Developmental biology of Osmia lignaria and rearing of its populations for orchard pollination
Jordi Bosch, Jordi.Bosch@uab.es, Universitat AutÚnoma de Barcelona, Ecologia/CREAF, Edifici C, Barcelona, Bellaterra, Spain and William P. Kemp, email@example.com, USDA-ARS, Bee Biology & Systematics Laboratory, Logan, UT.
The solitary bee Osmia lignaria has been developed as a manageable orchard pollinator in North America. Adult O. lignaria are active in the spring, building and provisioning nests. By early summer, eggs laid during the current year complete development to fifth instars, which spin cocoons and enter an apparent dormant stage. Pupation occurs by late summer, followed by adult eclosion within one month. Eclosed adults remain in their cocoons for the winter, and emerge in the spring as temperatures increase. Thus, O. lignaria are univoltine and winter in the adult stage. Respiration rates indicate that O. lignaria undergoes two diapausing periods, one in the prepupal stage in the summer, and another in the adult stage during autumn and winter. Exposure to warm and/or fluctuating temperatures is required for summer diapause completion. Exposure to cold temperatures is necessary to complete winter diapause. The timing between adult eclosion and the onset of winter temperatures is critical to O. lignaria survival. Pre-wintering adults exposed to warm temperatures for too long use up their fat body reserves, loose weight and vigor and are more likely to die during the winter. In this study, we discuss the implications of these results for the establishment of appropriate rearing methods for O. lignaria populations used in orchard pollination.