Plant feeding by an omnivorous predator affects plant phenology and omnivore performance

Plant feeding by omnivorous predators can induce plant defences, which decreases the performance of herbivores and influence behaviour of other predators. However, it is not known what are the consequences of this feeding for the plant and how this, in turn, affects the omnivore. We therefore investigated the effects of plant feeding by the omnivorous predator Macrolophus pygmaeus on plant development and reproduction. We also assessed the effects of these plant changes on survival and reproduction of the omnivore. Sweet pepper plants exposed to M. pygmaeus had significantly lower numbers of leaves and open flowers than clean plants, but numbers of fruits were similar. Moreover, the presence of the omnivore significantly shortened the period for flowers to become fruits. The dry weights of leaves plus stems and fruits were similar on clean plants and plants with the omnivore. Significantly higher numbers of seeds were found in fruits from plants with the omnivore than from clean plants. The survival rates of M. pygmaeus females and nymphs increased with numbers of flowers. Our results show that the presence of this omnivorous predator can benefit plants by increasing seed production, but the changes in plant phenology do not seem to benefit the omnivore.