Deciphering the plant- insect interactions between specialist biocontrol insects and invasive plants

Classical biological control is recognized as a highly effective and economically efficient method for managing invasive plant species. However, there is little understanding of the various factors that influence the success of biological control agents (BCAs) on invasive plants.

In this study, we aim to investigate the plant defense responses of Dioscorea bulbifera L. (air potato), a highly problematic invasive weed in Florida, and the counter-insect responses of Lilioceris cheni (Coleoptera), a specialist herbivore of D. bulbifera.

Specifically, we tested whether the application of salicylic acid (SA) and jasmonic acid (JA), two phytohormones known to regulate plant defense responses, would alter the level of beetle damage on air potato plants and the saponin content, a phytochemical produced by air potato with pesticidal properties.

Additionally, we aim to investigate whether the beetles sequester these chemicals in their bodies to overcome plant defenses and whether their performance exhibits a dose-dependent pattern.

Our findings suggest that air potato plants produce higher levels of saponins and subsequently suffer greater damage in response to JA treatment. Furthermore, we expect that beetles will sequester higher levels of saponins from JA-treated plants compared to SA-treated plants and that herbivory may be positively correlated with saponin dose initially, followed by a drop in herbivory with any increase in dosage. This study will be instrumental in exploiting plant defenses to better strategize biocontrol programs for invasive plants.