Comparative susceptibilities of species T and U of the Anopheles fluviatilis complex to Plasmodium vinckei petteri sporogony.

Anopheles fluviatilis James is an important malaria vector in Indian subcontinent. An. fluviatilis exists as a complex of three sibling species, of which two species, T and U, have been colonized so far. Attempts were made to study the comparative susceptibility of species T and U of the An. fluviatilis complex to rodent malaria parasite Plasmodium vinckei petteri by using Anopheles stephensi Liston as calibrator for variable infectivity in different isolates. An. stephensi, which was used as control, became readily infected, with 60-65% mosquitoes carrying developing oocysts, whereas in species T and species U, approximately 50 and 63%, respectively, of mosquitoes carried oocyts. An. fluviatilis species T was found comparatively less susceptible to P. v. petteri sporogonic development compared with species U. Moreover, significantly lesser sporozoites rate (11%) was observed in species T compared with 31% in species U. Species T and species U are not considered as malaria vectors in India in the field. However, in the laboratory, both these species are able to support the malaria sporogony.

Species B of Anopheles culicifacies (Diptera: Culicidae) is reproductively less fit than species A and C of the complex.

Anopheles culicifacies, the most important malaria vector of peninsular India exist as a complex of five sibling species. The member species of the complex have various biological differences including their susceptibility to malaria parasites. The present attempt is made to study and compare the fecundity of the differentially susceptible members of the An. culicifacies complex. Gravid female mosquitoes of species A, B and C were allowed to lay their eggs individually during first and second gonotrophic cycle. The eggs were counted after hatching and categorized as 'hatched eggs', 'unhatched eggs', 'embryonated eggs', 'unembryonated eggs' and 'non/partially melanized eggs'. The data was analyzed using Student's t test, ANOVA, Chi-square and Pearson's correlation analysis. All females that were visually categorized as 'gravid' did not lay eggs. Species C laid maximum number of eggs per female. The eggs laid per female mosquito of each species were found to be significantly higher during second gonotrophic cycle as compared with the first gonotrophic cycle. The eggs hatched per female in species C were found to be significantly higher than that of species A and B. The poor-vector species B mosquitoes were found to be the least fecund among the members of the species complex. The unembryonated eggs constitute the biggest proportion of the unhatched eggs in species A, B and C of the species complex.