Standardizing bee sampling protocols using geostatistics
Osmia cornifrons Radoszkowski (Hymenoptera: Megachilidae) is a solitary mason bee managed for pollination of early season fruit crops such as apple and pear. O. cornifrons larvae are susceptible to cold temperatures specifically during the transition from spring to summer. Because temperature plays such a vital role in the ontogeny of insects, the impacts of weather change on O. cornifrons development are important to understand to enhance population management practices. O. cornifrons were collected from the field within 12 h of oviposition and placed in incubators at one of six temperatures (5, 13, 21, 29, 37, and 45° C). Individuals were checked for survival and development at each temperature daily until cocoon formation. Biophysical models such as Briére and Weibull functions were used to describe the relationship between O. cornifrons development and temperature. The lower developmental threshold and thermal constant of eggs using linear regression was 12.73°C and 16.66 degree days, respectively. O. cornifrons were only able to develop from egg to prepupa at 21 and 29°C. Eggs survived at 13, 21, and 29°C, but early instar larvae were not able to continue development at 13°C. The results of this study indicate that O. cornifrons eggs and larvae have different thermal windows, and are unable to develop when temperatures drop below 12.7°C. When temperatures drop below the low developmental threshold it may be beneficial to augment temperature by temporarily relocating or artificially heating nests.