Nitrogen and water inputs to tomato plant do not trigger bottom‐up effects on a leafminer parasitoid through host and non‐host exposures

BACKGROUND Bottom-up and top-down forces are major components for biological control against pests in agro-ecosystem. Understanding the multi-trophic interactions from plants to secondary consumers would serve to optimize pest control strategies. We manipulated nitrogen and/or water inputs to tomato plants (Solanum lycopersicum) to test if those manipulations could trigger bottom-up effects on the parasitoid Necremnus tutae via host (Tuta absoluta) and/or non-host (Bemisia tabaci) exposures, and compared the control efficacy of N. tutae on T. absoluta in the presence and absence of B. tabaci. RESULTS The results showed no cascading effects of plant nitrogen and/or water inputs on N. tutae via both host and non-host exposures. Bottom-up force was mitigated by chewing or sap-feeding insect consumers at the second energy level. On the contrary, top-down force on T. absoluta from parasitoids was enhanced by additionally provided non-host, which could produce alternative food resources contributing to extend N. tutae longevity and to enhance its offspring fitness. CONCLUSION Our results provided an evidence to allow combining bottom-up and top-down approaches in tomato Integrated Pest Management programs.