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Nesting Preferences of Osmia orientalis (Hymenoptera: Megachilidae) in the Field and Its Potential as a Strawberry Pollinator in Greenhouses
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Laboratory of Entomology, Faculty of Agriculture, Kindai University, Naka-machi, Nara 631-8505, Japan
2
Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
*
Author to whom correspondence should be addressed.
Insects 2025, 16(5), 473; https://doi.org/10.3390/insects16050473
Submission received: 8 March 2025
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Revised: 24 April 2025
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Accepted: 26 April 2025
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Published: 29 April 2025
(This article belongs to the Collection Insects on Pollination Ecology)
Simple Summary
The mason bee, Osmia orientalis, native to Japan, is a promising crop pollinator. It exhibits the unique behavior of nesting in empty snail shells, although many aspects of its nesting behavior remain unknown. To investigate its nesting preferences, we placed the empty shells of four snail species in six different environments in the field. The bees showed a clear preference for the medium-sized shells of Euhadra amaliae. Regarding their surrounding environment, they preferred grasslands to bare ground and forest interiors. Next, to evaluate whether this bee can be used as a pollinator for strawberries as an alternative to the introduced western honeybee, Apis mellifera, we investigated the per-visit pollination efficiency of strawberry flowers in a greenhouse. The results suggested that O. orientalis has the same or greater pollination efficiency as A. mellifera. When E. amaliae shells and three-dimensionally printed plastic replicas were placed in a greenhouse, the bees nested equally frequently in E. amaliae shells and in several types of artificial shells. This result suggests that artificial shells could be used as alternative nesting materials when natural snail shells are scarce. Although many questions remain before practical application, our study supports the potential for using O. orientalis as a pollinator of greenhouse-grown strawberries.
Abstract
The western honeybee, Apis mellifera, is used worldwide as a pollinator of crops such as strawberries; however, it is an introduced species in Japan. The mason bee, Osmia orientalis Benoist (Hymenoptera: Megachilidae), is native to Japan, where it nests in empty snail shells and has potential as a crop pollinator. We conducted three experiments to collect information on the nesting habits and potential agricultural use of this species as a pollinator of greenhouse-grown strawberries. Our first experiment investigated the bees’ nesting preferences in the field by placing the empty shells of four snail species, Euhadra amaliae, Satsuma japonica, Sinotaia quadrata histrica, and Helix lucorum, in six different environments. The nesting rate was significantly higher in medium-sized, empty E. amaliae shells. Regarding the surrounding environment, O. orientalis preferred tall and short grasslands to bare ground and forest interiors. Our second experiment investigated per-visit strawberry flower pollination efficiency. The results indicated that the efficiency of O. orientalis was equal to or greater than that of A. mellifera. In our third experiment, as a replacement for empty snail shells, which are scarce natural sources, four types of plastic artificial shells were created and placed inside a greenhouse together with E. amaliae shells. The nesting rates in three types of artificial shells were nearly identical to those in E. amaliae shells, implying that these artificial shells may be effective nesting materials. Although many questions remain before practical application, our results indicate the potential for using O. orientalis as a pollinator of greenhouse-grown strawberries.
