Interactions between Nosema pyrausta (Microsporidia: Nosematidae) and Bacillus thuringiensis subsp. kurstaki in the European corn borer (Lepidoptera: Pyralidae)

C. M.F. Pierce, L. F. Solter, R. A. Weinzierl

Research output: Contribution to journalArticlepeer-review

Abstract

Larval susceptibility to Bacillus thuringiensis was determined for Nosema pyrausta-infected and uninfected European corn borers, Ostrinia nubilalis (Hübner), in bioassays using a commercial formulation of B. thuringiensis subsp. kurstaki, Dipel ES, incorporated into diet. LC50 values for N. pyrausta-infected larvae were significantly lower (P < 0.0001) than for uninfected larvae and declined with increasing levels of infection. LC50 values for a 15-d bioassay using field-colony first instars were 0.006 and 0.027 mg of Dipel ES/kg of diet for larvae moderately infected by N. pyrausta and uninfected larvae, respectively. Nosema pyrausta-infected larvae reared on Dipel ES-amended diets produced 70-fold fewer spores (P < 0.0001) than larvae reared on standard diet. For example, 15 d after placement as first instars on standard diet, infected field-colony larvae produced 7.6-8.7 million N. pyrausta spores per larva; similar larvae placed on diet containing 0.09 mg of Dipel ES/kg of diet produced 85-103 thousand spores per larva. Infected larvae also weighed less and failed to mature on Dipel ES-amended diets. Increased susceptibility of N. pyrausta-infected larvae to Dipel ES and reduced N. pyrausta spore production in larvae feeding on diet containing Dipel ES suggest that Bt corn will have a direct adverse effect on the survival and continual impact of N. pyrausta as a regulating factor on European corn borer populations.

Original languageEnglish (US)
Pages (from-to)1361-1368
Number of pages8
JournalJournal of economic entomology
Volume94
Issue number6
DOIs
StatePublished - Dec 2001

Keywords

  • Bacillus thuringiensis
  • Bioassay
  • Insect pathogen
  • Larval development
  • Nosema pyrausta
  • Ostrinia nubilalis

ASJC Scopus subject areas

  • Ecology
  • Insect Science

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