Abstract
Many plants show significant biological activity against pests due to their unique chemical constituents. It is important to identify effective constituents for their development and utilization as botanical pesticides. Our previous study showed that Artemisia lavandulaefolia essential oil had biological activity against Plutella xylostella. Here, we isolated and identified the constituents of essential oil from A. lavandulaefolia by silica gel column chromatography. The main constituents identified were eucalyptol and caryophyllene oxide, and they were confirmed by gas chromatography–mass spectrometry (GC–MS). Eucalyptol and caryophyllene oxide showed strong contact toxicity against P. xylostella larvae after 24 h of application (Median lethal dose, LD50 = 76.97 μL/mL and 20.71 mg/mL. Furthermore, the two active constituents against P. xylostella adults showed significant fumigant activity (Mmedian lethal concentration, LC50 = 3.25 μL/L and 1.06 mg/L, respectively. Finally, we measured the detoxification enzymes and acetylcholinesterase of the larvae treated with active constituents. The eucalyptol-treated larvae displayed enhanced carboxylesterase (CarE) and glutathione-S-transferase (GST) activities in an in vivo experiment, but it was lower for acetylcholinesterase (AchE) activity. The activities of the CarE and GST significantly decreased when exposed to caryophyllene oxide. In general, the two active constituents, eucalyptol and caryophyllene oxide, showed high insecticidal activity, which demonstrates their potential to be used as natural insecticides.
Highlights
The diamondback moth Plutella xylostella Linnaeus (Lepidoptera: Plutellidae) is the most serious pest of cruciferous crops globally and causes economic losses amounting to US$ 4–5 billion annually [1]
The bioactivity of the essential oil from A. lavandulaefolia on P. xylostella was evaluated; we found that it had contact and fumigant activity on P. xylostella (LD50 = 0.045 μL/larva, LC50 = 0.113 mg/L) [15]
The results showed that the neutral constituent was the most active against P. xylostella (Table 1)
Summary
The diamondback moth Plutella xylostella Linnaeus (Lepidoptera: Plutellidae) is the most serious pest of cruciferous crops globally and causes economic losses amounting to US$ 4–5 billion annually [1]. Many plant-derived chemicals are used to control pests but have little or no impact on non-target organisms and the environment [5]. One such source is plant essential oils, which are extracted from the roots, stems, leaves, branches, fruits, seeds, flowers, and even the whole plant. Plant essential oils are made up of 20–60 constituents of different concentrations [6,7]. China’s vast territory and unique natural conditions harbor many plant resources from which essential oils have been extracted (more than 400 plant species found in more than 110 genera) [8,9,10]
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