Two neuropeptides that promote blood feeding in Anopheles stephensi mosquitoes

Animals routinely need to make decisions about what to eat and when. These decisions are influenced not only by the availability and quality of food but also by the internal state of the animal, which needs to compute and give weights to these different variables before making a choice. Feeding preferences of female mosquitoes exemplify this behavioural plasticity. Both male and female mosquitoes usually feed on carbohydrate-rich sources of nectar or sap, but the female also feeds on blood, which is essential for egg development. This blood-appetite is modulated across the female’s reproductive cycle, yet little is known about the factors that bring it about.We show that Anopheles stephensi females, a major vector for urban Malaria the Indian sub-continent and West-Africa, suppress blood-feeding between a blood-meal and until oviposition. Transcriptomics on blood-deprived and sated An. stephensi midbrains allowed us to shortlist several candidate genes that might promote bloodfeeding behaviour. Through dsRNA-mediated knockdown of nine of them, we identified two neuropeptides – short Neuropeptide F (sNPF) and RYamide - that promote blood-feeding. We find that these neuromodulators are expressed in nonoverlapping subsets of neurons in the brain suggesting that blood-feeding behaviour is likely modulated by multiple mechanisms acting across different brain neurons.