Effects of Sublethal Doses of Imidacloprid on Young Adult Honeybee Behaviour

PLoS One. 2015 Oct 21;10(10):e0140814. doi: 10.1371/journal.pone.0140814. eCollection 2015.

Abstract

Imidacloprid (IMI), a neonicotinoid used for its high selective toxicity to insects, is one of the most commonly used pesticides. However, its effect on beneficial insects such as the honeybee Apis mellifera L is still controversial. As young adult workers perform in-hive duties that are crucial for colony maintenance and survival, we aimed to assess the effect of sublethal IMI doses on honeybee behaviour during this period. Also, because this insecticide acts as a cholinergic-nicotinic agonist and these pathways take part in insect learning and memory processes; we used IMI to assess their role and the changes they suffer along early adulthood. We focused on appetitive behaviours based on the proboscis extension response. Laboratory reared adults of 2 to 10 days of age were exposed to sublethal IMI doses (0.25 or 0.50ng) administered orally or topically prior to behavioural assessment. Modification of gustatory responsiveness and impairment of learning and memory were found as a result of IMI exposure. These outcomes differed depending on age of evaluation, type of exposure and IMI dose, being the youngest bees more sensitive and the highest oral dose more toxic. Altogether, these results imply that IMI administered at levels found in agroecosystems can reduce sensitivity to reward and impair associative learning in young honeybees. Therefore, once a nectar inflow with IMI traces is distributed within the hive, it could impair in-door duties with negative consequences on colony performance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Appetitive Behavior / drug effects
  • Association Learning / drug effects
  • Bees / drug effects*
  • Behavior, Animal / drug effects*
  • Conditioning, Classical / drug effects*
  • Imidazoles / pharmacology*
  • Insecticides / pharmacology*
  • Memory / drug effects
  • Neonicotinoids
  • Nitro Compounds / pharmacology*

Substances

  • Imidazoles
  • Insecticides
  • Neonicotinoids
  • Nitro Compounds
  • imidacloprid

Grants and funding

This work was supported by CONICET (The National Scientific and Technical Research Council (Spanish: Consejo Nacional de Investigaciones Científicas y Técnicas)), ANPCYT (Agencia Nacional de Promoción Científica y Tecnológica), and the University of Buenos Aires for financial support.