Regulation of Diapause Entry and Termination in the Swede Midge, Contarinia nasturtii (Diptera: Cecidomyiidae)

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Date

2012-05-17

Authors

Des Marteaux, Lauren

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Publisher

University of Guelph

Abstract

This thesis is an investigation of several aspects of diapause in the swede midge, Contarinia nasturtii (Kieffer). After developing methodology for induction and quantification of diapause entry in the laboratory, heritability of diapause entry was assessed for sibling larvae reared under diapause-inducing conditions. The diapause-quantification technique was efficient, but diapause frequencies were highly variable across studies employing similar diapause-inducing conditions. The diapause entry trait may be weakly heritable. A field study was conducted on diapause entry and emergence patterns. Diapause frequency was inversely correlated with photoperiod and absolute maximum air temperature. Photoperiod did not influence emergence timing. Two emergence phenotypes were observed before mid-July and a third minor emergence phenotype may exist in mid-to-late August. Approximately one third of emergence in the field was attributed to larvae in diapause for two or more years. Avenues of future research on diapause regulation in both the laboratory and field are discussed.

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Keywords

Cecidomyiidae, swede midge, Contarinia nasturtii, diapause induction, emergence, heritability, methodology

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