Boina Dhana Raj, Lewis Edwin E, Bloomquist Jeffrey R
Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Pest Manag Sci. 2008 Jun;64(6):646-53. doi: 10.1002/ps.1591.
Because methyl bromide has been phased out as a soil sterilant, new nematicides are urgently needed. Four different chemical classes of organic acids acting as anion transport (AT) blockers were tested against a free-living nematode, Caenorhabditis elegans Maupas, a plant-parasitic nematode, Meloidogyne incognita (Kofoid and White) Chitwood, and an entomopathogenic nematode, Heterorhabditis bacteriophora Poinar, in toxicity bioassays. The materials tested were DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), 9-AC (anthracene-9-carboxylic acid), NPPB [5-nitro-2-(3-phenylpropylamino)benzoic acid] and IAA-94 (indanyloxyacetic acid).
All the compounds showed slowly developing nematicidal activity against second-stage juveniles of M. incognita and adults of C. elegans, but not against H. bacteriophora infective-stage juveniles. The LC(50) values of these compounds were < 50 mg L(-1) after 48 and 72 h incubation, while at 168 h incubation the LC(50) values were < 10 mg L(-1) for both sensitive species. Across both species and time, the LC(50) values generally differed no more than twofold among the four compounds tested in this study. In contrast, none of the compounds (200 mg L(-1)) caused more than control mortality to H. bacteriophora, even after 168 h of incubation.
These compounds are potential leads for commercial nematicides. The insensitivity to H. bacteriophora is consistent with the natural exposure of this nematode to DST (3,5-dihydroxy-4-isopropylstilbene), a stilbene produced by its symbiotic bacterium. Based on the known activity of the compounds used in this study, it is suggested that anion transporters form the probable target sites for DIDS, 9-AC, NPPB and IAA-94 in nematodes.
由于甲基溴已被淘汰不再用作土壤消毒剂，因此迫切需要新型杀线虫剂。在毒性生物测定中，测试了四种不同化学类别的作为阴离子转运（AT）阻滞剂的有机酸对自由生活线虫秀丽隐杆线虫、植物寄生线虫南方根结线虫以及昆虫病原线虫嗜菌异小杆线虫的作用。所测试的物质为4,4'-二异硫氰酸根合芪-2,2'-二磺酸（DIDS）、蒽-9-羧酸（9-AC）、5-硝基-2-(3-苯丙基氨基)苯甲酸（NPPB）和茚满氧基乙酸（IAA-94）。
所有化合物对南方根结线虫的二期幼虫和秀丽隐杆线虫的成虫均表现出缓慢发展的杀线虫活性，但对嗜菌异小杆线虫的感染期幼虫无活性。在孵育48小时和72小时后，这些化合物的半数致死浓度（LC50）值<50毫克/升，而在孵育168小时后，两种敏感线虫的LC50值均<10毫克/升。在两个物种和不同时间范围内，本研究中测试的四种化合物的LC50值一般相差不超过两倍。相比之下，即使在孵育168小时后，没有一种化合物（200毫克/升）对嗜菌异小杆线虫造成的死亡率超过对照组。
这些化合物是商业杀线虫剂的潜在先导化合物。对嗜菌异小杆线虫不敏感与该线虫天然接触其共生细菌产生的芪类化合物3,5-二羟基-4-异丙基芪一致。基于本研究中所用化合物的已知活性，表明阴离子转运蛋白可能是线虫中DIDS、9-AC、NPPB和IAA-94的靶位点。
