Abstract
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 of urban malaria in the Indian sub-continent and West-Africa, suppress blood-feeding between a blood-meal and oviposition. We identify several candidate genes through transcriptomics of blood-deprived and -sated An. stephensi midbrains that could modulate this behaviour. We show that short Neuropeptide-F (sNPF) and RYamide (RYa) act together to promote blood-feeding and identify a cluster of cells in the subesophageal ganglion that expresses sNPF only in the blood-hungry state. Such females also have more sNPF in their midguts. We propose that increased sNPF levels in the brain and gut promotes a state of blood-hunger, which may drive feeding behaviour either by sNPF’s action in the two tissues independently or via a communication between them.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
This version of the manuscript has been revised to shed light on how these neuropeptides might control blood-feeding behaviour in Anopheles stephensi. In this updated version, we show that: 1. Both neuropeptides are required in the head (along with a possible contribution from the abdomen) to affect blood-feeding behaviour. Their knockdown in the abdomen alone does not alter blood-feeding. 2. A set of neurons in the brain express sNPF only in the blood-hungry condition. Such females also have increased sNPF in their midguts. 3. Both sNPF and RYa receptors are widely expressed, and often co-expressed, in the brain. However, only sNPF receptor is expressed in the midgut.