inhibition of acetylcholinesterase by monoterpenoids to enhance toxic activity of chlorpyrifos on black cutworm (𝑨𝒈𝒓𝒐𝒕𝒊𝒔 𝒊𝒑𝒔𝒊𝒍𝒐𝒏)

Black cutworm (bcw), agrotis ipsilon hufnagel is a major underground pest poses a significant threat to many crops production. inappropriate and recurrent use of insecticides for bcw control results in resistance building and deleterious effects on humans and the environment. monoterpenes are the major constituents of essential oils of many aromatic plants and have different mechanisms so as to manage the pest resistance. chlorpyriphos was assessed separately and in mixtures with monoterpenes in three field-collected bcw populations. the results showed that bcw samples from qalyubia (qal), damietta (dam), and marsa-matrouh (mar) had a resistance ratio (rr) of 17.7, 12.5, and 7.8, respectively. it was interesting that the combination of chlorpyriphos with two monoterpenes showed a synergistic ratio (sr) in all populations tested. acetylcholinesterase (ache) activity was 51.8-fold higher in sample from qal than sample from laboratory susceptible (lab-sus). however, the mixture of chlorpyriphos + (−)-carvone (0.022, 0.032, and 0.038 nmol/min/mg protein) and + cuminaldehyde (0.045, 0.054, and 0.059 nmol/min/mg protein) substantially inhibited the activity of ache in samples from qal, dam, and mar, respectively. based on the results, these mixtures have the opportunity to manage resistant pests.