Modelling codling moth damage as a function of adult monitoring and crop protection

Abstract: The codling moth (Cydia pomonella) is responsible for most insecticide treatments in pear and apple orchards. In a context of reduction in pesticide use, we aim at better understanding factors that affect codling moth damage intensity. We modelled the link between the proportion of damaged fruits and both constant covariables (type of orchard: pear or apple, organic or not, with or without mating disruption) and time-varying covariables (weekly counts of adults and number of insecticide treatments). Observations were collected in 40 orchards in south-eastern France. We found that damage intensity increased with the number of adults trapped. An analysis of the random orchard effect indicated a certain temporal stability in the risk probability of orchards and a lower risk probability in orchards surrounded by numerous pomefruit orchards and windbreak hedgerows.