ARS | Publication request: Improved storage of the pollinator, Megachile rotundata

Submitted to: Association of Natural Biocontrol Producers (ANBP)
Publication Type: Other
Publication Acceptance Date: September 25, 2011
Publication Date: January 1, 2012
Citation: Yocum, G.D., Rinehart, J.P., Kemp, W.P. 2012. Improved storage of the pollinator, Megachile rotundata. (Newsletter, WInter 2011) Association of Natural Biocontrol Producers (ANBP). 10(2):6.

Technical Abstract: The alfalfa leafcutting bee, Megachile rotundata, is the 3rd most common pollinator used for crop pollination in North America and low-temperature storage protocols are a critical component of M. rotundata management. There are four times during the production cycle that bees may need to be subjected to low-temperature storage: 1) Wintering the diapausing prepupae between growing seasons; 2) Synchronizing the bee spring emergence with the alfalfa bloom may also require subjecting the developing bees to a period of low-temperature storage; 3) Some bee producers sell bees that are pre-incubated for immediate field release, and to prevent emergence during shipping, these bees are shipped under sub-ambient conditions; and 4) The final storage period is still more theoretical in nature than actual, but there is interest in long-term storage of M. rotundata not sold during the normal growing season be stored for subsequent sale the following year. Under current protocols, M. rotundata is stored under constant low temperature regimes. Constant temperature protocols have a number of disadvantages associated with them. The first is that constant temperatures are not natural. Insects, like all organisms, use environmental signals to optimize their reproduction and development to local conditions. Second, small differences (even one or two degrees) in temperature at sub-ambient conditions can have profound effects on survival and postemergence quality. We have demonstrated that exposing M. rotundata that are stored under sub-ambient conditions to short high temperature pulses (fluctuating thermal regime, FTR) can significantly increase survival. Examination of the various components of an FTR such as pulse temperature, ramp speed, and frequency of the pulse revealed that the positive effect of FTR was very tolerant to variation in these FTR components. Using FTR based storage protocols, we have successfully more than doubled the storage time for developing (#2 and 3 above) M. rotundata. Also, using an FTR protocol, we have stored M. rotundata prepupae for more then two years (see # 4 above) with little to no observable decrease in bee quality. In conclusion, from our results and that of others, FTR storage protocols provide clear advantages over that of the current constant-temperature storage protocols used to store M. rotundata and other beneficial insects. We expect that similar protocols can be developed for other beneficial insects.