A Small-Scale Investigation Into the Effect of A Larvicidal Oil On Oviposition Site Preference By Aedes aegypti.

Larvicidal oils can be used to control immature Aedes aegypti and other pestiferous mosquitoes. To test whether oil-based larvicides also act as oviposition deterrents, indoor and semi-field trials were conducted at the Navy Entomology Center of Excellence in Jacksonville, FL. In both studies, treatment cages consisted of oviposition cups lined with seed germination paper as an oviposition substrate and filled with 1-wk-old southern live oak ( Quercus virginiana) leaf litter-infused water. Treatment cages consisted of 2 cups treated with CocoBear™ Mosquito Larvicidal Oil, while 2 cups were untreated. Control cages contained oviposition cups with only oak leaf litter-infused water. Gravid Ae. aegypti were released into cages and allowed to oviposit for 24 h, after which eggs were counted. The number of eggs deposited in treatment and control cages was not significantly different (indoor P = 0.0865; outdoor P = 0.9765). However, the number of eggs deposited in untreated cups was significantly greater than that deposited in treated cups within treatment cages (indoor P < 0.0001; outdoor P = 0.0050). These results suggest that the presence of the larvicidal oil CocoBear may cause gravid female Ae. aegypti to seek alternative oviposition sites.