Anti-Varroa Efficiency of Coumaphos and Its Influence on Oxidative Stress and Survival of Honey Bees

Abstract

Apart from the efficiency of coumaphos against Varroa mites, its impact on the oxidative status and survival of the honey bee (Apis mellifera) was assessed. The research was conducted on hives from the same apiary, equalised regarding the number of bees, brood area and food storage. Based on Varroa infestation the hives were allotted to two groups: non-infested (N) and infested (I). Both groups were either treated (T) – NT and IT, or untreated (U) – NU and IU. The treatment of infested bees was controlled with a follow-up treatment with amitraz. The efficiency of coumaphos was 96-97%. This organophosphate had a negligible effect on bee survival, but it significantly affected their oxidative status: superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities, and the concentrations of malonyl dialdehyde (MDA). Coumaphos significantly (p˂0.0001) decreased SOD activity in non-infested bees, but increased it in those infested. By contrast, both CAT and GST activities, as well as MDA concentrations significantly increased (from p˂0.05 to p˂0.0001) after treatment in all groups, with the exception of IT, where it declined. Coumaphos in non-infested hives caused oxidative stress per se, not unlike varroa in infested colonies. However, in infested colonies it decreased oxidative stress, owing to its efficacy against Varroa mites and contributed to the recovery of bee colonies. In spite of its certain downsides, coumaphos remains an effective anti-varroa substance, but should be used with precaution, not to add to the effects of environmental factors which may cause red-ox misbalance.

Contact varroacidal efficacy of lithium citrate and its influence on viral loads, immune parameters and oxidative stress of honey bees in a field experiment

“…Consequently, oxalic acid leads to damage of the epithelial cells of bee digestive tract ( Gregorc and Škerl, 2007 ; Rademacher et al, 2017 ), which leads to an increased activity of antioxidant enzymes and an increase in MDA concentration in their organisms. Similar effects were reported for coumaphos which, applied in the winter treatment of varroosis, induced changes in parameters of oxidative stress ( Zikic et al, 2020 ).…”

“…Follow-up treatments were done using CheckMite+ ® (Bayer, Healthcare AG), the most efficient registered varroacide in Serbia, probably because it is the least used of all available varroacides (as documented by a recent work of Brodschneider et al, 2022 ) so Varroa populations have not developed resistance to it. This “hard” acaricide showed 96%–97% varroacidal efficacy in Serbia ( Zikic et al, 2020 ) and 91.70% efficacy in neighboring country Croatia ( Tlak-Gajger and Susec, 2019 ), it is chemically unrelated to the test substance, thus fulfilling all requirements of European Medicines Agency ( EMA, 2021 ) for follow-up treatment.…”

“…In each sample, consisting of 30 bees, following oxidative stress parameters were assessed: activities of three antioxidative enzymes: superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), and concentration of malondialdehyde (MDA). Analyses were done by UV/VIS Spectrophotometer BK-36 S390 (Biobase) with methodology described in Taric et al (2020) and Zikic et al (2020) .…”

Lithium salts: assessment of their chronic and acute toxicities to honey bees and their anti‐Varroa field efficacy

“…Over the last 20 years, coumaphos, taufluvalinate, flumethrin and amitraz have been the synthetic acaricides most commonly used against Varroa. [9][10][11] Overuse and repeated use of these acaricides have led to the evolution of resistance in mite populations, endangering the future efficacy of these substances. [12][13][14][15][16] In addition, residues of the aforementioned acaricides have been found in bee products such as honey, pollen and propolis, where they present potential health hazards to consumers.…”

“…Chemical treatments are the most effective way to control this mite. Over the last 20 years, coumaphos, tau‐fluvalinate, flumethrin and amitraz have been the synthetic acaricides most commonly used against Varroa 9–11 …”