Autoradiographic studies on mosquitoes and filarial parasites in mosquitoes

Aspects of the host parasite relationships which exist between larvae of the filarial nematode Brugia patei and two mosquito intermediate hosts are explored with the aid of an autoradiographic technique and selected histochemical staining methods. In Aedes togoi normal development of the worm occurs following a blood meal taken from a domestic cat infected with microfilariae of Brugia patei. Conversely Anopheles labranchiae atroparvus is refractory to infection with Brugia patei and it has been established previously that in the latter mosquito the parasite exhibits a number of abnormalities in its pattern of growth, and it rarely develops successfully to the second larval stage. The present study therefore concentrates largely on the principal histological events which take place in both the parasite and its two mosquito hosts during this early critical period of development. The results describe the incorporation of [H3]-labelled nucleosides, amino acids and carbohydrates in normal and abnormal worms and include autoradiographic and histochemical features of the host reaction elicited by Brugia patei when parasitic in Anopheles labranchiae atroparvus. Autoradiographic observations are also recorded for both host mosquitoes. Particular emphasis is given to the alimentary canal, fat body, heart, pericardial cells and female reproductive tract during the period when the mosquito is parasitised by the nematode. Differences between parasitised individuals and uninfected controls are noted. These findings are discussed in relation to our general understanding of host parasite relationships in insects and entomophilic nematodes.