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.

Plutella xylostella (L.) (Lepidoptera: Plutellidae), the major insect pest of cruciferous crops worldwide shows significant resistance to almost all classes of insecticides. In order to effectively prevent and manage the insecticidal resistance, it is crucial to understand the physiological adaptation of insects against insecticides. Identification of insect protein that interacting with insecticides and characterization of their modification in resistant strains can be done by using differential proteomics approach. This study focuses on optimizing a sensitive and rapid method for the extraction of high quality protein of both larva and adult tissues of P. xylostella to be used in two-dimensional gel electrophoresis. Five extraction methods were evaluated for protein concentration, yields and resolving patterns of one-dimensional and two-dimensional electrophoresis. The results showed that trichloroacetic acid/acetone extraction methods with two different concentrations of 2-mercaptoethanol produced the highest protein concentration and yield for both adult and larva tissues, respectively. Meanwhile, trichloroacetic acid/acetone with dithiothreitol extraction method gave better separation of spots and intensity for both larva and adult tissues compared to other methods tested. As such, we concluded that trichloroacetic acid/acetone with dithiothreitol successfully yielded high total protein concentration and good separation of two-dimensional electrophoresis gel spots in both adult and larva P. xylostella.