Rapid evolution and the cost of resistance to Bacillus thuringiensis in greenhouse populations of cabbage loopers, Trichoplusia ni.
The microbial insecticide Bacillus thuringiensis (Bt) has become the mainstay of non-chemical control of Lepidopteran pests, either as sprays or through the incorporation of Bt toxins into transgenic crops. Given the wide use of Bt, it is striking that currently only one pest species, Plutella xylostella, has been reported to have developed significant resistance to Bt outside the laboratory. By contrast, we report here the frequent and rapid development of resistance to B. thuringiensis kurstaki (Dipel, Abbott) in populations of cabbage loopers, Trichoplusia ni, in commercial greenhouses. Resistance to Bt appears to be costly and there is a rapid decline of resistance in populations collected from greenhouses and maintained in the laboratory without selection. Management of pests resistant to Bt in vegetable greenhouses will require sporadic use of Bt-based sprays or alternatively use of sprays containing other Bt toxins.
Janmaat
Alida F
AF
Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada. janmaat@zoology.ubc.ca
Myers
Judith
J
D000818:Animals; D001413:Bacillus thuringiensis / Q000472:pathogenicity*; D001681:Biological Assay; D005075:Biological Evolution; D001835:Body Weight; D007305:Insecticide Resistance / Q000502:physiology*; D007928:Lethal Dose 50; D009036:Moths / Q000382:microbiology* / Q000502:physiology*; D010572:Pest Control, Biological