Pesticide exposure assessment paradigm for solitary bees

Authors: SGOLASTRA, FABIO - Universita Di Bologna; HINAREJOS, SILVIA - Valent Usa Corporation; Pitts Singer, Theresa; JOSEPH, TIMOTHY - Landis International; LUCKMANN, JOHANNES - Rifcon Gmbh; RAINE, NIGEL - University Of Guelph

Submitted to: Environmental Entomology
Publication Type: Review Article
Publication Acceptance Date: 6/25/2018
Publication Date: 12/3/2018
Citation: Sgolastra, F., Hinarejos, S., Pitts-Singer, T., Joseph, T., Luckmann, J., Raine, N. 2018. Pesticide exposure assessment paradigm for solitary bees. Environmental Entomology. 48(1):22-35. https://doi.org/10.1093/ee/nvy105.
DOI: https://doi.org/10.1093/ee/nvy105

Interpretive Summary: Current pesticide risk assessment for bees relies on testing the European honey bee. However, most of the >20,000 species of bees worldwide are solitary, meaning that they do not live in large colonies. Huge differences in life histories traits between solitary bees and honey bees are likely to determine important differences in routes and levels of pesticide exposure. The objectives of this review and evaluation are to: 1) compare solitary bee and honey bee life history traits relevant for risk assessment; 2) summarize current knowledge about levels of pesticide exposure for solitary bee and honey bee; 3) identify knowledge gaps and research needs; 4) to ask if current honey bee risk assessment schemes cover routes and levels of exposure of solitary bees; and 5) identify potential solitary bee model species for pesticide risk assessment. Most solitary bee exposure routes seem well covered by current honey bee risk assessment schemes. Exceptions to this are exposure routes related to where these solitary bees build their nests and what materials (e.g., soil, leaves, resin) they use in nest construction. Exposure via soil is of particular concern because most solitary bee nest underground. Five commercially available cavity-nesting solitary bees fulfill most requirements to become model solitary bee species for risk assessment. Several characteristics of the lifestyles of these bees make them particularly suitable for semi-field and, to a lesser extent, field tests. Future studies are needed to address the levels of exposure of solitary bees in general, and the basic biology and rearing methods for ground-nesting species.

Technical Abstract: Current pesticide risk assessment for bees relies on a single social species, the honey bee, Apis mellifera L. (Hymenoptera: Apidae). However, most of the >20,000 species of bees worldwide are solitary. Huge differences in life histories traits between solitary bees and honey bees are likely to determine important differences in routes and levels of pesticide exposure. The objectives of this review and evaluation are to: 1) compare solitary bee and honey bee life history traits relevant for risk assessment; 2) summarize current knowledge about levels of pesticide exposure for solitary bee and honey bee; 3) identify knowledge gaps and research needs; 4) establish whether current honey bee risk assessment schemes cover routes and levels of exposure of solitary bees; and 5) identify potential solitary bee model species for pesticide risk assessment. Most solitary bee exposure routes seem well covered by current honey bee risk assessment schemes. Exceptions to this are exposure routes related to nesting substrates and nesting materials used by solitary bee. Exposure via soil is of particular concern because most solitary bee nest underground. Five commercially available cavity-nesting solitary bees (Osmia bicornis, O. cornifrons, O. cornuta, O. lignaria and Megachile rotundata) fulfill most requirements to become model solitary bee species for risk assessment. Several life history traits make these species particularly suitable for semi-field and, to a lesser extent, field tests. Future studies are needed to address the levels of exposure of solitary bees in general, and the basic biology and rearing methods for ground-nesting species.