Repellent and insecticidal effects of Rosmarinus officinalis and its volatiles on Tuta absoluta

Tomato leaf miner (Tuta absoluta) is a notoriously invasive pest that has spread from South America to over 110 countries worldwide and poses a significant threat to the global tomato industry. Adverse effects associated with the overuse of chemical insecticides have prompted researchers to seek ecologically-based management options, such as using secondary plants. However, research on the repellent plants of T. absoluta is missing. In this study, we assessed the potential of nine commonly reported repellent plants. Rosmarinus officinalis was found to exhibit a significant repellent effect against T. absoluta. We quantified the volatile organic compounds (VOCs) in R. officinalis, and further determined the repellent effects of the specific VOCs. The plant R. officinalis and the VOC eucalyptol delayed the developmental period of T. absoluta and decreased the egg-hatching rate. By running cage and greenhouse experiments, we confirmed that R. officinalis and eucalyptol reduced the damage caused by T. absoluta via antixenosis (i.e. reduced number of eggs laid). Our results showed the important function of R. officinalis and its VOCs in controlling T. absoluta, guiding the use of repellent plants as a key component of Integrated Pest Management packages.