Genetic structure of European and Mediterranean maize borer populations on several wild and cultivated host plants

Laurianne Leniaud, Philippe Audiot, Denis Bourguet, Brigitte Frérot, Gilles Genestier, Siu Fai Lee, Thibaut Malausa, Anne Hélène Le Pallec, Marie Claude Souqual, Sergine Ponsard*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

Target pests may become resistant to Bacillus thuringiensis (Bt) toxins produced by trangenic maize (Zea mays L.). Untreated refuge areas are set aside to conserve high frequencies of susceptibility alleles: a delay in resistance evolution is expected if susceptible individuals from refuges mate randomly with resistant individuals from Bt fields. In principle, refuges can be toxin-free maize or any other plant, provided it hosts sufficiently large pest populations mating randomly with populations from Bt-maize fields. Our aim was to examine the suitability of several cultivated or weedy plants [pepper (Capsicum frutescens L.), sorghum (Sorghum spec.), sunflower (Helianthus annuus L.), cocklebur (Xanthium spec.), cantaloupe (Cucumis melo L.), and hop (Humulus lupulus L.)] as refuges for Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) and Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae), two major maize pests in southern Europe. Larvae of both species were collected on these plants. Their genetic population structure was examined at several allozyme loci. We found little or no evidence for an influence of geographic distance, but detected a significant host-plant effect on the genetic differentiation for both species. Ostrinia nubilalis populations from sunflower, pepper, cocklebur, and sorghum appear to belong to the same genetic entity as populations collected on maize, but to differ from populations on hop. Accordingly, females from pepper and cocklebur produced exclusively the 'Z' type sexual pheromone, which, in France, characterizes populations developing on maize. Qualitatively, these plants (except hop) could thus serve as refuges for O. nubilalis; however, they may be of little use quantitatively as they were found much less infested than maize. Sesamia nonagrioides populations on maize and sorghum reached comparable densities, but a slight genetic differentiation was detected between both. The degree of assortative mating between populations feeding on both hosts must therefore be assessed before sorghum can be considered as a suitable refuge for this species.

Original languageEnglish
Pages (from-to)51-62
Number of pages12
JournalEntomologia Experimentalis et Applicata
Volume120
Issue number1
DOIs
Publication statusPublished - Jul 2006
Externally publishedYes

Keywords

  • Crambidae
  • Host races
  • Lepidoptera
  • Noctuidae
  • Ostrinia nubilalis
  • Refuge crop
  • Resistance evolution
  • Sesamia nonagrioides
  • Transgenic insecticidal maize

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