Field-Level Sublethal Effects of Approved Bee Hive Chemicals on Honey Bees (Apis mellifera L)

Abstract

In a study replicated across two states and two years, we tested the sublethal effects on honey bees of the miticides Apistan (tau fluvalinate) and Check Mite+ (coumaphos) and the wood preservative copper naphthenate applied at label rates in field conditions. A continuous covariate, a colony Varroa mite index, helped us disambiguate the effects of the chemicals on bees while adjusting for a presumed benefit of controlling mites. Mite levels in colonies treated with Apistan or Check Mite+ were not different from levels in non-treated controls. Experimental chemicals significantly decreased 3-day brood survivorship and increased construction of queen supercedure cells compared to non-treated controls. Bees exposed to Check Mite+ as immatures had higher legacy mortality as adults relative to non-treated controls, whereas bees exposed to Apistan had improved legacy mortality relative to non-treated controls. Relative to non-treated controls, Check Mite+ increased adult emergence weight. Although there was a treatment effect on a test of associative learning, it was not possible to statistically separate the treatment means, but bees treated with Apistan performed comparatively well. And finally, there were no detected effects of bee hive chemical on colony bee population, amount of brood, amount of honey, foraging rate, time required for marked released bees to return to their nest, percentage of released bees that return to the nest, and colony Nosema spore loads. To our knowledge, this is the first study to examine sublethal effects of bee hive chemicals applied at label rates under field conditions while disambiguating the results from mite control benefits realized from the chemicals. Given the poor performance of the miticides at reducing mites and their inconsistent effects on the host, these results defend the use of bee health management practices that minimize use of exotic hive chemicals.

Xenobiotic Effects on Intestinal Stem Cell Proliferation in Adult Honey Bee (Apis mellifera L) Workers

“…Thus, the mortality data and ISC proliferation rates indicate synergism between fluvalinate and coumaphos, which has been reported in other contexts [21], [22]. The dosages used in the second experiment may be higher than average field exposure but they fall within the limits of concentrations measured in honey bee hives [18], [67] and the findings may therefore be relevant for honey bee health. Coumaphos and fluvalinate both target primarily the nervous system: Coumaphos, when converted to its metabolite coumaphos oxon, inhibits the acetylcholinesterase enzyme and fluvalinate serves as an agonist of the voltage-gated sodium channel [22].…”

Acute toxicity of five pesticides to Apis mellifera larvae reared in vitro

“…In our study, the LC 50 of coumaphos to honey bee larvae was 90.01 mg L −1 , about the maximum amount that was found in wax. The use of coumaphos in colonies has been associated with increased larval mortality of workers . The accumulative mortality of larvae was more than 50% when larvae were fed the diet contained 8 mg L −1 coumaphos for 6 days .…”

Sublethal Effects of Imidacloprid on Honey Bee Colony Growth and Activity at Three Sites in the U.S.

“…High coumaphos concentrations, such as 100 ppm or greater, affect queens by reducing oviposition and ovarian weight, causing early supercedure and queen cell rejection [27], and increasing worker mortality [22]. In the Mississippi study presented here, coumaphos levels were lower (5.8 ppm) and coumaphos alone did not have a significant impact on the amount of brood, although its interaction with imidacloprid was significant.…”

“…Capped brood levels and other metrics of colony phenology and size were measured at all sites, and continuous weight and temperature data, which have been shown to reflect honey bee colony growth, adult bee population size, foraging activity and brood production [20, 21] were monitored at the Arizona sites. Coumaphos, often used against bee pests and a common contaminant of hive products [22, 23], was applied to colonies in Mississippi before the imidacloprid application and those data were evaluated for interactions with imidacloprid. Proper apiary management at each site was given primacy over consistency across sites.…”