Cotoxicity of Bacillus thuringiensis and fluvalinate combinations to the Lightbrown apple moth, Epiphyas postvittana (Lepidoptera:Tortricidae): A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Horticultural Science (Honours) at Lincoln College, University of Canterbury

Abstract

Reduced amounts of microbial and chemical insecticides can be combined to gain a potentiated response and so reduce residue levels, environmental hazards and the likelihood of resistance occuring. Potentiation can be obtained by combinations of Bacillus thuringiensis, (BT) and fluvalinate concentrations. 100% mortality levels ofLBAM can be obtained by applications of half the recommended field rate of BT (0.5 g/litre) and 0.2 times the field rate of fluvalinate (0.005 g a.i./litre ). Thus reduced rates of BT and sublethal doses of the synthetic pyrethroid, fluvalinate, in mixtures can produce Lightbrown apple moth, (Epiphyas postvittana), control levels equal to the recommended commercial field rate of each insecticide individually. However cotoxicity responses at varying concentrations were not consistent, varying from potentiated to antagonistic effects. Results at all stages of the experimental bioassay procedure contained high associated errors and the bioassay method needs to be revised and standardised in future work investigating the cotoxic response of BT and fluvalinate combinations.