Toxicity of the Essential Oil ofIllicium difengpiStem Bark and Its Constituent Compounds Towards Two Grain Storage Insects

Abstract

During our screening program for new agrochemicals from Chinese medicinal herbs, the essential oil of Illicium difengpi stem bark was found to possess strong insecticidal activities against the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) and red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). A total of 37 components of the essential oil of I. difengpi were identified. The main components of the essential oil were safrole (23.61%), linalool (12.93%), and germacrene D (5.35%). Bioactivities-directed chromatographic separation on repeated silica gel columns led to the isolation of two compounds: safrole and linalool. Safrole showed pronounced contact toxicity against both insect species and (LD50 = 8.54 for S. zeamais; 4.67 µg/adult for T. castaneum) and was more toxic than linalool (LD50 = 24.88 for S. zeamais; 8.12 µg/adult for T. castaneum). The essential oil acting against the two species of insects showed LD50 values of 13.83 and 6.33 µg/adult, respectively. Linalool also possessed strong fumigant toxicity against both insect species (LC50 = 10.02 for S. zeamais; 9.34 mg/L for T. castaneum) and was more toxic than safrole (LD50 = 32.96 and 38.25 mg/L), while the crude essential oil acting against the two species of insects showed LC50 values of 14.62 and 16.22 mg/L, respectively. These results suggest that the essential oil of I. difengpi stem bark and the two compounds may be used in grain storage to combat insect pests.

Chemical Composition and Insecticidal Activity of the Essential Oil of Illicium pachyphyllum Fruits against Two Grain Storage Insects

“…Howover, compared with the other essential oils reported in the previous studies, the essential oil of I. pachyphyllum fruits exhibited stronger acute toxicity against the maize weevils, e.g., essential oils of Artemisia capillaris (LD 50 = 105.95 μg/adult) and A. mongolica (LD 50 = 87.92 μg/adult) [ 25 ], A. vestita (LD 50 = 50.62 μg/adult) [ 8 ], I. fragesii fruits (LD 50 = 28.95 μg/adult) [ 23 ], I. simonsii (LD 50 = 112.74 μg/adult) [ 24 ]. The essential oil shows less acute toxic against the maize weevils than I. difengpi essential oil (LD 50 = 13.83 μg/adult) [ 22 ].…”

“…There are about 40 species in the Illiciaceae family, mostly found in East and Southeast Asia and 27 species (18 of them endemic) are found in China [ 16 ]. The essential oils derived from several Illiciaceae fruits exhibited insecticidal activity against insects, e.g., I. verum [ 17 , 18 , 19 , 20 ], I. anisatum [ 21 ], I. difengpi [ 22 ], I. fargesii [ 23 ], and I. simonsii [ 24 ]. However, a literature survey has shown that there is no report on the volatile constituents and insecticidal activity of I. pachyphyllum ; thus we decided to investigate the chemical constituents and insecticidal activities of the essential oil of I. pachyphyllum against two grain storage insects for the first time and to isolate any active constituent compounds from the essential oil.…”

Exploring Contact Toxicity of Essential Oils against Sitophilus zeamais through a Meta-Analysis Approach

“…A total of 53 plant EOs belonging to 14 different families were evaluated for topical application giving a LD 50 global mean value of 33.19 µg/insect (CI 95 29.81-36.95). As shown in the forest plot (Figure 2), half of the plant species presented mean values that were lower than the global mean.…”

Review on safrole: identity shift of the ‘candy shop’ aroma to a carcinogen and deforester

“…Plants from other families such as Lamiaceae, Rutaceae, Anacardiaceae, Atherospermataceae, Cupressaceae, Zingiberaceae, Myristicaceae, Apiaceae, Verbenaceae, Schisandrace, and Cucurbitaceae have also been reported to contain safrole . For example, an aromatic and medicinal Vietnamese plant, Illicium griffithii from the Schisandraceae family was reported to produce safrole in significantly high quantity across different tissues (51.6% in leaf, 65.3% in branch, 53.7% in fruit, and 59.6% in root bark) followed by 4‐methoxysafrole (root bark 19.6%) .…”

“…For example, an aromatic and medicinal Vietnamese plant, Illicium griffithii from the Schisandraceae family was reported to produce safrole in significantly high quantity across different tissues (51.6% in leaf, 65.3% in branch, 53.7% in fruit, and 59.6% in root bark) followed by 4‐methoxysafrole (root bark 19.6%) . Other Illicium species like Illicium parviflorum (leaves 68.1%) and Illicium difengpi (stem bark 23.6%) also showed high safrole contents. In another report, the fresh leaves of Zieria smithii (Rutaceae) collected from Australia showed 7.0% safrole in its essential oil .…”