Toxicity of Selected Acaricides to Honey Bees (Apis mellifera) and Varroa (Varroa destructor Anderson and Trueman) and Their Use in Controlling Varroa within Honey Bee Colonies.

Aleš Gregorc,John Adamczyk,Blair Sampson,Patricia R Knight,Mohamed Alburaki

doi:10.3390/insects9020055

Aleš Gregorc, John Adamczyk + Show 3 more

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https://doi.org/10.3390/insects9020055

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Abstract

The efficacies of various acaricides in order to control a parasitic mite, the Varroa mite, Varroa destructor, of honey bees, were measured in two different settings, namely, in laboratory caged honey bees and in queen-right honey bee colonies. The Varroa infestation levels before, during, and after the acaricide treatments were determined in two ways, namely: (1) using the sugar shake protocol to count mites on bees and (2) directly counting the dead mites on the hive bottom inserts. The acaricides that were evaluated were coumaphos, tau-fluvalinate, amitraz, thymol, and natural plant compounds (hop acids), which were the active ingredients. The acaricide efficacies in the colonies were evaluated in conjunction with the final coumaphos applications. All of the tested acaricides significantly increased the overall Varroa mortality in the laboratory experiment. Their highest efficiencies were recorded at 6 h post-treatment, except for coumaphos and thymol, which exhibited longer and more consistent activity. In the honey bee colonies, a higher Varroa mortality was recorded in all of the treatments, compared with the natural Varroa mortality during the pretreatment period. The acaricide toxicity to the Varroa mites was consistent in both the caged adult honey bees and workers in the queen-right colonies, although, two of these acaricides, coumaphos at the highest doses and hop acids, were comparatively more toxic to the worker bees.

Highlights

Varroa destructor [1] is a worldwide parasite of Apis, which causes significant brood and adult mortality in colonies of European honey bees (Apis mellifera L.)
The laboratory experiments tested the efficacy of the five acaricidal products (Apistan®, Apivar®, Apiguard®, HopGuard®, and CheckMite® ) in order to kill the Varroa mites and to determine the product toxicities to the worker honey bees
The highest cumulative Varroa mortality during the 48 h of exposure was recorded in the Apivar® (98.18% ± 1.8) and CheckMite®

Summary

Introduction

Varroa destructor [1] is a worldwide parasite of Apis, which causes significant brood and adult mortality in colonies of European honey bees (Apis mellifera L.). Reliable Varroa population diagnosis, monitoring, and control are the prominent issues in modern beekeeping, which, if improved, could reduce or reverse the global losses of honey bees and their colonies [2]. If the Varroa mites are left untreated, the commercial colonies will normally die within three to five years. Worsening the situation are the populations of the Varroa mites that have evolved a resistance to many of the synthetic acaricides [3,4,5]. Beekeepers increasingly rely on acaricides with different modes of action, many of which contain essential oils and organic acids as active ingredients [5,6,7].

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