Anti-Termitic Activity of Three Plant Extracts, Chlorpyrifos, and a Bioagent Compound (Protecto) against Termite Microcerotermes eugnathus Silvestri (Blattodea: Termitidae) in Egypt

SIMPLE SUMMARY: The termite Microcerotermes eugnathus Silvestri (Blattodea, Termitidae) showed structural damage in Bir al-Shaghala cemeteries located in the oasis of Dakhla, Egypt. The mud tubes of this termite spread inside and over the mural painted floors of the tombs. Extracts from Lavandula latifolia, Origanum vulgare, and Syzygium aromaticum were tested for their anti-termitic activity and compared with the bio-insecticide, Bacillus thuringiensis var. kurstaki (Protecto 9.4% WP) and Dursban (Chlorpyrifos 48%). The bioassay experimental showed that the extracts have low activity against M. eugnathus compared to Protecto and Dursban, but the extract from O. vulgare showed promising natural termiticides. ABSTRACT: A trend towards environmentally friendly chemicals for use in termite management has been occurring globally. This study examined three naturally occurring plant extracts from Lavandula latifolia (Spike lavender), Origanum vulgare (Marjorum), and Syzygium aromaticum (Clove) against the termite Microcerotermes eugnathus. Plant extract results were compared to two commercially used termite pesticides, the bio-insecticide, Bacillus thuringiensis var. kurstaki (Protecto 9.4% WP) and Dursban (Chlorpyrifos 48%). Gas chromatography–mass spectrometry (GC-MS) analysis was used to identify the main compounds in the three plant extracts. The main compounds in Lavandula Latifolia were linalool (21.49%), lavandulol (12.77%), β-terpinyl acetate (10.49%), and camphor (9.30%). Origanum vulgare extract contained thymol (14.64%), m-cymene (10.63%), linalool (6.75%), and terpinen-4-ol (6.92%) as main compounds. Syzygium aromaticum contained eugenol (99.16%) as the most abundant identified compound. The extract of O. vulgare caused the highest termite death rate, with an LC(50) of 770.67 mg/L. Exposure to lavender extract showed a high death rate with an LC(50) of 1086.39 mg/L. Clove extract did not show significant insecticidal activity with an LC(50) > 2000 mg/L. Significant termiticide effects were found, with LC(50) values of 84.09 and 269.98 mg/L for soldiers and workers under the application of Dursban and Protecto, respectively. The LC(50) values reported for nymphs were <120, <164.5, and 627.87 mg/L after exposure to Dursban, Protecto, and O. vulgare extract, respectively. The results of the study show that some of the extracts have low toxicity compared to the bioagent and Dursban, and may show promise as natural termiticides, particularly as extracts from O. vulgare.