The American Mosquito Control Association (AMCA) is keenly aware of and appreciates the vital role that pollinating insects such as honey bees, wild bees and butterflies play in the availability of many agricultural products and fully supports science-based efforts to ensure pollinator populations are not adversely affected by application of mosquito management products designed to protect public health.
It is the policy of the AMCA that, to the extent practicable, governmental and contract mosquito management entities coordinate their activities with local beekeepers in addition to extension offices and conduct mosquito management operations so as to minimize exposures of beehives, individual bees and other arthropod pollinators to public health products used in mosquito management. To this end, the AMCA encourages an ongoing dialogue among all stakeholders, including pollinating insect ecologists so that mandated management activities result in minimal impact to pollinators. At a minimum, this dialogue should include: provision of lists of local beekeepers and contact information, notification procedures, hive locations, mosquito management products to be applied, status of native bee and butterfly populations and areas that are routinely sprayed based on survey data. In addition, all stakeholders need to acknowledge the operational constraints of both beekeepers and mosquito management personnel that may prevent full implementation of comprehensive pollinator protection measures at times. Regardless, it is the mosquito management entity’s responsibility to facilitate pollinator protection to the extent their mandate allows.
It is in the interest of all stakeholders that exposure of pollinators to mosquito management products be minimized. Developing more foraging habitats for pollinators is critical to their health and is fully endorsed by the mosquito management profession. In addition, mosquito management entities utilizing Ultra Low Volume (ULV) spray applications do so before dawn or after dusk to both target mosquitoes when they are most active and to avoid day-active pollinators such as butterflies and bees that have returned from foraging.
It is also the policy of the AMCA that applicators strictly conform to restrictions posted on product labels as a matter of both federal law and environmental stewardship. Product labels often contain specific language such as “do not apply when flowers are in bloom…” regarding application methods that minimize pollinator exposure. This is the law and it must be complied with.
As a practical matter, stakeholders must acknowledge that mosquito management efforts are usually significantly intensified shortly after weather disasters or disease outbreaks. Most states and/or counties maintain websites that post announcements concerning when and where a spray event will occur. In addition, mosquito management districts usually either have their own websites or are linked via county/municipal websites, with information regarding management operations. The critical point, though, is to maintain open and honest communication among all stakeholders and mosquito management entities to avoid mishaps and pollinator kills.
All this being said, there is no evidence, including incident reports, establishing that the extremely low product dosages used in ultra low volume (ULV) applications of mosquito adulticides present a material risk to pollinator health. This is demonstrated by the results of numerous studies on nontarget effects from truck-mounted and aerial ULV applications of labeled mosquito control products. These are space sprays and are not foliar applications and do not leave residues that might affect pollinators. A bibliography of published research is provided below, with additional documents available at the links.
There has been a recent push by some groups for establishing a standard of no harm to individual non‐target insects from exposure to mosquito control products. While theoretically a worthwhile goal, this represents an unattainable standard for broad-spectrum public health pesticides and extends far beyond the current standard of no unreasonable risk to populations of beneﬁcial insects.
There is little doubt that if bees and other pollinators are in the path of the mosquito control application treatment and are unprotected, they could be aﬀected. However, honey bees are typically in the hive and other pollinators are also sequestered for the night when treatments occur and therefore are mostly unaﬀected.
RESEARCH ON PESTICIDE EFFECTS ON HONEY
Dr. Kristen Healy and her colleagues in the Department of Entomology at Louisiana State University have sought to document effects of mosquito control applications and other stressors on honeybee health in collaboration with the USDA Honey Bee lab in Baton Rouge. A bulletin published by the LSU Agricultural Center details some recent work by Dr. Healy on mosquito control application’s effects on pollinators on honey bees.
(07/28/16) BATON ROUGE, La. – LSU AgCenter researchers in the Department of Entomology found mosquito control done properly has minimal effects on the health of honey bees. The three-part study, funded by a 2013 grant from the U.S. Environmental Protection Agency, evaluated the effects of pesticides on honey bees.
“You have a lot of attention focused on caring for bees and keeping them healthy,” said AgCenter entomologist Kristen Healy. “They produce honey, but they’re also important because they pollinate crops worldwide.”
The project was a collaboration among scientists at the LSU AgCenter, the U. S. Department of Agriculture Honey Bee Breeding, Genetics and Physiology Research Laboratory in Baton Rouge, East Baton Rouge Parish Mosquito Abatement and Rodent Control and USDA agricultural engineers from Texas. Local beekeepers were also involved in the study.
The research included laboratory, semi-field and field components. AgCenter researchers conducted lab tests using specific insecticides that target mosquitos to find toxicity levels for bees.
Research in the past focused on toxicity in a lab without real-world testing in the field. “We know the concentration that would kill a bee, but is it realistically going to get exposed to that concentration in the field?” Healy said.
After determining lethal concentrations, scientists conducted semi-field tests, where a truck sprayed six of the most common mosquito control insecticides toward pairs of cages containing bees and mosquitos. The cages were placed on poles from 50 feet apart to 300 feet apart, the typical distance insecticides can drift from spray trucks.
“This is the highest possible label rate that mosquito control would ever use out of a truck, and we didn’t see any bee mortality, even at 50 feet,” Healy said.
Mosquito control products use extremely small doses that target mosquitos, and the chemicals break down within hours. “Mosquitos are 100 times more susceptible to these pesticides than bees are,” she said.
The third stage included field tests. Local beekeepers volunteered, half of them with hives in areas of frequent mosquito treatment, with the other half in areas without control.
Scientists found no differences in the mortality rates of bees in both groups. “These pesticide concentrations used out in the field are not high enough to kill bees,” Healy said.
Researchers also measured stress by analyzing indicator enzymes from the field-test bees. They found no difference in stress between the two groups.
Mosquito control agencies do not indiscriminately spray chemicals, Healy said. They use science-based research like surveillance, trapping and population counts while testing for pathogens like West Nile virus and Zika virus to plan targeted mosquito control.
Bees stay inside their hives during the night when mosquito controls are usually sprayed and forage during the day when chemicals have disappeared. Still, it’s important for beekeepers and mosquito control agencies to communicate frequently.
“I’m happy that we’re not killing bees with mosquito control,” Healy said. “The exciting part was having people with both interests that were there every step of the way.”
“They say I don’t like mosquitos, so if it’s not having an effect on my bees, I think I’d rather opt for protecting my family and pets against West Nile and Zika,” she said.
Dr. Healy’s colleagues have published a number of studies on pesticide effects on pollinators, which are provided via links. In addition, a link to her podcast on mosquito control and pollinators is provided below:
Mosquito Abatement and Pollinators
Dr. Robert Peterson is a professor in the Department of Land Resources and Environmental Sciences. Montana State University. He is a well-published authority on
agricultural and biological risk assessment. Dr. Peterson’s lab has produced 3 youtube videos discussing the risks asociated with mosquito control products used in public health and the risks they present to nontargets
Acute Toxicity Of Permethrin, Deltamethrin, And Etofenprox To The Alfalfa Leafcutting Bee
Effects of Etofenprox on Leafcutter bees https://www.youtube.com/watch?v=JPftZeUJ_38&t=11s, and
Beneficial Insects and Mosquito Control Products
Mr. Kirk Tubbs is the manager of the Twin Falls County, Idaho Pest Abatement District, which has responsibility for vector control in his jurisdiction. He also runs a berry farm and is in a unique position to discuss the effects of mosquito control products on pollinators in the real world.
The following references regarding non-target effects of mosquito control applications was kindly provided by Dr. Carl Doud, Director of the Midland County, Michigan, Mosquito Control District and Dr.Robert Peterson. They include a number of studies specifically involving pollinators.
Abbene IJ, Fisher SC, Terracciano SA. 2005. Concentrations of insecticides in selected surface water bodies in Suffolk County, New York, before and after mosquito spraying, 2002-04 (No. 2005-1384). A study to measure contamination in surface waters by pyrethroids (resmethrin and sumithrin) before and following aerially-applied and truck-mounted ULV applications for West Nile Virus control was conducted in Suffolk County, New York. Among the samples taken following truck-mounted applications, none of the chemicals were detected in any samples.
Antwi, F.B., and R.K.D. Peterson. 2009. Toxicity of δ-phenothrin and resmethrin to non-target insects. Pest Management Science 65:300-305.
Boyce WM, Lawler SP, Schultz JM, McCauley SJ, Kimsey LS, Niemela MK, Nielsen CF, Reisen WK. 2007. Nontarget effects of the mosquito adulticide pyrethrin applied aerially during a West Nile virus outbreak in an urban California environment. Journal of the American Mosquito Control Association 23(3): 335-339. Examined the impact of ULV on honey bees, butterflies and dragonflies. The researchers observed little impact on these insects in the study, likely due to the very low amounts of pesticide.
Breidenbaugh, M.S., and F.A. de Szalay. 2010. Effects of aerial applications of naled on nontarget insects at Parris Island, South Carolina. Environmental Entomology 39:591-599.
Caron DM. 1979. Effects of some ULV mosquito abatement insecticides on honey bees. Journal of Economic Entomology 72(1): 148-151. Evaluated malathion, pyrethrum & naled. Caged bees suffered significant malathion moratlity. Night applications had no observable effect on bee colonies.
Chaskopoulou A, Thrasyvoulou A, Goras G, Tananaki G, Latham MD, Kashefi J, Pereira RM, Koehler PG. 2014. Nontarget effects of aerial mosquito adulticiding with water-based unsynergized pyrethroids on honey bees and other beneficial insects in an agricultural ecosystem of north Greece. Journal of Medical Entomology 51(3): 720-724. Tested two aquatic pyrethroid insecticides applied from rotary wing. Assessed impact on honey bees, ladybugs and lacewings. No non-target mortalities observed and bee hives showed no detrimental effects.
Davis RS, Peterson RKD. 2008. Effects of single and multiple applications of mosquito insecticides on non-target arthropods. Journal of the American Mosquito Control Association 24: 270-280. Efforts to measure the impact of single and multiple ULV applications of permethrin on aquatic invertebrates such as amphipods and Daphnia pulex took place in Benton Lake National Wildlife Refuge in Montana. Observed few if any deleterious effects and concluded that persistent biological impacts were very unlikely to occur.
Davis RS, Peterson RKD, Macedo PA. 2007. An ecological risk assessment for insecticides used in adult mosquito management. Integrated Environmental Assessment and Management 3: 373-382. Conducted an ecological risk assessment of common pyrethroids, including permethrin used for mosquito control. Monitored for potential effects on aquatic vertebrates as well as invertebrates. Risk quotients from the assessment were small and insignificant for both chronic and acute effects. For instance, they measured the insecticide residues to be more than ten orders of magnitude below toxic levels for trout.
Hester PG, Shaffer KR, Tietze NS, Zhong H, Griggs NL. 2001. Efficacy of ground-applied ultra-low-volume malathion on honey bee survival and productivity in open and forest areas. Journal of the American Mosquito Control Association 17(1): 2-7. Some mortality if within 7-15 m from spray for bees outside hive. No observable effects on overall colony to include health and honey production.
Hoang TC, Rand GM. 2015. Mosquito control insecticides: a probabilistic ecological risk assessment on drift exposures of naled, dichlorvos (naled metabolite) and permethrin to adult butterflies.Science of the Total Environment 502:252–265 DOI 10.1016/j.scitotenv.2014.09.027.
Hoang TC, Pryor RL, Rand GM, Frakes RA. 2011. Use of butterflies as nontarget insect test species and the acute toxicity and hazard of mosquito control insecticides. Environmental Toxicology and Chemistry 30(4):997–1005 DOI 10.1002/etc.462.
Jensen T, Lawler SP, Dritz DA. 1999. Effects of ultra-low volume pyrethrin, malathion, and permethrin on nontarget invertebrates, sentinel mosquitoes, and mosquitofish in seasonally impounded wetlands. Journal of the American Mosquito Control Association 15(3): 330-338. Evaluated effects on non-target aquatic invertebrates and mosquito fish of permethrin over two seasons in a wetland. No observable reduction in abundance of invertebrates was detected, although cages mosquitoes placed in the area sprayed were effectively killed. Furthermore, no mortality among fish was observed.
Knepper RG, Walker ED. 2001. Preliminary studies of the occurrence of Cottony Maple Scale in five Michigan counties. Wingbeats 12(2): 14. Study evaluated if mosquito control ULV applications result in outbreaks of CMS due to mortality of natural predators. Found higher CMS in Saginaw County, with mosquito control (MC) than areas without MC. However, abundance of CMS did not correlate with the abundance of sprays as years with more spraying also had fewer CMS.
Knepper RG, Walker ED, Wagner SA, Kamrin MA, Zabik MJ. 1996. Deposition of malathion and permethrin on sod grass after single, ultra-low volume applications in a suburban neighborhood in Michigan. Journal of the American Mosquito Control Association 12(1): 45-51. Measured deposition on grass following ULV. Found that materials quickly break down following application. Did not assess human exposure risk but results were similar to other studies that have shown minimal risk (see Moore et al. 1993).
Kwan JA, Novak MG, Hyles TS, Niemela MK. 2009. Mortality of nontarget arthropods from an aerial application of pyrethrins. Journal of the American Mosquito Control Association 25(2):218–220DOI 10.2987/08-5858.1.
Lawler SP, Dritz DA, Johnson CS, Wolder M. 2008. Does synergized pyrethrin applied over wetlands for mosquito control affect Daphnia magna zooplankton or Callibaetis californicus mayflies? Pest Management Science 64(8): 843-847. Repeated applications of permethrin were made directly over a wetland area and effects measured on Daphnia magna and mayfly nymphs. Though they were able to measure residue of the insecticide in water samples, no detectible deleterious effects were observed to these non-target organisms.
Oberhauser KS, Manweiler SA, Lelich R, Blank M, Batalden RV, De Anda A. 2009. Impacts of ultra-low volume resmethrin applications on non-target insects. Journal of the American Mosquito Control Association 25(1): 83-93. Some mortality observed among Monarch larvae and adults within 150m of spray.
Peterson, R.K.D. 2010. Mosquito management and risk. Wing Beats, a publication of the Florida Mosquito Control Association 21(3):28-31.
Peterson, R.K.D., C.J. Preftakes, J.L. Bodin, C.R. Brown, A.M. Piccolomini, and J.J. Schleier. 2016. Determinants of acute mortality of Hippodamia convergens (Coleoptera: Coccinellidae) to ultra-low volume permethrin used for mosquito management. PeerJ DOI 10.7717/peerj.2167
Phillips BM, Anderson BS, Voorhees JP, Siegler K, Denton D, TenBrook P, Larson K, Isorena P, Tjeerdema RS. 2014. Monitoring the aquatic toxicity of mosquito vector control spray pesticides to freshwater receiving waters. Integrated Environmental Assessment and Management 10(3): 449-455. Some water and sediment samples toxic following ULV spray, mostly associated with naled rather than pyrethroids. PBO thought to contribute to some toxic samples due to synergy with background pyrethroids in water/sediment. Overall concluded that most ULV applications of adulticides do NOT pose a significant acute risk to aquatic organisms.
Piccolomini, A.M., M.L. Flenniken, K.M. O’Neill, and R.K.D. Peterson. 2018. The effects of an ultra-low-volume application of etofenprox for mosquito management on Megachile rotundata (Hymenoptera: Megachilidae) larvae and adults in an agricultural setting. Journal of Economic Entomology, in press, doi: 10.1093/jee/tox343. There was no significant difference in the proportion of dead and live larvae when the control group was compared with the group directly treated with etofenprox. We also did not observe a significant difference in the number of emerged adults reared from the treated shelters, and the number of completed cells after exposure to the insecticide continued to increase throughout the summer, indicating that provisioning adults were not affected by the insecticide treatment. The results suggest that the amount of etofenprox reaching nest shelters was not sufficient to cause significant mortality.
Schleier III JJ, Davis RS, Shama LM, Macedo PA, Peterson RKD. 2008. Equine risk assessment for insecticides used in adult mosquito management. Human and Ecological Risk Assessment 14: 392-407. Assessed risk of horse exposure to three pyrethroids and two organophosphates applied by ULV. Concluded that risk well below levels of concern based on risk quotients.
Schleier III JJ, Peterson RKD, Macedo PA, Brown DA. 2008. Environmental concentrations, fate, and risk assessment of pyrethrins and piperonyl butoxide after aerial ultralow-volume applications for adult mosquito management. Environmental Toxicology and Chemistry 27: 1063-1068. Measured deposition of pyrethrins following aerial ULV applications. No pyrethrins were detectable in water samples. Where pyrethrins were detected, the risk quotients for aquatic surrogate species did not reach the U.S. EPA level of concern for endangered aquatic organisms and returned to baseline levels within 36 hours.
Schleier III JJ, Peterson RKD. 2010. Deposition and air concentrations of permethrin and naled used for adult mosquito management. Archives of Environmental Contamination and Toxicology 58: 105-111. Study confirmed that risk assessment models used to estimate environmental deposition of ULV insecticides sufficiently overestimate concentrations (i.e. are sufficiently conservative).
Schleier III, J.J., and R.K.D. Peterson. 2010. Toxicity and risk assessment of permethrin and naled to non-target terrestrial insects after adult mosquito management. Ecotoxicology 19:1140-1146.
Schleier III, J.J. and R.K.D. Peterson. 2011. Pyrethrins and pyrethroid insecticides. In O. Lopez and J.G. Fernándes-Bolaños (eds.). Green Trends in Insect Control. RSC Green Chemistry No. 11. Royal Society of Chemistry, London.
Schleier III, J.J., and R.K.D. Peterson. 2012. The joint toxicity of type I, II, and non-ester pyrethroid insecticides. Journal of Economic Entomology 105:85-91.
Schleier III JJ, Peterson RKD. 2013. A refined aquatic ecological risk assessment for a pyrethroid insecticide used for adult mosquito management. Environmental Toxicology and Chemistry 32: 948-953. Developed an aquatic risk assessment for pyrethroid insecticides and estimated that the projected concentrations from ULV application would amount to less than 0.0001% of aquatic organisms potentially affected with a lethal concentration.
Solomon KR, Giddings JM, Maund SJ. 2001. Probabilistic risk assessment of cotton pyrethroids: I. Distributional analyses of laboratory aquatic toxicity data. Environmental Toxicology and Chemistry 20(3): 652-659. Regarding the relative risk to aquatic organisms, permethrin was measured among the lowest in aquatic toxicity of the various pyrethroids.
Stevenson HR. 1980. A review on the effects of ultra low volume insecticide treatments to honey bees, Apis mellifera (L.). Proceedings of the Florida Anti-Mosquito Association 51: 11-14. Except for chlorpyrifos, ULV insecticides, under ideal conditions, will not subject honey bees to lethal doses.
Weston DP, Holmes RW, You J, Lydy MJ. 2005. Aquatic toxicity due to residential use of pyrethroid insecticides. Environmental Science & Technology 39(24): 9778-9784. Investigated the source of toxic levels of pyrethroids in water and sediment in Roseville, California. The evidence pointed to residential lawn applications and against mosquito control as the specific pyrethroid used by mosquito control (resmithrin) was not detected in any of the samples.
Zhong H, Hribar LJ, Daniels JC, Feken MA, Brock C, Trager MD. 2010. Aerial ultra-low-volume application of naled: impact on nontarget imperiled butterfly larvae (Cyclargus thomasi bethunebakeri) and efficacy against adult mosquitoes (Aedes taeniorhynchus). Environmental Entomology 39(6):1961–1972 DOI 10.1603/EN10089.
Zhong HE, Latham M, Hester PG, Frommer RL, Brock C. 2003. Impact of naled on honey bee survival and productivity: aerial ULV application using a flat fan nozzle system. Archives of Environmental Contamination and Toxicology 45(2):216–220 DOI 10.1007/s00244-002-0185-8.
Zhong HE, Latham M, Payne S, Brock C. 2004. Minimizing the impact of the mosquito adulticide naled on honey bees, Apis mellifera (Hymenoptera: Apidae): aerial ultra-low-volume application using a high pressure nozzle system. Journal of Economic Entomology 97(1):1–7 DOI 10.1603/0022-0493-97.1.1.
Further information can be obtained at the Pesticide Environmental Stewardship Website at https://pesticidestewardship.org/pollinator-protection/. It should be noted that AMCA has been awarded the distinction of Pesticide Environmental Stewardship Program Champion. Information can also be found at https://www.epa.gov/pollinator-protection.