Neonicotinoid pesticides can reduce honeybee colony genetic diversity

PLoS One. 2017 Oct 23;12(10):e0186109. doi: 10.1371/journal.pone.0186109. eCollection 2017.

Abstract

Neonicotinoid insecticides can cause a variety of adverse sub-lethal effects in bees. In social species such as the honeybee, Apis mellifera, queens are essential for reproduction and colony functioning. Therefore, any negative effect of these agricultural chemicals on the mating success of queens may have serious consequences for the fitness of the entire colony. Queens were exposed to the common neonicotinoid pesticides thiamethoxam and clothianidin during their developmental stage. After mating, their spermathecae were dissected to count the number of stored spermatozoa. Furthermore, their worker offspring were genotyped with DNA microsatellites to determine the number of matings and the genotypic composition of the colony. Colonies providing the male mating partners were also inferred. Both neonicotinoid and control queens mated with drones originating from the same drone source colonies, and stored similar number of spermatozoa. However, queens reared in colonies exposed to both neonicotinoids experienced fewer matings. This resulted in a reduction of the genetic diversity in their colonies (i.e. higher intracolonial relatedness). As decreased genetic diversity among worker bees is known to negatively affect colony vitality, neonicotinoids may have a cryptic effect on colony health by reducing the mating frequency of queens.

MeSH terms

  • Animals
  • Bees / drug effects*
  • Bees / genetics
  • Female
  • Genetic Variation / drug effects*
  • Male
  • Nicotine / pharmacology*
  • Pesticides / pharmacology*
  • Sexual Behavior, Animal

Substances

  • Pesticides
  • Nicotine

Grant support

Financial support was provided by the Vinetum, Ricola, and Swiss National Science foundations, the Swiss Federal Office for the Environment, Agroscope, and the FIT BEE project (Bundesministerium für Ernährung und Landwirtschaft). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.