Secondary metabolites in host pears defense against two fruit borers and cytochrome P450-mediated counterdefense

Herbivores insects have evolved metabolic strategies to survive the challenges posed by plant secondary metabolites (SMs). This study reports an exploration of SMs present in pears, which serve as a defense against invasive Cydia pomonella and native Grapholitha molesta , and their counterdefense response. The feeding preferences of fruit borers are influenced by the softening of two pear varieties as they ripen. The content of SMs, such as quercetin and rutin, increasing due to feeding by fruit borers. Notably, quercetin levels only increase after C. pomonella feeding. The consumption of SMs affects the growth of fruit borers populations differently, potentially due to the activation of P450 genes by SMs. These two fruit borers equipped with specific P450 enzymes that specialize in metabolizing quercetin and rutin, enabling them to adapt to these SMs in their host fruits. These findings provide valuable insights into the co-evolution of plants and herbivorous insects.