Insecticidal activity of essential oils of species from the genus Lippia against Nasutitermes corniger (Motschulsky) (Isoptera: Termitidae)

Abstract

Lippia is one of the main genera in the family Verbenaceae, with 200 species described. Despite its richness in bioactive molecules, with several scientifically proven applications, there is little information on the insecticidal potential of its species. This study aimed to assess the insecticidal potential of essential oils from the species Lippia thymoides (Martius & Schauer); Lippia lasiocalycina (Schauer) and Lippia insignis (Moldenk) against Nasutitermes corniger (Motschulsky) (Isoptera- Termitidae). Insecticidal activity was evaluated by exposure to a contaminated surface, whereby plastic pots were lined with filter paper and imbibed in 1.5 ml of solution containing essential oils (10 μl/ml), with 10 N. corniger specimens per pot. The mortality count was performed at 24 and 48 h. The LC50was determined by diluting the essential oils to concentrations of 0, 0.625, 1.25, 2.5, 5.0 and 10 μl/ml, which were chemically analyzed by GC-FID and GC-MS. The data indicated high toxicity for the essential oils for the Lippia species tested. The lowest LC50(0.46 μl/ml) was recorded for L. lasiocalycina. The most common constituents were β-myrcene and (E)-ocimenone in essential oil of L. lasiocalycina, β-myrcene and limonene for L. insignis, and (E)-caryophyllene and caryophyllene oxide for L. thymoides. The results demonstrate the viability of developing biopesticides for N. corniger control.