Does fertilization plant-mediated bottom-up effect reach the third trophic level in the tomato-pest-NE tritrophic system?

In agroecosystems, arthropod communities may be influenced by bottom-up forces induced by environmental variations (e.g., fertilization) through the modification of plant traits. The way bottom-up forces affect the 2^nd trophic level is particularly well documented, but less is known about their ability to affect the third trophic level. Furthermore, plant-mediated bottom-up forces may affect natural enemies directly or indirectly (through herbivores). We aim to disentangle 1) if bottom-up effects reach the 3^rd trophic level with equivalence between parasitoids and predators and 2) If bottom-up effects modify the ability of natural enemies to control pests in real growing conditions.
We set up a lab experiment where variations in fertilization regime were tested as bottom-up factors. The studies were carried out on three different “tomato plant-herbivores-natural enemies” systems. Selected herbivores are frequent pests on tomato systems (Macrosiphum euphorbiae, Bemisia tabaci, and Tuta absoluta). The respective parasitoids were Aphidius ervi and Encarsia formosa, and the respective predators Adalia bipunctata (carnivorous), Macrolophus pygmaeus (omnivorous), and Dicyphus errans (omnivorous). We recorded plant, and herbivores as well as various parasitoid/predator traits-survival, development, reproduction, and biocontrol ability.
We found strong evidence of diluted bottom-up forces through trophic levels depending on the herbivore types. Parasitoids seem less affected than predators. Predators were able to control the increase in pest populations with increased fertilizer. This work offers perspectives in the framework of Integrated Pest Management on how smart manipulation of plant nutrient solutions might save resources while maintaining efficient biocontrol in crop production.