Bioassay‐guided isolation of potent aphicidal Erythrina alkaloids against Aphis gossypii from the seed of Erythrina crista‐galli L

BACKGROUND

The cotton aphid (Aphis gossypii Glover) is one of the most invasive pests of cotton. Many botanical phytochemicals have a long history as a source of insecticides, and as templates for new insecticides. This study was undertaken to isolate aphicidal compounds from the seeds of Erythrina crista‐galli L. using the bioassay‐guided isolation method.

RESULTS

Three novel and 11 known Erythrina alkaloids were isolated. Erysodine ( 9 ), erysovine ( 10 ), erysotrine ( 8 ) and erythraline ( 11 ) showed moderate to excellent aphicidal activity with LD₅₀ values of 7.48, 6.68, 5.13 and 4.67 ng aphid^–1, respectively. The Potter spray tower bioassay gave corresponding LC₅₀ values of 186.81, 165.35, 163.74 and 112.78 µg ml^–1. A unique substructure, which presents an sp³ methylene at C‐8, a non‐oxygenated site at N‐9 and a conjugated dienes group (Δ^1,2 and Δ^6,7), plays a crucial role in the aphicidal activity. Application of erythraline ( 11 ) led to different increases in the activities of superoxide dismutase, catalase and glutathione S‐transferase.

CONCLUSION

The study demonstrated that the Erythrina alkaloids erysodine ( 9 ), erysovine ( 10 ), erysotrine ( 8 ) and erythraline ( 11 ) have potential use as botanical aphicides for commercial application, or as templates for the development of new insecticides. © 2017 Society of Chemical Industry     

长蛸平衡囊的形态结构和神经支配模式

采用光镜、扫描电镜、透射电镜和同步辐射等方法对长蛸平衡囊的形态和神经支配进行了研究。平衡囊位于长蛸头后部两侧的软骨腔中,表面是近似椭圆形的膜质结构。平衡囊表面缠绕的大量纤维丝,与软骨壁粘联后使囊悬浮于腔内的淋巴液中。平衡囊中的感觉毛细胞分为感觉斑(macula)和感觉脊(crista)两个区域,其中感觉斑毛细胞区被包裹着胶质粘液层的耳石覆盖,毛细胞动纤毛顶端嵌入耳石底层钙质微晶体间隙中;感觉脊区毛细胞呈带状螺旋型排列,共分九节,其毛细胞均由胶质顶(cupula)覆盖。毛细胞仅含等长、9+2微管型动纤毛,无静纤毛,其周围细胞含微绒毛。平衡囊内的一软骨凸起结构,相对感觉脊(anticrista),其表面无感觉毛细胞。同步辐射结果表明:支配感觉斑区的神经仅一条,而感觉脊区却由两条神经束从脑部经囊表后分支进入各自支配的毛细胞节区。