Two in one: the neotropical mirid predator Macrolophus basicornis increases pest control by feeding on plants.

Background: Plant defenses activated by European zoophytophagous predators trigger behavioral responses in arthropods, benefiting pest management. However, repellence or attraction of pests and beneficial insects seems to be species-specific. In the neotropical region, the mirid predator Macrolophus basicornis has proved to be a promising biological control agent of important tomato pests; nevertheless, the benefits of its phytophagous behavior have never been explored. Therefore, we investigated if M. basicornis phytophagy activates tomato plant defenses and the consequences for herbivores and natural enemies.

Results: Regardless of the induction period of M. basicornis on tomato plants, Tuta absoluta females showed no preference for the odors emitted by induced or control plants. However, Tuta absoluta oviposited less on plants induced by M. basicornis for 72 h than on control plants. In contrast, induced plants repelled Bemisia tabaci females, and the number of eggs laid was reduced. Although females of Trichogramma pretiosum showed no preference between mirid-induced or control plants, we observed high attraction of the parasitoid Encarsia inaron and conspecifics to plants induced by M. basicornis. While the mirid-induced plants down-regulated the expression of genes involving the salicylic acid (SA) pathway over time, the genes related to the jasmonic acid (JA) pathway were up-regulated, increasing emissions of fatty-acid derivatives and terpenes, which might have influenced the arthropods' host/prey choices.

Conclusion: Based on both the molecular and behavioral findings, our results indicated that in addition to predation, M. basicornis benefits tomato plant resistance indirectly through its phytophagy. This study is a starting point to pave the way for a novel and sustainable pest-management strategy in the neotropical region. © 2022 Society of Chemical Industry.