The Effects of Juvenile Exposure to Sub-lethal Concentrations of Pesticides on the Adult Reproductive Biology of the Male Southern House Mosquitoe, Culex quinquefasciatus
Semester of Graduation
Master of Science (MS)
Mosquitoes transmit pathogens capable of causing significant diseases, the worst of which can permanently disfigure or kill. Mosquito control efforts can be strengthened by better understanding all aspects of mosquito biology, but there is deficient information regarding sperm production in male mosquitoes. Understanding the sperm production and capacity of vector species may reveal new control strategies.
The goal of this research was to determine if larval exposure to sub-lethal concentrations, defined as killing less than half of the sample population, of pesticides negatively impacts the adult male reproductive health of the southern house mosquito, Culex quinquefasciatus Say. This study quantified sperm counts for wild and lab reared (Sebring) Cx. quinquefasciatus. The Sebring colony produced more sperm than the wild collected mosquitoes. After baseline sperm counts were determined, each population was exposed to sub-lethal quantities of the larvicides spinosad, Lysinibacillus sphaericus, and methoprene, and the herbicides glyphosate and atrazine. Larvae were exposed during their third instar and remained in an environment with pesticide until eclosion. Adult males were dissected at one, four, seven, and fourteen days post eclosion.
The reproductive tracts were removed and the sperm diluted, and the sperm were counted in subsamples. Sperm counts for the Sebring colony were significantly reduced after the spinosad and L. sphaericus treatments, and significantly increased after the methoprene treatment. Sperm counts for the wild collected mosquitoes experienced no decrease from any treatment, but they did experience significant increase after the methoprene treatment. Wing lengths (as a proxy for body size) were measured for all experiments, but the treatments had no observed effects on body size. These results show that exposure to some chemicals during larval development can alter spermatogenesis in Culex quinquefasciatus males.
Judd, Shiloh Dean, "The Effects of Juvenile Exposure to Sub-lethal Concentrations of Pesticides on the Adult Reproductive Biology of the Male Southern House Mosquitoe, Culex quinquefasciatus" (2018). LSU Master's Theses. 4794.