Field-Evolved Resistance to Bacillus thuringiensis Toxin CryIC in Diamondback Moth (Lepidoptera: Plutellidae)
Authors: LIU, YONG-BIAO; TABASHNIK, BRUCE E.; PUSZTAI-CAREY, MARIANNE
Source: Journal of Economic Entomology, Volume 89, Number 4, August 1996 , pp. 798-804(7)
Publisher: Entomological Society of America
Abstract:Previous results have shown that diamondback moth, Plutella xylostella (L.), populations resistant to toxins from Bacillus thuringiensis subsp. kurstaki were susceptible to toxin CryIC. Use of commercial formulations of B. thuringiensis subsp. aizawai that contain CrylC has increased recently. Analysis of two commercial formulations by high pressure liquid chromatography showed that CryIC accounted for 26% of the CryI protein in the B. thuringiensis subsp. aizawai formulation, but did not occur in the B. thuringiensis subsp. kurstaki formulation. CryIAb was the most abundant CryI protein in the commercial formulations of B. thuringiensis subspp. aizawai and kurstaki. We found resistance to CryIC in a field population of diamondback moth from Hawaii that had been treated with B. thuringiensis subsp. aizawai. Leaf residue bioassays showed that, at 5 d after treatment with CryIC, LC50s for colonies derived from this population in 1993 and 1995 were ≍20 times greater than the LC50 for a susceptible laboratory colony. For a nearby population that had not been treated with B. thuringiensis subsp. aizawai, responses to CryIC did not differ significantly from those of the susceptible laboratory colony. Resistance to CryIAb was lower in a CryIC-resistant colony than in a CryIC-susceptible colony that had been selected with B. thuringiensis subsp. kurstaki. These results suggest that the gene(s) conferring resistance to CryIC segregate independently from the gene(s) conferring resistance to CryIAb. In contrast with previous results with colonies derived in 1989, resistance to B. thuringiensis subsp. kurstaki in a colony derived in 1993 from the same field population did not decline when exposure to B. thuringiensis stopped. Thus, stability of resistance is not necessarily a fixed character, even for a specific population and pesticide. Despite substantial resistance to CryIC and B. thuringiensis subsp. kurstaki, resistance to a spore-crystal formulation of B. thuringiensis subsp. aizawaiwas only 2- to 4-fold.
Document Type: Research Article
Publication date: August 1996
- Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.
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