Does Imidacloprid Seed-Treated Maize Have an Impact on Honey Bee Mortality?

Abstract

Beekeepers suspected maize, Zea mays L., treated with imidacloprid to result in substantial loss of honey bee (Hymenoptera: Apidae) colonies in Belgium. The objective of this study was to investigate the potential impact of maize grown from imidacloprid-treated seeds on honey bee mortality. A survey of 16 apiaries was carried out, and all maize fields treated or not with imidacloprid were located within a radius of 3,000 m around the observed apiaries. Samples of honey, beeswax, and bees were collected in three colonies per apiary and analyzed for pesticide contain by liquid chromatography-tandem mass spectrometry and gas chromatography-tandem mass spectrometry. We first found a significant correlation between the number of colonies per apiary and the mortality rates in an apiary. In addition, this mortality rate was inversely correlated with the surface of maize fields treated and not with imidacloprid, suggesting that this pesticide do not interact with bees' fitness. Moreover, a very large number of our samples contained acaricides either prohibited or ineffective against Varroa destructor (Anderson & Trueman) (Acari: Varroidae), suggesting that the treatment methods used by the beekeepers to be inadequate for mite control. Our results support the hypothesis that imidacloprid seed-treated maize has no negative impact on honey bees.

Effects of exposure of honey bee colonies to neonicotinoid seed–treated maize crops

“…The residues of neonicotenoids have been extensively studied in recent years. And yet, beecollected pollen contaminated with imidacloprid was found only in the two studies, however, reported residues caused no negative impact on honey bees colonies (Nguyen et al 2009;Chauzat et al 2011). Though the surface of maize crops protected with clothianidin was significantly lower, the proportion of Z. mays grains in pollen loads was 15 times higher, and it was 6 times higher in bee bread.…”

Honeybee health in South America

“…Sublethal doses of pesticides induce negative effects on honeybees (Nguyen et al 2009;Xavier et al 2015). In Brazil, de Almeida Rossi et al (2013) reported that sublethal doses of imidacloprid induced negative effects on malpighian tubules of Africanized bees.…”

Short communication. The detection of Israeli Acute Paralysis virus (IAPV), fipronil and imidacloprid in professional apiaries are not related with massive honey bee colony loss in Spain

“…Imidacloprid is a neonicotinoid that is toxic to honey bees, and authorized in Spain to treat corn (Zea mays) crops, fruit trees and vegetable crops but their prevalence in stored pollen samples from Spain is very low as described previously and not related with colony losses from professional apiaries (Higes et al, 2009b). Actually the bee losses observed by beekeepers in France or Belgium are not attributed to imidacloprid and other causes such as pathogens or other unidentified synergistic factors have been considered in the origin (Schmuck, 2004;Faucon et al, 2005;Nguyen et al, 2009).…”