Sub-lethal effects of dietary neonicotinoid insecticide exposure on honey bee queen fecundity and colony development

Abstract

Many factors can negatively affect honey bee (Apis mellifera L.) health including the pervasive use of systemic neonicotinoid insecticides. Through direct consumption of contaminated nectar and pollen from treated plants, neonicotinoids can affect foraging, learning, and memory in worker bees. Less well studied are the potential effects of neonicotinoids on queen bees, which may be exposed indirectly through trophallaxis, or food-sharing. To assess effects on queen productivity, small colonies of different sizes (1500, 3000, and 7000 bees) were fed imidacloprid (0, 10, 20, 50, and 100 ppb) in syrup for three weeks. We found adverse effects of imidacloprid on queens (egg-laying and locomotor activity), worker bees (foraging and hygienic activities), and colony development (brood production and pollen stores) in all treated colonies. Some effects were less evident as colony size increased, suggesting that larger colony populations may act as a buffer to pesticide exposure. This study is the first to show adverse effects of imidacloprid on queen bee fecundity and behavior and improves our understanding of how neonicotinoids may impair short-term colony functioning. These data indicate that risk-mitigation efforts should focus on reducing neonicotinoid exposure in the early spring when colonies are smallest and queens are most vulnerable to exposure.

Early life stress affects mortality rate more than social behavior, gene expression or oxidative damage in honey bee workers

“…Mortality dynamics were more consistent than molecular and behavioral outcomes, indicating that life-time mortality patterns represent an important measure in a variety of experimental contexts. No evidence was found that our stressors specifically affected late-life mortality or senescence, which may be due to social buffering of early life stress effects in social species (Wu-Smart and Spivak, 2016) and small sample sizes to estimate mortality rates at advanced ages. Furthermore, our results corroborate the importance of social behavior in the determination of the lifespan of honey bee workers (Rueppell et al, 2007) and other social species.…”

Arthropod Pest Control for UK Oilseed Rape – Comparing Insecticide Efficacies, Side Effects and Alternatives

“…Take the impacts of neonicotinoid seed treatments on pollinators as an example: since the research gaps were identified by [71] (a literature review up to June 2015), many studies have investigated other active ingredients besides imidacloprid [72], pollinator species besides honey bees ( Apis ) [73], and/or impacts on the colony besides individual development [74]. Although more work needs to be done to improve the evidence base on this issue [75], respondents’ opinions could be changed by the new evidence.…”

Weight of evidence evaluation of a network of adverse outcome pathways linking activation of the nicotinic acetylcholine receptor in honey bees to colony death

“…But there are also concerns for declining or disappearing unmanaged wild and native bee species including bumble bees, stingless, and solitary bees (Goulson et al, 2015;Tomé et al, 2012;Mommaerts et al, 2010;Cameron et al, 2011;Sandrock et al, 2014). Pesticides, including neonicotinoids, have been identified as potentially contributing to the noted declines, possibly through many of the same KEs that were developed for the AOPs initiated via activation of the nAChR (Mommaerts et al, 2010;Wu-Smart and Spivak, 2016). From the AOPs described herein, upstream KEs are more likely to be conserved across a majority of bee species than downstream events, which may unfold differently due to, for example, variations in colony structure, including a complete lack thereof in most species.…”

“…It is recognized that even when considering activation of the nAChR there are other AOPs that could be, and subsequently should be, described. As examples, altered Ca 2+ -calmodulin activated signal transduction could also lead to impacts on mobility that could affect brood care, hygienic behavior, food processing, etc., or reduced pollen stores from abnormal foraging could affect queen egg laying activity, however these additional AOPs are yet to be described (Thiel and Köhler, 2016;Wu-Smart and Spivak, 2016). Therefore, the foundational AOP work described here on honey bees was conducted to facilitate further collaboration and additional AOP development by making it less daunting for other researchers to build on predefined KEs and KER descriptions.…”