Entomophaga

, Volume 23, Issue 1, pp 95–102 | Cite as

Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel

IV. Oviposition, host preferences and sex ratio
  • Y. Rechav
Article

Abstract

The oviposition rate of fertilized and unfertilized females ofChelonus inanitus (L.) was studied at different temperatures. The average number of eggs laid by fertilized females at 20°C was 612 and at 28°C, 1219. Unfertilized females laid an average of 689 eggs at 20°C and 1323 eggs at 28°C.C. inanitus can develop in various hosts such as:Anagasta kuehniella (Zeller),Cadra cautella (Walker) andSitotroga cerealellaOlivier, but the females prefer to lay their eggs in those of their natural hosts,Spodoptera littoralis (Boisduval) andSpodoptera exigua (Hübner). The sex ratio ofC. inanitus was affected by environmental conditions. Increase in the size of the egg host and decrease of daylength or temperature, increased significantly the number of females in the population. The ratio females/males at light-dark regimes of 14∶10 was 0.66 and at L:D 12∶12, 1.11. An increase of the temperature from 20°C to 25°C and 28°C decreased this ratio from 1.22 to 1.05 and 0.72 respectively.

Keywords

Plant Pathology Ecological Study Natural Host Oviposition Rate Unfertilized Female 

Résumé

La fécondité des femelles accouplées ou non deChelonus inanitus (L.) a été étudiée à différentes températures. Le nombre moyen d'œufs déposés par les femelles accouplées fut 612 à 20°C et 1 219 à 28°C. Les femelles non accouplées ont pondu une moyenne de 689 œufs à 20°C et de 1 323 œufs à 28°C.C. inanitus peut se développer chez des hôtes divers tels que:Anagasta kuehniella (Zeller),Cadra cautella (Walker) etSitotroga cerealellaOlivier, mais les femelles préfèrent pondre dans leurs hôtes naturels,Spodoptera littoralis (Boisduval) etSpodoptera exigua (Hübner). La proportion des sexes deC. inanitus dépend des conditions de milieu. L'augmentation de la taille de l'œuf-hôte et la diminution de la durée du jour ou de la température accroissent significativement le nombre de femelles dans la population. Le rapport femelles/mâles sous un régime lumière-obscurité de 14∶10 a été de 0,66 et de 1,11 pour le régime 12∶12. L'accroissement de la température de 20°C à 25°C et à 28°C réduit ce rapport de 1,22 à 1,05 et 0,72 respectivement.

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References

  1. Bradley, W. G. — 1941. Methods of breedingChelonus annulipes on the mediterranean flour moth for use against the European corn borer. —U.S.D.A. Circ. No. 616, 22 pp.Google Scholar
  2. Broodryk, S. W. — 1969. The biology ofChelonus (Microchelonus) curvimaculatus Cameron [Hymenoptera: Braconidae]. —J. Entomol. Soc. Sth. Afr., 32, 169–189.Google Scholar
  3. Clausen, C. P. — 1939. The effect of host size upon the sex ratio of hymenopterous parasites and its relation to methods of rearing and colonization. —N. Y. Entomol. Soc., 47, 1–9.Google Scholar
  4. DeBach, P. — 1964. The scope of biological control. In: Biological Control of Insect Pests and Weeds (P. DeBach ed.). —Chapman & Hall, London, 844 pp.Google Scholar
  5. Flanders, S. E. — 1939. Environmental control of sex in hymenopterous insects. —Ann. Soc. Entomol. Am., 32, 11–26.Google Scholar
  6. Flanders, S. E. — 1947. Elements of host discovery exemplified by parasitic Hymenoptera. —Ecology, 28, 299–309.Google Scholar
  7. Flanders, S. E. — 1956. The mechanism of sex ratio regulation in the (parasitic) Hymenoptera. —Insectes Sociaux, 3, 325–334.CrossRefGoogle Scholar
  8. Gerling, D. — 1969. The parasites ofSpodoptera littoralis Bois [Lepidoptera: Noctuidae] eggs and larvae in Israel. —Isr. J. Entomol., 4, 73–81.Google Scholar
  9. Hoelscher, C. E. &Vinson, S. B. — 1971. The sex ratio of a hymenopterous parasitoidCampoletis perdistinctus as affected by photoperiod, mating and temperature. —Ann. Entomol. Soc. Am., 64, 1373–1376.Google Scholar
  10. Rechav, Y. — 1974. Effects of common insecticides applied to cotton on adults of a braconid parasitoidChelonus inanitus (L.). —Environ. Entomol., 3, 737–738.Google Scholar
  11. Rechav, Y. — 1975. Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] in Israel. I. — Distribution, abundance and parasitism in natural host populations. —Entomophaga, 20, 365–372.CrossRefGoogle Scholar
  12. Rechav, Y. — 1978. Biological and ecological studies of the parasitoidChelonus inanitus [Hym.: Braconidae] n Israel. III. Effects of temperature, humidity and food on the survival of adults. —Entomophaga, 23, 89–94.Google Scholar
  13. Rechav, Y. &Orion, T. — 1975. The development of the immature stages ofChelonus inanitus. —Ann. Entomol. Soc. Am., 68, 457–462.Google Scholar
  14. Salt, G. — 1935. Experimental studies on insect parasitism. III. Host selection. —Proc. R. Entomol. Soc. B., 117, 413–435.Google Scholar
  15. Subba Rao, B. R. &Gowda, G. K. U. — 1961. Effect of temperature and humidity on the fecundity and longevity ofChelonus rufus Lyle [Hymenoptera: Braconidae]. —Proc. Ind. Acad. Sci. B., 54, 241–250.Google Scholar
  16. Thorpe, W. H. &Jones, F. G. W. — 1937. Olfactory conditioning in a parasitic insect and its relation to the problem of host selection. —Proc. R. Entomol. Soc. Lond. B. 124, 81–95.Google Scholar
  17. Vance, A. M. — 1932. The biology and morphology of the braconidChelonus annulipes Wesm. a parasite of the European corn borer. —U. S. Dep. Agric. Tech. Bull. No. 294, 48 pp.Google Scholar
  18. Wishart, G. — 1938. Some observations on the effect of temperature on the sex ratio of a hymenopterous parasite.Chelonus annulipes Wesm. —Ann. Entomol. Soc. Ontario, 69, 85–87.Google Scholar

Copyright information

© Le François 1978

Authors and Affiliations

  • Y. Rechav
    • 1
  1. 1.Division of EntomologyAgricultural Research Organisation, The Volcani CenterBet DaganIsraël

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