2012. “In situ replication of honey bee colony collapse disorder.” Bulletin of Insectology

The concern of persistent loss of honey bee (Apis mellifera L.) colonies worldwide since 2006, a phenomenon referred to as col-ony collapse disorder (CCD), has led us to investigate the role of imidacloprid, one of the neonicotinoid insecticides, in the emer-gence of CCD. CCD is commonly characterized by the sudden disappearance of honey bees (specifically worker bees) from hives containing adequate food and various stages of brood in abandoned colonies that are not occupied by honey bees from other colo-nies. This in situ study was designed to replicate CCD based on a plausible mechanistic hypothesis in which the occurrence of CCD since 2006 was resulted from the presence of imidacloprid, one of the neonicotinoid insecticides, in high-fructose corn syrup (HFCS), fed to honey bees as an alternative to sucrose-based food. We used a replicated split-plot design consisting of 4 inde-pendent apiary sites. Each apiary consisted of 4 different imidacloprid-treated hives and a control hive. The dosages used in this study were determined to reflect imidacloprid residue levels reported in the environment previously. All hives had no diseases of symptoms of parasitism during the 13-week dosing regime, and were alive 12 weeks afterward. However, 15 of 16 imidacloprid-treated hives (94%) were dead across 4 apiaries 23 weeks post imidacloprid dosing. Dead hives were remarkably empty except for stores of food and some pollen left, a resemblance of CCD. Data from this in situ study provide convincing evidence that expo-sure to sub-lethal levels of imidacloprid in HFCS causes honey bees to exhibit symptoms consistent to CCD 23 weeks post imida-cloprid dosing. The survival of the control hives managed alongside with the pesticide-treated hives unequivocally augments thi