Optimization of pest control by the predatory bug Macrolophus pygmaeus in greenhouse tomato production

Abstract: Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) is the most important beneficial insect in greenhouse tomato production. This generalist predator is capable of controlling several pest species like whiteflies, aphids, mites, thrips and several Lepidoptera. However, as the population densities build up very slowly after release in the greenhouse, chemical interventions are often required to control early pest infestations. Faster population development would enhance biological control.In a first study, we tested the hypothesis that M. pygmaeus populations do not build up in the winter months. Results illustrated that M. pygmaeus is actually able to develop and reproduce in December, January or February under semi-commercial and commercial conditions.In a second study, we checked the hypothesis that high release rates of M. pygmaeus should be avoided as this might lead to adverse interactions like cannibalism. No such effects were found. We do however advise that M. pygmaeus should be distributed throughout a production area to enhance prey-finding and avoid negative inter-guild interactions.