A sterile back cross tobacco bud worm strain (TBW-BC) of Heliothts virescens (F.) was developed before extensive use of pyrethroid insecticides. Although this strain has been maintained free of pyrethroid insecticides, most tobacco bud worm populations have been exposed to pyrethroids and have demonstrated enhanced tolerance. Our estimated LD50 (cypermethrin) for third instars was significantly lower than tobacco bud worm from Mississippi. Thus, the TBW-BC strain could be at a disadvantage if exposed to pyrethroids after release. We developed a lineage of TBW-BC strain that is resistant to cypermethrin by repeatedly back crossing TBW-BC females to resistant tobacco bud worm males and selecting for tolerance. Resistant TBW-BC strain (R-TBW-BC) (LD50,638 ˜g per larva) should survive field applications that would kill most wild tobacco bud worm. Back cross mortalities were consistent with polygenic inheritance, but not with monogenic inheritance. Release of RTBW- BC strain cannot change tolerance in wild tobacco bud worm, because introduced resistance alleles will be carried only by individuals that also carry the sterility trait. Resistance of sterile insects would be diluted by outcrossingto wild tobacco bud worm, but sterile insects should remain significantly more tolerant than fertile insects for at least two generations. Use of R-TBW-BC strain could reduce costs in sterile-release programs.
Document Type: Research Article
Publication date: August 1, 1991
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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.