Abstract
The chemical composition of the essential oil from Juniperus formosana leaves and its contact and repellent activities against Tribolium castaneum and Liposcelis bostrychophila adults were investigated. The essential oil of J. formosana leaves was obtained by hydrodistillation and analyzed by GC-MS. A total of 28 components were identified and the main compounds in the essential oil were α-pinene (21.66%), 4-terpineol (11.25%), limonene (11.00%) and β-phellandrene (6.63%). The constituents α-pinene, 4-terpineol and d-limonene were isolated from the essential oil. It was found that the essential oil exhibited contact activity against T. castaneum and L. bostrychophila adults (LD50 = 29.14 μg/adult and 81.50 µg/cm2, respectively). The compound 4-terpineol exhibited the strongest contact activity (LD50 = 7.65 μg/adult). In addition, data showed that at 78.63 nL/cm2, the essential oil and the three isolated compounds strongly repelled T. castaneum adults. The compounds α-pinene and d-limonene reached the same level (Class V) of repellency as DEET (p = 0.396 and 0.664) against L. bostrychophila at 63.17 nL/cm2 after 2 h treatment. The results indicate that the essential oil and the isolated compounds have potential to be developed into natural insecticides and repellents to control insects in stored products.
Highlights
IntroductionJuniperus formosana Hayata (Pinales: Cupressaceae), an evergreen shrub or tree, is endemic to
Juniperus formosana Hayata (Pinales: Cupressaceae), an evergreen shrub or tree, is endemic toChina and widely distributed in nearly 14 provinces [1]
The J. formosana essential oil was light green with a yield of 0.46% (v/w) and density of 0.94 g/mL
Summary
Juniperus formosana Hayata (Pinales: Cupressaceae), an evergreen shrub or tree, is endemic to. During our screening program for new agrochemicals from Chinese medicinal herbs [11,12,13,14,15], the essential oil from J. formosana was found to possess contact and repellent activities towards the red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae), and the booklouse, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae). The essential oils of other plants from the Juniperus genus have been demonstrated to possess bioactivity against several insects, e.g., Anopheles stephensi, Aedes aegypti, Culex quinquefasciatus [19], S. oryzae [20,21], T. castaneum [21,22], Pseudaletia unipuncta [23], Xenopsylla cheopis [24], Resseliella oculiperda [25], Reticulitermes speratus [26] and Acanthoscelides obtectus [27]. This work is undertaken to investigate the contact and repellent activities of the essential oil against the two stored product insects for the first time
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