Action de Diaeretiella Rapae sur le Développement et la Morphologie de Brevicoryne Brassicae

Summary

The eggs of Diaeretiella rapae, laid into the body of males, alatae or apterae virginoparae, or sexed females of Brevicoryne brassicae give rise to various morphological anomalies. This special effect could be more clearly defined by making some individuals of D. rapae, sterilized by a chemosterilant (tepa), by their eggs into the bodies of the four morphs mentioned above.

The anomalies observed seen to be due to:

— the « stress » produced by the ovipositor of the parasite penetrating into the body of the Aphid, and possibility also by acid and alcaline secretions of glands; this acts mainly on ocelli, wings, posterior tibia, shape of the cauda and sensoria; by picking Aphid larvae with a needle, the result is nearly the same.

— a substance produced by the embryo of the parasite, diffusing into the haemolymph of the Aphid and thus altering its hormonal equilibrium; the most masked result is an atrophy of the genital apparatus of the males.