Measuring Expression of Antioxidant Genes in Spermathecae of Culex pipiens

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The Ohio State University

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Spermathecae are receptacles that are found in the reproductive tracts of female insects such as honey bees and mosquitoes. Female insects use the spermathecae to receive and store sperm until the female decides to use the sperm to fertilize the eggs. The function of certain antioxidant enzymes like Superoxide Dismutase-2 (SOD-2), Catalase, and Glutathione S-transferase (GST) are believed to promote sperm longevity and storage by protecting sperm from oxidative stress. Collins et al. (2004) examined the gene-expression profiles of the anti-oxidative enzymes Catalase and GST in the spermathecae of queen honey bees. They found that Catalase and GST levels were higher in mature males and queens than younger honey bees. Culex pipiens, commonly known as the Northern House Mosquito, is prevalent in West Nile Virus transmission. Adult female mosquitoes can lay 50-200 eggs per oviposition leading to over 800-1000 mosquito offspring in a lifetime (CDC 2015). The reproductive capacity of mosquitoes makes them the perfect vector for disease transmission. As the enzymes mentioned above are believed to promote sperm viability, they could potential pose a solution to controlling reproduction in Cx. pipiens. Diapause is a mechanism used by mosquitoes, and other insects, to survive the harsh conditions such as lack of food and cooler temperatures. While the exact process by which mosquitoes molecularly enter diapause, shortened day length has been shown to initiate diapause in mosquitoes. When in diapause a female is less likely to take blood and lay eggs as they divert their resources from reproduction to survival (Meuti, 2015). Due to that fact that male mosquitoes do not survive winters, it is pivotal that females store and protect the sperm (3-6 months) so that they can lay fertile eggs that following spring. To better understand how anti-oxidatative enzyme levels were affected by diapause and the relative age of female Cx. pipiens, the levels of SOD-2, Catalase and GST were measured via spermathecae RNA qPCR. The conditions assed in this experiment were as followed: young (10-day old) female Cx. pipiens spermathecae (LD:18 and SD:18) and older (30-day old) females (LD:18 and SD18).


Second place in the Conservation and Environmental Monitoring


spermathecae, mosquitoes, diapause, antioxidant enzymes