Insecticidal and synergistic activity of two monoterpenes against diamondback moth (Lepidoptera: Plutellidae)

Abstract

We examined the insecticidal activity of linalool and thymol, against diamondback moth,Plutella xylostella(Linnaeus) (Lepidoptera: Plutellidae), and whether they would synergise the activity of spinosad against this pest. Both linalool and thymol were toxic to diamondback moth larvae by topical and oral exposure, but orders of magnitude less so than spinosad. We found that low concentrations of linalool weakly synergised spinosad, increasing its toxicity more than twofold. An interaction between spinosad, and acetone meant it was not possible to identify any potential synergisms between thymol and spinosad. Our results demonstrate limited potential for thymol and linalool to act as biopesticides or synergists for managing diamondback moth.

Origanum vulgare Terpenoids Induce Oxidative Stress and Reduce the Feeding Activity of Spodoptera littoralis

“…Therefore, similar synergistic effects can explain the lower toxicity of individual compounds with respect to O. vulgare leaves. Despite the known effects of thymol as an insecticide [ 49 , 50 , 51 ], no significant effects were observed in our study, probably because of the very low amount of thymol produced by the O. vulgare chemotype used in this study.…”

Insecticidal Activity of Compounds of Plant Origin on Mahanarva spectabilis (Hemiptera: Cercopidae)

“…It is worth noting that the only structural difference between these two compounds is the position of the hydroxyl group on the benzene ring relative to the larger aliphatic chain and may be related to this difference in activity [60]. However, it is important to note that the efficacy of thymol is well reported for several insect species, such as Anopheles stephensi (Liston, 1901) (Diptera: Culicidae) [61], S. zeamais [62], and Plutella xylostella (Linnaeus, 1758) (Lepidoptera: Plutellidae) [19].…”

“…Natural products are generally efficient, low cost, and less harmful than synthetic products to nontarget organisms, and because of their biodegradability, they are ecologically appropriate [17,18]. Both commercially available formulations and rudimentary essential oils have shown promise in pest control for crops [19]. Recent research has shown a growing interest in the bioactive effects of essential oils and their derivatives on insects [20,21,22,23].…”