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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Mosquito and Fly Research » Research » Publications at this Location » Publication #394746
Research Project: Integrated Pest Management of Mosquitoes and Biting Flies

Location: Mosquito and Fly Research

Title: Lethal and sublethal concentrations of formulated larvicides against susceptible Aedes aegypti

Author
item Aldridge, Robert
item ALTO, BARRY - University Of Florida
item CONNELLY, ROXANNE - Centers For Disease Control And Prevention (CDC) - United States
item OKECH, BERNARD - University Of Florida
item SIEGFRIED, BLAIR - University Of Florida
item Linthicum, Kenneth - Ken

Submitted to: Journal of the American Mosquito Control Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2022
Publication Date: 12/1/2022
Citation: Aldridge, R.L., Alto, B.W., Connelly, R.C., Okech, B.A., Siegfried, B., Linthicum, K. 2022. Lethal and sublethal concentrations of formulated larvicides against susceptible Aedes aegypti. Journal of the American Mosquito Control Association. 38(4):250-260. https://doi.org/10.2987/22-7084.
DOI: https://doi.org/10.2987/22-7084

Interpretive Summary: Controlling mosquito populations depends on successfully applying formulated products that kill adults and immatures. In this study we evaluated formulated products to kill immature mosquitoes using a test to compare survivorship for yellow fever mosquitoes (Aedes aegypti). We estimated the quantity to kill 50% of immature mosquitoes exposed to formulated products which were 5.7 µg /L (Natular 2EC), 3.13 µg /L (Abate 4E), 0.43 µg /L (Altosid), 0.03 µg /L (Nyguard), and 500.6 ITU/L (VectoBac12AS). Effects observed in survivors of pesticide exposure were changes in net growth and the sex ratio of survivors. Larvae exposed developed into 0.1 - 10.6% smaller males, and 1.1 - 13.6% smaller females compared to those not exposed to pesticide. Sex ratios varied between adults following exposure to pesticides as immatures, with some generating higher numbers of females than males.

Technical Abstract: Chemical control of vectors depends on the effective application of formulated insecticides. In this study we evaluated formulated larvicides using a larval bioassay against susceptible Aedes aegypti. The estimated larvicide LC50’s were 25.7 µg /L (Natular 2EC), 3.13 µg /L (Abate 4E), 0.43 µg /L (Altosid), 0.03 µg /L (Nyguard), and 500.6 ITU/L (VectoBac12AS). Sublethal effects were identified and documented from adults that survived exposure to these estimated LC50’s (body size and sex proportion). We observed changes in net growth as measured by adult wing lengths. For those larvae exposed to estimated LC50’s the average size of adults was between 0.1 - 10.6% smaller for males and 1.1 – 13.6% smaller for females compared to controls. Sex proportions varied between larvicides but some were significantly different from the control, favoring greater survival of females than males.