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

• Main Authors: Norazila Yusoff, Idris Abd Ghani, Nurul Wahida Othman, Wan Mohd Aizat, Maizom Hassan
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Insects
• Subjects: <i>Plutella xylostella</i>; farnesyl derivatives; sublethal concentration; biological parameters; pest management; morphological abnormalities
• Online Access: https://www.mdpi.com/2075-4450/12/2/109

The diamondback moth, <i>Plutella xylostella</i> (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 <i>P. xylostella</i>. 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 <i>P. xylostella</i> compared to other tested farnesyl derivatives. The LC₅₀ value was 56.41 mg/L on the second-instar larvae of <i>P. xylostella</i>. Then, the sublethal effects of farnesyl acetate on biological parameters of <i>P. xylostella</i> 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 <i>P. xylostella</i> was extended after being exposed to farnesyl acetate. Moreover, the application of farnesyl acetate on <i>P. xylostella</i> 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 <i>P. xylostella</i>. The sublethal concentration of farnesyl acetate could reduce the population of <i>P. xylostella</i> by increasing abnormal pupal and adults, and by delaying its development period.