Mediterranean ants can increase nymph mortality in the stink bug Nezara viridula without interfering with its egg parasitoid Trissolcus basalis

Ants (Hymenoptera: Formicidae) play a relevant ecological role across terrestrial ecosystems. Recent studies suggest that the presence of ants in crops could lead to a decrease in the populations of insect pests, but how these actions can vary along the different trophic levels is not well known. The southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), is a cosmopolitan agricultural pest which is regularly found on horticultural agroecosystems closely associated with its main egg parasitoid, Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae). We conducted laboratory experiments to test whether two Mediterranean ant species, the generalist predators Crematogaster scutellaris (Olivier) and Tapinoma magnum Mayr, attack N. viridula eggs or nymphs, and whether they interfere with the parasitization activity of T. basalis. The experiment showed that both ant species significantly increased the mortality of N. viridula nymphs, whereas they do not attack their eggs and do not interfere with the egg parasitoids. Our results suggest that ants and egg parasitoids may have an integrable role in biocontrol strategies against this pest.