Modeling the integration of parasitoid, insecticide, and transgenic insecticidal crop for the long-term control of an insect pest

David W. Onstad, Xiaoxia Liu, Mao Chen, Richard T. Roush, Anthony M. Shelton

Research output: Contribution to journalArticle

12 Scopus citations


The tools of insect pest management include host plant resistance, biological control, and insecticides and how they are integrated will influence the durability of each. We created a detailed model of the population dynamics and population genetics of the diamondback moth, Plutella xylostella L., and its parasitoid, Diadegma insulare (Cresson), to study long-term pest management in broccoli Brassica oleracea L. Given this pest's history of evolving resistance to various toxins, we also evaluated the evolution of resistance to transgenic insecticidal Bt broccoli (expressing Cry1Ac) and two types of insecticides. Simulations demonstrated that parasitism provided the most reliable, long-term control of P. xylostella populations. Use of Bt broccoli with a 10% insecticide-free refuge did not reduce the long-term contribution of parasitism to pest control. Small refuges within Bt broccoli fields can delay evolution of resistance >30 generations if resistance alleles are rare in the pest population. However, the effectiveness of these refuges can be compromised by insecticide use. Rainfall mortality during the pest's egg and neonate stages significantly influences pest control but especially resistance management. Our model results support the idea that Bt crops and biological control can be integrated in integrated pest management and actually synergistically support each other. However, the planting and maintenance of toxin-free refuges are critical to this integration.

Original languageEnglish (US)
Pages (from-to)1103-1111
Number of pages9
JournalJournal of economic entomology
Issue number3
StatePublished - Jun 1 2013


All Science Journal Classification (ASJC) codes

  • Ecology
  • Insect Science

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