(1st Place) Understanding the bottom-up effects of soil microbiota in tri-trophic interactions under drought

The soil microbiome is widely recognized as an important factor influencing plant performance. It not only regulates plant growth and metabolism but also plays a significant role in shaping plant defenses against herbivores. Environmental factors, such as drought, can disrupt the functional performance of the soil microbiome, leading to substantial repercussions on plant growth and defense. Consequently, there is a need for research to understand the effects of drought on interactions among insect, plant, and soil microbiomes. Here, we investigate how the soil microbiome contributes to the responses of a predator, Hippodamia convergens to herbivore-induced plant volatiles (HIPVs) under drought conditions. We use soil from cover crops and fallow fields as a proxy for high and low-diversity microbiome treatments, respectively. Previous studies have demonstrated that the soil from cover crops is richer and more diverse microbial community compared to fallow fields. Hence, we planted tomato plants in the sterilized potting mix soil inoculated with microbiomes extracted from either cover crop or fallow fields. We then subjected all plants to different water regimes (drought or well-watered), and infested tomato plants with aphids (Macrosiphum euphorbiae) to assess the preference of predators to HIPVs using a Y-tube olfactometer. Our findings provide insights into the complex multi-trophic interactions mediated by chemical compounds and highlight the importance of the soil microbiota in influencing higher trophic interactions under changing climates. Understanding these dynamics can contribute to our knowledge of plant defense mechanisms and aid in developing sustainable strategies for pest management in agricultural systems.