Planting of neonicotinoid-coated corn raises honey bee mortality and sets back colony development.

Olivier Samson-Robert,Valérie Fournier,Geneviève Labrie,Madeleine Chagnon

doi:10.7717/peerj.3670

Olivier Samson-Robert, Valérie Fournier + Show 2 more

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https://doi.org/10.7717/peerj.3670

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Abstract

Worldwide occurrences of honey bee colony losses have raised concerns about bee health and the sustainability of pollination-dependent crops. While multiple causal factors have been identified, seed coating with insecticides of the neonicotinoid family has been the focus of much discussion and research. Nonetheless, few studies have investigated the impacts of these insecticides under field conditions or in commercial beekeeping operations. Given that corn-seed coating constitutes the largest single use of neonicotinoid, our study compared honey bee mortality from commercial apiaries located in two different agricultural settings, i.e. corn-dominated areas and corn-free environments, during the corn planting season. Data was collected in 2012 and 2013 from 26 bee yards. Dead honey bees from five hives in each apiary were counted and collected, and samples were analyzed using a multi-residue LC-MS/MS method. Long-term effects on colony development were simulated based on a honey bee population dynamic model. Mortality survey showed that colonies located in a corn-dominated area had daily mortality counts 3.51 times those of colonies from corn crop-free sites. Chemical analyses revealed that honey bees were exposed to various agricultural pesticides during the corn planting season, but were primarily subjected to neonicotinoid compounds (54% of analysed samples contained clothianidin, and 31% contained both clothianidin and thiamethoxam). Performance development simulations performed on hive populations’ show that increased mortality during the corn planting season sets back colony development and bears contributions to collapse risk but, most of all, reduces the effectiveness and value of colonies for pollination services. Our results also have implications for the numerous large-scale and worldwide-cultivated crops that currently rely on pre-emptive use of neonicotinoid seed treatments.

Highlights

In recent years, decline in pollinators, both wild and managed, has garnered much attention, prompting considerable amount of research (see Lundin et al, 2015; Godfray et al, 2015How to cite this article Samson-Robert et al (2017), Planting of neonicotinoid-coated corn raises honey bee mortality and sets back colony development
A total of 38 different pesticides and metabolites, 19 insecticides, 11 fungicides, seven herbicides and one synergist, were found in the 74 dead honey bee samples (≥100 specimens) that were analysed throughout the study
In the 16 dead honey bee samples collected in control areas, three pesticides were identified, with some samples containing two pesticides and an average of 1 chemical per sample (Table 1)

Summary

Introduction

How to cite this article Samson-Robert et al (2017), Planting of neonicotinoid-coated corn raises honey bee mortality and sets back colony development. While a growing body of evidence has shed light on the multiple routes of exposure to these insecticides and their negative impacts of bee health (Maini, Medrzycki & Porrini, 2010; Pisa et al, 2015; Samson-Robert et al, 2015; Lundin et al, 2015; Tsvetkov et al, 2017; Woodcock et al, 2017) their implications in colony decline are still much debated (Blacquière & Van der Steen, 2017). Current gaps in our knowledge, at colony-level (Godfray et al, 2015) and from field-based approaches (Lundin et al, 2015), contribute to uncertainty surrounding these insecticides

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