Chemical Constituents and Toxicity of Essential Oils of Oriental Arborvitae, Platycladus orientalis (L.) Franco, against Three Stored-Product Beetles Componentes Químicos y Toxicidad de Aceites Esenciales de Tuya Oriental, Platycladus orientalis (L.) Franco, contra Tres Escarabajos de Productos Almacenados

Plant secondary metabolites play an important role in plant-insect interactions and therefore such compounds may have insecticidal or biological activity against insects. Fumigant toxicity of essential oils of leaves and fruits from oriental arborvitae (Platycladus orientalis (L.) Franco) (Cupressaceae) was investigated against adults of cowpea weevil (Callosobruchus maculatus Fab.), rice weevil (Sitophilus oryzae L.), and red flour beetle (Tribolium castaneum Herbst). Fresh leaves and fruits were subjected to hydrodistillation using a Clevenger-type apparatus and the chemical composition of the volatile oils was studied by gas chromatography-mass spectrometry (GC-MS). Twenty-six compounds (92.9%) and 23 constituents (97.8%) were identified in the leaf and the fruit oils, respectively. The major components of both leaves and fruits oils were α-pinene (35.2%, 50.7%), α-cedrol (14.6%, 6.9%) and Δ-3-carene (6.3%, 13.8%), respectively. Both oils in the same concentration were tested for their fumigant toxicity on each species. Results showed that leaf oils were more toxic than fruit oils against three species of insects. Callosobruchus maculatus was more susceptible than S. oryzae and T. castaneum. LC510 values of the leaf and the fruit oils at 24 h were estimated 6.06 and 9.24 μL L1 air for C. maculatus, 18.22 and 21.56 μL L-1 air for S. oryzae, and 32.07 and 36.58 μL L4 air for T. castaneum, respectively. These results suggested that P. orientalis oils may have potential as a control agent against C. maculatus, S. oryzae, and T. castaneum. Los metabolitos secundarios de las plantas juegan un papel importante en las interacciones planta-insecto, y por lo tanto pueden tener actividad insecticida o biológica en los insectos. La toxicidad fumigante de los aceites esenciales de hojas y frutos del árbol oriental de la vida (Platycladus orientalis (L.) Franco) (Cupressaceae) fue investigada contra adultos de gorgojo del guisante (Callosobruchus maculatus Fab.), gorgojo del arroz (Sitophilus oryzae L.), y escarabajo rojo de la harina (Tribolium castaneum Herbst). Las hojas frescas y las frutas fueron sometidas a hidrodestilación utilizando un aparato tipo Clevenger y la composición química de los aceites volátiles se estudió por cromatografía de gas-espectrometría de masa (GC-MS). Se identificaron 26 (92,9%) y 23 compuestos (97,8%) en los aceites de hoja y de frutos, respectivamente. Los componentes principales de los aceites de hojas y frutos fueron α-pineno (35,2%, 50,7%), α-cedrol (14,6%, 6,9%) y Δ-3-careno (6,3%, 13,8%), respectivamente. Ambos aceites fueron