Effects of late miticide treatments on foraging and colony productivity of European honey bees (Apis mellifera)

Authors: COLIN, THEOTIME - Macquarie University; FORSTER, CASEY - Macquarie University; WESTACOTT, JACK - Macquarie University; WU, XIAOBU - Jiangxi Agricultural University; Meikle, William; BARRON, ANDREW - Macquarie University

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2020
Publication Date: 1/16/2021
Citation: Colin, T., Forster, C.C., Westacott, J., Wu, X., Meikle, W.G., Barron, A.B. 2021. Effects of late miticide treatments on foraging and colony productivity of European honey bees (Apis mellifera). Apidologie. 52:474-492. https://doi.org/10.1007/s13592-020-00837-3.
DOI: https://doi.org/10.1007/s13592-020-00837-3

Interpretive Summary: Varroa mites are perhaps the most important problem for beekeepers, and so bee colonies in the USA, as well as Latin America, Europe, Asia and Africa, are usually treated for Varroa mites using a variety of pesticides. Treating bee colonies for mites is important and can often save the colony, but the impact of the pesticides themselves on colony health, apart from the reduction in mite damage, is seldom studied because of the difficulty in separating the effects of mites from the effects of pesticides. Australia remains the only remaining beekeeping continent without Varroa, so researchers tested the mite pesticides there, carefully monitoring bee colony growth, activity and thermoregulation. The researchers did not find any significant effects on the number of adult bees or larvae, but one miticide, Tau-fluvalinate, caused bees to forage earlier in life than they otherwise would have and the other miticide, thymol, negatively affected thermoregulation in the colonies. The effects were in general not large, but may have longer-term impacts.

Technical Abstract: Chemical miticides are used routinely in honey bee colonies worldwide as treatment for the parasitic mite Varroa destructor, but there have been very few long term colony-level field studies of the impacts of miticides on the bees themselves. Lab-based studies with individual bees or bees in small groups have highlighted many negative effects of miticides on bee behaviour and physiology, hence there is an urgent need to better understand the consequences of miticides on honey bee colonies in an apicultural setting. Here we compared effects of commercial treatments of the miticides tau-fluvalinate and thymol, and controls, on honey bee colonies and bee foraging behaviour over five months, from Autumn through Winter in Sydney, Australia. Since V. destructor does not occur in Sydney, in this study we could isolate the direct effects of the miticides from indirect effects resulting from reduced mite load. We found the Autumn treatment of either miticide caused no significant change in bee adult or brood population or size of food stores. Neither miticide reduced bee longevity. Tau-fluvalinate caused bees to start foraging earlier in life and perform shorter trips, but no other effects on foraging behaviour were documented. To conclude, in the Australian environment, minimal negative effects of Autumn thymol or tau-fluvalinate treatments were observed on bees or bee colony performance.