Potential role of seed treatments in the management of emerging arthropod pests of canola

Conservation agriculture has changed the farming landscape. Reduced tillage, stubble retention and changes in crop agronomy have provided considerable benefits to farmers and the environment, but such practices have also influenced arthropod communities residing in these landscapes. Within Australia, there has been an increase in the pest status of several introduced arthropods including Armadillidium vulgare (common pillbug), Forficula auricularia (European earwig) and Ommatoiulus moreleti (black Portuguese millipede). In the present study, the role of insecticide seed treatments in managing these species was examined. Species differed in their responses when exposed to seedlings coated with four commercially-available seed treatments. F. auricularia numbers were reduced by treatments of fipronil (Cosmos) and a mixture of clothianidin and imidacloprid (Poncho Plus). These treatments also reduced A. vulgare numbers, as did a third product, a mixture of thiamethoxam and lambda-cyhalothrin (Cruiser Opti). Mortality of O. moreleti was affected by all four seed treatments. Importantly, arthropod mortality did not always correlate with the levels of protection conferred by each treatment. This points to a complexity of interactions between plant, chemical and pest feeding behaviour. These results are discussed in the context of developing pest management options for these widespread arthropods.