Essential Oils and Their Components Control Behaviour of Yellow Mealworm (Tenebrio molitor) Larvae

SIMPLE SUMMARY: This study investigated the use of essential oils (EOs) from different plants to control the behaviour of Tenebrio molitor L., a pest of grain and flour. Among the EOs tested, spearmint was the most effective repellent for mealworm larvae, followed by clove. East-Indian lemongrass, thymus, lavandin, and eucalyptus EOs showed lower repellent properties. Terpinene-4-ol and carvone, were the most effective repellents, while limonene, myrcene, and γ-terpinene had no significant activity. ABSTRACT: Beetle Tenebrio molitor L. (Coleoptera, Tenebrionidae) is a well-known pest of grain and flour in food stores and grocery shops. Recently, commercial cultivation of the insect was started for human food and animal feed. Behaviour control of this insect using natural repellents is promising both for grain protection and commercial cultivation. We analysed if natural products of plant origin, namely essential oils (EOs), could be used for this purpose. Behavioural tests were performed using EOs of six plants: thymus (Thymus vulgaris), eucalyptus (Eucalyptus globulus), spearmint (Mentha spicata), lavandin (Lavandula × hybrida), East-Indian lemongrass (Cymbopogon flexuosus), and clove (Eugenia caryophyllus). The most effective repellent for mealworm larvae was EO of spearmint, moderate activity showed that of clove and the least repellent were EOs of lemongrass thymus and lavandin. EO of eucalyptus caused almost no or very low effect. Six of the most abundant compounds of the EOs were selected for testing. The most effective single compounds were terpinene-4-ol and carvone, low-effective cis-sabinene hydrates and those of no significant activity were limonene, myrcene and γ-terpinene.