|Bosch, Jordi - UNIV. BARCELONA, SP|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2005
Publication Date: April 1, 2006
Citation: Bosch, J., Kemp, W.P., Trostle, G.E. 2006. Bee population returns and cherry yields in an orchard pollinated with Osmia lignaria (Hymenoptera: Megachilidae). Journal of Economic Entomology. 99(2):408-413. Interpretive Summary: The American Beekeeping Federation estimated that during 2005 about 50 percent of the honey bee colonies used for pollination in California almonds were either killed or severely weakened from varroa mite infestations. Press reports suggest that the chemical treatments that beekeepers rely on to combat varroa mites are being rendered ineffective due to the continued development of resistance in the mites. The solution to this pollinator crisis will likely come from two areas: 1) further research on honey bee genetics and novel pest management options, and 2) developing new bees for pollination to diversify our Nation’s pollinator portfolio. The blue orchard bee is being developed as a pollinator of tree fruit crops like almonds, cherries, pears, and apples. We report here on a demonstration program where we used the blue orchard bee as a cherry pollinator during 1998-2003 in a commercial orchard from northern Utah. For those years with harvestable crops during 1998-2003, the average cherry production in the demonstration orchard was 2.2 times higher than that for the period 1992-1997 when the orchard was pollinated in the traditional manner. Our work in this orchard and elsewhere has demonstrated that the blue orchard bee is easy to manage, provides excellent pollination service to early spring tree fruit crops, and has great potential for further development as a commercial scale pollinator.
Technical Abstract: The solitary bee Osmia lignaria Say is being developed as an orchard pollinator in throughout North America. Female bees are active during the early spring and construct nests consisting of a linear series of unlined cells delimited by mud partitions. Cells are provisioned with a pollen/nectar mass on which an egg is deposited, and nests are sealed with a mud plug. In 1997, we initiated two experiments on the development, mortality, and emergence of O. lignaria at selected laboratory temperature regimes and outdoors. In the first experiment (published previously), we compared temperature treatments for their adequacy in maintaining healthy O. lignaria populations. In a second experiment (reported here), we determined the relationship between rearing temperatures and prepupa-adult development rates, as well as emergence time and longevity after wintering and incubation the following spring. We observed important differences in O. lignaria prepupa versus pupa responses to selected temperature treatments. The relationship between temperature and days to pupa was U-shaped, with additional time to transit the prepupa-pupa interval at temperatures above and below 26ºC. The negative relationship between temperature and the length of the pupa to adult interval contrasts with the U-shaped thermal response observed for prepupae. Thus, with each increase in thermal heat units over the range of temperature treatments tested, we observed an additional reduction in the pupa-adult interval. Individuals reared at constant 18ºC required 2.4 times as many days to transit the pupa-adult interval compared with those at constant 32ºC. The implications of these results to the ultimate development of regionally adapted pollinator populations are discussed.