Non-steroidal ecdysteroid agonists: Tools for the study of hormonal action

The first non-steroidal ecdysteroid agonists are dibenzoyl hydrazines and are typified by the compounds designated RH-5849 and RH-5992. The discovery that these compounds mimic 20E in a variety of insect orders, and especially the Lepidoptera, generated great interest from the research and agricultural communities. Such compounds provide important new research tools for physiological, biochemical, and molecular studies. In addition, the potential for application to agricultural pests looks very promising, especially for RH-5992 (tebufenozide). This review evaluates the evidence on the specificity of the ecdysteroid-like actions of these materials and considers their application for research and pest management. © 1995 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of Amerira.

     

Integration between Steinernema feltiae and some of environmental friendly compounds to control Spodoptera littoralis (Lepidoptera: Noctuidae)

The efficacy of different concentrations of the commercial neem-based insecticide, Nimbicidine^® and the ecdysone agonist compound Methoxyfenozide (RH-2485), was evaluated against larvae of Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). RH-2485 and Nimbicidine^® significantly (p?<?0.001) reduced adult longevity by 2.7 and 1.9 d at the higher concentrations tested, respectively, but no significant differences were observed at low concentration. The tested compounds strongly affected the reproduction of S. littoralis by producing a high percentage of sterility. Fecundity and fertility were significantly affected by both insecticides. No egg laying has been recorded with the higher concentration 0.5% of Nimbicidine^® and 0.1?ppm of RH-2485, while no significant (p?>?0.05) difference was noticed on total number of eggs laid by the female when lower concentration 0.0001?ppm of RH-2485 was applied in the same stage as compared to the control. In the second part of this study, the invasion rate of Steinernema feltiae was affected by the addition of both Nimbicidine and RH-2485 to the diet of experimental host. At higher concentration of both compounds, the invasion rate was decreased despite the infection rate, while the percentage of invading nematodes increase to 56.7% with the combination treatment indicating a considerable improvement in the efficacy of S. feltiae nematode applied in combination with the lower concentration of Nimbicidine^® over that of nematode alone. On the other hand, the invasion of S. feltiae to the insects that were fed on the diet with the addition of ecdyson compound was strongly decreased with increasing concentration of RH-2485 in host diet.     

应用微核试验和单细胞凝胶电泳技术来检测农药对青蛙蝌蚪及成体的遗传毒性

应用青蛙红细胞微核试验和单细胞凝胶电泳试验研究了两种新型杀虫剂 -吡虫啉和抑食肼对青蛙蝌蚪和成体的遗传毒性 ,结果表明 :当吡虫啉为 2mg/L时 ,蝌蚪红细胞微核率与对照组相比 ,无显著性差异 (p >0 .0 5) ;浓度升高到 8mg/L时 ,微核率与对照组相比 ,有显著性差异 (p <0 .0 5) ;当浓度为 3 2mg/L时 ,微核率与对照组相比 ,有极显著性差异 (p <0 .0 1) ;并有明显的剂量 -效应关系 (r =0 .9843 )。而抑食肼在浓度为 2 .5mg/L和 10mg/L时 ,微核率与对照组相比 ,无显著性差异 (p >0 .0 5) ;当浓度增至 40mg/L时 ,微核与对照组相比 ,有极显著性差异 (p <0 .0 1) ;吡虫啉与抑食肼各浓度组对青蛙红细胞的DNA损伤与阴性对照组相比 ,都有极显著性差异 (p <0 .0 1) ,且具有明显的剂量 -效应关系 (r =0 .960 ,r=0 .990 )。     

合成己酸乙酯脂肪酶产生菌的筛选及产酶条件

从２７株脂肪酶产生菌中筛选到能由乙醇和己酸合成己酸乙酯的菌株８株。其中Ｒｈｉｚｏｐｕｓｓｐ．Ｈ－３菌株脂肪酶活力为５０－６０ｕ／ｍｌ,全细胞在有机溶剂中的酯化率可达己酸的９１％。Ｈ３产酶的最适碳源为淀粉或葡萄糖。６％黄豆饼粉加４％蛋白陈复合氮源有利于酶活力的增加。     

三种外源激素类物质对白背飞虱(Sogatella furcifera)翅型分化的影响

以白背飞虱为研究对象,首次使用保幼激素类似物ZR-515、早熟素和具有蜕皮激素活性的新型化合物RH-2485表面处理飞虱3龄或4龄若虫,来研究探讨激素对飞虱翅型分化的影响。结果表明：ZR-515可诱导短翅型分化,当用10ng／μl的ZR-515处理3龄若虫时,短翅率达到45．6％;而用1μg/μl及100ng／μl的ZR-515对4龄期若虫进行处理时,短翅率则分别达到50％和50．26％。早熟素具有明显的长翅化效应,随着处理浓度的增高,被处理的白背飞虱若虫形成的长翅型成虫数也逐渐增加,且早熟素在3龄期处理对白背飞虱长翅诱导作用强于在4龄期进行的处理,如在3龄期处理时,10μg／μl和100ng／μl的处理组长翅犁成虫比率分别高达100％和86．67％。而RH-2485对翅型分化无明显影响。     

Ecdysone agonist halofenozide affects corpora allata and reproductive physiology of the Formosan subterranean termite,Coptotermes formosanus

Following a short swarming flight, winged adults of the Formosan subterranean termite, Coptotermes formosanus lose their wings and form tandem pairs. These dealates or primary reproductives then form incipient colonies. Topical application of 5 microg of the non-steroidal ecdysone agonist RH-0345 (halofenozide) in 0.1 microl DMSO to the primary reproductives during the 2000 season resulted in significant reduction in the number of eggs laid. There was however complete recovery of the treated females. Apparently the non-treated partner removed the treatment chemical while grooming indicating oral activity. In 2001 both topical application as well as feeding methods were tried. Significant effects were observed only in the topical treatment group, perhaps because of inconsistency in feeding. In this group, total progeny, the number of ovarioles in ovaries and the size of the female's corpora allata (CA) were all significantly reduced. Ultrastructure of the CA of treated females showed extensive vacuolation near the surface of the gland. The experiment was repeated in 2002 using both topical application and an improved oral feeding method. Whereas there was apparent recovery in the topically treated group after 90 days, the oral treatment was more persistent in its effect perhaps due to a higher amount of halofenozide consumed during feeding.     

Effect of ecdysone agonist RH-0345 on reproduction of mealworm,Tenebrio molitor

RH-0345 belongs to a new group of insect growth regulators (IGRs) with a benzoylhydrazine structure that mimic the action of the natural insect molting hormone 20-hydroxyecdysone. After topical application on female adult beetles of mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae), first oviposition was delayed, the number of eggs per female was reduced by 32%, the follicular epithelium was thinner (-33%) during sexual maturation, the size of deposited eggs was reduced, and egg viability was lost by 68%. Treatment with RH-0345 had also reduced the ovarian protein content and two protein bands were missing in the ovaries. Ultrastructural observations of the ovaries at the end of vitellogenesis in treated females, however, showed no evident differences with the fine structure of both follicular cells and oocytes in controls. In addition, we measured the amount of ecdysteroids in the medium of treated ovary cultures in vitro and in the eggs deposited by treated females. Possible action sites with the reproductive system at different levels in T. molitor are discussed for this novel group of IGRs.     

新型非甾醇蜕皮激素类杀虫剂对棉铃虫幼虫蜕皮的影响

用透射电镜技术研究了新型非甾醇蜕皮激素类杀虫剂W200013对棉铃虫4龄幼虫蜕皮的影响。结果表明W200013使棉铃虫产生早熟、致死的蜕皮。中毒试虫6 h表现出内表皮层沉积加快,皮细胞中粗面型内质网大量增加,糖原颗粒减少;12 h蜕皮间隙开始形成,细胞质凝集;24 h新、旧表皮同时存在,皮细胞空泡化严重;36 h新上表皮覆盖于仅沉积几层的新原表皮上,旧表皮仍然保持,皮细胞呈恶化、降解状态,宏观上虫体不表现出蜕皮行为而死亡。而且比较研究可见W200013在中毒症状、生物测定结果、超微结构水平与RH-5992具有相似的作用。