Sugar-source preference, sugar intake and relative nutritional benefits in Anopheles arabiensis males

Plant-derived sugar is the only source of dietary carbohydrate for males of most mosquito species. Male resource acquisition and utilization remain an under-researched area of behavior in vectors of human diseases. However, the renewed interest in the use of sterile males against disease vector mosquitoes reinforces the urgent need for studies on the behavioral and ecological processes that underpin male fitness and reproductive success. Here an attempt was made first to characterize the conditions and modes of resource acquisition (plant derived sugar meals) early in the life of An. arabiensis males, and second to test the hypothesis that the plants chosen for their sugar meals are those which maximize their fitness in terms of energy gains (i.e. amount of lipids, proteins, glycogen and glucose). Olfactometry assays demonstrated the ability of An. arabiensis males to discriminate among a sample of ten abundant flowering plants present in their natural habitats. In further experiments, we observed significant variations in the sugar intake rates that matched their olfactory preferences, with the most attractive plants eliciting significantly higher sugar intake rates. Consistent with our expectations, analyses of the whole-body free sugars, lipids and glycogen unequivocally showed that the energy reserve accumulated post-feeding is dependent on the diet of the adult males, with the preferred plants providing more energy reserves than the less preferred ones, despite mosquitoes actively feeding on both. Taken together, these results show that An. Arabiensis males are able to discern between food sources, preferentially feeding on those species of plant that provide the highest metabolic payoff. Ensuring or somehow heightening the ability to detect and obtain rewarding sugar meals by male mosquitoes reared for field release could enhance their competitive ability in the field.