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

Abstract

Genetic models have been used to examine the evolution of insecticide resistance in pest species subject to data and assumptions regarding genetic, biological, and operational parameters. We used time-series data on pyrethroid tolerance and simple genetic models to estimate underlying genetic and biological parameters associated with resistance evolution in tobacco budworm, Heliothis virescens (F.), and bollworm, Helicoverpa zea (Boddie), Louisiana field populations. Assuming pyrethroid resistance is conferred by one gene at one locus in both species, inheritance of pyrethroid resistance was partially dominant in the tobacco budworm and partially recessive in the bollworm. Relative fitness estimates indicated that fitness costs associated with resistance selected against resistance alleles in the absence of selection pressure in the tobacco budworm, but not in the bollworm. In addition, relative fitness estimates obtained using the indirect method outlined in this study were similar in magnitude to estimates obtained using traditional direct approaches.

Dynamically optimal strategies for managing the joint resistance of pests to Bt toxin and conventional pesticides in a developing country

“…Based on these studies (from China) and empirical studies in the United States (Caprio, 1998;Burd et al, 2001;Storer et al, 2003;Livingston et al, 2004), we assume that the mortality rate of pests with double susceptible genes to Bt toxin is 0.90 in Bt cotton fields. As assumed in Livingston et al (2004Livingston et al ( , 2002, we also assume that the mortality rate of pests with double resistant genes to Bt toxin, the so-called 'fitness cost', is 0.05. Following interviews with Dr Wu Kongming, the chief entomologist in China, we make the assumption that the dominant level of susceptible genes in the heterozygote pests is 0.75.…”

“…As a result, this value has been widely used in many empirical studies, such as Onstad and Gould (1998), Livingston et al (2004Livingston et al ( , 2002, etc. In this study, we also assume an initial frequency of resistant alleles of one in a thousand.…”

“…According to equation (2), changes in the susceptible genes alleles (dependent variable) are a function of the level of susceptible genes, mortality rate of susceptible pests, mortality rate of resistant pests, etc. Using data collected by IPP, we estimated the coefficients using ordinary least squares (OLS) regression in a manner similar to that of Livingston et al (2002).…”

“…For example, Wu, a well-known entomologist in the Chinese Academy of Agricultural Sciences, implicitly believes that fitness cost is important (Wu et al, 2005). In addition, almost all economists working in this area (for example Livingston et al, 2002Livingston et al, , 2004 include the concept of fitness cost in their models.…”

棉铃虫的自然庇护所、抗性发展以及中国的零庇护所政策

“…之所以表示成离散形式是因为离散形式可以通 过现有的分析软件求得其最优解. 这样, 前面所面临问题 的 Bellman 方程为: (1 ) ( (1 ) ( [30] , Livingston 等人 [41] 初始抗药性(对普通农药)的基因频率 0.50 Ru 等人 [43] , Li 等人 [44] 转基因抗虫棉地里对于转基因毒素易感性害虫的死亡率 0.90 Livingston 等人 [41] , Wu 等人 [33] , Caprio [45] , Storer 等人 [46] 对于普通农药易感性害虫的死亡率…”