Toxic and behavioural effects of carvacrol and thymol on Frankliniella occidentalis larvae

Abstract

Bioassays using bean leaf discs were conducted to investigate toxic and behaviour-modifying effects of carvacrol and thymol, two monoterpenoid phenols, on second instar larvae of Frankliniella occidentalis (Thysanoptera: Thripidae) at concentrations of 0.1% and 1%. We tested the contact toxicity of carvacrol and thymol to F. occidentalis larvae and studied the settlement preference of thrips larvae for treated or untreated bean leaf discs and the effects of the compounds on their feeding activity. Mortality rates after 24 h were 24.1% for carvacrol at 1% concentration, 16.5% for carvacrol at 0.1%, 7.7% for thymol at 1% concentration and 3.6% for thymol at 0.1%. Thrips larvae showed a significant preference for untreated leaf discs in choice tests with carvacrol 1% or thymol 1%. Likewise, in the no-choice tests feeding damage after 24 h was significantly lower on leaf discs treated with 1% carvacrol or 1% thymol compared to the control, but not on discs treated with 0.1% concentration of either compound. We conclude that an application of carvacrol or thymol to bean leaves does not result in a high mortality of F. occidentalis larvae but affects their behaviour.

Integrated pest management in western flower thrips: past, present and future

“…Applications of methyl‐jasmonate and cis‐jasmone deterred WFT larvae from feeding and settling, although repeated exposure resulted in a dose‐dependent habituation . The monoterpenoid phenols thymol and carvacrol exhibited both a feeding as well as a oviposition deterrent effect to WFT …”

“…93,94 The monoterpenoid phenols thymol and carvacrol exhibited both a feeding as well as a oviposition deterrent effect to WFT. 95,96 Currently, the three commercially available WFT semiochemicals are mainly used as lures in conjunction with sticky card traps. Adult thrips constantly explore their host range for feeding and reproduction by utilising different cues, including volatiles.…”

Life Table and Preference Choice of Frankliniella occidentalis (Thysanoptera: Thripidae) for Kidney Bean Plants Treated by Exogenous Calcium

“…Numerous studies have demonstrated that exogenous biotic and abiotic elicitors have been used to induce host plant defense against F. occidentalis , for example, Pseudomonas syringae , coronatine [ 10 ], jasmonic acid (JA) [ 3 , 35 ], salicylic acid (SA) [ 36 ], ultraviolet [ 37 ], light intensity [ 38 ], nitrogen fertilizer [ 39 ], CO 2 [ 40 ], secondary substances (α-ionone, eugenol, thymol, carvacrol and alkaloids, etc.) [ 41 , 42 ], and protein inhibitors [ 43 ]. In the present study, Ca treatment on kidney bean plants also influenced the population parameters and preference of F. occidentalis .…”

Behavioural responses of Frankliniella occidentalis Pergande larvae to methyl jasmonate and cis-jasmone

“…As far as we know, only one study with antifeedants was carried out with thrips larvae so far: carvacrol and thymol, two monoterpenoid phenols, applied to the test plants at a concentration of 1 % deterred F. occidentalis second instar larvae in choice bioassays. In addition, the feeding damage of the larvae was reduced in a no-choice situation (Peneder and Koschier 2011 ).…”