Inheritance pattern of a strain of tobacco budworm, Heliothis virescens (F.), following a selection regime with permethrin, showed an incomplete dominance when crossed with a reference susceptible strain. In another cross inheritance pattern of the same reference susceptible strain was equal to a non-selected field collected strain and reciprocal crosses in filial generation one. LD_’s of permethrin to larvae for both reciprocal crosses of filial generation two were significantly greater than the field collected strain and both reciprocal crosses of filial generation one. Both inheritance patterns were compared with a previously published inheritance pattern with the same insecticide against different strains.

the LD_’s for larvae of the L x F was significantly greater than LD_’ of the F x L. Also, the LD_’s of larvae of reciprocal crosses in the second filial generation were significantly greater than the same reciprocal crosses shown in the first filial generation. Slopes of F in the first generation and L X F in second filial generation were <1 while all other slopes ranged from 1-2.

In 1983 crosses of L and F strains showed an incomplete dominance (Table
2). These results followed a selection regime for 12 generations (Wolfenbarger 1990). L strain was the same used in 1974. LD_’ of larvae of L and F differed by 17 and 4 fold in filial generations one and two, respectively. Both were significantly different. For both filial generations LD_’s of larvae of reciprocal crosses were significantly greater than L strain and significantly less than F strain. Slopes of strains and crosses ranged from 1-2 both generations.