Wound to survive: mechanical damage suppresses aphid performance on brassica

Plants exhibit a remarkable capacity to discern between self-inflicted damage, herbivore attacks, and mechanical harm through pattern recognition, detecting specific signals associated with each type of damage. Mechanical damage significantly influences plant defence responses against herbivorous insects. This study aimed to artificially activate the plant defence system and observe the performance of aphid (Myzus persicae Sulzer) (Hemiptera: Aphididae) and their parasitoid (Diaeretiella rapae M’Intosh) (Hymenoptera: Braconidae) on brassica plants. Mechanically damaged and undamaged plants were subjected to aphid infestation, and various parameters related to aphid and parasitoid performance, including adult survival, fecundity, aphid settlement, and oviposition behavior, were measured. Results revealed that plants with artificial damage exhibited greater resistance to aphids than undamaged plants. In the cage bioassay, there was a notable 17% reduction in aphid larviposition on damaged plants, with no significant impact on adult mortality. The aphid settlement bioassay demonstrated a significant 33% reduction in aphid settlement on damaged plants compared to undamaged ones. Conversely, mechanical damage increased parasitism behavior, leading to a substantial 32% increase in parasitoids’ oviposition preference on damaged plants. These findings highlight the significance of considering mechanical damage as a crucial factor in altering plant–insect interactions. The study suggests that mechanical damage could be a potential tool for plant protection in agricultural settings by significantly suppressing aphid performance and enhancing parasitoid behaviour.