M.L. BEN JAMÂA1
1Institut National des Recherches en Génie Rural, eaux et forêts ; Laboratoire de Gestion et Valorisation des Ressources Forestières ; BP. 10, 2080 Ariana, Tunisia ;
2Laboratoire de Parasitologie, Université de la Manouba, École Nationale de Médecine Vétérinaire de Sidi Thabet, 2020 Sidi Thabet, Tunisia ;
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 3rd concentration of M. pulegium is the most effective of the other concentrations. MMT was 15 min for the 3rd instar, 27 min for the 4th instar and 1 h 15 min for the 5th instar. Larvicidal activity of M. pulegium was more efficient on the 3rd 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.