Malaria parasites enhance blood-feeding of their naturally infected vector Anopheles punctulatus.

We investigated the blood-feeding behaviour of a natural population of the human-feeding mosquito Anopheles punctulatus in Iguruwe, Papua New Guinea. In particular we investigated the relationship between the mosquitoes' blood-feeding behaviour and their infection by the malaria parasites Plasmodium falciparum and P. vivax. Female mosquitoes were caught at 4 times of the night, the amount of blood they had obtained was measured and their status of infection was evaluated. Among uninfected mosquitoes the bloodmeal size steadily increased through the night, possibly because they were progressively less likely to be disturbed by human activity as the night drew on. Infected mosquitoes, on the other hand, tended to feed maximally at all times of the night. This suggests that infected mosquitoes were more tenacious in their blood-feeding behaviour, being either less readily disturbed during a bout of feeding (and thus feeding longer) or more likely to return to continue their feed following disturbance (and thus feeding several times). Either change would increase the parasites' rate of transmission. We conclude that in this natural situation the two species of malaria parasites modified the mosquitoes' behaviour with the effect of increasing their own transmission.