Field-Derived Fall Armyworm Colony for Bt Toxin Resistance Management
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Solution Overview
Problem
The evolution of insect resistance to Bt toxins in transgenic corn, such as Cry1F, poses a significant threat to the effectiveness of insecticidal control in agricultural fields, particularly in areas with continuous use and high selection pressure, leading to yield losses and potential loss of control efficacy.
Innovation Solution
A field-derived colony of fall armyworm (FAW) with decreased susceptibility to maize plants expressing Cry1F is produced through selective breeding, where FAW individuals surviving exposure to Cry1F are allowed to mate and pass on resistance alleles, maintaining the colony and periodically selecting for homozygous resistance, enabling the study of resistance mechanisms and management strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transgenic corn expressing Bt toxins is used for insecticidal control, then control efficacy against FAW is improved, but insect resistance evolves rapidly under continuous use and intensive selection pressure
Solution Approach 1:
The patent applies preliminary action by establishing refuge populations of susceptible insects before resistance becomes widespread. These refuges serve as a reservoir of susceptible genes that can be introduced into the population through mating, thereby preemptively counteracting resistance evolution before it compromises control efficacy
Solution Approach 2:
The patent employs parameter changes by modifying the genetic composition of the insect population through controlled introduction of susceptible individuals into resistant populations. This changes the allele frequency parameter of the population, restoring susceptibility and thereby extending the duration of Bt toxin effectiveness
2Productivity
If continuous use and intensive selection pressure is applied to Bt transgenic crops, then productivity is improved, but resistance evolution accelerates
Solution Approach 1:
The patent applies periodic action by implementing alternating cycles of high Bt toxin exposure (for productivity) followed by periods where susceptible individuals are introduced and allowed to mate with resistant individuals. This periodic intervention resets the selection pressure, maintaining crop yield while preventing resistance fixation
Solution Approach 2:
The patent employs feedback mechanisms by monitoring the susceptibility levels in the insect population and adjusting the introduction of refuge individuals accordingly. When resistance begins to accumulate, susceptible individuals are introduced to counteract it, creating a feedback loop that maintains the balance between productivity and susceptibility
Data Source
AI summary
Methods are provided for using field-derived colonies of insects that comprise field-evolved resistance to insecticidal toxins that are produced in transgenic plants. The methods find use in resistance management strategies for transgenic crop plants expressing insecticidal toxins.