Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2000
Publication Date: October 1, 2000
Citation: Bosch Gras, J., Kemp, W.P., Peterson, S.S. 2000. Management of osmia lignaria (hymenoptera: megachilidae) populations for almond pollination: methods to advance bee emergence. Environmental Entomology. Interpretive Summary: The blue orchard bee, Osmia lignaria, is an excellent almond pollinator. However, to use O. lignaria as a commercial pollinator for almonds, its nesting activity needs to be advanced by one or two months. In this study we tried nine different rearing methods to obtain O. lignaria emergence by early February, rather than April-May. Several of these methods were successful in providing emergence well timed with almond bloom, vigorous bees, and good establishment in almond orchards. As a result, the bee population obtained at the end of the flowering period was greater than the population initially released.
Technical Abstract: The objective of this study was to find one or more rearing methods that would allow us to release Osmia lignaria Say populations from natal nests to pollinate February-flowering almonds, Prunus amygdalus Batsch, in California's Central Valley. We exposed 3 phenologically distinct O. lignaria populations (Early-, Mid-, and Late-flying) to different temperature treatments through development and wintering for a total of 9 rearing treatments. These treatments combined three approaches to obtain early bee emergence:1) exposing bees to warmer and/or fluctuating temperatures during development, 2) exposing bees to warmer wintering temperatures, and 3) using early-flying bee populations from Central Valley California latitudes. Extended periods of high pre-wintering temperatures resulted in apparent fat body consumption of pre-wintering adults and reductions in springtime adult longevity. In general, temperature treatments that promoted rapid immature development, and thus longer wintering periods, resulted in earlier spring emergence patterns of bees well timed with bloom period of almonds. Warmer wintering periods also resulted in earlier emergence. In addition to providing good bee-bloom synchrony, several treatments also yielded vigorous emerging populations, rapid establishment and nesting, and population increases. The potential importance of our results to anticipated increases in the demand for pollination services in California's Central Valley almonds are discussed.