Harnessing Jasmonate-Triggered Olfactory Cues as a Bioengineering Strategy for Parasitoid-Mediated Pest Control in Cotton

Objective To investigate whether jasmonate-induced plants and genetically modified Bacillus thuringiensis (BT) cotton plants are more attractive to the parasitoid Cotesia marginiventris compared to non-induced and non-genetic modified (GM) cotton plants, specifically examining how different treatments (jasmonate application, Spodoptera exigua larval damage at varying intensities) influence the olfactory behaviour of this biocontrol agent. Material and Methods The olfactory responses of female C. marginiventris were assessed using a four-armed olfactometer. The experiment tested the attractiveness of jasmonate-induced plants against plants fed on by Spodoptera exigua larvae. These treatments were applied to both BT GM cotton and non-GM cotton plants. Three criteria were measured for the parasitoids: total search time, choice time, and the number of visits to each odour zone. Results They indicated that jasmonate-induced plants were significantly more attractive than plants fed on by two S. exigua larvae, which were in turn more attractive than plants fed on by a single larva. Female parasitoids showed a significant preference for jasmonate-induced areas on both GM and non-GM cotton plants. Parasitoids spent more time in areas with GM cotton compared to non-GM cotton in non-jasmonate treatments, a trend also observed in choice time and visit frequency. Conclusion It is well documented that plants treated with jasmonate or damaged with insect species could attract the biocontrol agents throughout the emission of insect-induced volatiles.