International Centre of Insect Physiology and Ecology (ICIPE) Nairobi 30772-00100, Kenya
The invasive weed Parthenium hysterophorus (Asteraceae) is widespread in tropical and sub-tropical regions of the world and is a preferred sugar source for the afro-tropical mosquito An. gambiae. Curiously P. hysterophorus and its key metabolite parthenin was found to be toxic to humans and animals but are tolerated by adult female An. gambiae mosquito. In this study we tested the hypothesis that tolerance is related to learned behavior from the immature stages through suboptimal exposure to the plant metabolite released in the root exudates. We assessed egg laying behavior of An. gambiae on the plant exudate and parthenin and quantified % egg hatchability, larval survival rate, larval and pupal development time and sex ratio of emerged adults. We found differential egg laying, hatching rates and larval development time, to different doses of the exudate and parthenin, relative to control sterile water, with no discernible effect on pupal development time and sex ratio of emerged adults. Findings will be discussed in light of plant influence on the vectorial capacity of disease vectors.