Evaluation of alternative rice planthopper control by the combined action of oil-formulated Metarhizium anisopliae and low-rate buprofezin

BACKGROUND: High resistance of brown planthopper (BPH) Nilaparvata lugens Stål to common insecticides is a challenge for control of the pest. An alternative control strategy based on the combined application of fungal and chemical agents has been evaluated. RESULTS: Three gradient spore concentrations of oil‐formulated Metarhizium anisopliae (Metschnikoff) Sorokin (Ma456) were sprayed onto third‐instar nymphs in five bioassays comprising the low buprofezin rates of 0, 10, 20, 30 and 40 µg mL^?1 respectively. Fungal LC₅₀ after 1 week at 25 °C and 14:10 h light:dark photoperiod decreased from 386 conidia mm^?2 in the buprofezin‐free bioassay to 40 at the highest chemical rate. Buprofezin (LC₅₀: 1647, 486 and 233 µg mL^?1 on days 2 to 4) had no significant effect on the fungal outgrowths of mycosis‐killed cadavers at the low application rates. The fungal infection was found to cause 81% reduction in reproductive potential of BPH adults. In two 40 day field trials, significant planthopper (mainly BPH) control (54–60%) was achieved by biweekly sprays of two fungal candidates (Ma456 and Ma576) at 1.5 × 10¹³ conidia ha^?1 and elevated to 80–83% by incorporating 30.8 g buprofezin ha^?1 into the fungal sprays. CONCLUSION: The combined application of the fungal and chemical agents is a promising alternative strategy for BPH control. Copyright © 2010 Society of Chemical Industry     

太湖稻区单季稻褐飞虱防控策略

太湖单季稻区褐飞虱的主峰迁入期是7月10-25日,20世纪90年代后是7月10-20日,迁入峰只有1个。若遇水稻分蘖中后期,则增殖1代就可进入主害代,若遇水稻分蘖前期,则需增殖2代才能进入主害代。处于分蘖后期至齐穗期的增殖代是主害代暴发的关键,盛夏高温对抑制褐飞虱的发生作用不大。随着农艺措施的改变,单季晚稻褐飞虱发生期由8月中下旬推迟到了9月25-30日,褐飞虱的发生已进入低迁入、高增长阶段,由此提出"治前补后"的防控策略和"狠治拔节至孕穗末期,补治穗期"的防治技术。     

褐稻虱生物型的形成

本文研究褐稻虱连续饲养于具Bph1抗虫基因的IR_(2?)稻种上表现不同致害力群体与生物型形成的关系.试验结果表明,实验室群体的个体间存有不同的致害力.用蜜露分泌量区分不同“致害力”的群体在连续选择压力下,它们间适应IR_(2?)的程度并无明显的差异.三个不同“致害力”的群体应用“苗期群体筛选法”和“群体建立法”测定,表明在IR_(2?)上饲养经过10代,即可使IR_(2?)致死并能适应于该品种;但它们却不能生存于具有BpH_1抗虫基因的Mudgo稻种上.此外,根据蜜露分泌量、飞虱生存率和成虫体重等指标在连续饲养世代的递增,亦证实飞虱群体在IR_(2?)上经过不断的选择,可以演变为一个致害力强的生物型.     

江淮稻区褐飞虱种群动态模拟模型

根据对褐飞虱实验种群的观察数据和一此地区的田间种群生命资料，结合江淮稻区水稻栽培模式和褐飞虱的发生特点，组建了江淮稻区褐飞虱种数量动态的模拟模型，经检验，效益较好，对发生高峰期和发生量的预测均符合标准，基本上能反映该地区褐飞虱的发生趋势，灵敏度分析显示，温度是影响褐飞虱种群数量动态的最关键因素，其次为初始迁入虫量，天敌和水稻生育期，提出用后验差方法评价预测效果，结果表明，该方法适合于对褐飞虱各种发     

水稻感性和抗性品种甲醇提取物对褐飞虱的影响

以水稻2个品种(IR36和TN1)为材料，研究其分蘖期的甲醇提取物对褐飞虱Nilaparvata lugens(stal)2个生物型成虫单向选择性和若虫死亡率的影响．结果表明，IR36提取物对褐飞虱生物型Ⅱ成虫的单向选择性有驱避作用，对若虫表现为负作用(即导致其死亡率增加)；而TN1提取物对其成虫有吸引作用，对若虫无不良影响．对孟加拉型成虫和若虫影响差异均不显著．     

水稻褐飞虱抗药性发展和控制技术研究

１９８７～１９９０年对水稻褐飞虱（Ｎｉｌａｐａｒｖａｔａｌｕｇｅｎｓ，ｓｔａｌ）的抗药性监测结果表明，褐飞虱对甲基对硫磷、马拉硫磷、杀螟硫磷产生了４．２～６．０倍的抗药性，对异丙威、西维因的抗性指数达２．５～３．４倍。选择以噻嗪酮、杀虫单为主要成分的增效复配剂，不仅能有效地控制水稻中后期多种害虫的危害，而且由于减少单剂用量，降低药剂的选择压力，达到延缓或控制抗药性产生和发展的目的。     

水稻抗虫品种对褐飞虱和白背飞虱种群增长的影响

 利用实验种群生命表和Morris-Watt模式综台评价了5个已推广的水稻品种对褐飞虱 Nilaparvata lugens Stal和白背飞虱Sogatetla furcifera Horvath的抗性及品种对稻飞虱各虫态的抗性作用大小。IR36、汕优6号、协优10号、秀水620和丙664对褐飞虱种群增长有明显的抑制作用；而品种秀水620、丙664和协优10号对白背飞虱呈中抗水平。同时发现，品种对稻飞虱各虫态抗性作用在成虫产卵期最明显，对褐飞虱表现为：成虫产卵期>卵孵化期>高龄(3-5龄)若虫期>低龄(1-2龄)若虫期；对白背飞虱则为：成虫产卵期>低龄若虫期>高龄若虫期>卵孵化期。     

饲料氨基酸对褐飞虱及其蜜露游离氨基酸的影响

 利用氨基酸组成不同的全纯人工饲料对褐飞虱(Nilaparvata lugens)成虫进行饲养，研究了饲料氨基酸对该虫及其蜜露中游离氨基酸的影响。结果表明：1）饲料对试虫体内游离氨基酸有明显影响。在不能摄入任何氨基酸的试虫体内，游离氨基酸总量降至可以获得全部氨基酸的试虫的63.2%，其中缬氨酸、苏氨酸、异亮氨酸、亮氨酸、赖氨酸和半胱氨酸下降明显，但蛋氨酸增多。在仅能摄取到非必需氨基酸的试虫体内，蛋氨酸、赖氨酸和亮氨酸的含量与不能摄取到任何氨基酸的试虫处在同一水平，甚至明显低于后者；苏氨酸和组氨酸则明显高于可以获得全部氨基酸的试虫，异亮氨酸、苯丙氨酸和精氨酸亦达到了后种试虫的含量水平，缬氨酸的含量虽然低于后者，但与仅能摄取到必需氨基酸的试虫处在同一水平。2）蜜露中的游离氨基酸组成基本与饲料内的相一致，但相对含量有较大差别，而且少数不存在于饲料中的氨基酸可以在蜜露中检测到。文中对必需氨基酸的补偿代谢进行了讨论，初步认为褐飞虱体内至少可以合成苏氨酸、组氨酸、异亮氨酸、苯丙氨酸、精氨酸和缬氨酸等6种必需氨基酸。     

Effects of triazophos on biochemical substances of transgenic Bt rice and its nontarget pest Nilaparvata lugens Stål under elevated CO2

The brown planthopper (BPH), Nilaparvata lugens Stål, is a serious rice pest throughout Asia. Recent outbreaks of N. lugens populations were mainly associated with the overuse of pesticides and resistance to insecticides. Warmer global temperatures that are associated with anthropogenic climate change are likely to have marked ecological effects on terrestrial ecosystems. However, the effects of elevated CO₂ concentrations on the biochemical, physiological and nutrient quality of transgenic Bt rice that has been treated with pesticides and on the control efficacy of the pesticides are not understood. The present study investigated changes in soluble sugar content, free amino acid levels, oxalic acid levels, flavonoids levels, and triazophos residues in transgenic Bt rice (TT51) and the control efficacy of triazophos for N. lugens following triazophos foliar spray under conditions of elevated CO₂ (eCO₂). Our findings showed that the soluble sugar content of TT51 treated with triazophos under eCO₂ was significantly higher than that under ambient CO₂ (aCO₂) and also higher than that of the non-transgenic parent (MH63) under aCO₂. However, the results for free amino acid levels were the opposite of those for soluble sugar levels. The oxalic acid and flavonoid contents of rice plants significantly decreased with increases in triazophos concentration, CO₂ concentration, and days after treatment (DAT). The oxalic acid and flavonoid contents of TT51 treated with triazophos under eCO₂ were significantly lower than those under aCO₂ and also lower than those of MH63 under aCO₂. The residue concentration of triazophos varied with CO₂ concentration, rice variety, and DAT. The residues in TT51 treated with 80 ppm of trizaopos under eCO₂ were significantly lower than those under aCO₂ and those in MH63 under aCO₂. The survival rate of nymphs N. lugens in TT51 under eCO₂ was significantly higher than that under aCO₂ and that in MH63 under aCO₂ at 1 DAT or 15 DAT after the release of 2nd instars nymphs. These findings indicated that (1) for TT51, triazophos reduced the resistance of rice plants to N. lugens with an elevated CO₂ concentration, as N. lugens consumed more phloem sap on TT51 plants; (2) triazophos dissipation in TT51 under eCO₂ was significantly faster than that under aCO₂ and that in MH63 under aCO₂; (3) the control efficacy of triazophos for N. lugens significantly decreased under eCO₂. The present findings provide important information for integrated pest management among transgenic varieties.