Toxicity and Sublethal Effect of Farnesyl Acetate on Diamondback Moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)

Abstract

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the most important pest of cruciferous vegetables worldwide. In this study, we evaluated the properties of selected farnesyl derivative compounds against P. xylostella. The toxicity and sublethal concentration (LC50) of farnesyl acetate, farnesyl acetone, farnesyl bromide, farnesyl chloride, and hexahydrofarnesyl acetone were investigated for 96 h. The leaf-dip bioassays showed that farnesyl acetate had a high level of toxicity against P. xylostella compared to other tested farnesyl derivatives. The LC50 value was 56.41 mg/L on the second-instar larvae of P. xylostella. Then, the sublethal effects of farnesyl acetate on biological parameters of P. xylostella were assessed. Compared to the control group, the sublethal concentration of farnesyl acetate decreased pupation and emergence rates, pupal weight, fecundity, egg hatching rate, female ratio, and oviposition period. Furthermore, the developmental time of P. xylostella was extended after being exposed to farnesyl acetate. Moreover, the application of farnesyl acetate on P. xylostella induced morphogenetic abnormalities in larval–pupal intermediates, adults that emerged with twisted wings, or complete adults that could not emerge from the cocoon. These results suggested that farnesyl acetate was highly effective against P. xylostella. The sublethal concentration of farnesyl acetate could reduce the population of P. xylostella by increasing abnormal pupal and adults, and by delaying its development period.

Toxicity and Sublethal Effects of Fluxametamide on the Key Biological Parameters and Life History Traits of Diamondback Moth Plutella xylostella (L.)

“…The result indicated that the fluxametamide toxicity to P. xylostella was higher than that of abamectin, spinosad, indoxacarb, chlorantraniliprole and fenoxycarb [21,41,42]. In addition, the second instar larvae of P. xylostella exhibited an LC 50 value of 56.41 mg L −1 when treated with farnesyl acetate, was higher than the present results with a lower toxicity [43]. However, the LC 50 of the technical grade fluxametamide, obtained from the present study, was also lower than that of rac-fluxametamide (1.90 mg L −1 ) and its enantiomers; S-(+)-fluxametamide (0.62 mg L −1 ), or R-(-)-fluxametamide (34.18 mg L −1 ) at 48 h [40].…”

Sublethal effects of fenoxycarb on female reproduction in Helicoverpa armigera (Lepidoptera: Noctuidae)

“…In the present study, fenoxycarb significantly increased the preoviposition period but shortened the oviposition period, compared to the control. Yusoff et al (2021) observed similar effects were observed with farnesyl acetate decreasing oviposition in P. xyllostella. According to Yusoff et al (2021), decreasing oviposition time may led to decreases in fecundity.…”

Sublethal effects of chlorfenapyr on Plutella xylostella (Lepidoptera: Plutellidae)

“…Otherwise, it will be difficult to uncover the full sublethal effects of pesticides and their dynamics. While there have been a number of studies investigating the sublethal effects on DBM of various insecticides including spinosad, 26 indoxacarb and hexaflumuron, 14,21 chlorantraniliprole, 18 tebufenozide, chlorfluazuron and indoxacarb, 46 metaflumizone, 47 tolfenpyrad, 48 fenoxycarb 49 spinetoram, 50 and farnesyl acetate, 51 all of these studies found deleterious impacts only. Since sublethal doses below the NOEC were omitted in these studies, people cannot rule out that the above insecticides may actually have hormetic effects.…”