Biology subjects

Butler, C. D.

Publications and source records attributed to Butler, C. D..

3 recordsLinked to original sources

bioRxiv2026

Spatial confinement of gene drives: Assessing risk of failure using global sensitivity analysis

Gene drives allow pest populations to be genetically modified to reduce their harm on agriculture and human health. The genetic modification, or payload, spreads within a target population at rates exceeding normal Mendelian inheritance. While gene drives have demonstrated immense potential in laboratory populations, they present unique challenges. Foremost among these challenges is spatial confinement, or ensuring that the payload remains confined to target populations. However, there is an inherent tension between gene drive spread and spatial confinement: increasing the spreading efficiency of a gene drive increases the risk of escape, while engineering confinement mechanisms increases the risk of gene drive extinction. In this work, we explore spatial outcomes in gene drives designed for spatial confinement and the dependence of these outcomes on target organism dispersal and payload fitness cost. We use a stochastic spatial model to compute the probability of failure for each gene drive, and use techniques from global sensitivity analysis to quantify the contribution of dispersal and fitness cost to variance in gene drive performance. Our findings reveal how spatial outcomes are affected by key parameters, and how this sensitivity varies tremendously between different gene drives. These spatial properties can be used to classify gene drive behavior and are useful to determine suitability for a particular application.

evolutionary biology↗

bioRxiv2025

Socioeconomic predictors of knockdown resistance in Aedes albopictus (Diptera: Culicidae)

Knockdown resistance (kdr) in the mosquito Aedes albopictus (Skuse) jeopardizes the effectiveness of insecticidal control. This is a pressing issue given the expanding range of the species and its role as vector to harmful viruses. Effectively preventing the emergence of resistance or removing the conditions that positively select for kdr mutations requires us first to understand how these conditions arise. Here, we investigate the association between wealth and the frequency of kdr in Ae. albopictus populations in Raleigh, North Carolina, USA. We hypothesized that kdr frequency correlates with wealth, measured by total property value. We speculate that wealthier neighborhoods apply chemical insecticides more frequently, leading to higher kdr frequencies. We tested this hypothesis by sampling mosquito populations from 31 different residential blocks across the city and along a property value gradient. We found a high frequency of 39.0% for mutations at locus F1534S of the voltage-gated sodium channel gene (vgsc). Kdr mutations were found at 84% of the blocks we sampled. Our statistical analysis indicates strong evidence for an association between wealth and F1534S frequency. We discuss these and other findings, and what this means for suburban mosquito control going forward.

evolutionary biology↗

bioRxiv2024

How population control of pests is modulated by density dependence: The perspective of genetic biocontrol

Managing pest species relies critically on mechanisms that regulate population dynamics, particularly those factors that change with population size. These density-dependent factors can help or hinder control efforts and are especially relevant considering recent advances in genetic techniques that allow for precise manipulation of the timing and sex-specificity of a control. Despite this importance, density dependence is often poorly characterized owing to limited data and an incomplete understanding of developmental ecology. To address this issue, we construct and analyze a mathematical model of a pest population with a general control under a wide range of density dependence scenarios. Using this model, we investigate how control performance is affected by the strength of density dependence. By modifying the timing and sex-specificity of the control, we tailor our analysis to simulate different pest control strategies, including conventional and genetic biocontrol methods. We pay particular attention to the latter as case studies by extending the baseline model to include genetic dynamics. Finally, we clarify past work on the dynamics of mechanistic models with density dependence. As expected, we find substantial differences in control performance for differing strengths of density dependence, with populations exhibiting strong density dependence being most resilient to suppression. However, these results change with the size and timing of the control load, as well as the target sex. Interestingly, we also find that population invasion by certain genetic biocontrol strategies is affected by the strength of density dependence. While the model is parameterized using the life history traits of the yellow fever mosquito, Aedes aegypti, the principles developed here apply to many pest species. We conclude by discussing what this means for pest population suppression moving forward.

ecology↗