【作者】 李海东；

【导师】 韩召军；

【作者基本信息】 南京农业大学 ， 农业昆虫与害虫防治， 2011， 硕士

【摘要】 二化螟Chilo suppressalis (Walker)是水稻的重要害虫之一,随着耕作制度的变更、品种更新以及害虫抗药性增强,二化螟在许多地区危害加重,甚至出现局部爆发危害现象,给水稻高产、稳产带来极大威胁。为了搞好二化螟防治,江苏等地区运用推迟播栽期和隔离育秧等措施进行栽培避螟,取得了一定的效果。但由于水稻生育期所限,推迟播栽和隔离育秧并不能完全避开发蛾高峰,因此还需筛选持效期较长的药剂进行移栽前施药(送嫁药)。此外,春季螟蛾在不接触水稻的情况下,是否仍能利用其他寄主正常繁衍种群,目前也不清楚。为了明确并进一步提高“利用栽培避螟,选用高效药剂,狠治一代”等综合治理技术措施的效果,本文进行了相关研究,获得的主要研究结果如下：1、不同杀虫剂对二化螟的毒力测定采用四龄幼虫Potter喷雾塔法和初孵幼虫饲料涂药法分别测定了1.8%阿维菌素乳油、20%氯虫苯甲酰胺悬浮剂、5%氟铃脲乳油、10%醚菊酯乳油、40%毒死蜱乳油、50%稻丰散乳油、90%杀虫单可湿性粉剂、15%三唑磷微乳剂、40%丙溴磷乳油9种杀虫剂对二化螟四龄幼虫和初孵幼虫的室内毒力,结果表明,虽然方法和试虫龄期不同,但两种生测方法测定的9种药剂对二化螟的室内毒力顺序基本一致,阿维菌素和氯虫苯甲酰胺毒力最高,氟铃脲、醚菊酯、毒死蜱和稻丰散次之,杀虫单、三唑磷和丙溴磷相对较差。为生产上防治二化螟提供了药剂选择的直接参考依据。2、防治水稻二化螟复配药剂的筛选利用四龄幼虫Potter喷雾塔法和初孵幼虫饲料涂药法,分别检测了以氯虫苯甲酰胺、阿维菌素、醚菊酯、毒死蜱等为主的13种不同的复配药剂组合。结果发现两种测定方法获得的结果基本一致,即13种组合中有2种组合为增效作用(氯虫苯甲酰胺+阿维菌素；毒死蜱+三唑磷),6种组合为相加作用(毒死蜱+稻丰散；毒死蜱+丙溴磷；阿维菌素+三唑磷；氯虫苯甲酰胺+醚菊酯；氯虫苯甲酰胺+三唑磷；氯虫苯甲酰胺+丙溴磷),3种组合为拮抗作用(醚菊酯+丙溴磷；氯虫苯甲酰胺+氟铃脲；氯虫苯甲酰胺+稻丰散)。两种测定方法结果不一致的仅有醚菊酯+稻丰散和醚菊酯+毒死蜱2种组合,以四龄幼虫Potter喷雾塔法测定时分别表现为相加和增效作用,而以初孵幼虫涂药法进行测定时则分别表现为拮抗和相加作用,表现出一定的差异。讨论发现2种方法共同检测出的增效配伍中,毒死蜱+三唑磷已经被推广应用,而氯虫苯甲酰胺+阿维菌素是本研究新发现的增效复配组合,同时对阿维菌素和氯虫苯甲酰胺的不同配比组合用potter喷雾塔法进行生测筛选,结果发现其不同配比的共毒系数顺序为CTC2:1>CTC1:1>CTC4:1>CTC1:4>CTC1:2,即以LC50按2：1复配时CTC值最大(347.18),增效明显；配比1:1、4：1的CTC值分别为166.08和147.83,有增效作用；配比为1：4和1：2的CTC值均小于100。进一步研究开发,可以为二化螟防治提供新型有效药剂品种,在生产上推广应用,一方面通过混用延缓氯虫苯甲酰胺和阿维菌素抗药性的产生,另一方面可以降低害虫防治的用药成本。同时本研究还建议在生产上应避免混合使用表现为拮抗作用的复配组合药剂。3、不同药剂防治二化螟的持效期分析本研究利用不同剂量毒死蜱喷雾处理稻苗进行接虫试验,验证了用药浓度与持效期的正相关关系。而后在不产生药害的前提下采用不同剂量喷雾处理,比较了氯虫苯甲酰胺、阿维菌素和毒死蜱防治二化螟的持效期。喷雾处理稻苗后定期接种蚁螟观察发现,喷施20%氯虫苯甲酰胺悬浮剂1：5000倍液,可以维持在14 d内接种蚁螟无侵入为害,而用高剂量1：1000倍液处理稻苗后,28 d内接虫二化螟的死亡率仍达到100%,不能侵入危害；喷施1.8%阿维菌素乳油1：1000倍液仅在7d内接种蚁螟无侵入为害,使用高剂量1：500倍液处理后,延长至14d内无侵入危害；40%毒死蜱乳油1：1000倍液处理后7d的防效仅为84.3%,使用高剂量1：300倍液处理,7d内无侵入危害,14d的防效仍为89.5%。不同药剂的持效性差异明显,并且与药剂的毒力不完全一致。讨论分析认为,氯虫苯甲酰胺和阿维菌素的持效期较长,使用高剂量处理可以进一步延长其持效期。因此,生产上在不产生药害和经济许可的情况下,使用高剂量进行移栽前处理(送嫁药),可以更有效的防治水稻本田早期的螟虫危害,减轻螟虫后续世代的发生量,并避免本田过早用药干扰天敌种群的建立。4、二化螟寄主选择及寄主对种群的影响本研究在实验室条件下就二化螟对不同寄主的产卵选择,以及在不同寄主上初孵幼虫的成活率进行了研究。试验结果表明,水稻二化螟种群在茭白、水稻、小麦、甘蔗、玉米上的落卵量分别为48.03%、44.16%、3.38%、2.39%、2.04%,二化螟在水稻、茭白上所产卵粒的分布无显著差异,但显著大于在小麦、玉米和甘蔗上的产卵量。水稻二化螟初孵幼虫在茭白、水稻、小麦、甘蔗、玉米上的成活率分别为10.75%、51.22%、44.11%、1.45%、7.15%,在水稻和小麦上的成活率无显著差异,但显著大于在茭白、玉米和甘蔗上的成活率。研究结果表明二化螟的多种传统寄主实际上有显著差异,本研究综合分析认为仅有水稻最适宜水稻二化螟的繁殖。本文首先测试确定了这9种常用药剂对二化螟的毒力顺序,为生产上防治二化螟提供了药剂选择的直接参考依据。筛选确定了氯虫苯甲酰胺+阿维菌素是防治二化螟新的增效复配组合,可以用混用的方式在生产上推广应用,一方面通过混用延缓氯虫苯甲酰胺和阿维菌素抗药性的产生,另一方面降低害虫防治的用药成本。通过研究不同剂量和不同药剂的持效期,确定了生产上可以通过选用持效期长的药剂,在不产生药害的前提下,使用高剂量进行移栽前处理,以便更有效的防治水稻本田早期的螟虫危害,减轻螟虫后续世代的发生量,并避免本田过早用药干扰天敌种群的建立。通过研究二化螟对不同寄主的产卵选择,以及在不同寄主上初孵幼虫的成活率,发现二化螟在不同寄主上的产卵量和成活率有显著差异,其中仅有水稻最适宜水稻二化螟的繁殖,由此证实阻止一代二化螟在水稻上产卵繁殖,可以降低当地二化螟种群的密度。更多还原

【Abstract】 The rice stem borer, Chilo suppressalis (Walker), is one of major insect pests of rice in China. With cropping system reform, rice varieties substitution and insecticide resistance development, population of this pest and its damage to rice increased dramatically, severely threatening the production of rice. In Jiangsu and some other areas, postponing sowing and isolation culture of seedlings with covering membrane were employed to improve the management of this pest. However, due to the limited growing season for rice in the single cropping rice areas, these countermeasures could be not maintained longer enough to keep the moths of all the first generation from contacting the seedlings. So long persistence insecticides are required to handle rice seedlings before transplant. Otherwise, it is not clear if the moths in early spring could breed populations normally by using host plants other than rice. In order to evaluate and strengthen the strategy of "Taking it as the key for the management of borers to control their 1st generation by postponing rice sowing and transplanting date appropriately, and using effective insecticides", some related work has been done and the main results are summarized as follows:1. Toxicity of various insecticides on Chilo suppressalisThe toxicities of abamectin 1.8% EC, chlorantraniliprole 20% SC, hexaflumuron 5% EC, ethofenprox 10% EC, chlorpyrifos 40% EC, phenthoate 50% EC, triazophos 15% ME, monosultap 90% WP and profenofos 40% EC against the neonates and the forth-instar larvae of C. suppressalis were tested by Residues on Artificial Diet and Potter Tower Spraying, respectively. Similar results were obtained, which both showed that abamectinn and chlorantraniliprole were higher toxic, and followed by hexaflumuron, ethofenprox, chlorpyrifos and phenthoate, but monosultap, triazophos and profenofos were lower toxic to this pest. These results provide a direct and comprehensive reference basis for chemical control of C. suppressalis. 2. Selection of efficient mixtures of insecticides against Chilo suppressalThe toxicities of 13 different combinations of chlorantraniliprole, abamectin, ethofenprox and chlorpyrifos against the neonates and the forth-instar larvae of C. suppressalis were tested by Residues on Artificial Diet and Potter Tower Spraying, respectively. Similar results were obtained, which proved that the mixtures chlorantraniliprole with abamectin and chlorpyrifos with triazophos showed obvious synergism; chlorpyrifos with phenthoate, chlorpyrifos with profenofos, abamectin with triazophos, chlorantraniliprole with ethofenprox, chlorantraniliprole with triazophos and chlorantraniliprole with profenofos were additive, and three mixtures, ethofenprox with profenofos, chlorantraniliprole with hexaflumuron and chlorantraniliprole with phenthoate were antagonistic. Ethofenprox mixed with phenthoate and ethofenprox mixed with chlorpyrifos showed, respectively, additive and synergism when tested with Potter Tower Spraying. However, they were antagonistic and additive when tested by Residues on Artificial Diet. chlorpyrifos mixed with triazophos has been extensively used in practice. However, chlorantraniliprole mixed with abamectin was the synergistic combination newly discovered in this study. Further tests with mixtures of abamectin and chlorantraniliprole of different ratios found that their co-toxicity coefficient (CTC) values were as fellows:CTC2:1>CTC1:1>CTC4:1> CTC1:4>CTC1:2. The mixture with the ratio of 2 to 1 showed highest synergism(CTC 347.18). The mixture with the ratio of 1 to 1 and 4 to 1 were also synergistic (CTC 166.08 and 147.83). But all the other mixtures of different ratio were not synergistic with their CTC less than 100. Obviously, a new efficient insecticide formulation could be developed against C. suppressal in practice, which might delay the development of resistance to chlorantraniliprole and abamectin and reduce the control cost. The study also suggested those mixtures showed antagonistic should not be used in practice。3. Comparison of the persistence of insecticide representatives with indoor trialsPositive correlation between pesticide concentration and persistence of control effect was first proved by the trials controlling the inoculated neonates of C. suppressalis with rice seedlings treated with different doses of profenofos. Then, chlorantraniliprole, abamectin and profenofos were compared for their persistence of control effect under the prerequisite for no phytotoxicity. The results showed that treatment with 5000 time dilution of 20% chlorantraniliprole SC could keep the rice seedlings from infestation for 14 days, and high doses (1000 time dilution) could keep for 28 days. One thousand time dilution of 1.8% abamectin EC can keep no infestation for only 7 days, which could be extended to 14 days when 500 time dilution was used. The persistent control effect of 40% chlorprifos EC was poorest of the 3 insecticides. The control effect of only 84.3% in 7 days and 57.2% in 14 days was observed when 1000 time dilution was applied. However, the corresponding control effect could be enhanced to 100%,89.5% by using 300 time dilution. Obviously, insecticides varied in their persistent effect, which was not always consistent with their toxicity. It was concluded that chlorantraniliprole and abamectin have good persistent control effect, which could be further enhanced by use of high doses. Discussion came to the conclusion that with higher dose of long persistence insecticides, the first generation of C. suppressalis in a year could be effectively controlled by handling rice seedlings before transplant under the prerequisite for no phytotoxicity. Thus, the population density of the following generations in the whole year could be depressed, and also the early insecticide spray after transplant could be saved which is helpful for nature enemies to set up their population in rice field.4. The oviposition preference and population developing of Chilo suppressalis on different host plantsThe oviposition preference and survival rate of the neonates of C. suppressalis on different host plants was studied at laboratory condition. The result showed that the accumulated borer’s eggs distributed on wildrice, rice, wheat, sugarcane and maize with the corresponding portion as 48.03%、44.16%、3.38%、2.39% and 2.04%. There was no significant difference between wildrice and rice, but the egg number was significantly higher on these two hosts than on other plants tested. The survival rate of neonates of C. suppressalis on wildrice, rice, wheat, sugarcane and maize was 10.75%,51.22%,44.11%, 1.45%,7.15%, respectively. No difference on rice and wheat was found, but the survival rate on these two was significantly higher than that on wildrice, maize and sugarcane. These results demonstrated that traditionally named host plants might be definitely different in maintaining borer’s population. Only rice is thought to be suitable for breeding of this borer, when oviposition preference and survival rate were both taken into consideration.In this paper, the toxicities of 9 commonly used insecticides against C. suppressalis were tested, an efficient mixture was selected, and it was also proved that efficient and persistent control could be achieved by handling rice seedlings with high doses of insecticides under the prerequisite for no phytotoxicity. The results could be used to improve the management of rice stem borers. Otherwise, different host plants were evaluated for their role in maintaining borer’s population, and evidences were provided for population depressing effect of the strategy to keep the borer moths of first generation from contacting with rice seedlings in single cropping rice areas.更多还原