Toxicity and repellent activities of Thymus pallescens and Cymbopogon citratus essential oils against Sitophylus granarius

Abstract

This study evaluated the toxicity and repellent activities of essential oils (EOs) against Sitophilus granarius (Linnaeus, 1758), both in vitro and in vivo conditions. The EOs obtained from Thymus pallescens Noë. (Lamiaceae) and Cymbopogon citratus Stapf. (Poaceae) were analyzed by GC-MS, and revealed that carvacrol (56.64%) and geraniol (20.8%) as the respective major components. T. pallescens EO was found to be a more effective toxicant, with LC<sub>50</sub> and LC<sub>90</sub> values of 9.3 and 34.6 µL/mL, respectively, in the contact test vs 8.2 and 25.3 µL/mL in the fumigation test. T. pallescens EO showed also a stronger repellent effect with values ranging from 83.4% to 100%. In the in vivo test, the survival probability decreased from 99.9 to 2.48% among insects exposed to T. pallescens EO. These data demonstrated that EOs could be considered effective alternatives to chemical insecticides, providing pest control for stored products in an ecologically sustainable manner.

Evaluation of Three Plant Essential Oils against Striped Mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae)

“…This was likely because the pest needed more of these energy reserves to produce esterase enzymes. These findings corroborated those of Yazdani et al (2014) and Moutassem et al (2021), who found that insect pests treated with Thymus essential oils had lower carbohydrates and lipids levels. The enzymatic activities of an organism were significantly impacted by exposure to lethal and sublethal doses, reflecting the biochemical disruptions (Kiran and Prakash,2015).…”

Larvicidal and pupicidal effects of some essential oils against Musca domestica Linnaeus, 1758 (Diptera:Muscidae)

“…The results of the present study indicated that A. sativum (Inyang and Emosairue, 2005;Chiam et al, 1999;Karci and Isikber, 2007;Isikber et al, 2009). In the same vein, Meriga et al (2012) The essential oil may impact insect development and metabolism (Moutassem et al, 2021). However, EOs causes reduced food ingestion (Roel et al, 2010), inhibits digestive enzymes (Yousef et al, 2018) and can result in prolongation of the development duration.…”

Chemical Profiles and Insecticidal Potential of Essential Oils Isolated from Four Thymus Species against Rhyzopertha dominica (F.)

“…Along with lethality, the T. pallescens essential oil decreased total protein, lipid, and carbohydrate of treated weevil. In another study, fumigation with Thymus quinquecostatus Celak essential oil and its major components linalool (52.00%), borneol (10.91%), and anethole (5.33%) resulted in significant mortality of the cigarette beetle (Lasioderma serricorne (F.)) and T. castaneum adults [19].…”