Greetings,
One often hears statements like: no pesticides are needed to raise
food, or keep bees, or in general. Some people have had very good luck
raising food, bees, or kids without resorting to modern chemicals or
medicines. The problem comes when they try to project the experience
onto situations other than their own.
For example, in my area if I don't treat for mites, the bees are
overun by September, and most hives die. The presence of large numbers
of commercially run hives no doubt has some influence on the
situation. Agriculture and livestock production can have a profound
effect on native populations of plants and animals as shown by studies
of domesticated bumble bees pathogens spilling over into native
populations
> Introduced pathogens often spread rapidly and devastate naïve host populations. Among wildlife, diseases may be introduced via the spread, or ‘spillover’, of pathogens from heavily infected domestic animals. Here, we use a combination of mathematical modelling and field data to show that spillover from commercially reared bumble bees has introduced the contagious pathogen Crithidia bombi into wild bumble bee populations. During two years, and across nine sites in southern Ontario including our previous work, we have found C. bombi infecting up to 75% of wild bumble bees, depending on the time of year and the host species, near industrial greenhouses that use commercial Bombus for pollination. At sites distant to greenhouses, we have not found any bees harbouring this pathogen. Furthermore, we show that the prevalence and intensity of C. bombi infections decline with increasing distance from greenhouses. Given that wild bumble bee populations in our area were almost entirely free of C. bombi before to the use of commercial Bombus in Canada [ca. 1990], our results suggest a dramatic increase in infection rates near greenhouses.
--
Does Pathogen Spillover from Commercially Reared Bumble Bees Threaten
Wild Pollinators?
Michael C. Otterstatter, James D. Thomson
Department of Ecology and Evolutionary Biology, University of Toronto,
Toronto, Ontario, Canada
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