Abnormally high digestive enzyme activity and gene expression explain the contemporary evolution of a diabrotica biotype able to feed on soybeans

Matìas J. Curzi, Jorge A. Zavala, Joseph L. Spencer, Manfredo J. Seufferheld

Research output: Contribution to journalArticlepeer-review

Abstract

Western corn rootworm (Diabrotica virgifera) (WCR) depends on the continuous availability of corn. Broad adoption of annual crop rotation between corn (Zea mays) and nonhost soybean (Glycine max) exploited WCR biology to provide excellent WCR control, but this practice dramatically reduced landscape heterogeneity in East-central Illinois and imposed intense selection pressure. This selection resulted in behavioral changes and "rotation-resistant" (RR) WCR adults. Although soybeans are well defended against Coleopteran insects by cysteine protease inhibitors, RR-WCR feed on soybean foliage and remain long enough to deposit eggs that will hatch the following spring and larvae will feed on roots of planted corn. Other than documenting changes in insect mobility and egg laying behavior, 15 years of research have failed to identify any diagnostic differences between wild-type (WT)- and RR-WCR or a mechanism that allows for prolonged RR-WCR feeding and survival in soybean fields. We documented differences in behavior, physiology, digestive protease activity (threefold to fourfold increases), and protease gene expression in the gut of RR-WCR adults. Our data suggest that higher constitutive activity levels of cathepsin L are part of the mechanism that enables populations of WCR to circumvent soybean defenses, and thus, crop rotation. These new insights into the mechanism of WCR tolerance of soybean herbivory transcend the issue of RR-WCR diagnostics and management to link changes in insect gut proteolytic activity and behavior with landscape heterogeneity. The RR-WCR illustrates how agroecological factors can affect the evolution of insects in human-altered ecosystems.

Original languageEnglish (US)
Pages (from-to)2005-2017
Number of pages13
JournalEcology and Evolution
Volume2
Issue number8
DOIs
StatePublished - Dec 1 2012

Keywords

  • Contemporary evolution
  • Landscape heterogeneity
  • Plant defenses
  • Plant-insect interactions
  • Protease inhibitors

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation

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