Origanum vulgare Essential Oil against Tenebrio molitor (Coleoptera: Tenebrionidae): Composition, Insecticidal Activity, and Behavioral Response

Abstract

Tenebrio molitor is one of the main stored product pests. This study characterized oregano essential oil (OEO) by gas chromatography (GC/FID and GC/MS) and assessed its insecticidal properties against T. molitor. Mortality, survival, respiration, and behavioral response in larva, pupa, and adult of this insect were determined. The major components of OEO were carvacrol (25.6%), p-cymene (12.3%), linalool (8.71%), thymol (7.22%), γ-terpinene (7.21%), caryophyllene oxide (4.67%), α-pinene (2.71%), and eucalyptol (2.69%). OEO caused high contact toxicity in larvae (LD50 = 3.03 µg insect–1), pupae (LD50 = 5.01 µg insect–1), and adults (LD50 = 5.12 µg insect−1) of T. molitor. Survival rates were 100% in larvae, pupae, and adults of T. molitor not treated with OEO, declining to 65–54%, 38–44%, 30–23%, and 6–2% in insects treated with LD25, LD50, LD75, and LD90, respectively. Low respiration rates of T. molitor at different developmental stages was observed after OEO exposure. Additionally, OEO exposure affects behavioral avoidance response and causes repellency in larvae and adults. These findings show that OEO exerts insecticidal and repellent effects against T. molitor, suggesting a potent alternative to synthetic insecticides for controlling the beetle.

Juniperus horizontalis Moench: Chemical Composition, Herbicidal and Insecticidal Activities of Its Essential Oil and of Its Main Component, Sabinene

“…The results obtained in the larvicidal bioassay indicate the potential of juniper EO in limiting the survival of yellow mealworm. However, the larvicidal effect of J. horizontalis EO is several times lower in comparison to clove and cinnamon [ 39 ], garlic [ 40 ], or oregano essential oils [ 20 ], although it was not excluded that J. horizontalis EO or its main compound sabinene may exhibit some toxicity to non-target organisms, the doses that affected root growth were not toxic to either sludge worms or blood worms.…”

“…Several studies have provided evidence of larvicidal activity on Artemia salina , Aedes aegypti , Anophelus sinensis [ 17 , 18 , 19 ], and others. In particular, Tenebrio molitor Linnaeus, the mealworm beetle (Coleoptera: Tenebrionidae), is a parasite of stored products, such as starches and pasta: this insect is able to infest the broken grains of Zea mays (L.) and Triticum aestivum L. The presence of body fragments and/or feces in stored grain and bran can lead to a loss of food quality [ 20 ].…”

Insecticidal Effect of an Enhanced Attapulgite for the Control of Four Stored-Product Beetle Species

“…Origanum plant species have essential oils which are rich in terpenoids, with carvacrol, thymol, γ-terpinene, and p-cymene as major components [24,29,[33][34][35]. In addition to their antimicrobial, antifungal, and acaricidal properties, Origanum essential oils have strong insecticidal value against a wide range of stored product insects and moths [15,18,29,[35][36][37][38][39]. For instance, the essential oil extracted form Origanum onites (L.) (Lamiales: Lamiaceae) was effective against larvae of P. interpunctella, when it was used as a fumigant [18], while the essential oil of O. majorana was the most effective among the seven essential oils of different plants tested against larvae of E. kuehniella [37].…”

“…(Lamiales: Lamiaceae) showed some insecticidal activity against the S. granarius and T. castaneum. Moreover, O. vulgare essential oil exhibited strong contact toxicity against T. castaneum [35], the yellow mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae) [39], and S. oryzae [38]. Although the available literature on the efficacy of O. vulgare essential oils when applied alone for the control of stored product insects is abundant [35,38,39], the corresponding literature on the combined use of the particular essential oil with inert dusts is limited, despite the fact that there are data that underline the positive effects of the combined effects of plant extracts with inert materials in stored product protection [10,[40][41][42].…”

Insecticidal Activity of Plant Secondary Metabolites

“…Changbunjong et al [ 3 ] investigated the fumigant and contact toxicity activities of bitter orange ( Citrus aurantium ) essential oil against the stable fly Stomoxys calcitrans . Plata-Rueda et al [ 4 ] studied the sensitivity and behavioral response of the mealworm Tenebrio molitor towards oregano ( Origanum vulgare ) essential oil. Kostić et al [ 5 ] tested three Apiaceae essential oils, namely anise ( Pimpinella anisum ), dill ( Anethum graveolens ) and fennel ( Foeniculum vulgare ) against Lymantria dispar, showing them as potential agents for gypsy moth control.…”