Insecticidal activity of pogostone against Spodoptera litura and Spodoptera exigua (Lepidoptera: Noctuidae).

BACKGROUND: Essential oil of Pogostemon cablin (Blanco) Benth. has been reported to exhibit strong insecticidal activities, but few studies have focused on the insecticidal activity of its main individual constituent, pogostone (PO). The goal of this research was to investigate the insecticidal activity of PO against two harmful noctuid insects, Spodoptera litura (Fabricius) and Spodoptera exigua (Hübner). RESULTS: In a no-choice assay, PO exhibited strong antifeedant activity against S. litura and S. exigua. PO showed pronounced larvicidal activities, including oral toxicity (LC50 986.88 mg L(-1) and 545.61 mg L(-1) respectively) and contact toxicity (LC50 1041.42 mg L(-1) and 519.48 mg L(-1) respectively) against these two noctuid insects. Additionally, PO treatment significantly increased the larval and pupal developmental period. Furthermore, PO showed moderate ovicidal activities and influenced the emergence and deformity of the moth. However, PO failed to exert a potent effect on adult development. These tested parameters proved to be dose dependent for both insect species. CONCLUSION: PO possesses strong insecticidal activities, especially antifeedant, larvicidal, growth inhibitory and pupicidal activities, against S. litura and S. exigua. PO may partly account for the insecticidal activity of patchouli oil and may be a promising candidate for the control of agricultural insects.

[Suppressive effects of non-preferable plant alcohol extracts on diamondback moth Plutella xylostella population].

In this paper, a life table and an interference index of population control (IIPC) were used to evaluate the effects of spraying the alcohol extracts of non-preferable plants on the dynamics of diamondback moth Plutella xylostella) population. The results showed that the alcohol extracts of Eupatorium odoratum, Lantana camara and Wedelia chinensis were available to protect kidney bean from Plutella xylostella infestation. Their IIPC were 0.110, 0.136 and 0.165, and the efficacies of controlling P. xylostella were 89.0%, 86.4% and 83.5%, respectively, compared with control.

[Bioactivity of Myoporum bontioides extracts to Plutella xylostella].

The bioactivity of Myoporum bontioides extracts to Plutella xylostella was studied with IIPC as evaluated index. The results showed that petroleum ether and chloroform extracts had a higher activity than ethyl acetate and alcohol extracts. At 0.01 gDW x ml(-1), the ODR of petroleum ether and chloroform extracts was 84.69% and 79.90%, and 76.47% and 45.70% after treated 1d and 3d, while the IIPC was 0.1565 and 0.2055, respectively. Provided with a higher concentration of 0.05 gDW x ml(-1), the ODR was 88.52% and 72.25%, and 87.33%, 58.37%, while the IIPC was 0.1125 and 0.2620, respectively. From the chloroform extract of Myopdrum Bontioides, three flavonoids, 2, 3-dihydro-5, 7-dihydroxy-2-phenyl-4H-1-Benzopyran-4-one (I), 3, 5, 7-trihydroxy-2-phenyl-4H-1-Benzopyran-4-one (II) and 5, 7-dihydroxy-3-methoxy-2-(4-methoxyphenyl)-4H-1-Benzopyran-4-one (III), were isolated, and their structure were identified based on the analyses of physical and spectrum data. Among these compounds, (II) had a better bioactivity to Plutella xylostella.

[Suppressive effect of secondary substances on Liriomyza sativae population].

Life table and interference index of population control (IIPC) were used to evaluate the effects of spraying alcohol extracts of plant secondary substances on the population of Liriomyza sativae. Field experiment results showed that alcohol extracts derived from Lantana camara, Eupatorium odoratum, and Wedelia chinensis, and one kind of commercial petroleum spray oil were positive to protect kidney bean from infestation of L. sativae. The IIPC of these repelling substance compared with control were 0.136, 0.163, 0.213, and 0.222, and the control effects on L. sativae were 86.4%, 83.7%, 78.7%, and 77.8%, respectively. At the same time, the parasitism of vegetable leafminer was increased compared with control, indicated that the effects of parasitism were increased. The results indicated that these substances had strong effects in controlling the population of L. sativae.