Tolerant Western Corn Rootworm Colonies for Resistance Management
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Solution Overview
Problem
The development of resistance in western corn rootworm populations to transgenic maize event DAS-59122-7 poses challenges for effective pest management, as existing strategies lead to resistance development and yield reduction, necessitating new approaches to maintain control efficacy.
Innovation Solution
Laboratory-selected western corn rootworm colonies, such as the York and Rochelle Selected Colonies, exhibit increased tolerance to event DAS-59122-7, enabling the development of novel resistance management strategies, including negative cross-resistance and reduced refuge requirements, to delay resistance evolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transgenic maize event DAS-59122-7 is used to control western corn rootworm, then pest control efficacy is improved, but resistance development occurs over time
Solution Approach 1:
The patent implements periodic action through alternating toxin deployment strategies. Laboratory-selected tolerant colonies are used to identify toxins that can be alternated with DAS-59122-7, creating periodic cycles of different toxic modes of action that prevent continuous selection pressure for resistance to a single toxin.
Solution Approach 2:
The patent applies parameter changes by modifying the toxin type parameter over time. By using tolerant colonies to screen for alternative toxins with different modes of action, the system changes the toxic parameter periodically, preventing the pest population from adapting to a constant toxin parameter.
2Duration of action of stationary object
If refuge strategy is implemented to slow resistance development, then resistance evolution is delayed, but yield is reduced due to 20% susceptible crop
Solution Approach 1:
The patent extracts the refuge requirement from the resistance management system by using tolerant colonies to identify alternative toxins. This allows near-complete deployment of transgenic maize without sacrificing yield, while the alternative toxin strategy maintains resistance management effectiveness.
Solution Approach 2:
The patent changes the refuge parameter from 20% susceptible area to near-zero by introducing alternative toxin deployment. The tolerant colonies enable identification of toxins that work synergistically with DAS-59122-7, eliminating the need for large refuge areas.
3Speed
If continuous exposure to toxin is used to select for tolerant organisms, then tolerance development is accelerated, but the selection model may not reflect field conditions
Solution Approach 1:
The patent uses partial exposure strategies in laboratory selection, exposing colonies to sublethal or intermittent toxin levels rather than continuous lethal doses. This partial action accelerates tolerance development while better mimicking the variable exposure conditions found in field environments.
Solution Approach 2:
The patent introduces an intermediary layer between continuous exposure and field conditions by using controlled intermittent exposure regimes. This intermediary selection approach accelerates tolerance development while incorporating variability that better predicts field resistance outcomes.
Data Source
AI summary
Laboratory-selected colonies of western corn rootworm exhibiting tolerance to maize containing event DAS-59122-7 are described. Further, methods for various uses of these resistance western corn rootworm colonies are also described, including development of negative cross-resistance strategies and improved resistance management strategies.