LARVAE UNDER PRESSURE: EXPLORING GROUP DYNAMICS AND REGURGITATIVE REPONSES OF TRICHOPLUSIA NI LARVAE**

In the face of predation, larval insects exhibit diverse defensive responses to enhance survival. However, defensive activities such as unique movement behaviors or the release of compounds combined with unique group dynamics can incur fitness costs to the individual and the group. Therefore, understanding how group dynamics alter the risk-reward behavior of defense is important. For example, in the lepidopteran Pieris brassicae, the group-housing of larvae causes a reduction in defensive action of regurgitation. This study aims to investigate a different lepidopteran species, Trichoplusia ni, with specific focus on larval regurgitation frequency, fitness costs, and variations in defensive behaviors based on grouped (10 larvae housed together from the first in-star) or individual housing. We have a working protocol to elicit regurgitation using a pair of standardized pressure forceps to simulate a predatory attack. We hypothesize that a decrease in group-housed regurgitation rates (regurgitation event per 20 forceps squeezes) compared to single-housed individuals results in a fitness trade-off in T. ni. To this end, we will compare regurgitation rates of individually housed subjects to group-housed subjects and analyze the data using a t-test. Furthermore, we will explore the fitness cost by measuring pupal weight, which we hypothesize to be negatively correlated with regurgitation rate. Additional behavioral data will be collected by coding behaviors observed during and after the simulated attack sequence. We hypothesize unique behavioral responses between regurgitators and non-regurgitators, which may indicate regurgitation is indeed part of a larger behavioral response and not a random event incited by pressure on the gastric cavity. This study contributes to our understanding of defensive behaviors in T. ni and expands the species ethogram whilst shedding light on the role of group dynamics in eliciting defensive behaviors