Limited impacts of truck-based ultra-low volume applications of mosquito adulticides on mortality in honey bees (Apis mellifera)

Authors: Rinkevich, Frank; MARGOTTA, JOSEPH - Louisiana State University Agcenter; POHKREL, VIVEK - Louisiana State University Agcenter; OTTEA, JAMES - Louisiana State University Agcenter; HEALY, KRISTEN - Louisiana State University Agcenter; WALKER, TODD - East Baton Rouge Parish Mosquito Abatement And Rodent Control; VAETH, RANDY - East Baton Rouge Parish Mosquito Abatement And Rodent Control; Aldridge, Robert; Fritz, Bradley - Brad; Danka, Robert; Rinderer, Thomas; Hoffmann, Wesley; Linthicum, Kenneth - Ken

Submitted to: Bulletin of Entomological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2017
Publication Date: 12/1/2017
Citation: Rinkevich Jr, F.D., Margotta, J.W., Pohkrel, V., Ottea, J.A., Healy, K.B., Walker, T.W., Vaeth, R.H., Aldridge, R.L., Fritz, B.K., Danka, R.G., Rinderer, T.E., Hoffmann, W.C., Linthicum, K. 2017. Limited impacts of truck-based ultra-low volume applications of mosquito adulticides on mortality in honey bees (Apis mellifera). Bulletin of Entomological Research. 107(6):724-733. https://doi.org/10.1017/S0007485317000347.
DOI: https://doi.org/10.1017/S0007485317000347

Interpretive Summary: Effective mosquito control operations often rely on ultralow volume applications of insecticides to decrease populations of adult mosquitoes. These insecticides are applied over large areas that may include honey bee colonies. Impacts of these insecticide applications have been evaluated, but instances where impacts on honey bees alongside of effective mosquito control are lacking. Our experiment evaluated impacts of the application of four commonly used mosquito control products (Aqua-PursuitTM, Duet®, Fyfanon®, and Scourge®) at high and low application rates up to 91 m from the application site on honey bee and mosquito mortality. We found that many products had minimal impact on honey bee mortality but acceptable mosquito mortality at the low application rate and far distances from the application site. While honey bee mortality was higher at the higher application rate, it was significantly lower than mosquito mortality. When accounting for variables encountered in the field, application rate, droplet size and distance were significant factors that determined honey bee mortality in some instances. Mosquito mortality was significantly influenced by distance, insecticide deposition, application rate, wind speed, and temperature. These findings provide valuable information for mosquito control professionals to utilize to minimize the impact of their necessary operations on honey bee populations.

Technical Abstract: Mosquito control reduces populations of mosquitoes to minimize the risk of mosquito-borne diseases. As part of an integrated approach to mosquito control, application of adulticides can be effective in rapidly reducing mosquito populations during times of high arbovirus transmission. However, impacts of these control measures on pollinators and other non-target organisms is of concern to mosquito control professionals, beekeepers, growers, and the general public. We evaluated mosquito and honey bee mortality when exposed to four commonly used mosquito adulticides (Aqua-PursuitTM, Duet®, Fyfanon®, and Scourge®) at regularly spaced distances up to 91.4 m from a truck mounted ULV application at high and low application rates. Insecticide deposition amount as well as the number and size of ULV droplets were measured. Honey bee mortality was significantly lower than mosquito mortality for all products, distances, and application rates, except the low rate of Scourge, which had low mortality for both bees and mosquitoes. Honey bee mortality significantly decreased with increased distance only for Fyfanon. Application rate was a significant factor for honey bee mortality for Aqua-Pursuit and Fyfanon. Increased number of drops significantly increased honey bee mortality due to Fyfanon. Increased droplet sizes (Dv50 and Dv90) were significant factors that increased honey bee mortality due to Aqua-Pursuit, Duet, and Fyfanon. No factors were significant for honey bee mortality due to Scourge. Mosquito mortality was significantly influenced by distance for Aqua-Pursuit and Fyfanon. Insecticide deposition and application rate were significant factors for mosquito mortality due to Aqua-Pursuit, Fyfanon, and Scourge. Mosquito mortality was significantly increased by higher wind speed for both Aqua-Pursuit and Scourge. Higher temperature significantly reduced mortality induced by Scourge. None of these factors were significant for mortality due to Duet. These results demonstrate that mosquito adulticides applied at low application rates and at far distances (i.e. >61 m) have limited impacts on honey bee mortality.