Toxicity of thiamethoxam and mixtures of chlorantraniliprole plus acetamiprid, esfenvalerate, or thiamethoxam to neonates of oriental fruit moth (lepidoptera: Tortricidae)

Moneen M. Jones, Jacqueline L. Robertson, Richard A Weinzierl

Research output: Contribution to journalArticle

Abstract

To assess the toxicity of thiamethoxam and three mixtures of insecticides to oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), we added the insecticides to diet and fed it to neonates of two laboratory colonies; mortality was assessed after 96 h. Thiamethoxam was much less toxic than insecticides previously tested. Five of six analyses of the joint action of chlorantraniliprole plus acetamiprid, esfenvalerate, or thiamethoxam indicated that toxicity was not independent and not correlated. For chlorantraniliprole plus acetamiprid, mortality was slightly lower than expected at low concentrations and greater than expected at high concentrations. For chlorantraniliprole plus esfenvalerate, mortality was less than expected at nearly all concentrations, suggesting antagonism despite the two compounds' different modes of action. For chlorantraniliprole plus thiamethoxam, observed mortality exceeded expected mortality at low concentrations, but this trend did not continue at higher concentrations. Although the null hypothesis of independent and uncorrected toxicity was rejected for chlorantraniliprole plus acetamiprid and chlorantraniliprole plus thiamethoxam in three of four analyses, differences between observed and expected mortality were minor and inconsistent over the range of concentrations tested. We do not expect these mixtures to exhibit significant synergism or antagonism in the field. Apparent antagonism between chlorantraniliprole and esfenvalerate is particularly relevant because these insecticides (or chlorantraniliprole plus a different pyrethroid) may be used together in apples or peaches for control of oriental fruit moth and hemipteran pests. The effectiveness of each insecticide against oriental fruit moth might be reduced in such applications.

Original languageEnglish (US)
Pages (from-to)1426-1431
Number of pages6
JournalJournal of economic entomology
Volume105
Issue number4
DOIs
StatePublished - Aug 1 2012

Keywords

  • Grapholita molesta
  • bioassay
  • insecticide resistance
  • joint action

ASJC Scopus subject areas

  • Ecology
  • Insect Science

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