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Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/2/1999 Publication Date: 2/1/2000 Citation: Bosch Gras, J., Kemp, W.P. 2000. Development and emergence of the orchard pollinator, osmia lignaria (hymenoptera: megachilidae). Environmental Entomology. Interpretive Summary: The solitary bee Osmia lignaria has been developed as an orchard pollinator in the Western U.S.A. Immatures develop through the spring and summer. By late summer bees reach the adult stage and over-winter inside their cocoons. In this study, we reared O. lignaria at different temperature regimes in the laboratory and outdoors. Developmental rates increased with temperature: bees reared at 18 degrees C took over 120 days to complete development, whereas bees reared at 29 degrees C took only half that long. Bees reared outdoors under fluctuating ambient conditions took about 95 days. At 18 degrees C, some bees were unable to complete prepupal diapause.Different developmental stages responded differently to the various temperature regimes. Fluctuating temperatures averaging 22 degrees C significantly shortened the diapausing prepupal stage, and as a result bees developed faster than at the equivalent constant temperatures. Bees that developed faster (29 degrees C and fluctuating temperatures) could be wintered as early as August and incubated for emergence in March, a month ahead of bees exposed to natural conditions. These results are now being applied to field populations to test whether these can be released on early blooming almonds in California. Technical Abstract: The solitary bee Osmia lignaria has been developed as an orchard pollinator in the Western U.S.A. Immatures develop through the spring and summer. By late summer bees reach the adult stage and over-winter inside their cocoons. In this study, we reared O. lignaria at different temperature regimes in the laboratory and outdoors. Developmental rates increased with temperature: bees reared at 18 degrees C took over 120 days to complete development, whereas bees reared at 29 degrees C took only half that long. Bees reared outdoors under fluctuating ambient conditions took about 95 days. At 18 degrees C, some bees were unable to complete prepupal diapause. Different developmental stages responded differently to the various temperature regimes. Fluctuating temperatures averaging 22 degrees C significantly shortened the diapausing prepupal stage, and as a result bees developed faster than at the equivalent constant temperatures. Bees that developed faster (29 degrees C and fluctuating temperatures) could be wintered as early as August and incubated for emergence in March, a month ahead of bees exposed to natural conditions.These results are now being applied to field populations to test whether these can be released on early blooming almonds in California, U.S.A. |
