Humoral encapsulation in Diptera (Insecta): comparative studiesin vitro

Abstract

The humoral encapsulation reaction of larvae ofChironomushas been reproduced and studiedin vitro. This reaction is activated by entomogenous fungi and certain foreign bodies as well as by nematodes. The different stages of encapsulation and the duration of the process have been determined. In the larvae of a given species of Chironomidae encapsulation does not vary with age or sex. In contrast, the duration of the process differs according to the species of Chironomidae and is modified by temperature or by parasitism of the host by Mermithidae.The capsules contain melanin. Their formation is prevented by glutathion, an inhibitor of phenoloxidase.The humoral type of encapsulation also occursin vitroin the haemolymph of larvae of the nematocera families, Culicidae and Chaoboridae. However, the reaction of these insects differs in the amount, distribution and pigmentation of the capsular material.The results demonstrate similarities between humoral and cellular encapsulation.