A review of combinations of alternative pest control methods for Phthorimaea absoluta

Abstract: Phthorimaea (= Tuta) absoluta (Lepidoptera: Gelechiidae) is an invasive pest
causing serious damage in tomato worldwide. Long-term sustainable management cannot be
achieved with conventional insecticides, due to environmental impacts and emerging pest
resistance. Alternative methods though are rarely efficient and reliable enough on their own to provide sufficient control of P. absoluta. We therefore reviewed the literature on available
evidence for the effects of combinations of alternative pest control methods. We found 70
research articles, detailing 167 experiments on 30 combinations of methods using 53 different control agents or substances. The most studied systems focused on combinations involving predatory mirids and Trichogramma-egg parasitoids. Of the experiments, 137 investigated agent behaviour, fitness, reproduction or their attack rate on the target, while 53 researched effects on the P. absoluta population or its damage, mostly under laboratory conditions. In many cases effects depended on the time between the application of the two agents. Field or greenhouse evidence including both agents as comparators was limited. Here the combination of Azadirachtin with Beauveria bassiana as well as the pheromone trapping with Bacillus thuringiensis showed better control than either method alone. We advocate for the implementation of field experiments when assessing combinations of alternative pest control methods, inclusion of controls where the agents and substances are tested alone, and the consideration of economic aspects.