A Correlation of Malpighian Tubule Size with Development of Dirofilaria immitis in the Mosquito

Abstract

A direct correlation was observed between Malpighian tubule diam. and the development of larvae of the dog heartworm in Aedes aegypti, A. albopictus, Culex quinquefasciatus, and Anopheles quadri-maculatus. This was based upon measurements of the avg. diam. of 5 tubules per female of 100 females of each sp. and records of those females exhibiting normal development of the parasite. Mosquitoes with predominantly wide tubules showed far better development of the parasite than those with narrow tubuels. However, tubule diam. per se cannot asserted to constitute the critical factor in development of the dog filaria since the poor host spp. showed many individuals with wide tubules but negative for normal parasite development. Thus, although it seems clear that factors other than tuble size per se are undoubtedly operative, the present correlation may be an indication that dirofilarial growth is partially dependent upon the size of the cells composing the Malpighian tubules since the microfilariae enter these cells before initiating further growth.