Inheritance, Stability, and Reversion of Insecticide Resistance in Tobacco Budworm (Lepidoptera: Noctuidae) Field Populations

Use of Mathematical Models to Estimate Characteristics of Pyrethroid Resistance in Tobacco Budworm and Bollworm (Lepidoptera: Noctuidae) Field Populations

“…In addition, unrestricted parameter estimates for the tobacco budworm were very similar to previous estimates (Elzen et al 1994, Bagwell et al 2000, and relative Þtness estimates in the absence of selection pressure were consistent with previous studies that have indicated the presence of a Þtness cost associated with pyrethroid resistance in this species (Campanhola et al 1991, Park 1998, Lee et al 1999, Zhao et al 2000. Published estimates of Þtness-cost magnitudes, however, have until now been unavailable, presumably because they are difÞcult to obtain in a direct manner.…”

“…Unrestricted relative Þtness estimates under selection pressure were not statistically different from zero because both parameters were covariant, Cov(RR p , RS p ) ϭ 0.4224; however, the levels of the estimates 0.65 and 0.49 (Table 3) were similar to the published estimates 0.71 and 0.41 (Table 2). Pub- lished estimates were given by genotype survival rates in spray chamber bioassays (Elzen et al 1994); however, Þtness in our model is deÞned as the rate a genotype survives exposure to pyrethroids in the Þeld and successfully reproduces. The result that our Þt-ness estimates differed slightly from those reported by Elzen et al (1994), therefore, is reasonable.…”

“…Pub- lished estimates were given by genotype survival rates in spray chamber bioassays (Elzen et al 1994); however, Þtness in our model is deÞned as the rate a genotype survives exposure to pyrethroids in the Þeld and successfully reproduces. The result that our Þt-ness estimates differed slightly from those reported by Elzen et al (1994), therefore, is reasonable. Standard errors for the remaining estimates were considerably lower, and the unrestricted estimate of the initial resistance allele frequency (0.44) was very similar to the published estimate (0.45).…”

“…Resistance has been associated with nerve insensitivity (Taylor et al 1993, Taylor et al 1996, Lee et al 1999, enhanced metabolism (Nicholson andMiller 1985, Plapp et al 1990a), and reduced penetration and frequencies of larvae and adults expressing nerve insensitivity and enhanced metabolism have been shown to ßuctuate during the growing season (Ottea et al 1995, Ottea andHolloway 1998). Inheritance has been characterized as recessive (Plapp et al 1990a), partially recessive (0 Ͻ d Ͻ 0.5, Payne et al 1988, Watson andKelly 1991), and partially dominant (0.5 Ͻ d Ͻ 1.0, Elzen et al 1994), where d denotes the degree of dominance constrained to the unit interval (Bourget et al 2000). Resistance instability in the absence of selection pressure has been reported (Nicholson and Miller 1985, Staetz 1985, Leonard et al 1987, Payne et al 1988, Campanhola and Plapp 1989, Elzen et al 1994, Ottea et al 1995, as have potential Þtness costs associated with resistance.…”

“…Inheritance has been characterized as recessive (Plapp et al 1990a), partially recessive (0 Ͻ d Ͻ 0.5, Payne et al 1988, Watson andKelly 1991), and partially dominant (0.5 Ͻ d Ͻ 1.0, Elzen et al 1994), where d denotes the degree of dominance constrained to the unit interval (Bourget et al 2000). Resistance instability in the absence of selection pressure has been reported (Nicholson and Miller 1985, Staetz 1985, Leonard et al 1987, Payne et al 1988, Campanhola and Plapp 1989, Elzen et al 1994, Ottea et al 1995, as have potential Þtness costs associated with resistance. Campanhola et al (1991) reported that laboratory-selected resistant females were less able to produce viable offspring than susceptible females, and that resistant females produced less pheromone and were less attractive to males than susceptible females.…”