larvicidal efficacy of monoterpenes and their role on enzymes inhibition and protein-content of 𝑇𝑢𝑡𝑎 𝑎𝑏𝑠𝑜𝑙𝑢𝑡𝑎 (meyrick)

Tomato leaf miner, tuta absoluta is a highly destructive pest of tomato crop. the exhaustive use of synthetic insecticides has led to widespread resistance. using monoterpenes as novel insecticides is a promising alternative approach for controlling this pest. in the current study, two monoterpenes [(-)-carvone and cuminaldehyde] were evaluated for larvicidal activity against t. absoluta and compared with chlorpyrifos insecticide. the inhibitory effect of monoterpenes on acetylcholinesterase (ache), non-specific esterase (nse α/β) and total protein content, was also evaluated. both of (-)-carvone and cuminaldehyde exhibited good larvicidal (lc50 = 1.30 and 1.41 mg/l, respectively) compared to chlorpyrifos (lc50 = 2.63 mg/l) activities. on the other hand, (−)-carvone and cuminaldehyde showed pronounced inhibitory effects on ache and nse activity of t. absoluta larvae. the (−)-carvone (0.024 µmol/min/mg protein) and cuminaldehyde (0.049 µmol/min/mg protein) caused the highest inhibition of ache and nse (α/β) activity, respectively. however, there was no significant difference between chlorpyrifos and control. the tested monoterpenes also considerably decreased the larval protein content. monoterpenes tested provide with novel opportunities to target different t. absoluta enzymes, due to its natural origin, it can be further developed as a safer and more potent larvicide/insecticide capable of combating insecticide resistance.