Is a larger refuge always better? Dispersal and dose in pesticide resistance evolution

Abstract

The evolution of resistance against pesticides is an important problem of modern agriculture. The high‐dose/refuge strategy, which divides the landscape into treated and nontreated (refuge) patches, has proven effective at delaying resistance evolution. However, theoretical understanding is still incomplete, especially for combinations of limited dispersal and partially recessive resistance. We reformulate a two‐patch model based on the Comins model and derive a simple quadratic approximation to analyze the effects of limited dispersal, refuge size, and dominance for high efficacy treatments on the rate of evolution. When a small but substantial number of heterozygotes can survive in the treated patch, a larger refuge always reduces the rate of resistance evolution. However, when dominance is small enough, the evolutionary dynamics in the refuge population, which is indirectly driven by migrants from the treated patch, mainly describes the resistance evolution in the landscape. In this case, for small refuges, increasing the refuge size will increase the rate of resistance evolution. Our analysis distils major driving forces from the model, and can provide a framework for understanding directional selection in source‐sink environments.

Optimal management strategy of insecticide resistance under various insect life histories: Heterogeneous timing of selection and interpatch dispersal

“…For example, a spatially explicit model may be required when dispersal distances must be considered, or a stochastic model may be necessary to evaluate the effects of finite population size. In addition for specific cases, particular dispersal (0 < d x < 1) and refuge values (k ≠ 0.5) should be examined, as the waiting time to resistance is a nonlinear function of these parameters (Takahashi, Yamanaka, Sudo, & Andow, 2017).…”

Escalating insecticide resistance in Australian grain pests: contributing factors, industry trends and management opportunities

“…In part, this leads to indecision and the prophylactic application of insecticides potentially increasing the risk of resistance. The risk is dependent on numerous factors such as the genetic basis of resistance across field doses, the starting resistance allele frequencies and pest dispersal rates . Thresholds help to rationalize the use of insecticides and are a fundamental tenet underpinning IPM practices, assuming they are accurate and appropriately applied.…”

“…The risk is dependent on numerous factors such as the genetic basis of resistance across field doses, the starting resistance allele frequencies and pest dispersal rates. 56 Thresholds help to rationalize the use of insecticides and are a fundamental tenet underpinning IPM practices, 57 assuming they are accurate and appropriately applied. A recent review commissioned by the GRDC identified numerous gaps in economic thresholds available within the Australian grain industry (Miles M, personal communication).…”

The opportunity for sexual selection and the evolution of non-responsiveness to pesticides, sterility inducers and contraceptives

“…The second approach, selectively applying treatment, involves targeting treatments to particular pests, and providing specific remedies long enough and in high enough concentrations to eliminate the pest populations entirely (Takahashi et al., 2017, transgenic crops and susceptible arthropods). A variant of this approach includes integrated pest management, in which locally variable application of treatments creates a spatially heterogeneous environment of selection intensities, designed to slow the rate at which resistance evolves (Tabashnik et al., 2003, 2008; lepidopterous insects).…”

“…Techniques for generating sterile males include ionizing radiation (reviews in VanDyck et al., 2005; Balestrino et al., 2017), conditional-lethal genotypes (Ant et al., 2012), and CRISPR-cas9 applications (Borel, 2017; Drury et al., 2017). Additional detail on the approaches described above are available elsewhere (Palumbi, 2001; Tabashnik et al., 2008; Frieri et al., 2016; Takahashi et al., 2017; Harris, 2017; Borel, 2017).…”