EPPO Bull. 6 ( 4 ) : 323-330 (1976)

Studies on the Fecundity of Acarid Mites (Acarina : Acaridae) 11

by J. BOCZEK and B. CZAJKOWSKA Agricultural University of Warsaw IPoland)

ABSTRACT

The effect of food on fecundity and its distribution during the life of Acurur siro L. was studied. In addition, the effect of repeated matings, of age of females and males, of parental age and of sex ratio on the fecundity of Tyrophugus putrescentiae (Schr.) was studied.

Nutrition affects the total fecundity and its distribution in A. siro. The highest fecundity of T . putrescentiue females occurred when mating occurred more than once a week. The fecundity of ageing virgin females decreases gradually with delays in the time of the first mating. The effect of male's age is not significant until the age of 60 days onwards. Females descending from 100-day-old parents showed 25 % lower fecundity than females from young parents.

Density of males above the sex ratio 1 : l diminishes the fecundity of females molested by males. The higher the number of the males in the cage per female, the lower their fecundity.

Introduction

Acarid mites have relatively high fecundity, up to 800 eggs being laid by fema!es of some species. Fecundity is a specific character but it depends, to a high degree, upon the conditions to which the female is exposed: nutrition, temperature, humidity and other factors.

According to BOCZEK (1957), fecundity of Acurus siro L. is highly dependent upon nutrition, temperature and relative humidity (RH) of the air. To lay the maximal number of eggs, a female has to mate every week.

JAKUBOWSKA (1071), studying the fecundity of Acurus farris (Oud.), found a very significant and positive effect of an increase in RH. The highest fecundity was obtained on yeast, at 20" C.

BARKER (1967) reported some differences in total fecundity and in the egg- laying period of Tyrophagus putrescentiae (Schr.) in relation to temperature, with an optimum at 22.2" C.

GOLEBIOWSKA (1963) found the fecundity of T. putrescentiue to be highest during the first 4 weeks of its life. At high temperatures and extreme humidities, the highest fecundity was shown by females in the first days of life and, at low

1) Paper presented at the EPPO Conference on Storage Pests and Diseases, Paris, 11-14 June, 1974. The study was supported by a grant from the USDA under PL 480 (FG-PO-271).

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temperatures, in the third week. The oviposition period was also longer at lower temperatures. A higher density of population in the rearing cage lowered fecundity.

Frequency of matings did not affect fecundity.

BARKOVA (1972) found fecundity, and its distribution during the life span on various foods, to be very variable, but all females, independent of the kind of food, started egg-laying soon after mating.

According to CZAJKOWSKA (17721, some plant oils and many alkaloids reduced the fecundity of T. pgtrescentiae, while several glycosides stimulated it. BOCZEK and CZAJKOWSKA (1968) found that many antimicrobial agents and antibiotics mixed with food lowered the fecundity of A . sir0 and Carpoglyphus luctis (L.).

CHMIELEWSKI (1971) found that C. bctis was 2.5 times more fecund on yeast than on dry plums. At a temperature of 30" C, highest fecundity occurred at 7 days o'd, at 20" C, at 11 days old, and at 10" C, at 16 days old. He recorded the highest total fecundity on yeast at 15-25' C and 85 RH.

Since, in the majority of the above studies on mites, only the effects of temperature and R H were studied, the following work was carried out to investigate the Effect of food on fecundity of A. siro, and of mating, age of female and male, parental age and sex ratio on fecundity of T. putrescentiae.

Materials and Methods

The effect of food on the fecundity of A . siro was studied using 9 different natural products, chosen according to their composition of proteins, fats and carbo- hydrates (cf. table 1). Each test was repeated 25 times, with 25 females. Single pairs of mites were kept in rearing cages with a food supply throughout their life. The eggs laid were counted and removed every few days.

TABLE 1 Composition of food (%). ~ ~~~

Food ~ ~~ ~ ~~~ ~

rye germ yeast casein hazel nuts marrow dried apple dried cod suet mushroom/Bo/etus edulis, dried

~~~~~ ~

Proteins

42.0 46.0 98.0

7.2 3.2 1.4

15.9 2 .o

36.7

~. ~ ~~~~~

Fats

11.2 1.6 1.5

33.0 89.9

1 .o 0.3

93.0 2.7

___~ ~

~~ ~~ ~

Carbohydrates

26.0 13.0 0.0 5.5 0.0

73.2 0.0 0.0

41.4

__ -~ ~~ ~~

To obtain females of a defined age, inert deutonymphs were isolated. Hatched Mites of the appropriate age were paired,

Eggs were counted and mites remained in cages in isolation. mating was noted and, afterwards, males were removed. removed every few days.

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no. of eggs

40

30

A _ _ - - rye germ

...................... yeast

---------_ mushroom

-.-.-.-.- dried cod

no. of eggs

40

30

20

10

- Fig. 1

B

/- /

I // I I I

I I

I ; / ' / I

7

\ \ \ \

Dependence of fecundity on food (A. slrol.

hazel nut - ---- -.- .-.-.- suet

-.-cE-.- marrow ....................... dried apple

To study the effect of parental age, fecundity of females descending from 1, 10, 60, 80, 90 and 100-day-old parents was compared. Females studied were kept

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in cages with single males throughout their life. Eggs were counted and removed every few days, as above.

The effect of the sex ratio on fecundity was compared by placing one virgin Both sexes were of the same age, female with various numbers of virgin males.

a few days old.

All rearings were maintained on rye germ at 25" C and 85 % RH. Results for the various combinations are presented in tables 1-4.

Results and Discussion

Effect of Food on Total Fecundity and its Distribution (fig. 1 A and B )

It may be seen that mites started egg-laying later on products like dried apple and suet, than on other foods. It was noted that on some foods, e.g. rye germ, hazel nuts and apple, fema!es of a defined age lay a maximum number of eggs, and on others, like yeast, dried cod or casein, egg-laying is regularly distributed throughout the mites' life. Highest fecundity was found on food containing large amounts of proteins and carbohydrates. Those mites living on foods containing large amounts of fats laid only a few eggs.

Similar differences in total fecundity and its distribution were found by She did not observe, however, a delay in ZDARKOVA (1972) for T . putrescentine.

egg-laying on any of the products studied.

Effect of Repeated Mating

Young virgin females of T. putrescentiae mating only once lay about 230 eggs during about one month, and later they stop egg-laying until their death. Repeating the mating every month increases the fecundity of females to 338 eggs. Mating every fortnight or every week increases the fecundity to about 411 eggs, while females living with males for their whole life lay about 490 eggs.

Effect of Age of Female and Male (T . putrescentiae)

Total fecundity of females mating every month, but starting their reproduction at various ages, is presented in table 2. It can be seen that fecundity decreased with delay in the start of egg-laying. A remarkable decrease in fecundity was observed at the age of 60 days ; after mating, 60-day-old virgin females laid an average of 201 eggs and 70-day-old females only 100 eggs.

Fecundity was also dependent upon the age of males. From the age of 60 days onwards, males distinctly affected the fecundity of females. Young virgin females mating with 60-day-old virgin males laid only about half the number of eggs in comparison to those mating with young males. Further ageing of males up to the age of 100 days did not, however, cause any further decrease in fecundity.

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TABLE 2 Relationship between age and fecundity.

Females' age (days)

1 10 30 60 70 80 90

100

Fecundity (no. of eggs)

338 295 260 201 100 68 60 39

Males' age (days)

1

10 - 60 - - 90

100

Fecundity (no. of eggs)

338 335

104

- - - 176 190

Effect of Parental Age

Since the age of parents in insects is known to affect many biological processes of their offspring, this relationship was studied in mites (cf. table 3).

It can be seen that the age of parents up to 80 days old did not affect fecundity. Females of T. putreJcentiae descending from 1, 10 and 60-day-old parents laid similar numbers of eggs, about 490. Females of 80-day-old parents laid about 9 9% fewer eggs, and females of 100-day-old parents laid almost 25 96 fewer eggs than females of young parents.

TABLE 3 Dependence of fecundity upon parental age.

I I I (days) (no. of eggs] ( % 1 I Parental age Fecundity Fecundity decrease

I 10 60 80

100

487 472 499 443 368

- - - 9.1

24.4

Effect of Sex Ratio (T . putrescentiae)

A pronounced dependence of fecundity of females upon the number of males per female was found (cf. table 4) . Females molested by many males lay fewer and fewer eggs. At 4 males per female, fecundity was reduced by 50 96 ; at 5-7 males per female, fecundity decreased by 80 9% and at 15 males per female, fecundity reached only about 8 % of the level of one male per female.

Similar relationships were found for Cochliomyia homnivorax Coq. (Diptera ; BAUMHOVER, 1965) and for Heliothh virescenJ F. (Lepidoptera ; GUBRRA et al., 1972).

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TABLE 4 Relationship between sex ratio and fecundity.

Sex ratio

males : females

1 : 1 1 : 2 1 : 3 I : 4 1 : 5 1 : 6 1 : 7 1 : 8 1 : 9 1 : 12 1 : 15

Fecundity

no. of eggs

471 406 334 230 97 99

121 80 51 30 37

decrease [%I

13.8 29.0 51.2 79.4 79.0 74.3 83 .O 89.2 93.6 92.1

Conclusions

1) Fecundity of various, even closely related species of acarid mites is usually very variable, even in optimal conditions. The effect of consecutive conditions m a y variously affect the fecundity of various species.

2) Fecundity is dependent not only on temperature, relative humidity and food, but also on such factors as frequency of mating, age of females and males when starting reproduction, parental age and sex ratio.

3) Nutrition affects not only the total fecundity, but also the distribution of fecundity in the oviposition period, and it further defines the pre-oviposition period.

4) The highest fecundity was found for females that spent their whole life together with males, mating more often than once a week.

5 ) Fecundity of ageing virgin females decreases gradually; however, the &ect of males’ age is only distinct from the age of 60 days onwards. Fecundity of young females mating with males of 60 to 100 days old was almost half that of those mating with young males.

6) Females descending from 100-day-old parents showed a 25 96 reduction in fecun- dity in relation to females descending from young parents, of 1 to 60 days old.

7) Density of males above the sex ratio 1 : 1 decreases fecundity. On increasing the proportion of males, fecundity of molested females decreases rapidly.

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Bull. OEPP 6 (4 ) : 323-330 (1976)

RESUME

Etude sur la fecondite des acariens

par J. BOCZEK et B. CZAJKOWSKA Agricultural University of Warsaw, Warszawa-Ursynow (Pologne)

Les acariens ont en gCniral une fCconditC assez elevie, pouvant atteindre, chez certaines espkes, jusqu’h 800 oeufs par femelle. Cette ficonditi, qui est un caracthre spkifique de chaque espke, est igalement en Ctroite relation avec les conditions du milieu environnant : nutrition, temperature, humiditi, sex ratio.

De nombreux chercheurs ont etudiC ces diffirents facteurs, et la prCsente etude concerne, d’une part, l’influence de I’alimentation sur la feconditk d’dcarm sir0 L. et, dauue part, I’influence de I’accouplement, de l’ige respectif du mile et de la femelle, du sex ratio et de I’ige des parents sur la fkonditi de Tyrophagus putrescerttiae (Schr.).

Lalimentation et la composition de celle-ci (cf. tableau 1) n’influent PQS seulement sur la fkonditi dans son ensemble, mais kgalement sur la repartition, dans le temps, de la ponte et de son intensite (fig. 1, A et B). La fkonditk maximale a ktk observCe avec les aliments les plus riches en protiines et en hydrates de carbone, tan& que les acariens Clevis sur des substances lipidiques fournissaient le nombre d’ceufs le plus faible.

Par ailleurs, la frkquence des accouplements perturbe notablement la fkonditk, qui demeure la plus Plevie chez des femelles s’accouplant au moins une fois par semaine. La fkonditi potentielle des femelles vierges igees dkroit progressivement avec I’iige, l’influence de I’Age du mile n’intervenant qu’i partir de 60 jours et plus.

La fkonditk de femelles jeunes s’accouplant avec des miles Pges de 60 jours et de 100 jours est identique, mais moitii moindre de celle que I’on observe lors d’accouple- ment avec des miles jeunes (cf. tableau 2). Les femelles issues de parents igCs de 100 jours prksentent une fkonditk diminuie du quart par rapport h celles issues de parents ayant un ige compris entre 1 et 60 jours (cf. tableau 3).

Enfin, les densitis de miles sup6rieures au sex ratio de 1: 1 font baisser la fkonditi (cf. tableau 4). En effet, une femelle importunde par plusieurs m2les h la fois depose de moins en moins d’aeufs. Des phCnomPnes cornparables sont cids par BAUMHOVER (1965) chez Cochliomyia homniuorax Coq. (Diptera) et par GUERRA et al. (1972) chez Heliothis uirescens F. (Lepidoptera).

REFERENCES BARKER, P.S. (1967). The effects of high humidity and different temperatures on the biology

of Tyrophagus putrescentiae (Schrank) (Acarina : Tyroglyphidae). Can. J. Zool. 45 : 91-96. BAUMHOVER, A.H. (1965). Sexual aggressiveness of male screw worm flies measured by effect

on female mortality. J. Econ. Entomol. 58 : 544-548. BOCZEK, J. (1957). Bozkruszek maczny Tyroglyphus furinae (L.) (Acarina). Roczn. Nuuk Rolnicz.,

Warszawa, 75A (4) : 559-644.

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BOCZEK, J. & B. CZAJKOWSKA (1968). Mplyw antyseptykow i antybiotykow na niektore gatunki rozkruszkow. Roczn. Nauk Rolnicz. 93A (4) : 597-612.

CHMIELEWSKI, W. (1971). Morfologia, biologia i ekologia Carpoglyphus lactis (L. 1758) (Glycyphagidae, Acarina). Pr. nauk. Inst. Ochr. Rod. 13 (2) : 63-166.

CZAJKOWSKA, B. (1972). Wplyw niektorych sladnikow czynnych ziol na rozktuszki. H e t h Polonica 18 (1) : 79-86.

GOLEBIOWSKA, Z. (1963). Rokruszek dtobny (Tyrophugus putrescentiae [Shrank, 17811 = Tyrophagus noxius Zachwatkin, 1935). Morfologia, biologia i ekologia. Pr. nauk. Inst. Ochr. Rod. 5 (2) : 29-88.

GUERRA, A.A., D.A. WOLFENBARGER & R.D. GARCIA (1972). Factors affecting reproduction of the tobacco budworm in the laboratory. J. Econ. Entomol. 65 : 1341-1343.

JAKUBOWSKA, J. ( 1971). Biologia i ekologia rozkruszka polowo-magazynowego Acarus farris (Oud.) (Acarina : Acaridae). Roczn. Nauk Rolnicz. E 1 : 75-94.

ZDARKOVA, E. ( 1972). Roztoci v potravinarskem prumyslu. Kandid. prace. Praha. Ceska akad. zemed. 143 str. Ph. D. Thesis.

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