Comparison of Pesticide Exposure in Honey Bees (Hymenoptera: Apidae) and Bumble Bees (Hymenoptera: Apidae): Implications for Risk Assessments

This paper examines morphological, behavioral, and life history differences between honey bees (Apis mellifera L.) (Hymenoptera: Apidae) and bumble bees and the implications for exposure and susceptibility to pesticides to inform pesticide risk assessment.

Traditionally, regulatory pesticide risk assessments have relied on the honey bee as a surrogate test species for estimating the risk of pesticide exposure to all bee species.  However, concern has grown that pesticide risk assessment protocols may not be protective for non-Apis bees. The paper summarizes the bumble bee (Bombus spp.) portion of a workshop discussion hosted by the US EPA in 2017 (Pesticide Exposure Assessment Paradigm for Non-Apis Bees).

The authors point out that while the major pesticide exposure routes for bumble bees and honey bees are similar, bumble bees face exposure routes not relevant for honey bees, including the direct exposure of foraging queens and the exposure of larvae and adults to soil residues.

The major identified differences in probability of exposure between the two groups include:

  • Bumble bee queens have a very high probability of bodily contact from spray, dust, and plant surface residues compared to the honey bee queen’s low probability, since honey bee queens do not leave the hive except to mate or swarm.
  • Bumble bee queens have a very high probability of oral exposure through their direct consumption of nectar and pollen compared to honey bee queen’s low probability, since honey bee queens consume royal jelly, which has lower pesticide residues than unprocessed pollen and nectar.
  • Bumble bee larvae have increased oral exposure compared to honey bee larvae, due to bumble bee larvae’s higher consumption of pollen, consumption of unprocessed pollen and nectar, and longer larval development time.
  • Foraging bumble bee adults may experience higher exposure due to their ability to be active during weather conditions and at times that honey bees do not forage, and because bumble fee foragers visit more flowers per day.

The authors conclude that honey bee pesticide risk assessments may not always be protective of bumble bees, especially queens, in terms of exposure. A number of data gaps are identified.

 

Authors: 
Gradish, A. E., J. van der Steen, C. D. Scott-Dupree, A. R. Cabrera, G. C. Cutler, D. Goulson, O. Klein, D. M. Lehmann, J. Luckmann, B. O'Neill, N. E. Raine, B. Sharma, and H. Thompson
Journal: 
Environmental Entomology
Year published: 
2018
DOI: 
10.1093/ee/nvy168