Dietary traces of neonicotinoid pesticides as a cause of population declines in honey bees: an evaluation by Hill's epidemiological criteria

Abstract

It is concluded that dietary neonicotinoids cannot be implicated in honey bee declines, but this position is provisional because important gaps remain in current knowledge. Avenues for further investigations to resolve this longstanding uncertainty are therefore identified.

UHPLC-DAD method for the determination of neonicotinoid insecticides in single bees and its relevance in honeybee colony loss investigations

“…Its main advantage is its capability to evaluate the uptake variability of individual exposed bees, an important parameter in the assessment of both real exposure and its consequent toxic effects [13]. The method is currently applied in the quantification of new mechanisms of exposure of honeybees to neonicotinoid insecticides and in the study of their degradation processes, both in vivo and post mortem.…”

“…Although several causes have been hypothesized, pesticides have received more consideration by the scientific community. The experimental evidence for an association between the colony loss phenomena, including losses occurring in early spring, and the use of neonicotinoid insecticides, in particular as seed dressing in corn crops, an agricultural practice used worldwide, is extensive and there is sufficient mechanistic understanding to put the question of causality beyond reasonable doubt [6][7][8][9][10][11][12][13].…”

“…In fact, since Greatti et al [20] demonstrated the possible release of seed coating insecticides through the fan drain of the pneumatic drilling machine during corn sowing and hypothesized that bees are exposed to the neonicotinoid-containing particles falling off to the vegetation at the field margin, experimental results have shown that the neonicotinoid content in nectar and pollen collected from the surrounding vegetation was always around 50 ppb or lower [12,[21][22][23], whereas higher doses are necessary for an acute toxic effect [13,[16][17][18]24].…”

Neonicotinoid clothianidin adversely affects insect immunity and promotes replication of a viral pathogen in honey bees

“…Concurrent studies on bumblebees have provided further confirmation of the hypothesis that neonicotinoids can have a wider negative impact on pollinators (19,20). Importantly, exposure to neonicotinoids is often associated with a higher pathogenic impact on bees (21)(22)(23), although the merely descriptive results reported are somewhat contrasting and do not support any clear epidemiological interpretation, due to significant gaps in our knowledge of if and how these insecticides act on honey bee immunity (24). Here we address this issue, focusing on the mechanism underlying the presumed immunosuppressive activity of neonicotinoids on insects.…”

Genotoxic Potential of the Insecticide Imidacloprid in a Non-Target Organism (<i>Oreochromis niloticus</i>-Pisces)

“…It can cause toxicity in ecosystem organisms, such as earthworms [18], amphipods, microalgae [19] and crustacean [20] among others. Also, the application of this insecticide has been associated with the death of bees in different regions of the country [21] [22]. Besides toxicity studies, it has been evaluated the genotoxicity in plants and animals.…”