The Effect of Stress on Mosquito (Culex pipiens) Immunity and Development

Insecticide based vector control is an important strategy for vector disease control.  One aspect that has not yet been studied is the immune response to anthropogenic stress, which includes the application of insecticides and pesticides. Understanding the impact of vector control strategies such as insecticide use is critical for population and disease control. The aim of this study is to investigate the effect of this stress on immunity and development of the common house mosquito, Culex pipiens. Quantitative realtime PCR was used to assess antimicrobial peptide expression of the Toll and Imd immune pathways as well as key developmental genes in larvae and adults. We quantified the expression of five immune and developmental genes (Cecropin, Gambicin, Defensin, Toll 1B, and Dorsal) in C. pipiens larvae and adult mosquitoes in response to 4 pesticide and insecticide treatments (Malathion, Glyphosate, Carbaryl, Atrazine). Results show that some transcripts were less abundant in stressed larvae and adult mosquitoes compared to controls. Other transcripts, such as Cecropin, increased in expression in adults but not in larvae while other transcripts had increased expression in larvae and not in adults in accordance with treatment.  The results indicate that anthropogenic stress may alter immune functions as well as affect expression of key development genes.