30％吡虫啉微乳剂对水稻褐飞虱田间药效试验

30％吡虫啉微乳剂是一种新型杀虫剂,对多种农作物上的蚜虫有特效。作者用该药剂防治水稻褐飞虱,结果表明：喷施30％吡虫啉微乳剂75－100g/hm^2防效高达95％以上。     

褐飞虱的发生及其防治

2006年，水稻褐飞虱在我国南方地区再一次大暴发。药价上涨，无特效良药等问题困扰着稻农。笔者结合实际调查，就发生情况、防治误区以及进一步的防治对策展开分析，尤其对目前市场上流行的低毒药剂吡虫啉高抗性的问题进行了一次阐述，以便为来年的科学防治做为参考。     

不同杀虫剂防治水稻褐飞虱田间药效评价

2013年对褐飞虱进行6种杀虫剂田间防治效果评价。结果表明:施药后5 d和10 d,22%氟啶虫胺腈SC、20%呋虫胺SG、25%噻虫嗪WG、50%吡蚜酮WG对褐飞虱的防效分别为77.9%~90.9%和77.0%~90.5%,20%异丙威EC、25%噻嗪酮WP的防效分别为40.1%~65.9%和20.6%~49.9%。22%氟啶虫胺腈SC、20%呋虫胺SG、25%噻虫嗪WG、50%吡蚜酮WG防效较好。建议在实践中,轮换使用噻虫嗪、吡蚜酮、呋虫胺、氟啶虫胺腈防治褐飞虱。     

稻褐飞虱的抗药性研究

用毛细管点滴法测定了16种杀虫剂对褐飞虱的触杀毒力。1985～1990年,褐飞虱对同一杀虫剂的敏感度变异不大,抗药性发展缓慢。作者认为,褐飞虱在一定时间内不会出现抗药性突增的变化,氨基甲酸酯类仍可作为防治药剂,但需加强监测。     

几种药剂防治褐飞虱效果比较

选择毒死蜱、噻虫嗪、噻嗪酮、啶虫脒、吡虫啉、氟虫腈等6种药剂进行了防治褐飞虱田间试验,结果表明,当前,氟虫腈、毒死蜱(高含量)、噻虫嗪和噻嗪酮对水稻褐飞虱防治效果较好,药后7～10d,平均校正防治效果达到81.9%～92.7%;褐飞虱对吡虫啉产生了极高抗药性,防治效果显著下降。     

抗吡虫啉褐飞虱品系中扑虱灵、仲丁威对吡虫啉的增效作用

室内筛选获得了一个高抗吡虫啉的褐飞虱品系，对吡虫啉的抗性倍数达到72．83倍，属于高抗水平。交互抗性研究发现，该高抗品系对马拉硫磷、甲胺磷、仲丁威、甲萘威和扑虱灵都不表现出显著的交互抗性。研究扑虱灵和仲丁威在田间品系和抗性品系中对吡虫啉的增效作用。结果表明两个药剂在两个品系中对吡虫啉都存在很好的增效作用，而且在抗性品系中的增效作用更为显著。     

水稻褐飞虱预报模型的研究

根据监利县1981～1995年系统调查和灯诱资料,结合当地气象资料及南方有关地区对褐飞虱多年观测资料,利用逐步回归方法组建多元回归预测模型,预测监利褐飞虱的发生期和发生量。结果表明,监利褐飞虱发生的迟早和主害代发生量的大小主要受迁入峰期的迟早、迁入量、虫源地发生情况以及本地当年的气候因素的影响。     

吡蚜酮与异丙威复配对褐飞虱的增效作用和田间防治

室内生测结果表明:吡蚜酮与异丙威质量比为1∶2,对褐飞虱3龄若虫具有较高的生物活性,其LC50值为11.01 mg/L,共毒系数为166.65,表现出明显的增效作用;按此配比加工成30%吡蚜·异丙威WP(有效成分:吡蚜酮10%、异丙威20%).田间防治结果表明:该混剂对褐飞虱表现出良好的速效性和持效性.药后3 d,30%吡蚜·异丙威WP 450～600 g/hm2对褐飞虱若虫的防治效果为90.83%～94.94%,药后21 d,30%吡蚜·异丙威WP 450～600 g/hm2对褐飞虱若虫的防治效果仍有87.60%～89.32%,均好于对照药剂吡蚜酮、异丙威对褐飞虱的防治效果.从防效和经济的角度考虑,30%吡蚜·异丙威WP推荐剂量为450 g/hm2,防治适期宜在褐飞虱若虫高峰期.     

褐飞虱抗药性及再猖獗研究进展

褐飞虱是一种重要的农业害虫,其对许多杀虫剂都产生了抗药性。对褐飞虱抗药性的形成和发展及其抗药性机理等方面进行了综述,并对该虫的再猖獗进行了探讨。     

0.3%印楝素乳油对水稻褐飞虱的生物活性

系统研究了印楝素对褐飞虱的生物活性。试验结果表明,0.3%印楝素乳油对褐飞虱具有拒食、内吸、抑制生长发育等作用。3.00mg/L和6.00mg/L印楝素溶液处理稻茎,对褐飞虱的拒食率分别为67.91%和77.65%,拒食中浓度AFC50为0.6126mg/L。3.00mg/L的印楝素溶液经根内吸传导12h和24h后,褐飞虱若虫校正死亡率分别为81.63%和88.47%,LC50值分别为1.4028mg/L和1.1115mg/L。印楝素经根内吸传导的速度较快,3.00mg/L和1.50mg/L浓度下,LT50值分别为4.1812h和23.0409h。亚致死剂量处理后,褐飞虱若虫的体重和蜜露分泌量都显著降低,1.00mg/L处理后3d、7d,体重减轻比率分别为52.49%和48.08%,蜜露分泌量减少比率分别为58.01%和62.60%。田间试验结果也表明,0.3%印楝素乳油对褐飞虱具有良好的控制效果。     

Characterization of MicroRNAs Associated with Reproduction in the Brown Planthopper,Nilaparvata lugens

Insects have a robust capacity to produce offspring for propagation, and the reproductive events of female insects have been achieved at the molecular and physiological levels via regulatory gene pathways. However, the roles of MicroRNAs (miRNAs) in the reproductive development of the brown planthopper (BPH), Nilaparvata lugens, remain largely unexplored. To understand the roles of miRNAs in reproductive development, miRNAs were identified by Solexa sequencing in short-winged (SW) female adults of BPH. Small RNA libraries derived from three developmental phases (1 day, 3 days, and 5 days after emergence) were constructed and sequenced. We identified 905 miRNAs, including 263 known and 642 novel miRNAs. Among them, a total of 43 miRNAs were differentially expressed in the three developmental phases, and 14,568 putative targets for 43 differentially expressed miRNAs (DEMs) were predicted by TargetScan and miRanda. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the predicted miRNA targets illustrated the putative roles for these DEMs in reproduction. The progress events were annotated, including oogenesis, lipid biosynthetic process, and related pathways such as apoptosis, ABC transporters, and amino acid metabolism. Four highly abundant DEMs (miR-9a-5p, miR-34-5p, miR-275-3p, and miR-317-3p) were further screened, and miR-34-5p was confirmed to be involved in the regulation of reproduction. Overexpression of miR-34-5p via injecting its mimics reduced fecundity and decreased Vg expression. Moreover, target genes prediction for miR-34-5p showed they might be involved in 20E signaling cascades, apoptosis, and gonadal development, including hormone receptor 4 (HR4), caspase-1 (Cp-1), and spermatogenesis-associated protein 20 (SPATA20). These findings provide a valuable resource for future studies on the role of miRNAs in BPH reproductive development.     

吡虫啉防治褐稻虱应用技术及其对天敌的影响研究

在三代褐稻虱低龄若虫高峰期，亩用吡虫啉１６克，对水６０公斤常规喷雾，药后２天的防效为８０．８％，比噻嗪酮高２９．０％，持效期长达３０天以上。吡虫吡对稻田蜘蛛的杀伤率为２７．９％，与噻嗪酮相似；对黑肩绿盲蝽的杀伤率为８５．９％，比噻嗪酮高２７．２％，仅次于甲胺磷、毒死蜱、喹硫磷的杀伤率１００％。     

共生菌在褐飞虱防治中的应用

褐飞虱（Nilaparvata lugens stal）体内类酵母共生菌在褐飞虱的生长、繁殖和抗药性的产生中起着重要作用。系统总结了国内外相关研究结果,分析讨论了共生菌研究在褐飞虱防治中的应用前景、可行性及存在的问题等,旨在为深入开展“抑菌防虫”研究提供参考。     

氟啶虫胺腈对褐飞虱的田间防治效果

[目的]明确240g/L氟啶虫胺腈悬浮剂对褐飞虱的田间控制作用及最佳使用剂量。[方法]采用田间喷雾法,对氟啶虫胺腈37.5、50、75、100 ga.i./hm2四种不同剂量处理防治褐飞虱效果进行试验研究。[结果]240 g/L氟啶虫胺腈悬浮剂37.5、50ga.i./hm2两种剂量处理,药后1~3 d对褐飞虱的防效为51.42%~68.51%,药后7~14 d的防效为61.00%~79.10%,与对照药剂25%噻嗪酮可湿性粉剂112.5ga.i./hm2剂量处理相比,速效性相当,但持效性差;而75、100ga.i./hm2两种剂量处理,药后1~3 d防效为67.18%~74.11%,药后7~14 d防效为81.26%~89.22%,与对照药剂25%噻嗪酮可湿性粉剂112.5ga.i./hm2剂量处理相比,速效性更好,而持效性相当。[结论]240 g/L氟啶虫胺腈悬浮剂75~100 ga.i./hm2剂量喷雾处理,能有效控制褐飞虱的发生为害,可供生产上推广应用。     

Repellency Mechanism of Natural Guar Gum-Based Film Incorporated with Citral against Brown Planthopper,Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

Using of plant essential oil that coevolved as a defense mechanism against agriculture insects is an alternative means of controlling many insect pests. In order to repel brown planthoppers (BPHs), the most notorious rice insect pest, a new film based on guar gum incorporated with citral (GC film) was formulated, which was effective while being environmentally friendly. In this paper, the effect and mechanism of GC film repellency against BPHs were determined. Repellent activity test and olfactory reaction analysis showed that GC film had repellency effect against BPHs, with repellency of 60.00% and 73.93%, respectively. The result of olfactory reaction indicated that GC film repellency against BPHs relied on smell. EPG analysis showed the proportion and mean duration of np waveform were significantly higher than in CK and increased following the treatment concentration, which indicated that GC film affected the recognition of BPHs to rice. Further analysis by RNA sequencing analysis showed a total of 679 genes were significantly upregulated and 284 genes were significantly downregulated in the BPHs fed on the rice sprayed with GC film compared to control. Odorant-binding protein (OBP) gene 797 and gustatory receptor gene (GR)/odorant receptor (OR) gene 13110 showed a significant decrease in differential expression and significant increase in differential expression, respectively. There were 0.66 and 2.55 differential expression multiples between treated BPHs and control, respectively. According to the results described above, we reasoned that GC film repellency against BPHs due to smell, by release of citral, caused the recognition difficulties for BPHs to rice, and OBP gene 797 and GR/OR gene 13110 appeared to be the crucial candidate genes for GC film repellency against BPHs. The present study depicted a clear and consistent repellency effect for GC film against BPHs and preliminarily clarified the mechanism of GC film as a repellent against BPHs, which might offer an alternative approach for control of BPHs in the near future. Our results could also help in the development and improvement of GC films.     

Heritable Epigenomic Modifications Influence Stress Resilience and Rapid Adaptations in the Brown Planthopper (Nilaparvata lugens)

DNA methylation in insects is integral to cellular differentiation, development, gene regulation, genome integrity, and phenotypic plasticity. However, its evolutionary potential and involvement in facilitating rapid adaptations in insects are enigmatic. Moreover, our understanding of these mechanisms is limited to a few insect species, of which none are pests of crops. Hence, we studied methylation patterns in the brown planthopper (BPH), a major rice pest, under pesticide and nutritional stress, across its life stages. Moreover, as the inheritance of epigenetic changes is fundamentally essential for acclimation, adaptability, and evolution, we determined the heritability and persistence of stress-induced methylation marks in BPH across generations. Our results revealed that DNA methylation pattern(s) in BPH varies/vary with environmental cues and is/are insect life-stage specific. Further, our findings provide novel insights into the heritability of stress-induced methylation marks in BPH. However, it was observed that, though heritable, these marks eventually fade in the absence of the stressors, thereby suggesting the existence of fitness cost(s) associated with the maintenance of the stressed epigenotype. Furthermore, we demonstrate how 5-azacytidine-mediated disruption of BPH methylome influences expression levels of stress-responsive genes and, thereby, highlight demethylation/methylation as a phenomenon underlying stress resilience of BPH.