Abstract
ntroduction: We must pay attention to what insects actually do in the field. When observations and empirical data contradict the conventional wisdom, we should pay attention to the stories that the insects tell. During 20 years studying the rotation-resistant (and now Bt-resistant) western corn rootworm (WCR, Diabrotica virgifera virgiferaLeConte) (Coleoptera: Chrysomelidae) in Illinois, my laboratory has gained an appreciation for the details of WCR local movement, mating, and dispersal. Those insights are helping us understand current management challenges posed by the most significant U.S. pest of corn.
Methods: WCR beetles were collected within and above the plant canopies of soybean and cornfields (planted with Bt or non-Bt corn hybrids) using insect nets, collection jars, and malaise traps. Analyses measured physical and reproductive characteristics of individuals and analyzed WCR gut contents to identify where adults had been feeding. The temporal context of collections, combined with information about the types of plants at collection sites, enrich the interpretation of individual characteristics and movement patterns.
Results/Conclusion: Rotation-resistant WCR engage in extensive interfield movement; however, their intrafield movement patterns and distributions of mating activity in Bt cornfields fall short of expectations fundamental to insect resistance management plans. Patterns of aerial dispersal from Bt cornfields indicate that many females leave their natal fields shortly after mating and move long distances. A poor match between refuge design and WCR biology contributed to the evolution of Bt resistance while patterns of dispersal from Bt cornfields will make it difficult to manage resistance on a local scale.
Methods: WCR beetles were collected within and above the plant canopies of soybean and cornfields (planted with Bt or non-Bt corn hybrids) using insect nets, collection jars, and malaise traps. Analyses measured physical and reproductive characteristics of individuals and analyzed WCR gut contents to identify where adults had been feeding. The temporal context of collections, combined with information about the types of plants at collection sites, enrich the interpretation of individual characteristics and movement patterns.
Results/Conclusion: Rotation-resistant WCR engage in extensive interfield movement; however, their intrafield movement patterns and distributions of mating activity in Bt cornfields fall short of expectations fundamental to insect resistance management plans. Patterns of aerial dispersal from Bt cornfields indicate that many females leave their natal fields shortly after mating and move long distances. A poor match between refuge design and WCR biology contributed to the evolution of Bt resistance while patterns of dispersal from Bt cornfields will make it difficult to manage resistance on a local scale.
| Original language | English (US) |
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| DOIs | |
| State | Published - Sep 27 2016 |