Mosquitoes are the deadliest animals on the planet, due to their role as vectors of diseases such as malaria and dengue. These two diseases alone account for approximately 500,000 human deaths every year. In addition to deaths, mosquitoes are important in spreading diseases that can be life altering or cause extensive suffering (e.g. Zika virus and Chikungunya). Mosquitoes also cause diseases in animals (e.g. avian malaria has had a devastating impact on endemic island birds).
While progress has been made in understanding the ecology of the mosquitoes themselves, there are still many gaps to fill. For example, the natural predators of adult mosquitoes are relatively poorly known, as is the role of these predators in controlling mosquito populations. Bats especially are known to be voracious predators, and may be able to consume 600 mosquitoes per hour, however it remains unclear which species they may be consuming (disease vectors or those that are relatively benign). Our DNA sequence data from bird and bat faecal samples collected from Cameroon show that at least 15 species of bats and birds consume mosquitoes from five different genera, including Anopheles, Culex, Coquillettidia, Eretmapodites, and Mansonia, which include important human disease vectors. However, our data remain incomplete, because it is currently very difficult to assign species-level taxonomy to mosquitoes with the traditionally used DNA barcoding approach of sequencing the COI gene. A related key question regards the role of mosquitoes in natural food webs. Some mosquito control strategies (e.g. using genetic modification) aim to produce sterile mosquitoes, which would cause populations to collapse. However, the ecological impact of such an action on food webs remains unclear.
It also remains unclear if wild animals consume a particular subset of mosquitoes at a higher rate. Insecticides are widely used to prevent crop damage and kill harmful pests, including mosquitoes. However, repeated use has led to the evolution of mosquitoes (e.g. in the genus Anopheles) that can survive treatment, making this control measure less effective. Some research suggests that insecticide resistance comes at a cost: alterations during development may make them more vulnerable to predation. Understanding sex bias in consumption of mosquitoes would also be valuable. Male mosquitoes form aerial mating swarms at dusk, which may make them especially vulnerable to predators like bats, but only females take blood meals, thus bats may not control the portion of the mosquito population causing disease. On the other hand, some mosquito control strategies target individuals of one sex (sometimes males and sometimes females), thus understanding if predators preferentially target a specific sex would be important.
Thus, this project aims to:
1) (a) Identify animals consuming mosquito vectors – focusing on birds and bats, but potentially also amphibians – as well as (b) the species of mosquitoes being consumed.
2) Using network and ecological modeling approaches, investigate the food webs that these species participate in, and perform sensitivity analyses to answer questions such as: what would happen if one or more predators were removed (e.g. due to land use or climate change)? What would happen if one or more mosquito species were removed from the system (e.g. due to vector control strategies)?
3) Identify if predators preferentially consume mosquitoes of particular types (i.e. insecticide resistant mosquitoes or a particular sex).