Discovery of a critical time-point in the development and handling of an orchard pollinator, the blue orchard bee (Osmia lignaria, Hymenoptera: Megachilidae)

Authors: WILLIAMS, MARY-KATE - Utah State University; Cox-Foster, Diana

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: As part of orchard pollination, blue orchard bees (Osmia lignaria) are propagated in nesting boxes and the nest boxes are handled during the summer while the bees are in the larval and pupal stages. Insects are normally resilient to physical damage, utilizing unique morphologies to protect themselves against predators, pathogens, and multiple types of physical damage (like punctures, piercing, or blunt force). Other structures, such as cocoons and puparia, may add an extra layer of protection during metamorphosis; however, from our observations, this may not be the case, even if insects fall a short distance during metamorphosis. During an experiment, a sticky board holding cocoons of blue orchard bees (Osmia lignaria) was dropped on a linoleum floor. The samples were thought to not be harmed by the short distance fall; however, an X-radiation image and follow up revealed that all samples on the dropped sticky board died after impact. Utilizing a sticky board from the same study that had not fallen, we were able compare survivorship, developmental time points, and the damage to bees to document what happens when immature O. lignaria are dropped a short distance. Our results indicate that rough handling during development increases the risk of death to O. lignaria, especially during immature stages (larval and pupal stages). Our findings should be used a cautionary tale for O. lignaria bee managers propagating bees for pollination.

Technical Abstract: Insects are normally resilient to physical damage, utilizing unique morphologies to protect themselves against predators, pathogens, and multiple types of physical damage (like punctures, piercing, or blunt force). Other structures, such as cocoons and puparia, may add an extra layer of protection during metamorphosis; however, from our observations, this may not be the case, even if insects fall a short distance during metamorphosis. During an experiment, a sticky board holding cocoons of blue orchard bees (Osmia lignaria) was dropped on a linoleum floor. The samples were thought to not be harmed by the short distance fall; however, an X-radiation image and follow up revealed that all samples on the dropped sticky board died after impact. Utilizing a sticky board from the same study that had not fallen, we were able compare survivorship, developmental time points, and the damage to bees to document what happens when immature O. lignaria are dropped a short distance. Additionally, we estimated the average force of impact our samples experienced after being dropped on the floor. With our data, the findings highlight the handling risks to O. lignaria during larval and pupal development, and how mechanical injury during immature development may impact survivorship. As part of orchard pollination, the blue orchard bees are propagated in nesting boxes and the nest boxes are handled during the summer while the bees are in the larval and pupal stages. Our results indicate that rough handling during development increases the risk of death to O. lignaria, especially during immature stages (larval and pupal stages). Our findings should be used a cautionary tale for O. lignaria bee managers.