, 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


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.


Plant Pathology Ecological Study Natural Host Oviposition Rate Unfertilized Female 
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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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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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