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The effect of Coelomomyces indicus on the fecundity and longevity of Anopheles Gambiae, Culex fatigans and Aedes aegypti exposed to infection at each larval instar

Published online by Cambridge University Press:  19 September 2011

E. S. Nnakumusana
E. S. Nnakumusana
Affiliation:
Department of Entomology, Uganda Virus Research Institute, P.O. Box 49, Entebbe, Uganda
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Abstract

Coelomomyces indicus was reisolated from six larvae of Anopheles gambiae in Uganda. A crustacean copepod Cyclops sp. was found to be infected (63%). This indicated that the copepod could be an intermediate host for the fungus. All the four instars were highly susceptible to C. indicus but fourth instar Aedes aegypti was fairly susceptible (94.2%), while second instar An. gambiae (100%) and second instar C. fatigans (100%) were the most susceptible.

Laboratory tests were conducted to compare reproductive capacity and longevity of An. gambiae, C. fatigans and Ae. aegypti when infections of C. indicus were induced in each of the different larval instars. Infections of C. indicus sharply reduced the reproductive capacity and longevity of An. gambiae, C. fatigans and Ae. aegypti, regardless of the instar that were exposed and became infected. The reductions were highest when first and second instars were exposed. The tests indicated that introduction of C. indicus into laboratory populations of An. gambiae, C. fatigans and Ae. aegypti consisting of mixed larval instars, could significantly reduce the number and fertility of eggs and thus result in an average reduction of about 65.4% for An. gambiae, about 46.7% for C. fatigans and 58.7% for Ae. aegypti of the F1 progeny from those females that became infected. The importance of these results in biological control is discussed.

Résumé

Coelomomyces indicus a été réisolé à partir de 6 larves d'Anopheles gambiae en Uganda. On a trouvé qu'un copépode crustacéen Cyclops sp. était infecté (63%). Cela indiquait que le copépode pourrait être un hôte intermédiaire pour le champignon. Tous les stades morphologiques étaient très susceptibles au C. indicus, mais le quatrième stade Aedes aegypti était assez suceptible (94.2%), tandis que le 2 ème stade An. gambiae (100%) et le 2 ème stade C. fatigans (100%) étaient les plus susceptibles.

On a effectué des examens de laboratoire pour comparer la capacité reproductive et la longévité de An. gambiae, C. fatigans et Ae. aegypti lorsque les infections de C. indicus étaient induites dans chacun des différents stades larvaires. Les infections causées par C. indicus ont réduit d'une façon prononcée la capacité reproductive et la longévité de An. gambiae, C. fatigans et Ae. aegypti indépendemment du stade morphologique exposé et infecté. Les réductions les plus importantes étaient observées lorsque les 1 ère et 2 ème stades étaient exposés. Les examens ont indiqué que l'introduction de C. indicus dans les populations de An. gambiae, C. fatigans et de Ae. aegypti consistant de mélanges de larves à différents stades morphologiques pouvaient réduire de façon significative les effectifs et la fertilité des oeufs et ainsi donner lieu à une réduction d'environ 65, 4% pour An. gambiae, environ 46, 7% pour C. fatigans et 58, 7% pour Ae aegypti des decendants F1 provenant des femelles qui étaient infectées. L'importance de ces résultats dans le contrôle biologique est discutée.

Keywords

Anopheles gambiaeCulex fatigansAedes aegyptiCoelomomyces indicusmosquito larvaebiological controlfecundity and longevityCyclops sp. copepodAnopheles gambiaeCulex fatigansAedes aegyptiCoelomomyces indicuslarve de moustiquecontrôle biologiquefécondité et longévitécopépode Cyclops sp.
Type
Research Article
Information
International Journal of Tropical Insect Science , Volume 7 , Issue 2 , April 1986 , pp. 139 - 142
Copyright
Copyright © ICIPE 1986

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