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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Temperature and Relative Humidity on Alfalfa Leafcutting Bee Immature Survival

Authors
item Pitts Singer, Theresa
item James, Rosalind

Submitted to: Entomological Society of America Regional Meetings
Publication Type: Other
Publication Acceptance Date: June 20, 2004
Publication Date: N/A

Interpretive Summary: Samples of alfalfa leafcutting bees, Megachile rotundata, were collected at the end of the nesting season from commercial alfalfa fields in five northwestern states for a total of eight samples. Using x-rays, up to 100 cells with solid masses appearing to lack healthy larvae were opened for examination. The content of each cell was determined (provision only, egg or early larva, pre- or post-defecating larva, moldy, or with pest), and the condition of any pollen-nectar provision was categorized as very dry, very wet, or moist. Cell content and condition as well as length of nesting season was correlated with temperature and relative humidity collected using Hobo dataloggers placed with bee boards in nesting shelters. The results will give a better understanding of why many alfalfa leafcutting bee cells fail to produce larvae, or why bees fail to lay eggs on provisions.

Technical Abstract: Samples of alfalfa leafcutting bees, Megachile rotundata, were collected at the end of the nesting season from commercial alfalfa fields in five northwestern states for a total of eight samples. Using x-radiographs, up to 100 cells with solid masses appearing to lack viable larvae were selected and dissected. The content of each dissected cell was determined (provision only, egg or first instar larva, pre- or post-defecating larva, moldy, or with pest), and the condition of any pollen-nectar provision was categorized as very dry, very wet, or moist. Cell content and condition as well as duration of nesting season was correlated with temperature and relative humidity collected using Hobo dataloggers placed with bee boards in nesting shelters. The results will afford a better understanding of why many alfalfa leafcutting bee cells fail to produce larvae, or why bees fail to lay eggs on provisions.

Last Modified: 7/22/2014