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Reticulitermes flaviceps is an economically important pest in agriculture, forestry, and construction. Recent studies have shown an increase in research focusing on the anti-termite properties of plant essential oils, however, there remains a lack of information regarding the specific molecular mechanism involved. In this study, RNA-seq analysis was conducted on termites exposed to Mentha spicata essential oil (EO) and carvone, leading to the discovery of various genes that were expressed differentially under different treatment conditions. Numerous genes that exhibited a response to M. spicata EO and carvone found to be associated with stress-related pathways, such as drug metabolism cytochrome P450, glutathione metabolism, fatty acid metabolism, citric acid cycle, neuroactive ligand-receptor interaction, cell apoptosis, the AMPK signalling pathway, the mTOR signalling pathway, the longevity regulation pathway, ubiquitin-mediated protein hydrolysis, and the calcium signalling pathway. The up-regulation of genes (SPHK) associated with calcium channels, such as SPHK, indicates a potential mechanism of neurotoxicity, while the up-regulation of apoptosis-associated genes, including ACTB_G1, PYG, SQSTM1, RNF31, suggests a potential mechanism of cytotoxicity. The metabolism of M. spicata EO induces oxidative stress, elevates free Ca 2+ levels in mitochondria, and initiates the generation of reactive oxygen species (ROS), ultimately resulting in programmed cell necrosis and apoptosis, as well as facilitating cellular autophagy. The monoterpenes exhibited neurotoxic and cytotoxic effects on R. flaviceps and could be exploited to advance termiticide development and eco-friendly termite control., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The volatile metabolites of Salvia sclarea , Rosmarinus officinalis , Thymus serpyllum , Mentha spicata , Melissa officinalis , Origanum majorana , Mentha piperita , Ocimum basilicum and Lavandula angustifolia were determined by gas chromatography-mass spectrometry. The vapor insecticidal properties of the analyzed essential oils and their compounds were screened using Reticulitermes dabieshanensis workers. The most effective oils were S. sclarea (major constituent linalyl acetate, 65.93%), R. officinalis (1,8-cineole, 45.56%), T. serpyllum (thymol, 33.59%), M. spicata (carvone, 58.68%), M. officinalis (citronellal, 36.99%), O. majorana (1,8-cineole, 62.29%), M. piperita (menthol, 46.04%), O. basilicum (eugenol, 71.08%) and L. angustifolia (linalool, 39.58%), which exhibited LC 50 values ranging from 0.036 to 1.670 μL/L. The lowest LC 50 values were recorded for eugenol (0.060 μL/L), followed by thymol (0.062 μL/L), carvone (0.074 μL/L), menthol (0.242 μL/L), linalool (0.250 μL/L), citronellal (0.330 μL/L), linalyl acetate (0.712 μL/L) and 1,8-cineole (1.478 μL/L). The increased activity of esterases (ESTs) and glutathione S-transferase (GST) were observed but only alongside the decreased activity of acetylcholinesterase (AChE) in eight main components. Our results indicate that S. sclarea , R. officinalis , T. serpyllum , M. spicata , M. officinalis , O. marjorana , M. piperita , O. basilicum and L. angustifolia essential oils (EOs) and their compounds, linalyl acetate, 1,8-cineole, thymol, carvone, citronellal, menthol, eugenol and linalool could be developed as control agents against termites.

The essential oil (EO) of Thymus serpyllum and thymol were evaluated for their insecticidal activity against the housefly (Musca domestica) larvae and pupae. Contact toxicity and fumigation bioassays were used. Chemical composition analysis of T. serpyllum EO by gas chromatographic mass spectrometry (GC-MS) revealed that thymol (41.6%), p-cymene (21.9%), and γ-terpinene (19.2%) were the major components. For larval assays, the LC 50 value of T. serpyllum EO was 0.4 μl/cm 2 for contact toxicity and 20.9 μl/l for fumigation toxicity. For thymol, the contact toxicity LC 50 value was 0.035 μl/cm 2 and the fumigation LC 50 value was 2.0 μl/l. For the pupal assay, T. serpyllum EO had a percentage inhibition rate (PIR) value of 100% for both contact toxicity (1.0 μl/cm 2 ) and fumigation toxicity assay (25 μl/l), whereas thymol had a PIR of 100% for contact toxicity (0.1 μl/cm 2 ) and fumigation assay (5 μl/l). This study shows that T. serpyllum EO and thymol are toxic to housefly larvae and pupae and have the potential for use in the population control of this species.

The toxicity of Origanum vulgare essential oil to the housefly Musca domestica L. was evaluated. The major constituents of the O. vulgare essential oil by gas chromatographic mass spectrometry (GC-MS) analysis were carvacrol (58.13%), p-cymene (17.85%), thymol (8.15%), γ-terpinene (4.96%), and linalool (3.69%). Toxicity of O. vulgare essential oil against larvae and pupae was evaluated using fumigation and contact assays. The contact toxicity (LC 50 ) of O. vulgare essential oil and carvacrol for larvae was 0.23 and 0.03 μL/cm 2 , respectively. The fumigation toxicity (LC 50 ) of O. vulgare essential oil and carvacrol for larvae was 9.52 and 2.78 μL/L, respectively. Pupal toxicity was evaluated by percentage inhibition rate (PIR). PIR of O. vulgare essential oil at 0.25 μL/cm 2 was 90.9% for the contact assay and 100% at 20 μL/L for the fumigation assay. PIR of carvacrol was 29.5% (0.025 μL/cm 2 ) and 81.8% (1.25 μL/L) for the contact toxicity and fumigation assay, respectively. O. vulgare essential oil and carvacrol have significant toxicity to the housefly and are potential insecticides for housefly control.

The development of natural plant extracts and essential oils will assist to decrease the negative effects of synthetic chemicals. Many plant extracts and essential oils contain monoterpenes, sesquiterpenes, and aliphatic compounds. In the present study, the fumigation activity of 42 pure monoterpenes against housefly, Musca domestica, was evaluated. Results from fumigation tests revealed that ρ-cymene, terpinolene, (±)-menthol, thymol, carvacrol, (-)-carvone, (+)-camphor, (+)-pulegone, (-)-menthone, citral, (±)-citronellal, cuminaldehyde, and citronellyl acetate exhibited strong fumigation activity against M. domestica. Specifically, the compounds of (+)-pulegone, cuminaldehyde, citral, and ρ-cymene had a highest toxicity toward M. domestica with LC 50 values of 0.26, 0.60, 0.64, and 0.77 μl/L, respectively. The present results indicated that (+)-pulegone, cuminaldehyde, citral, and ρ-cymene are promising toxicants against M. domestica and could be useful in the search for new natural insecticides.

In this study antitermitic activities of essential oils from different tissues of Chinese cedar (Cryptomeria fortunei Hooibrenk) against Reticulitermnes chinensis were investigated. In addition, the yields of essential oils obtained by water distillation were compared and their constituents determined by GC-MS analyses. The yields of bark, sapwood, heartwood, and leaf essential oils of Chinese cedar were 0.9, 0.4, 1.0, and 1.5%, respectively. GC-MS analyses showed that the major compounds of bark, sapwood, heartwood, and leaf essential oils of Chinese cedar were ferruginol (30.6%), y-cadinene (18.3%), y-cadinene (31.0%), and kaurene (30.6%), respectively. Bioactivity tests against R. chinensis demonstrated that the leaf and heartwood essential oils had an excellent effect, and the LC) values after 5 days were 0.9 and 1.8 microL/mL (LC90=1.4 and 2.9 microL/mL), respectively. The results of this study showed that the leaf and heartwood essential oils of Chinese cedar might be considered as a potential source of a fine natural termiticide.

The persistent use of synthetic termiticides is at present of environmental concern and has resulted in the need to search for plant-derived compounds as an alternative for termite control. Antitermitic activity of Chinese cedar (Cryptomeria fortunei Hooibrenk) against Reticulitermes chinensis was demonstrated in laboratory tests. Bioactivity tests against the termite R. chinensis demonstrate that the lethal concentration (LC50) value of leaf essential oil is 2.80 mg/mL. Furthermore, α-terpineol, which was responsible for the antitermitic property and isolated from Chinese cedar that exhibited very strong antitermitic activity, was found to be significantly effective against R. chinensis with median LC50 values of 0.86 mg/mL. The findings suggested that the essential oil from Chinese cedar leaf and α-terpineol might be considered as a potent source for the production of effective, environmentally friendly and safe termiticides.