Insecticidal activity of a chemotype VI essential oil from Lippia alba leaves collected at Caatinga and the major compound (1,8-cineole) against Nasutitermes corniger and Sitophilus zeamais

Lippia alba is an aromatic shrub known to produce a diversity of essential oils, which can be classified into chemotypes. This study reports on the insecticidal activity of essential oil from L. alba leaves collected at Caatinga and its major compound against termite Nasutitermes corniger and maize weevil Sitophilus zeamais. The chromatographic analysis revealed the presence of 19 compounds, with 1,8-cineole being the most common (70.01%). When ingested, the oil promoted the mortality of N. corniger (LC50: 18.25 and 8.4 nL/g for workers and soldiers, respectively). The compound 1,8-cineole was also termiticidal for workers (LC50: 13.7 nL/g). The oil inhibited the activity of N. corniger exoglucanase, xylanase, and proteases. Toxicity by ingestion to S. zeamais was detected for the oil (LC50: 0.297 mu L/g) but not for 1,8-cineole; however, both the oil and 1,8-cineole showed antinutritional effects. Fumigant effects of the oil and 1,8-cineole against S. zeamais (LC50 of 78.0 and 13.64 mu L/L in air, respectively) were detected. This is the first record of a chemotype VI oil from L. alba collected at Caatinga and the first report of the insecticidal activity of a chemotype VI oil. Our study demonstrates that essential oil from L. alba and 1,8 cineole have the potential for the development of natural insecticides.

Automated summary

This study investigates the insecticidal activity of essential oil from Lippia alba leaves collected at Caatinga and its major compound against termite Nasutitermes corniger and maize weevil Sitophilus zeamais. The essential oil promoted the mortality of N. corniger and showed antinutritional effects against S. zeamais. 1,8-cineole had termiticidal effects on N. corniger workers and fumigant effects against S. zeamais.