Decoys could help in the battle against malaria mosquitoes

There’s a new weapon in the battle against outdoor-biting malaria mosquitoes: decoys that look and smell like cattle.

Efforts to spread mosquito netting, indoor spraying and other techniques have gone a long way toward controlling populations of the biting insects in areas where malaria is endemic. But it’s not enough, officials say. Outdoor-biting mosquitoes are just as capable of spreading the devastating illness.

So an international team of scientists from Kenya, the United Kingdom, Germany and the United States teamed up to develop a way to keep outdoor malaria mosquitoes from biting.

“In regions with high bed net coverage like western Kenya, mosquitoes are likely to rest and bite outdoors since bed nets prevent them from feeding indoors. With increased outdoor biting and resting of mosquitoes, it becomes extremely difficult to collect and study the vectors due to their wide dispersal in the outdoor environment,” Bernard Abong’o, a doctoral student at the Liverpool School of Tropical Medicine, said in a press release.

The team created decoy traps that mimic humans and cattle using scent, heat and visual stimuli to attempt to attract the biting bugs. They compared the traps against the old method of using human volunteers to trap malaria mosquitoes.

The team collected a total of 1,807 Anopheles mosquitoes, finding that the mosquitoes seemed most attracted to the cattle-baited traps, and less attracted to volunteers or human-baited traps. They also discovered that, in the two villages in western Kenya used for the study, four different species of malaria mosquitoes – An. arabiensis, An. gambiae, An. funestus and An. coustani – resort to outdoor biting when indoor biting doesn’t provide enough food.

“Host decoy traps may provide us with a new system to monitor and potentially control outdoor-biting mosquitoes and to obtain insights into their host choice, while minimising the risk to human volunteers otherwise exposed to mosquitoes during landing catches,” Abong’o said.

The study has been published in the journal Parasites & Vectors.