Azadirachtin-A and tetrahydroazadirachtin-A concentrates: preparation, LC-MS characterization and insect antifeedant/IGR activity against Helicoverpa armigera (Hübner)

A 60% azadirachtin-A concentrate has been obtained through repeated precipitation with hexane from a methanolic solution of a 20% concentrate. Azadirachtin-A (90%) has been obtained by medium-pressure liquid chromatography of the 60% concentrate with an RP-18 column and a methanol + water (1 + 1 by volume) solvent system. Catalytic hydrogenation of the 60 and 90% azadirachtin concentrates yielded the corresponding tetrahydroazadirachtin concentrates. Dihydroazadirachtin and tetrahydroazadirachtin formed during the first 5 h of hydrogenation were identified by LC-ESI-MS on the basis of their unique mass fragmentation pattern. The efficacy of tetrahydroazadirachtin concentrates in inhibiting the feeding and growth of Helicoverpa armigera (Hübner) larvae has been compared with that of azadirachtin concentrates. They were in general more active and deterred larvae from feeding at all concentrations. Tetrahydroazadirachtin-A (90%) and azadirachtin-A (90%) with respective IC(50) values of 280 and 390 mg L(-1) were effective as insect growth regulators, while tetrahydroazadirachtin-A (90%) displayed higher antifeedant activity (AI(50) 14 mg L(-1)) against the test insect.     

Conservation of natural enemies in cotton: comparative selectivity of acetamiprid in the management of Bemisia tabaci

The integrated control concept emphasizes the importance of both chemical and biological control for pest suppression in agricultural systems. A two-year field study was conducted to evaluate the selectivity of acetamiprid for the control of Bemisia tabaci (Gennadius) in cotton compared with a proven selective regime based on the insect growth regulators (IGRs) pyriproxyfen and buprofezin. Acetamiprid was highly effective in controlling all stages of B tabaci compared with an untreated control, and generally produced lower pest densities than the IGR regime. Univariate analyses indicated that nine of 17 taxa of arthropod predators were significantly depressed with the use of acetamiprid compared with an untreated control, including common species such as Geocoris punctipes (Say), Orius tristicolor (White), Chrysoperla carnea Stephens sensu lato, Collops vittatus (Say), Hippodamia convergens Guérin-Méneville, and Drapetis nr divergens. Compared with results from independent, concurrent studies using mixtures of broad-spectrum insecticides at the same research site, acetamiprid depressed populations of fewer predator taxa; but, for eight predator taxa significantly affected by both regimes, the average population reduction was roughly equal. In contrast, only four taxa were significantly reduced in the IGR regime compared with the untreated control and three of these were omnivores that function primarily as plant pests. Principal response curves analyses (a time-dependent, multivariate ordination method) confirmed these patterns of population change for the entire predator community. Predator:prey ratios generally increased with the use of both IGRs and acetamiprid compared with an untreated control, but ratios were consistently higher with IGRs. Parasitism by aphelinid parasitoids was unaffected or depressed slightly in all insecticide regimes compared with the control. Because of its high efficacy, acetamiprid may play an important role in later stages of B tabaci control where less emphasis is placed on selectivity. However, our results suggest that acetamiprid would be a poor substitute for the currently used IGRs in the initial stage of control where insecticide selectivity is crucial to a functional integrated control program for B tabaci in cotton.     

Insect resistance to Nilaparvata lugens and Cnaphalocrocis medinalis in transgenic indica rice and the inheritance of gna+sbti transgenes

Molecular genetic analysis and insect bioassay of transgenic indica rice 'Zhuxian B' plants carrying snowdrop lectin gene (gna) and soybean trypsin inhibitor gene (sbti) were investigated in detail. PCR, 'dot' blot and PCR-Southern blot analysis showed that both transgenes had been incorporated into the rice genome and transmitted up to R3 progeny in most lines tested. Some transgenic lines exhibited Mendelian segregation, but the other showed either 1:1 (positive: negative for the transgenes) or other aberrant segregation patterns. The segregation patterns of gna gene crossed between R2 and R3 progeny. In half of transgenic R3 lines, gna and sbti transgenes co-segregated. Two independent homozygous lines expressing double transgenes were identified in R3 progeny. Southern blot analysis demonstrated that the copy numbers of integrated gna and sbti transgenes varied from one to ten in different lines. Insect bioassay data showed that most transgenic plants had better resistance to both Nilaparvata lugens (Stahl) and Cnaphalocrocis medinalis (Guenee) than wild-type plants. The insect resistance of transgenic lines increased with the increase in transgene positive ratio in most of the transgenic lines. In all, we obtained nine lines of R3 transgenic plants, including one pure line, which had better resistance to both N lugens and C medinalis than wild-type plants.     

球孢白僵菌对亚洲玉米螟幼虫血细胞数量和包囊作用的影响

为明确亚洲玉米螟Ostrinia furnacalis幼虫对球孢白僵菌Beauveria bassiana的细胞免疫作用,研究了注射不同剂量球孢白僵菌芽生孢子后亚洲玉米螟幼虫血细胞总数的时间动态变化和活体与离体条件下血细胞对芽生孢子的包囊作用。各处理组的血细胞总数均在注射后0.25 h达到一个低谷之后上升,注射剂量为102个/虫和103个/虫芽生孢子组血细胞总数在注射后24 h仍高于正常值,注射剂量为104个/虫和105个/虫芽生孢子组血细胞总数在注射后24 h低于正常值。在活体条件下亚洲玉米螟幼虫血细胞粘附在球孢白僵菌芽生孢子表面形成包囊;在离体条件下包囊形成的速度较慢,其致密程度不如活体状态。表明亚洲玉米螟幼虫对球孢白僵菌芽生孢子具有强烈的细胞防御能力。     

转cry1C和cry2A不同抗虫基因水稻品种对非靶标害虫灰飞虱生物学特性的影响

为明确转cry1C和cry2A不同抗虫基因水稻品种对非靶标害虫灰飞虱生物学特性的影响,在室内恒温25 ℃条件下观察转cry1C和cry2A不同抗虫基因水稻品种对非靶标害虫灰飞虱寄主选择行为的影响,以及个体发育与种群发展情况,记录并分析各虫态的发育历期、存活率及实验种群生命表参数。结果表明,灰飞虱对转cry2A、cry1C基因水稻和对照亲本水稻‘明恢63’的定向选择栖息率反正弦转换值分别为27.5、28.5、26.5,差异不显著。灰飞虱对3种供试水稻品种的喜好程度基本一致,但在转cry1C基因水稻上的平均取食刺痕数508.3个/d显著高于转cry2A基因水稻（288.5个/d）和亲本水稻‘明恢63’（297个/d）。灰飞虱在两个转基因抗虫水稻上的若虫全历期、卵孵化率、各虫态存活率和成虫羽化率与对照亲本水稻相比均差异不显著。灰飞虱在转cry2A、cry1C基因水稻和对照亲本水稻‘明恢63’上的初羽化成虫鲜重分别为0.731、0.744 mg和0.821 mg,差异不显著。上述结果表明,转不同Bt抗虫基因水稻对非靶标害虫灰飞虱个体发育及种群生命参数影响不大,与对照亲本水稻相比较在统计学上差异不显著。     

转Bt基因抗虫作物对非靶标生物的影响

迄今为止,已经获得了大量的抗虫转Bt基因作物。尽管这些作物中表达的Bt蛋白只是针对靶标害虫起到杀虫效果,但是抗虫转Bt基因作物是否会对非靶标生物产生影响一直存在争议。本文就抗虫转Bt基因作物对节肢动物群落、非靶标植食性昆虫、天敌和有益昆虫的影响进行了综述。综合评价认为,现有的抗虫转Bt基因作物对非靶标生物是安全的。     

不同类型昆虫粉对肉鸡生长性能、血液生化指标及肠道发酵的影响

本研究旨在评估昆虫粉对肉鸡生长性能、血液生化指标及肠道发酵的影响。试验将432只1日龄商品肉鸡分为3组,每组6个重复,每个重复24只。各组肉鸡分别饲喂基础日粮（对照组）、基础日粮+0.5%黄粉虫粉（黄粉虫组）和基础日粮+0.5%水虻粉（水虻组）,饲养试验为期4周。结果：对照组15～28?d肉鸡料重比较黄粉虫和水虻组分别显著提高8.10%和4.13%（P＜0.05）,对照组1～28?d肉鸡料重比较黄粉虫组显著提高5.35%（P＜0.05）。黄粉虫和水虻粉组肉鸡血清白蛋白和磷浓度显著高于对照组（P＜0.05）,但胆固醇浓度显著降低（P＜0.05）。黄粉虫组肉鸡血清GOT活性显著低于对照组和水虻粉组（P＜0.05）。水虻粉组血清MDA浓度显著低于黄粉虫组（P＜0.05）,但血清SOD活性表现最高（P＜0.05）。对照组肉鸡盲肠α-葡萄糖苷酶和β-半乳糖酶活性显著高于水虻粉组（P＜0.05）,而β-葡萄糖苷酶活性显著高于黄粉虫组（P＜0.05）。对照组盲肠内容物乙酸、丙酸和挥发性脂肪酸总量浓度显著高于处理组（P＜0.05）。结论：1～28?d肉鸡日粮中补充0.5%黄粉虫可以改善饲料效率,降低血清胆固醇浓度,而0.5%水虻粉可以提高肉鸡血清抗氧化功能。 [关键词]昆虫粉|肉鸡|生长性能|血液生化|肠道发酵     

昆虫蛋白粉作为蛋白原料对肉兔生长性能、养分消化及饲养成本的影响

本研究评估了日粮添加昆虫蛋白粉（黄粉虫）替代豆粕对肉兔生长性能、养分消化及饲养成本的影响。试验选择平均体重为（712.16±0.37）g的60只肉兔,随机分为2组,每组5个重复,每个重复6只。对照组和处理组肉兔在整个为期8周的饲养试验中分别饲喂8%豆粕型和8%黄粉虫型基础日粮。结果：处理组肉兔12?w体重较对照组显著提高1.11%（P＜0.05）,但4～8?w平均日采食量、9～12?w和4～12?w料重比分别显著降低4.38%、4.55%和4.15%（P＜0.05）。对照组与处理组对肉兔干物质、有机物、粗蛋白质、总能、中性洗涤纤维和酸性洗涤纤维表观消化率及氮沉积量的影响无显著差异（P＞0.05）。对照组肉兔氮摄入量、粪氮和尿氮排泄量分别较处理组显著提高12.88%、15.45%和46.67%（P＜0.05）。对照组与处理组的饲料价格无显著差异（P＞0.05）,处理组肉兔在各阶段的饲料成本较对照组分别显著降低0.8、0.74和1.54元,同时生长后期（8～12?w）和试验全期（4～12?w）增重饲料成本分别显著降低1.19和0.86元/kg。结论：日粮用8%黄粉虫替代豆粕作为生长期肉兔的蛋白原料可以改善生长后期和整个生长期的饲料效率,降低粪氮、尿氮排泄量,使整个试验期的增重成本降低0.86元/kg。 [关键词]昆虫蛋白粉|肉兔|生长性能|养分消化     

不同梨树品种对梨瘿蚊的抗虫性研究初探

摘要：为探明不同梨树品种对梨瘿蚊的抗性,为梨树抗性品种选育和梨瘿蚊（Dasineura pyri Bouche）的防治提供理论参考。以国家果树种质武昌砂梨圃内的30个砂梨品种为材料,通过人工接种梨瘿蚊的方式,对30个砂梨品种接种梨瘿蚊后的植株受害率和叶片受害率进行了调查,并依据一定的标准计算得到综合受害率,从而对其抗虫性进行了评价,筛选出了金黛梨、早生黄金梨和华山梨等3个对梨瘿蚊的抗性较强的砂梨品种。这可为今后开展梨树抗梨瘿蚊品种选育提供重要材料。     

离体昆虫细胞对 AcNPV和BmNPV的敏感性测定与分析

采用来源于3个目14种昆虫的离体细胞系对苜蓿银纹夜蛾核型多角体病毒AcNPV(Autographa californica nuclear polyhedrosis virus)和家蚕核型多角体病毒BmNPV(Bombyx mori nuclear polyhedrosis virus)进行敏感性测定.试验结果表明:各...