC

Schmidtmann E T andPAWMartin 1992 Relationshipbetween selected bacteria and the growth of immaturehouse szligies Musca domestica in an axenic test systemJ Med Entomol 29 232ETH235

ShermanRAMJRHall and S Thomas 2000 Medicinalmaggots an ancient remedy for some contemporary af-szligictions Annu Rev Entomol 45 55ETH81

Spiller D 1964 Nutrition and diet of muscoid szligies BullWorld Health Organ 341 551ETH554

Urban J E and A Broce 1998 Flies and their bacterialloads in greyhound dog kennels in Kansas Curr Micro-biol 36 164ETH170

Zurek L Schal C andWatson DW 2000 Diversity andcontribution of the intestinal bacterial community to thedevelopment of Musca domestica (Diptera Muscidae)larvae J Med Entomol 37 924ETH928

Received 3 April 2006 accepted 17 July 2006

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1133

respectively In total 49 plates and 98 eggs were usedfor each treatment in four bioassays (9 10 10 and 20plates in each bioassay respectively)

Plates were incubated at 28C and monitored dailyfor larval mortality until pupation The length of larvaldevelopment (egg hatching to pupation) larval sur-vival and pupal duration were recorded Pupae weregently removed using a sterile camelOtildes-hair brush andweighed within 24 h of pupation followed by surfacesterilization (as described above) and placed individ-ually in sterile plastic petri plates (60 by 15 mm)Emerged adults from all treatments were weighedwithin 12ETH24 h of emergence surface sterilized (asdescribedabove)homogenized in1mlofPBS seriallydiluted and drop-plated onto TSBA to determine thediversity and concentration of bacteria in the digestivetract Plates were incubated at 28C for 48 h andcolony-forming units (CFU) counted Voucher spec-imens of C macellaria were submitted to the KansasState University Museum of Entomological and PrairieArthropod Research Department of EntomologyManhattan KS (voucher no 183)Data Analysis Data for the duration of larval de-

velopment pupal weight pupal duration adult bodyweight and bacterial counts were analyzed using one-way analysis of variance (ANOVA) and means werecompared using the least-squares means (LSMEANS)procedure (P 005) of a general linear model (PROCGLM) (SAS Institute 2003)

Data for the proportion () of larvae that reachedpupation and proportion that survived to the adultstage were transformed by the arcsine square root[arcsine ( pupation100)] or [arcsine ( adultemergence100)] to stabilize error variance and an-alyzed using ANOVA Means were compared by theLSMEANS test (P 005) of PROC GLM (SAS In-stitute 2003) Although all tests of signiTHORNcance werebased on the transformed data the untransformeddata on the proportion of larvae that reached pupation() and proportion () that survived to adult stageare reported

Results

Identification of BacteriaThe analysis of 16S rDNAsequences revealed that our isolates represented fourspecies Providencia spp (99 identity withAM040495)Escherichia coliO157H7 (99 identity toAY513502) Enterococcus faecalis (99 identity withAY850358) and Ochrobactrum sp (99 withAF028733) Results of the phenotypic tests were inagreement with the identiTHORNcation by 16S rDNA anal-ysisDevelopmentalAssaysCmacellaria larvae success-

fully developed on a sterile blood agar (no bacteria)(Table 1) Overall a signiTHORNcantly greater proportionof szligy larvae reached the pupal stage when kept on asterile blood agar (888) and C macellaria rearingmedium (949) than on any other medium (F 1426 df 6 21P 00001) However the proportion

of pupation on sterile blood agar did not differ signif-icantly from that on blood agar inoculated withOchrobactrum sp (816) andE faecalis (755) (Ta-ble 1) A signiTHORNcantly lower proportion of pupationwas observed on the blood agar inoculated withE coliO157H7 (357) Providencia sp (174) and thebacterial mixture (276) compared with that of allother treatments (Table 1)

The length of larval development varied signiTHORN-cantly among treatments (F 369 df 6 21 P 00115) (Table 1) The longest larval developmentaltime (98 07 d) was observed on the blood agarinoculated with Providencia sp and that was signiTHORN-cantly different from all other treatments except thatfrom the blood agar inoculated with E coli O157H7(91 02 d) and the bacterial mixture (93 01 d)Larval development was faster on the sterile bloodagar and C macellaria rearing medium than on anyother media (Table 1)

The pupal weight from different media varied butit was not signiTHORNcantly different among treatments(F 166 df 6 21 P 01795) The lightest pupaewere recovered from the blood agar inoculated withthe bacterial mixture (247 13 mg) and Providenciasp (255 12 mg) The length of the pupal stagevaried signiTHORNcantly among treatments (F 356 df 6 21P00137)The longestpupalduration(5d)wasrecorded from the blood agar inoculated with thebacterial mixture

The proportion of larvae that developed to the adultstagevaried signiTHORNcantlyamong treatments(F1101df 6 21 P 00001) (Table 1) The highest adultemergence was recorded from the standard rearingmedium (867) followed by the sterile blood agar(745) blood agar inoculated withOchrobactrum sp(725) and E faecalis (694) A signiTHORNcantly lowerproportion of adult emergence was recorded on theblood agar with Providencia sp and the blood agarwith the bacterial mixture compared with that of allother treatments (Table 1) Fresh adult body weightdiffered signiTHORNcantly among treatments (F 446 df 6 21 P 00046) The lightest adults were recoveredfrom the blood agar inoculated with Providencia sp(152 05 mg) and the bacterial mixture (153 12mg) and these values were signiTHORNcantly different fromthat of all other treatments (Table 1)

Bacteria were detected in newly emerged C ma-cellaria adults that were fed as larvae on bacteria Thesterile blood agar treatment was excluded from theanalysis because no bacteria were detected in any ofthe newly emerged C macellaria The prevalence ofbacteria in newly emerged adults ranged from 574 to909 (Table 2) The bacterial counts from C macel-laria adults that developed as larvae on the standardrearing medium and the blood agar inoculated withthe bacterial mixture together were signiTHORNcantlygreater than those fed on blood agar inoculated withindividual bacteria (F 2405 df 5 18 P 00001) The bacterial counts ranged from 51 103 to35 105 CFU per szligy (Table 2)

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1131

Discussion

Studies addressing the signiTHORNcance of bacteria in thedevelopment of immature stages of muscoid szligies in-cluding house szligies (Schmidtmann and Martin 1992Zurek et al 2000) stable szligies (Lysyk et al 1999 Ro-mero et al 2006) horn szligies (Perotti et al 2001) andface szligies (Hollis et al 1985) have shown that larvae ofthese szligies fail to develop in a sterile substrate dem-onstrating their dependence on live bacterial cellsThe principle of this symbiosis is unknown it is pos-sible that larvae require bacteria as a direct source ofnutrients andor as a source of nutritional supple-ments (eg vitamins) (Espinosa-Fuentes and Terra1987) Bacteria also may contribute to szligy develop-ment by breaking down nutrients in organic substratesmaking them more suitable for larval digestion ab-sorption and metabolism (Zurek et al 2000) It hasbeen reported that larval survival and development ofmuscoid szligies vary greatly depending on the bacterialspecies (Lysyk et al 1999 Zurek et al 2000 Perotti etal 2001 Romero et al 2006) Interestingly the bac-teria that support larval development of stable szligiesalso stimulate oviposition of gravid females (Romeroat al 2006)

Our bioassays using artiTHORNcial media demonstratedthatCmacellaria larvae are able to develop on a sterileblood agar and no bacteria are required to completelarval development Furthermore development andsurvival of C macellaria larvae on the sterile bloodagar and standard C macellaria rearing medium weregreater compared with that of all other treatmentswith bacterial isolates This is in stark contrast to re-sults of similar developmental studies with muscoid szligylarvae showing strict dependence on live bacteria Cmacellaria larvae are able to develop without bacteriaindeed some bacterial isolates (eg Providencia spand E coli O157H7) negatively inszliguenced the larvaldevelopment These bacteria may produce toxic com-pounds andor compete for the nutrients andor makethe conditions in the medium unsuitable for szligy de-velopment The growth and metabolism of bacteria onthe blood agar may cause break down of hemoglobinpH changes andor production of compounds thatlimit or inhibit larval development (Schmidtmann andMartin 1992) The reason for the poor development of

C macellaria larvae in the presence of Providencia spand E coli O157H7 is unknown Zurek et al (2000)also reported no larval growth of M domestica withProvidencia rettgeri (Haddley Elkins amp Caldwell) andProvidencia stuarti (Ewing) Likewise Rochon et al(2004) found that stable szligy larvae and pupae had lowsurvival when fed onE coli alone They suggested thatstable szligy larvae cannot digestE coli and therefore usethe cells as a food source In our study larval survivalof C macellaria on blood agar inoculated with Efaecalis and Ochrobactrum sp was comparable withthat of larvae on sterile blood agar AlthoughOchrobacter spp occur in human clinical specimens(Holt et al 1994) no pathogenicity was reported toinsects including Galleria mellonella (L) and Spo-doptera littoralis (Boisduval) (Babic et al 2000) Be-cause C macellaria larvae could not develop on theblood agar with the mixture of all four bacterial iso-lates it is likely that one or more of these isolates wassomehow inhibiting the larval development (thegrowth of all four isolates on the blood agar was com-parable)

Although bacteria are not required for the devel-opment of C macellaria larvae it is possible that theyplay a role in oviposition attraction of this szligy to po-tential developmental habitats such as carrion andwounds of animals andor nutrition of adult szligies Bac-teria andor bacterially derived volatile compoundsplay a role as oviposition stimulants for gravid szligiesincluding the blow szligies C hominovorax (Devaney etal 1973 Eddy et al 1975 Bromel et al 1983Chaudhury et al 2002) and L cuprina (Emmens andMurray 1983) and the muscoid stable szligy (Romero etal 2006)

The presence of bacteria in newly emerged C ma-cellaria adults fed as larvae on bacteria shows thatbacteria in the gut of larvae can survive pupation andcolonize the gut of adult insects The high concentra-tion of bacteria associated with individual szligies is animportant factor in potential transmission of humanand animal pathogens by these szligies Urban and Broce(1998) reportedM domestica and C macellaria as themost important vectors of potentially pathogenic bac-teria in dog kennels in Kansas

In conclusion this study shows that development oflarvae of C macellaria does not depend on bacterialcells In contrast some bacterial isolates negativelyimpact the szligy development

Acknowledgments

We thank Kent E Hampton for technical assistance and JWhitworth for reviewing the manuscript This article is con-tribution 06-290-J of the Kansas Agricultural ExperimentStation

References Cited

Altschul S F W Gish W Miller E W Myers and D JLipman 1990 Basic local alignment search tool J MolBiol 215 403ETH410

Table 2 Prevalence and concentration of bacteria associatedwith C macellaria adults that fed as larvae on blood agar withselected bacteria

TreatmentPrevalence

no positivetotal ()Concn

(CFUszligy)

Sterile blood agar 073 (0) NAStandard rearing medium 7285 (847) 35 105aProvidencia sp 914 (643) 51 103bE coli O157H7 2131 (677) 28 104bE faecalis 3968 (574) 11 104bOchrobactrum sp 2471 (662) 27 104bBacterial mixture 2022 (909) 35 105a

Means within a column followed by the same letter are not signif-icantly different (P 005 PROC GLM LSMEANS SAS Institute2003) NA not applicable

1132 JOURNAL OF MEDICAL ENTOMOLOGY Vol 43 no 6

Babic I M F Saux E Giraud and N Boemare 2000Occurrence of natural dixenic associations between thesymbiont Photorhabdus luminescens and bacteria relatedto Ochrobactrum spp in tropical entomopathogenic Het-erorhabditis spp (Nematoda Rhabditida) Microbiology146 709ETH718

Barbieri E B J Paster D Hughes L Zurek D P MoserA Teske and M L Sogin 2001 Phylogenetic charac-terization of epibiotic bacteria in the accessory nidamen-tal gland and egg of the squidLoligo pealei (CephalopodaLoliginidae) Environ Microbiol 3 151ETH167

Baumgartner D L and B Greenberg 1985 Distributionand medical ecology of the blow szligies (Diptera Callipho-ridae) of Peru Ann Entomol Soc Am 78 565ETH587

Broce A B 1985 Myiasis-producing szligies pp 83ETH100 InR E Williams R D Hall A B Broce and P J Scholl[eds] Livestock Entomology Wiley New York

Bromel M F M Duh G R Erdmann L Hammack andG Gassner 1983 Bacteria associated with the screw-worm szligy Cochliomyia hominivorax (Coquerel) and theirmetabolites Endocytobiology 2 791ETH800

Byrd J H and J F Butler 1996 Effects of temperature onCochliomyia macellaria (Diptera Calliphoridae) devel-opment J Med Entomol 33 901ETH905

Chaudhury M F J B Welch and L A Alvarez 2002Responses of fertile and sterile screwworm (Diptera Cal-liphoridae) szligies to bovine blood inoculated with bacteriaoriginating from screwworm-infested animal woundsJ Med Entomol 39 130ETH134

DrsquoAmatoLA FWKnappDLDahlman 1980 Survivalof the face szligy in feces from cattle fed alfalfa hay or graindiets effect of fermentation and microbial changes En-viron Entomol 9 557ETH560

DeVaney J A G W Eddy E M Ellis and R HarringtonJr 1973 Attractancy of inoculated and incubated bo-vine blood fractions to screwworm szligies (Diptera Calli-phoridae) role of bacteria J Med Entomol 10 591ETH595

Eddy G W J A Devaney and B D Handke 1975 Re-sponse of the adult screwworm (Diptera Calliphoridae)to bacteria-inoculated and incubated bovine blood inolfactometer and oviposition test J Med Entomol 12379ETH381

Emmens R and M Murray 1983 Bacterial odors as ovi-position stimulants for Lucilia cuprina (Wiedemann)(Diptera Calliphoridae) the Australian sheep blowszligyBull Entomol Res 73 411ETH416

Espinosa-Fuentes F P and W R Terra 1987 Physiolog-ical adaptations for digesting bacteria Water szliguxes anddistribution of digestive enzymes inMusca domestica lar-val midgut Insect Biochem 17 809ETH817

GreenbergB 1968 Model for destruction of bacteria in themidgut of blow szligy maggots J Med Entomol 5 31ETH38

Greenberg B andM L Szyska 1984 Immature stages andbiology of THORNfteen species of Peruvian Calliphoridae(Diptera) Ann Entomol Soc Am 77 488ETH517

Greenberg B 1991 Flies as forensic indicators J Med En-tomol 28 565ETH577

Harris R L E F Gersabeck C Corso and O H Graham1985 Screwworm larval production on gelled mediaSouthwest Entomol 10 253ETH256

Hollis J H F W Knapp and K A Dawson 1985 Inszligu-ence of bacteria within bovine feces on the developmentof the face szligy (Diptera Muscidae) Environ Entomol 14568ETH571

Holt J H N R Krieg PHA Sneath J T Staley and S TWilliams [eds] 1994 BergeyOtildes manual of determinativebacteriology Williams amp Wilkins Baltimore MD

Kerridge A H Lappin-Scott and J R Stevens 2005 An-tibacterial properties of larval secretions of the blowszligyLucilia sericata Med Vet Entomol 19 333ETH337

Laake EW E C Cushing andH E Parish 1936 Biologyof the primary screwworm szligy Cochliomyia americanaand a comparison of its stages with those ofC macellariaUS Dep Agric Tech Bull 500

Lysyk T J L Kalischuk-Tymensen L B Selinger R CLancaster LWever andK-J Cheng 1999 Rearing sta-ble szligies larvae (Diptera Muscidae) on an egg yolk me-dium J Med Entomol 36 382ETH388

Maldonado M A and N Centeno 2003 Quantifying thepotential pathogens transmission of the blowszligies(Diptera Calliphoridae) Mem Inst Oswaldo Cruz 98213ETH216

Mullen G and L Durden [eds] 2002 Medical and veter-inary entomology Academic San Diego CA

Mumcuoglu K Y J Miller M Mumcuoglu M Friger andMTarshis 2001 Destruction of bacteria in the digestivetract of the maggot of Lucilia sericata (Diptera Callipho-ridae) J Med Entomol 38 161ETH166

Perotti M A T J Lysyk L D Kalischuk-Tymensen L JYanke and L B Selinger 2001 Growth and survival ofimmature Haematobia irritans (Diptera Muscidae) is in-szliguenced by bacteria isolated from cattle manure andconspeciTHORNc larvae J Med Entomol 38 180ETH187

RochonK T J Lysyk andLB Selinger 2004 Persistenceof Eschericha coli in immature house szligy and stable szligy(Diptera Muscidae) in relation to larval growth andsurvival J Med Entomol 41 1082ETH1089

Romero A A Broce and L Zurek 2006 Role of bacteriain oviposition behavior and larval development of stableszligies Med Vet Entomol 20 115ETH121

SAS Institute 2003 SAS OnlineDoc 91 SAS Institute CaryNC

Schmidtmann E T andPAWMartin 1992 Relationshipbetween selected bacteria and the growth of immaturehouse szligies Musca domestica in an axenic test systemJ Med Entomol 29 232ETH235

ShermanRAMJRHall and S Thomas 2000 Medicinalmaggots an ancient remedy for some contemporary af-szligictions Annu Rev Entomol 45 55ETH81

Spiller D 1964 Nutrition and diet of muscoid szligies BullWorld Health Organ 341 551ETH554

Urban J E and A Broce 1998 Flies and their bacterialloads in greyhound dog kennels in Kansas Curr Micro-biol 36 164ETH170

Zurek L Schal C andWatson DW 2000 Diversity andcontribution of the intestinal bacterial community to thedevelopment of Musca domestica (Diptera Muscidae)larvae J Med Entomol 37 924ETH928

Received 3 April 2006 accepted 17 July 2006

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1133

Discussion

Studies addressing the signiTHORNcance of bacteria in thedevelopment of immature stages of muscoid szligies in-cluding house szligies (Schmidtmann and Martin 1992Zurek et al 2000) stable szligies (Lysyk et al 1999 Ro-mero et al 2006) horn szligies (Perotti et al 2001) andface szligies (Hollis et al 1985) have shown that larvae ofthese szligies fail to develop in a sterile substrate dem-onstrating their dependence on live bacterial cellsThe principle of this symbiosis is unknown it is pos-sible that larvae require bacteria as a direct source ofnutrients andor as a source of nutritional supple-ments (eg vitamins) (Espinosa-Fuentes and Terra1987) Bacteria also may contribute to szligy develop-ment by breaking down nutrients in organic substratesmaking them more suitable for larval digestion ab-sorption and metabolism (Zurek et al 2000) It hasbeen reported that larval survival and development ofmuscoid szligies vary greatly depending on the bacterialspecies (Lysyk et al 1999 Zurek et al 2000 Perotti etal 2001 Romero et al 2006) Interestingly the bac-teria that support larval development of stable szligiesalso stimulate oviposition of gravid females (Romeroat al 2006)

Our bioassays using artiTHORNcial media demonstratedthatCmacellaria larvae are able to develop on a sterileblood agar and no bacteria are required to completelarval development Furthermore development andsurvival of C macellaria larvae on the sterile bloodagar and standard C macellaria rearing medium weregreater compared with that of all other treatmentswith bacterial isolates This is in stark contrast to re-sults of similar developmental studies with muscoid szligylarvae showing strict dependence on live bacteria Cmacellaria larvae are able to develop without bacteriaindeed some bacterial isolates (eg Providencia spand E coli O157H7) negatively inszliguenced the larvaldevelopment These bacteria may produce toxic com-pounds andor compete for the nutrients andor makethe conditions in the medium unsuitable for szligy de-velopment The growth and metabolism of bacteria onthe blood agar may cause break down of hemoglobinpH changes andor production of compounds thatlimit or inhibit larval development (Schmidtmann andMartin 1992) The reason for the poor development of

C macellaria larvae in the presence of Providencia spand E coli O157H7 is unknown Zurek et al (2000)also reported no larval growth of M domestica withProvidencia rettgeri (Haddley Elkins amp Caldwell) andProvidencia stuarti (Ewing) Likewise Rochon et al(2004) found that stable szligy larvae and pupae had lowsurvival when fed onE coli alone They suggested thatstable szligy larvae cannot digestE coli and therefore usethe cells as a food source In our study larval survivalof C macellaria on blood agar inoculated with Efaecalis and Ochrobactrum sp was comparable withthat of larvae on sterile blood agar AlthoughOchrobacter spp occur in human clinical specimens(Holt et al 1994) no pathogenicity was reported toinsects including Galleria mellonella (L) and Spo-doptera littoralis (Boisduval) (Babic et al 2000) Be-cause C macellaria larvae could not develop on theblood agar with the mixture of all four bacterial iso-lates it is likely that one or more of these isolates wassomehow inhibiting the larval development (thegrowth of all four isolates on the blood agar was com-parable)

Although bacteria are not required for the devel-opment of C macellaria larvae it is possible that theyplay a role in oviposition attraction of this szligy to po-tential developmental habitats such as carrion andwounds of animals andor nutrition of adult szligies Bac-teria andor bacterially derived volatile compoundsplay a role as oviposition stimulants for gravid szligiesincluding the blow szligies C hominovorax (Devaney etal 1973 Eddy et al 1975 Bromel et al 1983Chaudhury et al 2002) and L cuprina (Emmens andMurray 1983) and the muscoid stable szligy (Romero etal 2006)

The presence of bacteria in newly emerged C ma-cellaria adults fed as larvae on bacteria shows thatbacteria in the gut of larvae can survive pupation andcolonize the gut of adult insects The high concentra-tion of bacteria associated with individual szligies is animportant factor in potential transmission of humanand animal pathogens by these szligies Urban and Broce(1998) reportedM domestica and C macellaria as themost important vectors of potentially pathogenic bac-teria in dog kennels in Kansas

In conclusion this study shows that development oflarvae of C macellaria does not depend on bacterialcells In contrast some bacterial isolates negativelyimpact the szligy development

Acknowledgments

We thank Kent E Hampton for technical assistance and JWhitworth for reviewing the manuscript This article is con-tribution 06-290-J of the Kansas Agricultural ExperimentStation

References Cited

Altschul S F W Gish W Miller E W Myers and D JLipman 1990 Basic local alignment search tool J MolBiol 215 403ETH410

Table 2 Prevalence and concentration of bacteria associatedwith C macellaria adults that fed as larvae on blood agar withselected bacteria

TreatmentPrevalence

no positivetotal ()Concn

(CFUszligy)

Sterile blood agar 073 (0) NAStandard rearing medium 7285 (847) 35 105aProvidencia sp 914 (643) 51 103bE coli O157H7 2131 (677) 28 104bE faecalis 3968 (574) 11 104bOchrobactrum sp 2471 (662) 27 104bBacterial mixture 2022 (909) 35 105a

Means within a column followed by the same letter are not signif-icantly different (P 005 PROC GLM LSMEANS SAS Institute2003) NA not applicable

1132 JOURNAL OF MEDICAL ENTOMOLOGY Vol 43 no 6

Babic I M F Saux E Giraud and N Boemare 2000Occurrence of natural dixenic associations between thesymbiont Photorhabdus luminescens and bacteria relatedto Ochrobactrum spp in tropical entomopathogenic Het-erorhabditis spp (Nematoda Rhabditida) Microbiology146 709ETH718

Barbieri E B J Paster D Hughes L Zurek D P MoserA Teske and M L Sogin 2001 Phylogenetic charac-terization of epibiotic bacteria in the accessory nidamen-tal gland and egg of the squidLoligo pealei (CephalopodaLoliginidae) Environ Microbiol 3 151ETH167

Baumgartner D L and B Greenberg 1985 Distributionand medical ecology of the blow szligies (Diptera Callipho-ridae) of Peru Ann Entomol Soc Am 78 565ETH587

Broce A B 1985 Myiasis-producing szligies pp 83ETH100 InR E Williams R D Hall A B Broce and P J Scholl[eds] Livestock Entomology Wiley New York

Bromel M F M Duh G R Erdmann L Hammack andG Gassner 1983 Bacteria associated with the screw-worm szligy Cochliomyia hominivorax (Coquerel) and theirmetabolites Endocytobiology 2 791ETH800

Byrd J H and J F Butler 1996 Effects of temperature onCochliomyia macellaria (Diptera Calliphoridae) devel-opment J Med Entomol 33 901ETH905

Chaudhury M F J B Welch and L A Alvarez 2002Responses of fertile and sterile screwworm (Diptera Cal-liphoridae) szligies to bovine blood inoculated with bacteriaoriginating from screwworm-infested animal woundsJ Med Entomol 39 130ETH134

DrsquoAmatoLA FWKnappDLDahlman 1980 Survivalof the face szligy in feces from cattle fed alfalfa hay or graindiets effect of fermentation and microbial changes En-viron Entomol 9 557ETH560

DeVaney J A G W Eddy E M Ellis and R HarringtonJr 1973 Attractancy of inoculated and incubated bo-vine blood fractions to screwworm szligies (Diptera Calli-phoridae) role of bacteria J Med Entomol 10 591ETH595

Eddy G W J A Devaney and B D Handke 1975 Re-sponse of the adult screwworm (Diptera Calliphoridae)to bacteria-inoculated and incubated bovine blood inolfactometer and oviposition test J Med Entomol 12379ETH381

Emmens R and M Murray 1983 Bacterial odors as ovi-position stimulants for Lucilia cuprina (Wiedemann)(Diptera Calliphoridae) the Australian sheep blowszligyBull Entomol Res 73 411ETH416

Espinosa-Fuentes F P and W R Terra 1987 Physiolog-ical adaptations for digesting bacteria Water szliguxes anddistribution of digestive enzymes inMusca domestica lar-val midgut Insect Biochem 17 809ETH817

GreenbergB 1968 Model for destruction of bacteria in themidgut of blow szligy maggots J Med Entomol 5 31ETH38

Greenberg B andM L Szyska 1984 Immature stages andbiology of THORNfteen species of Peruvian Calliphoridae(Diptera) Ann Entomol Soc Am 77 488ETH517

Greenberg B 1991 Flies as forensic indicators J Med En-tomol 28 565ETH577

Harris R L E F Gersabeck C Corso and O H Graham1985 Screwworm larval production on gelled mediaSouthwest Entomol 10 253ETH256

Hollis J H F W Knapp and K A Dawson 1985 Inszligu-ence of bacteria within bovine feces on the developmentof the face szligy (Diptera Muscidae) Environ Entomol 14568ETH571

Holt J H N R Krieg PHA Sneath J T Staley and S TWilliams [eds] 1994 BergeyOtildes manual of determinativebacteriology Williams amp Wilkins Baltimore MD

Kerridge A H Lappin-Scott and J R Stevens 2005 An-tibacterial properties of larval secretions of the blowszligyLucilia sericata Med Vet Entomol 19 333ETH337

Laake EW E C Cushing andH E Parish 1936 Biologyof the primary screwworm szligy Cochliomyia americanaand a comparison of its stages with those ofC macellariaUS Dep Agric Tech Bull 500

Lysyk T J L Kalischuk-Tymensen L B Selinger R CLancaster LWever andK-J Cheng 1999 Rearing sta-ble szligies larvae (Diptera Muscidae) on an egg yolk me-dium J Med Entomol 36 382ETH388

Maldonado M A and N Centeno 2003 Quantifying thepotential pathogens transmission of the blowszligies(Diptera Calliphoridae) Mem Inst Oswaldo Cruz 98213ETH216

Mullen G and L Durden [eds] 2002 Medical and veter-inary entomology Academic San Diego CA

Mumcuoglu K Y J Miller M Mumcuoglu M Friger andMTarshis 2001 Destruction of bacteria in the digestivetract of the maggot of Lucilia sericata (Diptera Callipho-ridae) J Med Entomol 38 161ETH166

Perotti M A T J Lysyk L D Kalischuk-Tymensen L JYanke and L B Selinger 2001 Growth and survival ofimmature Haematobia irritans (Diptera Muscidae) is in-szliguenced by bacteria isolated from cattle manure andconspeciTHORNc larvae J Med Entomol 38 180ETH187

RochonK T J Lysyk andLB Selinger 2004 Persistenceof Eschericha coli in immature house szligy and stable szligy(Diptera Muscidae) in relation to larval growth andsurvival J Med Entomol 41 1082ETH1089

Romero A A Broce and L Zurek 2006 Role of bacteriain oviposition behavior and larval development of stableszligies Med Vet Entomol 20 115ETH121

SAS Institute 2003 SAS OnlineDoc 91 SAS Institute CaryNC

Schmidtmann E T andPAWMartin 1992 Relationshipbetween selected bacteria and the growth of immaturehouse szligies Musca domestica in an axenic test systemJ Med Entomol 29 232ETH235

ShermanRAMJRHall and S Thomas 2000 Medicinalmaggots an ancient remedy for some contemporary af-szligictions Annu Rev Entomol 45 55ETH81

Spiller D 1964 Nutrition and diet of muscoid szligies BullWorld Health Organ 341 551ETH554

Urban J E and A Broce 1998 Flies and their bacterialloads in greyhound dog kennels in Kansas Curr Micro-biol 36 164ETH170

Zurek L Schal C andWatson DW 2000 Diversity andcontribution of the intestinal bacterial community to thedevelopment of Musca domestica (Diptera Muscidae)larvae J Med Entomol 37 924ETH928

Received 3 April 2006 accepted 17 July 2006

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1133

Babic I M F Saux E Giraud and N Boemare 2000Occurrence of natural dixenic associations between thesymbiont Photorhabdus luminescens and bacteria relatedto Ochrobactrum spp in tropical entomopathogenic Het-erorhabditis spp (Nematoda Rhabditida) Microbiology146 709ETH718

Barbieri E B J Paster D Hughes L Zurek D P MoserA Teske and M L Sogin 2001 Phylogenetic charac-terization of epibiotic bacteria in the accessory nidamen-tal gland and egg of the squidLoligo pealei (CephalopodaLoliginidae) Environ Microbiol 3 151ETH167

Baumgartner D L and B Greenberg 1985 Distributionand medical ecology of the blow szligies (Diptera Callipho-ridae) of Peru Ann Entomol Soc Am 78 565ETH587

Broce A B 1985 Myiasis-producing szligies pp 83ETH100 InR E Williams R D Hall A B Broce and P J Scholl[eds] Livestock Entomology Wiley New York

Bromel M F M Duh G R Erdmann L Hammack andG Gassner 1983 Bacteria associated with the screw-worm szligy Cochliomyia hominivorax (Coquerel) and theirmetabolites Endocytobiology 2 791ETH800

Byrd J H and J F Butler 1996 Effects of temperature onCochliomyia macellaria (Diptera Calliphoridae) devel-opment J Med Entomol 33 901ETH905

Chaudhury M F J B Welch and L A Alvarez 2002Responses of fertile and sterile screwworm (Diptera Cal-liphoridae) szligies to bovine blood inoculated with bacteriaoriginating from screwworm-infested animal woundsJ Med Entomol 39 130ETH134

DrsquoAmatoLA FWKnappDLDahlman 1980 Survivalof the face szligy in feces from cattle fed alfalfa hay or graindiets effect of fermentation and microbial changes En-viron Entomol 9 557ETH560

DeVaney J A G W Eddy E M Ellis and R HarringtonJr 1973 Attractancy of inoculated and incubated bo-vine blood fractions to screwworm szligies (Diptera Calli-phoridae) role of bacteria J Med Entomol 10 591ETH595

Eddy G W J A Devaney and B D Handke 1975 Re-sponse of the adult screwworm (Diptera Calliphoridae)to bacteria-inoculated and incubated bovine blood inolfactometer and oviposition test J Med Entomol 12379ETH381

Emmens R and M Murray 1983 Bacterial odors as ovi-position stimulants for Lucilia cuprina (Wiedemann)(Diptera Calliphoridae) the Australian sheep blowszligyBull Entomol Res 73 411ETH416

Espinosa-Fuentes F P and W R Terra 1987 Physiolog-ical adaptations for digesting bacteria Water szliguxes anddistribution of digestive enzymes inMusca domestica lar-val midgut Insect Biochem 17 809ETH817

GreenbergB 1968 Model for destruction of bacteria in themidgut of blow szligy maggots J Med Entomol 5 31ETH38

Greenberg B andM L Szyska 1984 Immature stages andbiology of THORNfteen species of Peruvian Calliphoridae(Diptera) Ann Entomol Soc Am 77 488ETH517

Greenberg B 1991 Flies as forensic indicators J Med En-tomol 28 565ETH577

Harris R L E F Gersabeck C Corso and O H Graham1985 Screwworm larval production on gelled mediaSouthwest Entomol 10 253ETH256

Hollis J H F W Knapp and K A Dawson 1985 Inszligu-ence of bacteria within bovine feces on the developmentof the face szligy (Diptera Muscidae) Environ Entomol 14568ETH571

Holt J H N R Krieg PHA Sneath J T Staley and S TWilliams [eds] 1994 BergeyOtildes manual of determinativebacteriology Williams amp Wilkins Baltimore MD

Kerridge A H Lappin-Scott and J R Stevens 2005 An-tibacterial properties of larval secretions of the blowszligyLucilia sericata Med Vet Entomol 19 333ETH337

Laake EW E C Cushing andH E Parish 1936 Biologyof the primary screwworm szligy Cochliomyia americanaand a comparison of its stages with those ofC macellariaUS Dep Agric Tech Bull 500

Lysyk T J L Kalischuk-Tymensen L B Selinger R CLancaster LWever andK-J Cheng 1999 Rearing sta-ble szligies larvae (Diptera Muscidae) on an egg yolk me-dium J Med Entomol 36 382ETH388

Maldonado M A and N Centeno 2003 Quantifying thepotential pathogens transmission of the blowszligies(Diptera Calliphoridae) Mem Inst Oswaldo Cruz 98213ETH216

Mullen G and L Durden [eds] 2002 Medical and veter-inary entomology Academic San Diego CA

Mumcuoglu K Y J Miller M Mumcuoglu M Friger andMTarshis 2001 Destruction of bacteria in the digestivetract of the maggot of Lucilia sericata (Diptera Callipho-ridae) J Med Entomol 38 161ETH166

Perotti M A T J Lysyk L D Kalischuk-Tymensen L JYanke and L B Selinger 2001 Growth and survival ofimmature Haematobia irritans (Diptera Muscidae) is in-szliguenced by bacteria isolated from cattle manure andconspeciTHORNc larvae J Med Entomol 38 180ETH187

RochonK T J Lysyk andLB Selinger 2004 Persistenceof Eschericha coli in immature house szligy and stable szligy(Diptera Muscidae) in relation to larval growth andsurvival J Med Entomol 41 1082ETH1089

Romero A A Broce and L Zurek 2006 Role of bacteriain oviposition behavior and larval development of stableszligies Med Vet Entomol 20 115ETH121

SAS Institute 2003 SAS OnlineDoc 91 SAS Institute CaryNC

Schmidtmann E T andPAWMartin 1992 Relationshipbetween selected bacteria and the growth of immaturehouse szligies Musca domestica in an axenic test systemJ Med Entomol 29 232ETH235

ShermanRAMJRHall and S Thomas 2000 Medicinalmaggots an ancient remedy for some contemporary af-szligictions Annu Rev Entomol 45 55ETH81

Spiller D 1964 Nutrition and diet of muscoid szligies BullWorld Health Organ 341 551ETH554

Urban J E and A Broce 1998 Flies and their bacterialloads in greyhound dog kennels in Kansas Curr Micro-biol 36 164ETH170

Zurek L Schal C andWatson DW 2000 Diversity andcontribution of the intestinal bacterial community to thedevelopment of Musca domestica (Diptera Muscidae)larvae J Med Entomol 37 924ETH928

Received 3 April 2006 accepted 17 July 2006

November 2006 AHMAD ET AL BACTERIA AND SECONDARY SCREWWORM 1133