A team of researchers has discovered that mosquitoes exhibit resistance to insecticides thanks to high levels of a particular protein in the mosquitoes’ legs.
Treating surfaces with residual insecticides is a key element of any mosquito control program. Mosquitoes landing on the treated surface pick up insecticide on their legs and subsequently die. This is key to the performance of bed nets. However, field observations on bed net performance indicated increased resistance in certain mosquito populations. Recent research suggests this may be due to a completely new mechanism for pyrethroid resistance.
Researchers from the Liverpool School of Tropical Medicine have discovered that a sensory appendage protein (SAP2) was found at elevated levels in the legs of pyrethroid-resistant populations of the Anopheles gambiae mosquito. Furthermore, the levels of SAP2 expression increased after the mosquitoes came into contact with pyrethroids. The SAP2 appears to have a high affinity for pyrethroids. In binding strongly to the pyrethroids, it prevents the pyrethroid acting on the insect’s nervous system.
The discovery of a new mechanism of insecticide resistance presents a challenge to mosquito control programs, especially as residual insecticide treatments are a key element of population control and protection measures. However, the researchers have also established that by silencing the production of SAP2, the susceptibility of mosquitoes to pyrethroids can be fully restored. This provides an avenue for future research to develop potential compounds to counteract this resistance mechanism.
Further reading: Ingham, V.A et al (2019) A sensory appendage protein protects malaria vectors from pyrethroids. Nature, 577: 387-380