‘If you succeed, what about the other animals?’
Posted 30th July 2018
Often the first question that I am asked when I tell people about Target Malaria is ‘If you succeed, what about the other animals?’ This is an excellent question about potential ecological consequences and is rightly asked by all sorts of people in very many situations from academic meetings to day-to-day conversations.
This has been a long time coming, but we now have a really solid basis for beginning to answer this. Several student projects began the process by exploring academic literature for papers about animals documented to eat, or compete with, Anopheles gambiae mosquitoes in their natural habitat. More recently Jane Bonds searched very thoroughly far-and-wide and together we wrote a substantial report on this delicate subject – it is about 10,000 words long. The literature is large and the researchers are imaginative: all sorts of methods have been used to identify and investigate mosquito relationships: lab studies, field studies, even using DNA probes on animal faeces to see if there are mosquitoes in it!
The report is now an academic paper ‘Effects of removal or reduced density of the malaria mosquito, Anopheles gambiae s. l., on interacting predators and competitors in local ecosystems’ and is in the public domain to support both the generally curious and those who are concerned with Environmental Risk Assessments.
So, what does eat a mosquito?
As adults, An. gambiae mosquitoes are small, hard to catch, most mobile at night and not very juicy, so they are not a rewarding prey for both insect and vertebrate predators. Many do eat them (sometimes accidentally) but there is no evidence that they are a big or vital part of the diet of any other animal. There is one curious, jumping spider known as ‘the vampire spider’ that lives in homes around the shores of Lake Victoria and does have a fondness for female blood-fed mosquitoes. Resting blood-fed females are easy and more nutritious prey as they digest their blood meal, but this spider will readily eat other available mosquito species as opportunity arises.
Female An. gambiae lay their eggs on the surface of available water and generally prefer smaller ephemeral pools. They can detect water that contains predators or competing mosquitoes and will avoid this. If they cannot, then there are many species of aquatic creatures that do eat the larvae, but none that have be found to have any dependence or strong, regular association.
Imperial College London: press release