Compatibility of CpGV with fungicides and Bacillus thuringiensis subsp. kurstaki

Abstract: The Cydia pomonella granulovirus, CpGV, has recently been used in Quebec,
Canada, to control codling moth, as an increasing number of apple growers adopt low risk pest control methods. For effective control, this bioinsecticide must be applied repeatedly
throughout a period when cooccurring pests and diseases which can also be subjected to
pesticide applications. This study therefore focused on CpGV efficacy when it is mixed with
pesticides used concurrently. Laboratory bioassays were performed to estimate the
compatibility of CpGV with three fungicides (sulphur, lime sulphur and potassium bicarbonate) used in organic production and a bioinsecticide containing Bacillus thuringiensis subsp. kurstaki (Btk). Formulated pesticides mixed with CpGV were tested at a concentration equivalent to recommended field rate, on codling moth neonates deposited on treated artificial diet. Mortality was estimated seven days post-application. Neonate mortality was significantly lower for the mixture composed of CpGV and sulfur-containing formulations (sulfur and lime sulphur) than for other mixtures. CpGV mixed with Btk reduced total larvae mortality but the highest mortality was induced by the virus.