Project 1: Plant defense metabolites and herbivore immunity
Herbivores must cope with plant anti-herbivore defenses including chemicals that are toxic or repellent —frequently via detoxification or excretion. At the same time, herbivores must avoid becoming prey to predators or hosts to parasitoids (frequently, parasitic wasps that develop inside their caterpillar hosts). Herbivores are well-known to employ specialized hemolymph (“blood”) cells that provide immunity against internally developing parasitoid eggs and larvae. These immune cells form hardened capsules around parasitoid eggs, resulting in the death of the parasitoid from asphyxiation.
At the intersection of the bottom-up effects of plant defense chemistry and the top-down effects of parasitoids are caterpillar immune systems, traits that are frequently overlooked in studies of plant-insect interactions. Ecoimmunological studies of multitrophic systems provide opportunities to examine the mechanisms of how herbivores simultaneously defend against natural enemies while coping with plant defense chemicals. To understand how caterpillars balance top-down and bottom-up selective pressures, it is essential to study how caterpillar immune responses are affected by plant defensive chemistry and how this, in turn, affects caterpillar–parasitoid interactions.
Eco-immunology and Trophic Interactions
Eco-immunology represents a relatively modern discipline that illuminates ecological inquiries through a comprehensive grasp of the immune systems of organisms under scrutiny. My research endeavors to unveil the intricate interplay between plant defense mechanisms—both direct and indirect—and their influence on trophic interactions, with a specific emphasis on herbivore immunity.
Project 2: Plant volatiles and herbivore immunity
Plants release volatile compounds to attract natural enemies of herbivores, such as parasitoids. While these volatiles primarily benefit the success of parasitoids, my research seeks to investigate whether herbivores have developed a defense mechanism by eavesdropping on the interactions between plants and parasitoids. My study suggests that exposure to specific plant volatiles, like (E)-β-ocimene, can alter herbivore physiology. This altered physiology results in an enhanced immune response driven by olfaction, providing herbivores with improved defense against parasitoids and harmful microbes. My study is among the first to uncover a direct impact of plant volatiles on herbivore physiology and immunity. It establishes a connection between plant volatiles and insect cellular immunity, highlighting the intricate role of chemical signals in trophic interactions.
Project 3: Oviposition preference and herbivore performance
Insect oviposition choice is critical for offspring survival but the correlation between adult preference and larval performance is mostly inconclusive. My research investigates this relationship by looking at multiple factors like direct and indirect defense of plants, herbivore physiology, and involvement of multiple natural enemies. My results show that, for a specialist herbivore, host plant quality and defense against natural enemies are key driving factors for their oviposition choice. I further investigate oviposition preference of parasitoids. My results highlight the importance of volatiles in parasitoid choice. Parasitoid host selection depends on their specialization, diet modulated short-range cues (such as larval body odor) and the nutritional physiology of the herbivore. These insights contribute to a multi-trophic perspective in understanding insect oviposition behaviour, which is vital for devising effective pest management strategies
