Analysis of methidathion resistance mechanisms in Phytoseiulus persimilis A.H

A resistant strain of Phytoseiulus persimilis selected by methidathion pressure for several years metabolizes the [¹⁴C]methidathion faster than does the corresponding susceptible strain. The metabolism is for the main part glutathione dependent and gives the methidathion conjugate on glutathione as a first metabolite: S[5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl]-l-glutathione. In addition, glutathione transferase with chlorodinitrobenzene as a substrate has a threefold lower K_m in R strain than in S strain. Furthermore, this reaction is competitively inhibited by methidathion with a K_i which is threefold lower in R than in S strain. These results indicated that in this strain of P. persimilis resistance is due to an elevated detoxication of methidathion by a glutathione transferase. Other parameters known to be able to induce resistance in arthropods have been compared in resistant and sensitive strains. Esterase and monooxygenase activity measured with chromogenic substrates are the same in the two strains as is the level of acetylcholinesterase and its inhibition by methidathion oxon. No difference between the two strains has been found in the penetration kinetics measured with [¹⁴C]methidathion. These results indicated that glutathione transferase is the only mechanism which has been selected in P. persimilis, although other mechanisms are known to be involved in resistance to other insecticides in phytoseiid mites.     

大叶芥菜对眼子菜化感作用潜力的初步评价

以眼子菜为受体,研究大叶芥菜水浸提液对眼子菜的化感作用。结果显示,浓度分别为0.500 0、0.250 0、0.125 0、0.085 0、0.062 5、0.050 0、0.033 5、0.008 5 g/m L的大叶芥菜水浸提液对眼子菜种子的萌发抑制效应以0.500 0 g/m L最高,平均抑制率为100.00%;低浓度(0.008 5 g/m L)处理对眼子菜种子萌发的抑制率为13.89%。此外研究发现,大叶芥菜水浸提液对眼子菜叶片数量及鲜质量积累有明显的抑制作用,对鲜质量积累的平均抑制率分别为100.00%、74.68%、65.19%、55.70%、47.79%、46.20%、35.13%和8.23%;对眼子菜种子萌发和鲜质量的化感综合效应(SE)分别为100.00%、74.84%、57.59%、47.29%、43.34%、36.99%、34.23%和11.06%。结果表明,大叶芥菜对眼子菜有很强的化感潜力,能为眼子菜的绿色防控提供理论依据。     

Dr. J. H. Wakker (1859–1927)

European Journal of Plant Pathology -     

外来入侵性杂草薇甘菊的研究进展

薇甘菊是20世纪80年代末传入我国的一种危害经济作物和森林植被的恶性杂草,原产于热带美洲,现已入侵到南亚、太平洋地区及我国华南地区。本文对薇甘菊的形态分类、生物学和生态学特性、危害性、防治及其综合开发与利用等方面的研究进行综述,并提出自己的研究建议。     

A new Huffmanela species, H. schouteni sp. n. (Nematoda: Trichosomoididae) from flying fishes in Cura?ao

A new nematode species, Huffmanela schouteni sp. n., has been established on the basis of its egg morphology and biological characters (adult nematodes are unknown). The dark-shelled eggs of this histozoic parasite occur in masses in the abdominal cavity, serose covers of internal organs and in the liver of the flying fishes Hirundichthys affinis Günther (type host) and Cypselurus cyanopterus Cuvier et Valenciennes in Cura?ao. The eggs of H. schouteni sp. n. differ from those in other congeneric species mainly in the absence of small spines on the surface of the transparent envelope enclosing the egg proper, measurements (size of eggs 0.069-0.075 x 0.027-0.030 mm) and their localization in the host. A key to Huffmanela species based on egg morphology has been provided.