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 (pË 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 pË 0.05 to pË 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.

Procenjivana je efikasnost kumafosa protiv varoe, kao i njegov uticaj na oksidativni status i preživljavanje medonosne pčele (Apis mellifera). Ispitivanje je obavljeno na košnicama iz istog pčelinjaka, ujednačenim po broju pčela, površini legla i količini uskladištene hrane. Na osnovu infestacije varoom, košnice su podeljene u dve grupe: neinfestirane (N) i infestirane (I). Obe grupe su bile ili tretirane (T) – NT i IT, ili netretirane (U) – NU i IU. Tretman infestiranih društava je kontrolisan naknadnom primenom amitraza. Efikasnost kumafosa iznosila je 96-97%. Ovaj organofosfat imao Zikic et al.: Anti-varroa efficiency of coumaphos and its influence on oxidative stress and survival of honey bees 373 je zanemarljiv efekat na preživljavanje pčela, ali je značajno uticao na njihov oksidativni status: aktivnosti superoksid-dismutaze (SOD), katalaze (CAT) i glutation Stransferaze (GST), i koncentracije malonil-dialdehida (MDA). Kumafos je značajno (p˂0,0001) smanjio aktivnost SOD kod neinfestiranih pčela, ali ju je povećao kod infestiranih. Za razliku od toga, aktivnosti CAT i GST, kao i koncentracije MDA značajno su se povećale (od p˂0,05 do p˂0,0001) posle tretmana u svim grupama, sa izuzetkom IT, u kojoj su opale. Kumafos je sam po sebi u neinfestiranim društvima prouzrokovao oksidativni stres kod pčela, slično kao Varroa u infestiranim. Međutim, u infestiranim košnicama on je smanjio oksidativni stress zahvaljujući efikasnosti protiv varoe, čime je doprineo oporavku društava. Uprkos određenim nedostacima, kumafos ostaje efikasna supstanca u borbi protiv varoe, ali ga treba koristiti sa oprezom, da bi se izbeglo dodatno opterećenje pčela prouzrokovano faktorima sredine koji mogu da izazovu red-oks neravnotežu.