Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2007
Publication Date: 11/1/2007
Citation: Barnard, D.R., Xue, R., Rotstein, M.J., Becnel, J.J. 2007. Microsporidiosis (Microspora: Culicosporidae) in Aedes aegypti (Diptera: Culicidae) affects host attraction, blood feeding responses, and the repellency of deet. Journal of Medical Entomology. 44(6):1040-1046. Interpretive Summary: The mosquito Aedes aegypti transmits viruses that cause yellow fever and dengue fever in humans. The mosquito is distributed from 20E north to 20E south of the Equator in a band that stretches around the globe and contains one-third of the world’s population. Efforts to control Aedes aegypti comprise the use of insecticides and/or sanitary measures that destroy mosquito developmental sites. As an alternative to these control methods, scientists at the Center for Medical, Agricultural, and Veterinary Entomology, in Gainesville, FL have developed a microorganism named Edhazardia aedis that infects Aedes aegypti and kills the mosquito larvae. Some of the larvae infected with the microbe survive to adulthood and remain infected with the microorganism. Before now, it was not known if these infected adults behaved differently than healthy mosquitoes, when attacking humans and seeking a blood meal, or if repellents such as deet were effective against them. The results reported in this paper showed that Aedes aegypti mosquitoes infected with Edhazardia aedis were in fact less aggressive and less efficient than their uninfected counterparts when attacking a human host and acquiring a blood meal and that the repellent deet was as least as effective against the sick mosquitoes as it was against the uninfected (healthy) mosquitoes. The results indicate that in a biological control program Aedes aegypti behavior is unlikely to change in response to infection with Edhazardia aedis.
Technical Abstract: Infection of Aedes aegypti (L.) (Diptera: Culicidae) with Edhazardia aedis (Microsporidia: Culicosporidae) reduced mean human host attraction and landing/probing rates in female mosquitoes by 53% and 62%, respectively, compared with rates in microsporidia-free females. Infection with E. aedis reduced the average weight of unfed female mosquitoes by 4%, caused them to imbibe 23% less blood, and to lay 30% fewer eggs than healthy females. In contrast, E. aedis-infected mosquitoes required 20% more time (> 1 h) than healthy females to bite skin treated with 15% deet. Statistically significant (P < 0.05) morbidity in E. aedis-infected females was indicated by reductions in host attraction and landing/probing responses, the mass of unfed and blood-engorged females, and fecundity, and by increased deet repellency.