BODENHEIMER, I:. S., 1935: Animal Life in Palestine (Jerusalem). DEKWESH, A. I., 1965: A preliminary List of Identified Insects and some Arachnids or

Iraq. Ministry of Agriculture, Iraq. HUSSAIN, A. A, , 1963: Provisional list of Insect Pests and Bibliography of Insect Faun,:

of Iraq. Bull. College of Science, Baghdad University, Vol. 7, 54. HUSSEINI, S. Y., 1954: The Leaf Miner, Syringopais temperatel la , i n Jordan. F A 0 Plant

Protection Bull., Vol. 11, No. 2, 22-33, Rome, Italy. HUSSEINY, M., 1966: Economic Insects in Syria (Arabic Virgin), Aleppo University, FA-

culty of Agriculture, pp. 169-171, Aleppo, Syria. KOSHAL, R. S., 1966: Progress report to the Government of the Republic of Iraq on thr

improvement of Agricultural statistics for May and June 1966. Ministry of Agriculture, Baghdad, Iraq.

MORRIS, H . M,, 1930: Annual report of the Entomology. Ann. Rep. Dept. Agric. 48-55. Cyprus.

RIVNAY, E., 1956: The biology and control of the Cereal Leaf Miner (Syringopais tempera- tella Led.) in Palestine. Ktavim, Records of the Agr. Res. Sta. 7 (I) , 5-23.

SUREYA, M., 1931: Crop Pest during 1930. Int. Bull. Plant Prot. 5, 74-75, Rome. WILTSHIRE, E. P., 1957: The lepidoptera of Iraq. Ministry of Agriculture. Government

ZOEBELEIN, G., 1968: Problems of the control of injurious insects in Agriculture in Iran. of Iraq. p. 134.

R.A.E., Vol. 56, No. 3, 121.

Survey and Biology of Agistemtts exsertns Gonzalez in U. A. R., with Description of the Immature Stages

(Stigmaeidae: Acarina)

By M. A. ZAHER~, A. M. A F I F Y ~ and E. A. GOMAA~

With 4 Figures

Abstract

A . exsertus was surveyed on numerous plant species in different localities of Egypt. Its biology was studied under room conditions for one year. The immature stages were de- scribed. Results revealed that the mites are more abundant in the Nile Delta, Cairo and Giza than in the coastal region. Thier density on ornamentals or fruit trees is distinctly higher than on truck and field crops. A list of more than 20 plant species that harboured the mite is given and the immature stages are illustrated.

Rearing in the laboratory yielded 21 generationsiyear (8 in summer, 5 in autumn, 2 in winter and 6 in spring). Laboratory records revealed a significant accelerating effect of temperature on development and oviposition.

Introduction

Species of the genus Agisternus were recently recorded in Egypt. ZAHER and ELBADRY (1961) gave a brief account of the biology of A. fleschneui

Faculty of Agriculture, University of Cairo.

National Research Center, Cairo. * El-Mansoura Faculty of Science, University of Cairo.

SiL>uey arid Biology oj A . exsertus Gonz. irz U.A.R. 273

~unimers during a short period of the warm season (May-July) and coni- pared its developmental periods and oviposition capacity in groups reared on tggs and iinmatures of the red spider mite Tetranychus cinnabarinus B o l d One year later, the same authors published a report on the abundance of this mite and other predaceous species in Giza. More recently, GONZALEZ (1963) reported on four species of this genus including A. exsertus and detcribed the adult stages of this latter species.

In the present work the immature stages of ,4. exsertus Gonzalez are described. A survey of this species was made during different seasons in various localities of U.A.R. The biological studies are also extended through- out a whole year.

Material and Methods

The distribution of A . exsertus was studied on the most common plants cultivated in the coastal region, the Nile Delta as well as in Giza and Cairo (representing middle Egypt). Samples of various parts of the plants (leaves of ornamentals. truck and field crops, leaves, twigs and fruits of fruit trees) were collected periodically during the different seasons for one year. Leaf debris and litter samples were collected as well and the mites were extracted by using Tulgren4 funnel. A mother culture of A. exsertus was raised under room tenipera- ture on fresh eggs of Tetranychus cinnabarinrts Boisd which were also used as diet in the subsequent biological studies. As a “shelter plant”, new green cuttings of sweet potato, Ipomoea batatas Lam. were used, being kept healthy in Hoagland’s nutrient solution (HOAGLAND and ARNER 1950). The biological studies were carried out under room temper- ature for a whole year. During the successive generations every biological experiment began with 50 newly hatched larvae, which were investigated separately. Observations were made twice daily (in the morning and just before sunset). The method used in rearing was adopted after ZAHER and ELBADRY (1961) using only one tangle foot-circle instead of two circles on each plant leaf. This method is briefly described in previous works of the present authors (1969a and b).

Results

A. Survey

The following is a list of plants which haboured A. exsertus during the year of the survey: 0 r n a m e n t a 1 s : Lantana camara, Buddlia spp., Rosa spp. and Duranta

pkmier i . F r u i t t r e e s : apple (Mollus spp.), pear (Pyrus spp.), guava (Guava spp.),

peach (Prunus praseca), apricot (Prunus armenica), grapes (Vitis venife- ra), edible fig (Ficus carica), oranges (Citrus sinensis, C. reticulata), lemon (Citrus lemon) and ficus (Ficus sycamorus).

T r u c k c r o p s : pepper (Capsicum spp.), egg-plant (Solanum melongena), tomato (Lycopersicrrm esculentum), cabbage (Brassica oleracea), arti- choke (Cynara scolymus), okra (Hibiscus esculentus) and cowpea (Vigna sinensis),.

F i e 1 d c r o p s : cotton (Gossypium barbadensej and corn (Zea mays). It was generally observed that the mites were inore abundant in the Nile

Delta, Cairo and Giza than in the coastal region. Most of them were c01- lected from ornamentals praticularly Lantana and Buddlia. The mites were collected in moderate numbers from most fruit trees and some truck crops

274 it!. A. Zahe i , A. ,tf. Afify and E . A. Gornua

e. g. the egg-plant and artichoke, but in smaller numbers from the investi- gated fields crops. In most cases the numbers coilected during sumiiier were higher than those collected during spring and autunm, while the number< collected during winter were distinctly fewer.

B. Morphology of the immatures

The larva

Body length = 255 !L, idiosoma = 147.5 p, width = 121 y, Leg I = 138.8 p. Chelicerae with retractile stylets, rostrum conical, palpus extends

to reach base of tarsus of I 0 02 mrn I leg I, palptibia with slightly

curved claw. Idiosonia widest anteriorly and gently narrow- ing posteriorly, with 5 deli- cate plates; the median pro- podoscmal plate trapezoidal, covers propodosoma, with 3 pairs of setae, one pair of post-ocular bodies and one pair of eyes; with a pair of hunieral plates carrying a pair of setae; the polygonal

plate centers over metapodosoma, with 5 pairs of setae; the unpaired suranal plate covers opithosoma and with 2 pairs of setae. Anal opening a t posterior end with 2 pairs of setae (Fig. 1).

F t g . 1 Terminal abdominal segment of the larva of Agzstemus exsertus (ventral view)

Chaetotaxy of legs

Leg femur genu tibia tarsus

I 4 3 5 10 I1 4 1 6 9 I11 2 - 6 7

The protonymph

Body length = 278.8 p, idiosoma = 188.8 p, width = 156.3 p, Leg I = 160 p. Chelicerae with retractile stylets, rostrum conical, palpus extends to reach tibia I, palptibia with claw. Idiosoma with 7 delicate plates; median propodosomal plate covers propodosoma; with 3 pairs of setae: “b e” longer

Chaetotaxy of legs

lea femur genu tibia tarsus

I 4 3 6 11 I1 4 1 6 10 I11 2 - 6 8 I V 1 - 6 6

F i g . 2. Upper : The deutonymph of A . exsevtus (dorsal view). -Lower: Terminal abdominal segment of the same (ventral view)

276 M. A . Zaher, A . ill. Afijy mu’ E . A . Gomaa

than the others, “ A e” and “L e” equal in length; one pair of eyes and one pair of postocular bodies present; huineral plates present and with a pair oi setae, polygonal plate with 5 pairs of setae: “ I m” shorter than the others a17d “C” reaches posterior end; intercalary plates present and their setae reach distal end of opithosoma; suranal plate with 2 pairs of setae: “e” longer tharl “1 e”; anal opening posterior with 3 pairs of simple setae and one lanceolatc pair.

The deutonymph (Fig. 2)

Body length = 397.5 p; idiosoma =- 285 p, width = 215.6 y, leg I -

21 3.8 p. Chelicerae with retractile stylets, rostrum conical, palpus extends to reach tibia I, palptibia with slightly curved claw. Idiosoina with 7 delicate plates; median propodosomal plate covers propodosoma, with 3 pairs of setae, one pair of eyes and one pair of post-ocular bodies; “a e” smaller than any other propodosomal setae, “b e” longer than any setae 011 median propo- dosomal plate; with a pair of humeral plates carrying a pair of setae, polygonal plate with 5 pairs of setae: “u”, “1 a”, “1 m” longer than “b” and “c ” ; latters equal in length, intercalary plates present and with one seta each, “L i” long and surpasses posterior end, suranal plate with 2 pairs of setae; anal opening posterior and with 3 pairs of simple setae and one lanceolate pair.

Cheatotaxy of legs

1% femur genu tibia tarsus

I 4 4 6 12 I1 4 1 6 10 I11 2 - 6 9 IV 2 - 6 9

Biology

1. Generation period

During the year of the present study 21 generations could be reared in the laboratory (8 generations in summer, 5 in autumn, 2 in winter and 6 in spring, Fig. 3). The generation period ranged between 9.7 days during summer (average temperature about 29.2O C) and 52 days in winter (average temperature about 15.6O C). The periods of the 21 generations are plotted against the corresponding temperatures (Fig. 4).

Experiments also showed that the minimum values of the developmental stages were about 2.5 days for incubation and about 1.6 days for either the larva, protonymph or deutonymph. During that period the prevailing tem- perature averaged about 28S0 C, 29.2, 29.7 and 30.0° C respectively. The maximum durations of these stages were 15.3, 8.9, 6.6 and 11.1 days respec- tively under an average temperature of about 16.2, 15.8, 15.8 and 14.7O C. The pre-oviposition period ranged between 1.5 days at an average temper- ature of about 28.9O C and 14.9 days a t an average temperature of about 15.3O C.

\ii,z.ey urzd Biology of A. cxwrtm Gonz. in L1.A.R. 277

2 2

2 0

i a

16

1 L

li

I 0

8 -

6 -

z P r 4

w z w 0

Y 0

0:

I 3 z

m

m - 0

-

-

-

-

-

-

I N C U B A T I O N P E R I O D 83

IMMATURE STAGES PERIOD a

El PREOVI POS 1 T I O N P E R I O D a

I 2 3 Q7

hs1 i33

n I -

t97 Q7

EQ ED

ED

2 la

0 I I I I I I I 1 I I

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JUL . AUG. SEP. O C T NOV. D E C . I J A N . F E E . MAR APR. MAY. J U N . J U L .

L

Fig. 3. Durations of the different developmental periods of A. exsertus in 21 successive generations reared undcr room conditions

2 T

52 9

48

44

40

36

32

2 8

24

20

16

12

8

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I I I I I I I I ,

16 18 20 22 24 26 28 30 32 3 4 1 C 0 )

MEAN JEMPERA JURE ( Co)

Fig . 4 . Relationship between atmospheric temperature and generation period of A. exsertus

278 IV. A . Zaher, A . M. Afijy and E . A . Comaa

These figures indicate evidently that rise i n atmospheric temperature h a s a strong accelerating effect on the development of A. exsertus. Statistica! analysis of the obtained data revealed a highly significant negative corrc- lation between temperature and the duration of any of the developmentai stages as well as the generation period as a whole.

Considering every season independantly, the generation period averaged about 10.9 days in summer, 16.9 i n autumn, 43.7 in winter and 14.5 i i i

spring. These averages were taken from 8, 5, 2 and 6 generations respective- ly. Fig. 3 shows the duration of the different stages of the 21 successive generations reared during the year of the study. I t may be concluded tha: about 65 O/o of the total number of generation could be completed durinr, the warm season from the beginning of May till the end of October. It was also observed that females usually reached the adult stage after males by n period that ranged between serveral hours during summer and 3 days during winter.

2. Adult longevity and oviposition

The data about adult longevity and oviposition were taken in every season from the individuals of one generation for representation.

Adult longevity for females averaged about 13.4 days in summer, 22.4 in autumn, 39.3 in winter and 23.2 days in spring. In all seasons males gener- ally lived for a slightly shorter period than females. These figures indicate a marked prolongation in adult longevity during winter as compared with any of the other seasons. The contrary may be stated with respect to summer. Comparing the figures of autumn and spring indicates no significant difier- ence between adult longevity in both seasons. This is most probably due to the negligible differences in temperature prevailing during these two sea- sons.

The female deposits eggs singly on both leaf surfaces. More preference was shown to the tops of the vertical hairs as a site of oviposition. These hairs are more abundant on the lower surface and accordingly the number of eggs deposited on this surface distinctly exceeded that on the upper sur- face.

The oviposition period and number of eggs female differed evidently according to season. The former ranged from 12 days during summer

Oviposition in A . exrerttls during different seasons

Avg. QC Oviposition Average No. of eggs per P daily rate Season period

in davs

spring 21.5 49.6 2.3 23.2 summer 12.0 56.3 4.7 29.8 autumn 20.6 47.8 2.3 24.6 winter 35.6 38.2 1.1 17.6

(average temperature about 29.8O C) to 35.5 days in winter (average temper- ature about 17.6O C). The number of eggs averaged 56.3 eggdfemale during summer and 38.2 eggs during winter. The daily rate of oviposition also followed a similar trend in its relationship to temperature. The data are summarized in the table.

S U T W E ~ and Biology of A . Cxsertus C o n z . in U.A.R. 279

Zusammenfassung

zui. TLi.ionomie und Biologie von Agistemus exsertus Gonz. irz den U.A.R. (S t igm. , Acarina) i rven - und Nymphenstadien der Milbe A . exscrtus werdcn beschrieben. Die Art wurde cr im Nil-Delta sowie im Gebiet von Kairo uiid Giza gefunden als in der Kusten-

region. lhre Dichte auf Zierstrauchern und Obstbiumen war hoher als auf Gcmuse und Fcldfruchten. Es wird eine Listc voti nichr als 20 K’irtspflanzen der Raubmilbe zusammen- qc;tcllt. Im Labor wurden 21 Generationen im Jahr ge;.ogen (8 im Sommer, 5 im Herbst, 2 +:i \Yiiitcr uiid 6 iin Fruhjahr). Steigeruiig cicr Teinperatur fiirderte dic Enturickluiig und Ej,:bl age.

References

A~. :FY, A. M., GOMAA, E. A,, and ZAHER, M. A,, 1969: Effectiveness of Agistemus exsertus Gonzalez (Acarina: stigmaeidae) as an egg-predator of the spider-mite Tetranycbus cinnaburinus Boisd., under varying room conditions. Z. ang. Ent. 63, 48-52.

GONZALEZ, R. H., 1963: Four new mites of the genus Agistemus Summers (Acarina: Stig- maeidae). Acarologia V, 3.

H o A G L A N D , D. R., and ARNER, D. I., 1950: The water culture method for growing plants without soil. Calif. Exp. Sta., Circ. 347, 31 pp.

SUMMERS, F. M., 1966: Key to families of the Raphignothoidea (Acarina). Acarologia, VIII, 2.

- 1966: Genera of the mite family Stigmaeidae. Acarologia, VIII, 2. - and EHARA, S., 1965: Revolution of the taxonomic characters in 4 species of the genus

Cbeylostigmueus Willmann. Acarologia, VII, 1. ZAHER, M. A., and EL-BADRY, E. A,, 1961: Life history of the predator mite Agistemus

flescbneri Summ. and effect of nutrition on its biology. Bull. Soc. ent. Egypt, XLV, 375-385.

- and EL-BADRY, E. A., 1962: Abundance of mites and insects predaceous on Tetranychid and Tenuipalpid mites in Giza. Bull. Soc. ent. Egypt, XLVI, 429-441.

WAFA, A. K., ZAHER, M. A., AFIFY, A. M., and GOMAA, E. A., 1969: Effect of diet on the development of the predaceous mite, Agistemus exser tu~ Gonzalez (Acarina: Stig- maeidae), Z. ang. Ent. 63, 382-388.