A recombinant immunosuppressive protein from Pimpla hypochondriaca (rVPr1) increases the susceptibility of Lacanobia oleracea and Mamestra brassicae larvae to Bacillus thuringiensis.
The precise mechanisms underlying Bacillus thuringiensis-mediated killing of pest insects are not clear. In some cases, death may be due to septicaemia caused by Bt and/or gut bacteria gaining access to the insect haemocoel. Since insects protect themselves from microbes using an array of cellular and humoral immune defences, we aimed to determine if a recombinant immunosuppressive wasp venom protein (rVPr1) could increase the susceptibility of two pest Lepidoptera (Lacanobia oleracea and Mamestra brassicae) to Bt. Bio-assays indicated that injection of 6 microl of rVPr1 into the haemocoel of both larvae caused similar levels of mortality (less than 38%). On the other hand, the LD(30-40) of Bt for M. brassicae larvae was approximately 20 times higher than that for L. oleracea larvae. Furthermore, in bio-assays where larvae were injected with rVPr1, then fed Bt, a significant reduction in survival of larvae for both species occurred compared to each treatment on its own (P<0.001); and for L. oleracea larvae, this effect was more than additive. The results are discussed within the context of insect immunity and protection against Bt.
Richards
Elaine H
EH
The Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, United Kingdom. elaine.richards@fera.gsi.gov.uk
Paulina Dani
M
M
D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D007915:Lepidoptera / Q000382:microbiology*; D010572:Pest Control, Biological / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000633:toxicity*; D014862:Wasp Venoms / Q000235:genetics / Q000633:toxicity*
D011994:Recombinant Proteins; D014862:Wasp Venoms