Glucosinolate hydrolysis products suppress entomopathogenic nematodes in vitro but do not protect sequestering flea beetle larvae in vivo.

The efficacy of entomopathogenic nematodes (EPNs) in the biological control of insect pests can be influenced by the host's chemical defenses. Phyllotreta flea beetles, among the most destructive pests of Brassica crops, deploy highly reactive glucosinolate hydrolysis products as a defense against natural enemies. Here, we investigate the susceptibility of EPNs and their symbiotic bacteria to glucosinolate hydrolysis products and assess how this defense shapes the interaction between the horseradish flea beetle, Phyllotreta armoraciae, and EPNs.