共查询到20条相似文献，搜索用时 359 毫秒
1.
2.
The toxicity and influence on chronic development regulation of dietary benzoxadiazole as well as the subsequent action on cuticle enzyme and antioxidant defense system in feed-thru housefly larvae are investigated. Dietary benzoxadiazole shows limited larvicidal activity and weak interference on larval pupation, but strong blockage against the succedent eclosion process. It does not change the content ratio of protein/chitin in the larval cuticle, but strongly regulates the constituents of cuticle proteins. Moreover, chitinase activities in the integument of third-instar larvae, in vivo, are enhanced and gradually decreased whereas phenoloxidase activities are inhibited and the inhibitory rates are gradually increased. Glutathione S-transferase activities are strongly improved whilst peroxidase activities decrease from about 42.25% to 17.36%, catalase activities decrease from about 80.31% to 27.98% and superoxide dismutase activities are almost unchanged during the different treatment procedures. Peroxidase SDS-PAGE analysis shows that band photodensities of 200.0 and 10.3 kDa proteins in feed-thru larvae are significantly weaker than the corresponding control band. Results suggest that dietary benzoxadiazole might exert strong regulation on larvae cuticle metabolism, interfere with cuticle enzymatic browning and protein sclerotization and weaken the self-protection of larvae against endogenetic oxidative damages. 相似文献
3.
The knowledge of the biochemical mode of action of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) is presented, explaining the insecticidal effect. Like its structural analog, 1-(2,6-dichlorobenzyl)-3-(3,4-dichlorophenyl)urea (Du 19111), it inhibits chitin synthesis in the cuticle of larvae. Virtually complete inhibition was demonstrable 15 min after the application of diflubenzuron. Neither diflubenzuron nor Du 19111 has any effect upon chitinase activity either in vivo or in vitro. The insecticidal effect upon the cuticle, therefore, must be explained as an inhibition of chitin synthesis and not as an activation of chitin degradation. In contrast to the action of Du 19111, no accumulation of N-acetylglucosamine occurs upon treatment of larvae with diflubenzuron. Similarities and differences in the mode of action of both compounds are discussed, together with other effects reported in the literature. 相似文献
4.
Effects of the chitin synthesis inhibitor diflubenzuron (DFB) on the integument of 5th instarGalleria mellonella L. larvae were investigated. When larvae were fed with semi-artificial diets containing 250, 500 and 1000 ppm of the compound,
DFB affected the integument. The affected larvae failed to ecdysis, their cuticle was ruptured, lost haemolymph and blackened.
In treated larvae, cuticle deposition was disrupted and the cuticle thickness was decreased by ∼50% compared with the untreated
control, particularly at day 3 1/2. However, statistically there was no significant difference among the three concentrations
(P>0.05). This may indicate that all three concentrations are equally effective in decreasing level. DFB at 500 and 1000 ppm
also affected the epidermal cells and caused the occurrence of vacuoles.
http://www.phytoparasitica.org posting Dec. 16, 2003. 相似文献
5.
Dietary ZR-512 and ZR-619 at concentrations of 10 — 1000 ppm induced prolongation of the larval feeding period up to tenfold, increasing larval weight up to double that of untreated larvae. A comparison study of four juvenoids, using 200 ppm of ZR-512, ZR-515, ZR-619 or ZR-777, showed that ZR-515 elicits the highest larval weight (6.2 mg) and ZR-777 the lowest (3.6 mg). In all cases a pronounced enhancement of larval weight — of 50 — 250% relative to untreated larvae (2.4 mg) — was obtained.Tr. castaneum larvae reared up to their 3rd instars on a diet containing 100 ppm of ZR-512, ZR-515, ZR-619 or ZR-777 and then transferred to a juvenile hormone-free diet, were not affected. The period between 4th instar larva and pupation should therefore be considered as critical for juvenile hormone effect. The induced prolongation of the larval stage after juvenile hormone treatment was followed by a pronounced enhancement of cuticle phenoloxidase activity, indicating an alteration of the larval biochemical processes. Although juvenile hormone treatment inhibitsTr. castaneum pupation and emergence, it markedly prolongs larval feeding stage and weight and thus accelerates damage. 相似文献
6.
The effects of the chitin synthesis inhibitor (CSI) novaluron on egg hatch and on larval development ofTribolium castaneum (Herbst) concentrations of 1.0, 0.3, 0.2 or 0.1 ppm were tested. The effect of novaluron at low concentrations depended strongly
on the exposure period. At 0.3 ppm, egg hatch ofT. castaneum was totally inhibited after 28 days; at 0.2 ppm the effect was much less but inhibition increased progressively to 66% in
the 35-day experiment; at 0.1 ppm novaluron was ineffective. The viability of the larvae that hatched from the laid eggs and
developed on untreated flour was also dependent on concentration of novaluron and exposure time: exposure ofT. castaneum adults to novaluron-treated flour at 0.3 ppm for 8 days, or at 0.2 ppm for 36 days, caused 100% or 97.5% mortality, respectively.
At both 0.3 and 0.2 ppm, larval deaths were mainly in the first instar. Exposure ofT. castaneum adults to treated flour may serve as a good model for evaluating the effect of CSIs on internal feeders, especiallySitophilus oryzae (L.). The present study contributes to our understanding of CSI transovarial activity against internal stored product coleopterans
whose larval stage develops inside the grain without contact with the toxicants.
http://www.phytoparasitica.org posting Dec. 11, 2007. 相似文献
7.
Homogenates of larvae, pupae, and adults of house flies (Musca domestica L.), flesh flies (Sarcophaga bullata Parker), and blow flies (Phormia regina (Meigen)) have been examined for enzymes which convert α- and β-ecdysone to apolar products. Most of the activity was found in the soluble fraction from house flies and flesh flies but none of the blow fly fractions was active. Two enzymes seem to be involved in the ecdysone metabolism, one requiring NADPH and the other functioning without this cofactor. The product of the latter enzyme is thought to be the 3-dehydro-ecdysone. This product is further converted to the 3α-hydroxy isomer of ecdysone by the NADPH-requiring enzyme. On feeding the insect growth regulator TH-6040 (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea) to larvae at dietary levels ranging from 0.3 to 10 ppm, the activity of the enzyme producing the 3-dehydro product is reduced by 20 to 82%. It is suggested that the growth regulator exerts its effect on pupal-adult ecdysis through its inhibition of ecdysone metabolism. 相似文献
8.
产生几丁质酶的食线虫真菌绿粘帚霉Gliocladium virens CFCC80915对南方根结线虫卵孵化的影响 总被引：3，自引：0，他引：3
根结线虫卵壳主要由几丁质和蛋白质构成。寄生根结线虫卵或产毒真菌产生几丁质酶特性是评价食线虫真菌生物防治潜力的重要生化指标之一。利用还原糖法和pNP法分别测定绿粘帚霉(Gliocladium virens)的几丁质酶的内切酶和外切酶活性。第14d内切酶活性达到最高值,其酶活为53.1μmol/h mL;外切酶活性第26d达到高峰,其酶活为0.432μmol/h mL。利用活性染色电泳测其几丁质酶的分子量分别为75.8kDa、42.8kDa和39.6kDa。表明筛选到的绿粘帚霉CFCC80915菌株具有较高产生几丁质酶的活性。绿粘帚霉12d的培养滤液对根结线虫卵孵化7d后的抑制率达到92.9%。显微观察线虫卵壳变形和破坏情况的结果表明,绿粘帚霉CFCC80915产生的几丁质酶可以引起根结线虫卵壳的裂解,抑制根结线虫卵的孵化。 相似文献
9.
ABSTRACT Stenotrophomonas maltophilia strain C3, a biocontrol agent of Bipolaris sorokiniana in turfgrass, produced chitinases in broth media containing chitin. Chitinases were partially purified from culture fluid by ammonium sulfate precipitation and chitin affinity chromatography. The chromatography fraction with the highest specific chitinase activity was inhibitory to conidial germination and germ-tube elongation of B. sorokiniana, but it was less inhibitory than the protein fraction or the raw culture filtrate. The fraction exhibited strong exochitinase and weak endo-chitinase activity. Optimum temperature and pH for chitinase activity were 45 to 50 degrees C and 4.5 to 5.0, respectively. Chitinase activity was inhibited by Hg(2+) and Fe(3+), but not by other metal ions or enzyme inhibitors. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the chromatography fraction revealed the presence of five protein bands of 25, 32, 48, 65, and 75 kDa. Partial amino acid sequences of the 32-, 65-, and 75-kDa proteins indicated that they are homologous to known bacterial chitinases. There was no homology found in the partial amino acid sequences of the 25- and 48-kDa proteins to any known chitinases. Five chitinase-active proteins were detected in the protein and chromatography fractions by activity gels, but when each protein was extracted and re-electrophoresed separately under denaturing conditions, only 32- or 48-kDa proteins were revealed. It was concluded that strain C3 produces at least two chitinases that are antifungal. 相似文献
10.
ABSTRACT The role of chitinase production by Stenotrophomonas maltophilia strain C3 in biological control of leaf spot on tall fescue (Festuca arundinacea), caused by Bipolaris sorokiniana, was investigated in vitro and in vivo. The filtrate of a broth culture of C3, with chitin as the carbon source, was separated into fractions. A high molecular-weight fraction (>8 kDa) was chitinolytic and more inhibitory than a low-molecular-weight, nonchitinolytic fraction to conidial germination and hyphal growth by B. sorokiniana and to leaf spot development. A protein fraction derived by ammonium sulfate precipitation and a chitinase fraction purified by chitin affinity chromatography also were chitinolytic and highly antifungal. The chitinolytic fractions caused swelling and vacuolation of conidia and discoloration, malformation, and degradation of germ tubes. When boiled, the chitinolytic fractions lost chitinase activity along with most of the antifungal properties. Two chitinase-deficient and two chitinase-reduced mutants of C3 were compared with the wild-type strain for inhibition of germination of B. sorokiniana conidia on tall fescue leaves and for suppression of leaf spot development in vivo. The mutants exhibited reduced antifungal activity and biocontrol efficacy, but did not lose all biocontrol activity. An aqueous extract of leaves colonized by wild-type C3 had higher chitinase activity than that of noncolonized leaves and was inhibitory to conidial germination. The addition of chitin to leaves along with the wild-type strain increased both chitinase and antifungal activity. The chitinase activity level of extracts from leaves colonized by a chitinase-deficient mutant of C3, with and without added chitin, was no higher than the background, and the extracts lacked antifungal activity. Chitinolysis appears to be one mechanism of biological control by strain C3, and it functions in concert with other mechanisms. 相似文献
11.
CME 134, a new benzoylphenyl urea chitin synthesis inhibitor, was less active than diflubenzuron and BAY SIR 8514, when tested againstSpodoptera littoralis eggs by a dipping method. AgainstS. littoralis larvae the compound was tested by feeding treated alfalfa, topical application and contact with crystalline residues on glass, followed by observation until the adult stage. With both 200–250 and 360–440-mg larvae 100% mortality was obtained by one-day feeding of alfalfa treated with 0.15 ppm a.i. Topical application to 100- and 200-mg larvae showed CME 134 to be about five and nine times more active than BAY SIR 8514 and diflubenzuron, respectively. These differences were even much greater in the contact tests. Cotton field plots were sprayed with either CME 134 or diflubenzuron formulations, leaves were collected at different intervals and fed for one day toS. littoralis larvae in the laboratory. 0.0009% a.i. CME 134 residues gave complete kill of 30–50-mg larvae after 5 and 20 days, and 86% kill after 28 days of aging. With 0.003 and 0.009% a.i., complete kill was obtained in 200–250-mg larvae until 50 days after spraying. 相似文献
12.
Purification of an Elicitor-Inducible Antifungal Chitinase from Suspension-Cultured Rice Cells 总被引：1，自引：0，他引：1
Suspension-cultured rice cells showed an appreciable amount of chitinase activity when the cultured cells were treated with
an elicitor isolated fromRhizoctonia solani, the rice sheath blight pathogen. A fivefold increase in chitinase activity was observed 24 h after elicitor treatment. The
elicitor-inducible chitinase was purified by ammonium sulfate fractionation, chitin affinity chromatography and gel filtration.
Its molecular weight is 35 kDa and it has an isoelectric point of 8.3. The 35 kDa basic chitinase inhibited mycelial growth
ofR. solani in vitro. Morphological changes appeared within 1 h following exposure of mycelium to the chitinase. The hyphal tip showed marked
swelling and subsequently lysis was also observed. 相似文献
13.
中华根瘤菌L03几丁质酶纯化及其酶学性质研究 总被引：1，自引：0，他引：1
中华根瘤菌Sinorhizobium sp.菌株L03是1株能产生几丁质酶的生防细菌.采用90%饱和度硫酸铵沉淀、DEAE-Sepharose Fast Flow阴离子层析、Phenyl-Sepharose疏水层析等方法获得了菌株L03的几丁质酶.SDS-PAGE检测发现该酶已被纯化,其分子量约为41.3kD.该酶反应的最适温度为45℃;最适反应的溶液pH值为6;酶液在pH5～8条件下和40℃下分别保存1h,酶活力基本保持稳定;Mg2+和Ba2+能显著促进几丁质酶活性上升,而Zn2+、Cu2+和Fe3+等对酶活力有明显的抑制作用.功能分析结果显示,该几丁质酶对供试的几种病原真菌细胞壁都有明显的降解作用. 相似文献
14.
Lethal and sublethal effects of two insect growth regulators (IGRs) buprofezin and pyriproxyfen were evaluated on larvae of cotton leafworm Spodoptera littoralis. Activity of chitinase and polyphenol oxidase (PPO) in surviving larvae after treatment was carried out in order to investigate the biochemical influences of these compounds. The compounds were low toxic against the larvae at 0.05, 0.1, 0.25, 0.5, and 1.0-fold of the field application rate. However, the overall mortalities within 6 days of feeding at 2.0-fold were 46.67% and 100% for buprofezin and pyriproxyfen, respectively. Larval weight gain was considerably decreased as concentration increased. Pyriproxyfen showed high antifeedant activity in a concentration-dependent manner, and larvae stopped to eat from the third day with high dose. Conversely, buprofezin did not significantly show antifeedant except with high concentration (3000 mg (a.i.)/kg diet) that gave 80.68%. The high doses of both compounds showed adverse effects on pupae, and emergence of adults. Buprofezin at the recommended dose (1500 mg (a.i.)/kg diet) caused 93.33% pupation and 53.33% emergence of adults. Otherwise, pyriproxyfen caused 21.33% pupation and zere emergence of adults at the recommended dose (75 mg (a.i.)/kg diet) compared to 100% pupation, and 96.30% emergence of adults in the control. Both compounds varied in their influences on chitinase and PPO activity, and these enzymes could have relation with toxicity of buprofezin and pyriproxyfen against S. littoralis larvae. 相似文献
15.
几丁质合成抑制剂灭幼脲三号对苹果金纹细蛾 Lithocolletis ringoniella Mats的生物活性及组织学影响研究结果表明 :以 2 50 mg/L药糖液连续饲喂成虫 ,导致部分成虫不能产卵 ,卵孵化率和后代幼虫存活率降低 ,对卵直接杀伤效果较低 ,但能干扰卵内胚胎体壁发育 ,使孵出的幼虫不能正常发育。对 1龄幼虫活性高 ,药后 5天的 L C50 和 L C95值分别为 4 .9733mg/L和 2 1.1533mg/L ,抑制老龄幼虫发育变态 ,幼虫体壁层次不清 ,表皮与真皮细胞分离 ,表皮厚度比正常幼虫降低 1/3,中肠基底膜皱缩 ,肠外肌肉层变薄 ,部分细胞刷状边破损 ,柱状细胞分辨不清。在叶片上有良好的渗透性和较长的持效期 相似文献
16.
The activities of the chitin synthesis inhibitors, diflubenzuron and PH 60–38, against Spodoptera littoralis larvae were assayed by feeding treated alfalfa or poisoned wheat bran baits, by allowing the larvae to imbibe sucrose-containing aqueous dispersions of the compounds, and by injection into larvae. PH 60–38 was less active than diflubenzuron. On alfalfa, diflubenzuron had to be fed for at least 2 days to prevent formation of normal pupae and emergence of adults. For very big (480–540 mg) larvae, feeding diflubenzuron at concentrations of 50 mg/litre for 2 days or 2.5 mg/litre for 3 days prevented adult emergence. For 200–250 mg larvae, this was achieved by feeding concentrations of 100 mg/litre for 2 days, 5 mg/litre for 3 days or 3.5 mg/litre for 4 days. In all larvae > 150 mg, mortality in feeding experiments occurred in the prepupal or the pupal stage. Only with 30–50 mg and 100–150 mg larvae was there considerable mortality during moults between larval instars, the larvae being unable to liberate themselves from the old larval skins and head capsules. Diflubenzuron incorporated into wheat bran baits at concentrations of from 2.5 to 10 000 μg/g killed approximately 70–90% of the insects. When imbibed, diflubenzuron was much less toxic as a wettable powder than as a liquid formulation but the two formulations were equitoxic when injected into the larvae. 相似文献
17.
Helicoverpa armigera is a serious pest of Cajanus cajan in many parts of world. Rapid development of resistance against number of insecticides and cry toxin-based biocontrol agents has led to search for biocontrol agents with alternative mode of action. The ability of chitinolytic bacteria to degrade vital chitinous structure in insects suggests their potential in insect control. The present investigation was carried out to study insect control potential of a high chitinase producing bacterium, Paenibacillus sp. D1. Biocontrol studies with Helicoverpa larvae showed Paenibacillus sp. D1 and its chitinase to be potent antifeedant that reduced the feeding rate and body weight of the larvae. The decreased body weight was attributed to hydrolysis of the chitinous structures of the larvae. This was evident from decrease in the total chitin content and increased mortality of the larvae fed on the leaves treated with Paenibacillus sp. D1 and chitinase as compared to untreated controls. A combined dose of Paenibacillus sp. D1 or its chitinase with an organophosphate insecticide, acephate, was found to be more lethal than their individual treatments suggesting integrated insect control potential of the bacterium. 相似文献
18.
Robert F. Ker 《Pest management science》1978,9(3):259-265
Cuticle consists of chitin microfibrils embedded in a matrix composed largely of hydrated proteins. The effect of diflubenzuron, an inhibitor of chitin synthetase, on the deposition of both these components is reviewed. The polymerisation reaction is but one step in the pathway leading to chitin microfibrils. Possibly interactions to other steps in the pathway serve to enhance the consequences of the inhibition. Such enhancement could help to explain the abrupt changes in the rate of chitin synthesis that can be observed as diflubenzuron is cleared from epidermal cells. Cuticle proteins differ widely in their ability to form a stable layer when chitin is largely absent. In the most stable regions, diflubenzuron has no effect on the amount or nature of the proteins deposited. In contrast, there are many regions where the deposition of solid cuticle is stopped, presumably because the proteins involved cannot form a coherent layer. Intermediate degrees of stability are found. There is an association between the regions of stability and those of high sclerotisation; though sclerotisation often takes place long after deposition. Even when the protein layer is fairly stable it may not be deposited in a regular manner. This statement is illustrated by electron micrographs of cuticle from the hind tibiae of adult locusts. These micrographs also show that diflubenzuron can affect epidermal cells. In normal cells the plaques are in contact with the newly secreted cuticle; they are still present but this contact is not maintained after treatment with diflubenzuron. 相似文献
19.
In May 1972, 0.309 ppm methoxychlor black fly larvicide was applied in a single test on the North Saskatchewan River. Eight to nine days later residues of 0.05-0.10 ppm methoxychlor occurred in sand 21-22 km downstream from the point of injection. Methoxychlor was not detected in water, insect larvae, shellfish, or muscle tissues of three fish species on the same sampling date. Perhaps because of relatively high oil content in goldeye fish, methoxychlor residues in muscle tissues were 1.0-1.5 ppm in 8 percent of those sampled, 0.21-0.99 in 21 percent, and 0.02-0.20 in 37 percent. In 34 percent of the goldeye fish no residues were detected. Goldeye and other fish collected before or 17 weeks after this injection did not contain detectable levels of methoxychlor. River water in two samples of the injected slug of water collected 6.5 km downstream from the point of injection contained 0.14 and 0.16 ppm methoxychlor. The suspended solids filtered from these sample contained 40 and 47 percent of this methoxychlor (437 and 892 ppm, respectively). Thus methoxychlor may act selectively against filter-feeding species, especially black fly larvae. 相似文献
20.
亚洲玉米螟Ostrinia furnacalis是我国玉米最重要的害虫，了解亚洲玉米螟表皮形成的机制将有助于对其开展生物防治。表皮蛋白和几丁质是构成昆虫表皮的两种主要成分，因此研究两者的相互作用对于阐明昆虫表皮形成机制具有关键意义。CPR9是亚洲玉米螟体壁表皮转录组中相对丰度最高的表皮蛋白基因。序列分析发现CPR9属于CPR家族中RR-1亚家族的表皮蛋白，含有R&R结构域，可能是通过结合几丁质来发挥功能。为了研究CPR9与几丁质的相互作用，本研究利用pET-SUMO载体实现了SUMO-CPR9融合蛋白的可溶表达，并通过SUMO蛋白酶处理及两次金属螯合亲和层析纯化了CPR9，平均收率为5 mg/L。几丁质结合试验发现，CPR9对不同类型的几丁质的结合具有选择性。CPR9对α-几丁质结合能力很强，对胶体几丁质结合能力较强，但不与β-几丁质结合。脱乙酰几丁质（壳聚糖）结合试验发现，CPR9能与脱乙酰几丁质结合并使其发生团聚。圆二色光谱分析表明，CPR9在结合脱乙酰几丁质后，其二级结构中平行β折叠和β转角比例上升，反平行β折叠及无规卷曲比例下降。本研究发现了CPR家族表皮蛋白与不同类型几丁质的结合存在特异性，而且在结合过程中会发生结构变化，有助于进一步了解昆虫表皮的形成机制。 相似文献