Genetic cost of insecticide resistance on the salivary profile of Culex pipiens quinquefasciatus mosquito

Culex quinquefasciatus mosquito has developed several resistant mechanisms to the main families of insecticides used in public health. Among these mechanisms, the insensitive acetyl cholinesterase (Ace.1R) confers cross resistance to organophosphorous and carbamates. Fortunately, in an insecticide-free environment, this mutation is associated with a severe genetic cost that affects different biological systems. In insects, the saliva contains bioactive molecules (vasodilatators, anticlotting and anti-hemostatic proteins) which permit a successful blood meal and also facilitate pathogen transmission. In this context, we studied the differential expression of salivary proteins between susceptible and carbamate-resistant (Ace.1R) strains of Cx. quinquefasciatus having a same genetic background. Electrophoresis on acrylamid gel was used to determinate the quantity and quality of salivary proteins expression. The results showed that three majority saliva proteins of the D7 family have lower expression in the resistant strain compared to the susceptible strain. Conversely, ten enzymes involved in metabolic reactions, were up regulated in the resistant strain. This differential expression according to the resistant status of the mosquito may have a repercussion on the biting behaviour and on the transmission of parasites/virus to vertebrate hosts. The next step will consist to study using a video based analysis system the feeding behaviour of susceptible (Ace1SS) and resistant (Ace1RR) mosquitoes in flying chambers. These studies will provide new elements to develop alternative insecticide resistance management strategies in Culex mosquito.