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Subject: search.filters.subject.Leaf dipping method

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    Effectiveness of bastard oleaster (Elaeagnus latifolia) extracts against the nymph of mealybug (Phenacoccus manihoti)
    (2019-01-01)
    Pumnuan, J.
    ;
    Sannongmueang, T.
    ;
    Inyod, T.
    ;
    Insung, A.
    Bastard oleaster (Elaeagnus latifolia) is sometimes gathered from subtropical wild for local use as food, medicine and fuel. The objective of this study was to investigate the insecticidal properties of extracts from leaves and fruits of bastard oleaster against the nymph of mealybug (Phenacoccus manihoti) by using leaf dipping method. The different extracts of bastard oleaster as water extract by decoction method, ethanol and hexane extracts by percolation and Soxhlet methods were applied with various concentrations; 0 (5% tween-20 water) 1, 2, 3, 4 and 5% (w/v), and imidacloprid insecticide used as positive control. Then the insect mortality was observed at 24 and 48 h, as well as the repellent index (%RI) was observed at 24 h. The results showed that ethanolic extract from bastard oleaster fruits by Soxhlet method and leaves by percolation method were highly effective in killing the nymph of mealybug with the LC50 at 48 h for 2.64 and 2.83%, respectively. The bastard oleaster leaves extracted by percolation and Soxhlet at 5% concentrations showed rather strong effect in repellence when the nymph of mealybug with >52% RI was found within 24 h. In addition, all extracts of bastard oleaster at 5% concentrations were more effective against the nymph of mealybug than imidacloprid insecticide at 24 h. Therefore, extracts from this wild plant, bastard oleaster leaves would be promoted and used as botanical insecticide in the future.
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    Insecticidal properties of bastard oleaster (Elaeagnus latifolia) extracts against diamondback moth (Plutella xylostella)
    (2019-01-01)
    Pumnuan, J.
    ;
    Sannongmueang, T.
    ;
    Inyod, T.
    ;
    Insung, A.
    Diamondback moth (DBM), Plutella xylostella is the major insect pest of cruciferous vegetables in Thailand. When chemicals are wildly used to control this insect pest, it results in an impact on farmer, consumers, environment, and also induces insecticide resistance. The application of plant extracts is an alternatively effective method to fulfill IPM program. This study aimed to evaluate the effects of different extracts from leaves and ripe fruit of bastard oleaster (Elaeagnus latifolia), a wild edible plant in Thailand, as water extracts by decoction method, ethanol and hexane extracts by percolation and Soxhlet methods against larvae of DBM. The experiment of insecticidal properties; killing activity, inhibiting growth and anti-feedant by oral test, were investigated on third instar larvae. The leaf dipping method by using various concentrations of extracts, 0.0 (5% tween-20 in water), 1, 2, 3, 4 and 5% (w/v) was applied, and then compared with fipronil, prothiofos, deltamethrin and abamectin insecticides. The larval mortality was checked at 24 and 48 h, where the percentages of anti-feedant activity were observed at 24 h. The surviving larvae are feeded with the treated remains until they develop to the mature and adult stages. The result showed that ethanol extract from leave of bastard oleaster by percolation and Soxhlet methods were highly effective in killing the larvae of DBM with the LC50 at 24 and 48 h for 4.94-5.47% and 3.42-3.63%, respectively. Both extracts also showed moderate effectiveness in anti-feedant with >45.0% within 24 h. Ethanol extracts from leave and fruit by percolation and Soxhlet methods presented the best inhibiting growth of DBM when the concentration at 5% caused 67-87% adult mortality. Whereas, all selected insecticides tended to be low toxic to this insect with no difference compared to the ethanol extract of bastard oleaster leave.