Sugar-feeding facilitates the mating behavior of Anopheles gambiae s.s

The first few days after an Anopheles gambiae female mosquito emerges are critical to her fitness. Yet, the order of behavioural events (mating, sugar feeding, blood feeding) during this time has received little attention. We discovered that among female cohorts sampled from emergence, sugar feeding has a higher probability than blood feeding of occurring first, and mating rarely occurs before a meal is taken. The night after emergence, 48% of females fed on sugar in mesocosms, and 25% fed on human blood; in the absence of sugar, 49% of females fed on human blood. After 5 days, 39% of the sugar-supplied females had blood fed, mated, and now were fructose negative, whereas by that time only 8% of the sugar-denied females had both blood fed and mated. The model that best explains the transitions suggests that females made use of two distinct behavioral pathways, the most common one being to sugar feed, then mate, and then seek blood. Other females sought blood first, then mated, and forewent a sugar meal. A follow-up mesocosm study was performed to elucidate how the apparently opportunistic initial meal choice depends on female body size, availability of nectar-bearing plants and blood hosts. Of these three factors, blood-host availability (a human host was available to mosquitoes 0, 1 or 8 hrs per night) had the most noticeable impact on the feeding choice of 1-d-old females.