Larvicidal activity of essential oil of Mentha pulegium on larvae of Orgyia trigotephras Boisduval, 1829 (Lepidoptera, Erebidae)

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Volume spécial - CIRS2017, Article20

[Volume spécial - CIRS2017, Article20]

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Abstract - To ensure better intervention and, in order to contribute to sustainable management of the environment, natural substances such as essential oils are used as insecticides. In this context, Mentha pulegium was used for its insecticidal activity against larvae of Orgyia trigotephras. Essential oil was diluted in ethanol (96%) to prepare 3 test solutions (S₁=0.05%, S₂=0.10%, and S₃=0.50%). The essential oil was tested by contact action. Larvicidal effect of essential oil was appreciated by comparison to Decis (positif test) and ethanol (negatif test). For each instar a total of 300 larvae were used for the test. Six replications were performed, in each 10 larvae were used. One larva was placed in a Petri dish and 10 µl of each oil solution prepared. The effects of the essential oils, Decis and ethanol were evaluated by measuring the mean mortality time of larvae (MMT). Results showed a highly significant difference between the three concentrations. The 3^rd concentration of M. pulegium is the most effective of the other concentrations. MMT was 15 min for the 3^rd instar, 27 min for the 4^th instar and 1 h 15 min for the 5^th instar. Larvicidal activity of M. pulegium was more efficient on the 3^rd instar than the others. A total of 23 compounds of the essential oil of flowers of M. pulegium were identified. Polegone was the dominant one at 56.22% seems to be responsible for the larvae mortality. This work should be complemented by histological sections of the caterpillars to identify the insecticidal effect of M. pulegium essential oil.

Keywords: contact action, 3 test solutions, chemical composition, mean mortality time, positif test, negatif test.