稻水象甲田间种群动态及化学控制技术

稻水象甲在福建省霞浦县长春镇田间种群发生动态的调查结果表明:5月中旬是稻水象甲越冬代成虫迁入稻田为害高峰期,5月下旬成虫种群数量迅速降低,并有少量幼虫开始为害水稻根部;6月初是幼虫发生为害高峰期,蛹高峰期出现在6月中旬,并开始有一代成虫羽化。药剂筛选试验结果表明:20%丁硫克百威乳油、48%毒死蜱乳油、40%三唑磷乳油、5%锐劲特悬浮剂对稻水象甲成虫具有良好的田间控制效果,药后7d防效均在92.31%—100%;5%丁硫克百威颗粒剂、15%乐斯本颗粒剂、3%呋喃丹颗粒剂施药后7d对稻水象甲幼虫的防效90.03%—93.56%。化学综合防治示范区水稻分蘖数和株高均显著大于对照区。     

Integrating flood depth and plant resistance with chlorantraniliprole seed treatments for management of rice water weevil,Lissorhoptrus oryzophilus (Coleoptera: Curculionidae)

Chlorantraniliprole seed treatments in rice provide effective suppression of rice water weevil populations in the United States; however, heavy reliance on prophylactic insecticide treatments as a sole strategy could destabilize management programs for this insect. The present research evaluated the compatibility of seed treatments with two other potential management tactics—plant resistance and shallow flooding–by conducting two split‐plot experiments in 2009 and 2011. In both experiments, no substantial antagonism was found among the 3 different tactics. Statistical interactions in these experiments arose from the strong and persistent effects of chlorantraniliprole on larval densities rather than incompatibility of tactics. In 2009, weevil densities differed among varieties and were significantly lower on the cultivar “Jefferson.” In 2011, weevil densities were reduced significantly in shallow‐flooded plots compared to deep‐flooded plots. Significant reductions in weevil numbers by chlorantraniliprole seed treatments, even at application rates 5 fold lower than commercially recommended rates, demonstrated the potential to reduce application rates of this highly potent larvicide. These latter results suggest that future studies on the relationship between chlorantraniliprole seed treatment rate and weevil fitness are warranted.     

Japonica cultivars' susceptibility to the rice water weevil Lissorhoptrus oryzophilus (Coleoptera: Curculionoidea: Brachyceridae)

Italy is the largest rice‐producing country in the European Union. In Italy, only japonica cultivars are listed in the Italian National Register. Almost all of the rice production is concentrated in the Po Valley, where the rice water weevil Lissorhoptrus oryzophilus Kuschel was first detected and settled. This study investigated the performance of this pest in terms of feeding, reproduction and plant injury on 10 rice cultivars chosen among the most widely grown in Italy. No‐choice experiments were conducted to evaluate the plant susceptibility to larval attack and to find out how cultivars can influence the adult leaf area consumption. The results gave evidence of different types of attack depending on the density of the insect (0.6 adults/plant vs. 0.9 adults/plant), the cultivar type and climatic conditions. Different cultivars with the same level of infestation gave different results in terms of productivity. Production was significantly affected by the larval presence in 4 of the 10 cultivars tested. A different population structure reflected a different damage severity. Statistically different values for total adult leaf area consumption were found according to adult female age and to the cultivar.     

Effects of defoliation on the resistance and tolerance of rice,Oryza sativa,to root injury by the rice water weevil,Lissorhoptrus oryzophilus

Understanding plant‐mediated interactions in agricultural systems may facilitate the development of novel and improved management practices, which is important, as management of these insects is currently heavily reliant on insecticides. The fall armyworm, Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae, Prodeniini), is a sporadic pest of rice fields in the southern USA. In southwestern Louisiana, this defoliating insect typically attacks rice early in the growth season, before fields are flooded. Defoliation by fall armyworm larvae may trigger increased expression of plant defenses, which may result in increased resistance to subsequent herbivores. The rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae, Stenopelmini), enters rice fields as an adult both before and after flooding, but oviposition and larval infestation occur only after fields are flooded. RWW may be affected by changes in plant resistance caused by fall armyworm defoliation before flooding. The objectives of this study were to investigate the plant‐mediated effects of natural and artificial defoliation on population densities of RWW larvae after flooding and on the ability of rice plants to compensate for root injury by RWW larvae. In the 2015 season, fall armyworm defoliation before flooding resulted in reduced RWW densities after flooding. However, in 2016 no significant effects of fall armyworm defoliation on densities of RWW larvae were detected. Similarly, mechanical defoliation of rice before flooding did not affect RWW densities after flooding. Although lowest yields were observed in plots subjected to both root injury and defoliation, there was little evidence of a greater than additive reduction in yields from simultaneous injury. These results suggest a lack of plant‐mediated interactions among these two pests in rice in the southern USA.     

Proteolytic gut activities in the rice water weevil,Lissorhoptrus brevirostris Suffrian (Coleoptera: Curculionidae)

Digestive endoprotease activities of the rice water weevil, Lissorhoptrus brevirostris Suffrian (Coleoptera: Curculionidae), were characterized based on the ability of gut extracts to hydrolyze specific synthetic substrates, optimal pH, and hydrolysis sensitivity to protease inhibitors. Larvae of this species were found to use a complex proteolytic system that includes cathepsin D-, cathepsin B-, trypsin-, and chymotrypsin-like activities. Trypsin-like activity was evenly distributed among the anterior, middle, and posterior portions of the gut, whereas cathepsin B- and cathepsin D-like activities were mainly located in the anterior and middle sections, and the chymotrypsin-like activity was highest in the middle and posterior sections. Gelatin-containing native-PAGE gels indicated the presence of several aspartyl, cysteine, and serine protease forms and confirmed the spatial organization of the proteolytic digestive process.     

The effects of feeding by the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on the growth and yield components of rice, Oryza sativa

Abstract 1 The effects of feeding by larvae of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on the growth and yield components of rice, Oryza sativa, were evaluated using four varieties of rice, ‘Cocodrie’, ‘Cypress’, ‘Bengal’ and ‘XP1003’, over 2 years. 2 Both adults and larvae of L. oryzophilus feed on rice plants, but it is feeding by the larval stage that causes economic losses. Feeding by L. oryzophilus larvae resulted in extensive damage to root systems. Pruning of root systems resulted in a decrease in tiller number and shoot biomass of rice plants in the vegetative stage of growth. 3 Yield losses were due to a combination of decreases in panicle densities, numbers of grains per panicle, and grain weights. Decreases in panicle densities were a direct result of the reductions in tiller numbers. Reductions in numbers of grains per panicle and grain weights probably resulted from decreases in shoot biomass. 4 Injury by rice water weevil larvae is chronic. The tillering stage of rice suffered the majority of weevil damage, but the growth effects were not manifested until later.     

稻水象甲成虫活动行为的日节律

为了摸清稻水象甲Lissorhoptrus oryzophilus Kuschel成虫在稻田中的日活动行为节律, 采用室外单头隔离饲养的方法, 将成虫 行为分为移动、 取食、 离水静息、 触水静息和其他5个行为类型, 每30 min观察记录1次, 从2012年4月30日至5月4日连续观察5 d, 共获得7 200个行为数据。结果显示： 稻水象甲越冬成虫行为的日时间分配以离水静息行为最多（47.83%）, 移动行为最少（5.64%）, 各行为的时间分配存在极显著差异（P<0.001）。离水静息行为最高峰值在23:30 （72.67%）, 最低值在7:30 （14.67%）; 触水静息行 为最大峰值在7:30 （75.33%）, 19:00还有一个小高峰（37.33%）; 取食行为在15:00达到最高峰（26.67%）, 在21:00达到第2个高峰 值（18.00%）; 移动行为在22:00-9:00较少（0~4.00%）, 从9:30开始持续增加, 在17:00达到最高峰（20.00%）; 其他行为在 1.33~18.67%之间波动。离水静息、 移动、 取食和其他行为白天和黑夜存在极显著差异（P<0.001）, 但触水静息行为白天和黑夜无显著 不同（P=0.834）; 上午、 中午、 下午和晚上4个时间段之间各行为也有显著差异（P<0.001）。在空间上, 离水静息行为在叶片上最高 , 移动行为以水中最高, 取食行为仅发生在叶片上, 离水静息、 移动和取食在水稻不同部位存在极显著差异（P<0.001）。水中发生触 水静息、 移动和其他共3种行为, 以触水静息行为的日波动最大, 3种行为在各时刻之间有极显著差异（触水静息和移动： P<0.001; 其他： P=0.002）; 叶片上发生离水静息、 移动和取食3种行为, 以离水静息和取食行为的日波动较大且在各时刻间具有极显著的差异 （P<0.001）; 茎秆和瓶壁或封口纱布处主要发生离水静息和移动行为, 所占比例均不高, 但在瓶壁或封口纱布处的移动行为各时刻之 间有极显著差异（P=0.008）。水中和叶片上是行为发生的主要空间, 在水中行为的最高峰值（81.33%）与叶片上的最低值（12.00%）出 现时间相同, 为7:30, 一天中各时刻水中和叶片上的行为呈交错性变化。结果提示, 稻水象甲成虫活动行为受到时空变化的影响, 且 时间变化对其行为的影响较空间变化更为明显。     

稻水象甲越冬成虫的耐寒力测定

测定了浙江乐清 (北纬 2 8 1 4°,东经 1 2 0 94°)稻水象甲LissorhoptrusoryzophilusKuschel越冬成虫的耐寒力 ,从 1 1月下旬至 3月下旬平均过冷却点温度为 -1 5 3～ -2 1 2℃ ,结冰点温度为 -1 4 0～ -1 8 6℃。结合发生地气温条件 ,讨论了该地冬春季低温对该虫越冬群存活的影响。     

稻水象甲Lissorhoptrus oryzophilus Kuschel卵巢、飞行肌及消长动态研究

本文在福鼎对稻水象甲消长动态进行了调查．并对成虫卵巢、飞行肌进行了解剖。通过解剖,所预测的各虫态发生期厦一代成虫迁移期与田间调查结果基本吻合。稻水象甲产卵高峰在4月底至5月上旬．幼虫、蛹和一代成虫的盛发期分别在5月上中旬、6月中下旬和6月下旬;一代成虫在6月下旬开始从稻田迁出。飞行肌解剖结果表明,飞行肌宽度随时间变化而变化,而长度则比较恒定,与发育历期无关,所以飞行肌宽度可作为监测依据,而长度则不宜采用。     

The influence of plant age on tolerance of rice to injury by the rice water weevil,Lissorhoptrus oryzophilus (Coleoptera: Curculionidae)

For most plant species, tolerance to many types of herbivory increases as plants age, but the applicability of this pattern to root herbivory has not been tested. Injury to roots of rice plants by larvae of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, causes severe reductions in yields in the United States. It is generally thought that young rice plants, because their root systems are smaller, are less tolerant than older plants of root feeding by L. oryzophilus. Field experiments were conducted to test this hypothesis. Plots of rice (4.7 to 6.5 m2) were established and subjected to natural infestations of L. oryzophilus larvae. A soil insecticide was applied to plots at different times during the tillering phase of rice in order to manipulate the timing of weevil infestation. The impact of these treatments (timings of insecticide applications) was assessed by comparing relationships between yield loss and larval pressure for each treatment using analysis of covariance. Yield losses ranged from 13% to over 40% in plots not treated with insecticide. Patterns of yield losses from plots treated with insecticide at different times were best explained by the hypothesis that yield loss is determined both by the age of plants infested and by the size of larvae infesting plants. Young plants appear to be less tolerant than older plants, and feeding by large larvae appears to be more deleterious than feeding by smaller larvae. Management practices that delay infestation of rice by L. oryzophilus until plants are older may be an important component of management programmes for this pest.     

稻水象甲(Lissorhoptrus oryzophilus Kuschel)滞育征候群中的飞行行为

１９９４～１９９６ 年对浙江省双季稻区稻水象甲（ Ｌｉｓｓｏｒｈｏｐｔｒｕｓ ｏｒｙｚｏｐｈｉｌｕｓ Ｋｕｓｃｈｅｌ）飞行行为的研究表明,稻水象甲飞行扩散的行为特征是：①长时间的起飞准备和不高的起飞成功率,每晚的迁出率只有三分之一左右;②卵巢、飞行肌呈季节性消长而无局地飞行（ｔｒｉｖｉａｌｆｌｉｇｈｔ）;③飞行速度不高,飞行能力不强,且风力稍大便无法起飞,一般情况下不会形成远距离自然扩散。因此,严格控制人为传带是控制疫区扩大的有效途径。     

稻水象甲(Lissorhoptrus oryzophilus Kuschel)滞育征候群中的飞行行为

１９９４－１９９６年对浙江省双季稻区稻水象甲（ＬｉｓｓｏｒｈｏｐｔｒｕｓｏｒｙｚｏｐｈｉｌｕｓＫｕｓｃｈｅｌ）飞行行为的研究表明,稻水象甲飞行扩散的行为特征是：（１）长时间的起飞准备和不高的起飞成功率,每晚的迁出率只有三分之一左右,（２）卵巢,飞行肌呈季节性消长而无局地飞行（ｔｒｉｖｉａｌｆｌｉｇｈｔ）;（３）飞行速度不高,飞行能力不强,且风力稍大便无法起飞,一般情况下不会形成远距离自然扩散,因此     

稻水象甲卵的空间分布型及抽样技术研究

本文利用Taylor幂法则和Iwao回归法对稻水象甲LissorhoptrusoryzophilusKuschel卵的空间分布型进行了测定 ,结果表明稻水象甲卵在田间呈聚集分布 ,且符合负二项分布 ,k值为 0 4 796。其种群聚集主要是由环境因子引起的。应用Iwao的抽样模型建立了稻水象甲卵的田间理论抽样数公式 :N =1D2 1 784 6M + 0 2 4 2 5 。并根据Gerrard的零频率模型建立了估计该种群平均密度的零频率模型 :X =1 5 787( -lnP0 ) 1 0 62 5。     

基于ISSR分子标记技术的稻水象甲遗传多样性研究

稻水象甲Lissorhoptrus oryzophilus Kuschel是一种世界性的水稻害虫,已侵入我国23个省市区,发生面积近千万亩。为弄清我国不同地区稻水象甲的遗传多样性水平、居群间的遗传分化及可能的扩散路线,本研究采用ISSR分子标记技术分析了我国13个省28个地区稻水象甲样本的遗传多样性。利用15条ISSR引物共扩增得到258条带,其中247条为多态性条带。在物种水平上,稻水象甲的多态位点百分率(PPB)为95.73%,Nei's基因多样性(H)为0.3578,Shannon信息多样性指数(I)为0.5330;在居群水平上,以上3项指标的平均值分别为46.28%、0.1768、0.2620。Nei's基因分化系数Gst为0.5059,表明有50.59%的遗传变异存在于居群间,49.41%的遗传变异存在于居群内,居群间表现出较高水平的遗传分化。通过UPGMA聚类可将稻水象甲28个居群分成2大支系:安徽池州、安徽合肥、云南嵩明、云南曲靖、江西南昌、四川盐亭、辽宁盘锦、辽宁东港、山西太原、山东东营、天津蓟县、陕西城固、河北唐山、云南寻甸等14个居群聚成第一个分支;贵州、贵州开阳、贵州龙里、贵州贵阳、贵州修文、四川隆昌、四川泸州、湖北武当山、湖北荆门、湖北利川、湖南宁乡、湖南双峰、湖南邵阳、天津宝坻等聚成第二个分支。     

OsPIN5b modulates rice (Oryza sativa) plant architecture and yield by changing auxin homeostasis,transport and distribution

Plant architecture attributes such as tillering, plant height and panicle size are important agronomic traits that determine rice (Oryza sativa) productivity. Here, we report that altered auxin content, transport and distribution affect these traits, and hence rice yield. Overexpression of the auxin efflux carrier‐like gene OsPIN5b causes pleiotropic effects, mainly reducing plant height, leaf and tiller number, shoot and root biomass, seed‐setting rate, panicle length and yield parameters. Conversely, reduced expression of OsPIN5b results in higher tiller number, more vigorous root system, longer panicles and increased yield. We show that OsPIN5b is an endoplasmic reticulum (ER) ‐localized protein that participates in auxin homeostasis, transport and distribution in vivo. This work describes an example of an auxin‐related gene where modulating its expression can simultaneously improve plant architecture and yield potential in rice, and reveals an important effect of hormonal signaling on these traits.     

The rice terpene synthase gene OsTPS19 functions as an (S)‐limonene synthase in planta,and its overexpression leads to enhanced resistance to the blast fungus Magnaporthe oryzae

Rice blast disease, caused by the fungus Magnaporthe oryzae, is the most devastating disease of rice. In our ongoing characterization of the defence mechanisms of rice plants against M. oryzae, a terpene synthase gene OsTPS19 was identified as a candidate defence gene. Here, we report the functional characterization of OsTPS19, which is up‐regulated by M. oryzae infection. Overexpression of OsTPS19 in rice plants enhanced resistance against M. oryzae, while OsTPS19 RNAi lines were more susceptible to the pathogen. Metabolic analysis revealed that the production of a monoterpene (S)‐limonene was increased and decreased in OsTPS19 overexpression and RNAi lines, respectively, suggesting that OsTPS19 functions as a limonene synthase in planta. This notion was further supported by in vitro enzyme assays with recombinant OsTPS19, in which OsTPS19 had both sesquiterpene activity and monoterpene synthase activity, with limonene as a major product. Furthermore, in a subcellular localization experiment, OsTPS19 was localized in plastids. OsTPS19 has a highly homologous paralog, OsTPS20, which likely resulted from a recent gene duplication event. We found that the variation in OsTPS19 and OsTPS20 enzyme activities was determined by a single amino acid in the active site cavity. The expression of OsTPS20 was not affected by M. oryzae infection. This indicates functional divergence of OsTPS19 and OsTPS20. Lastly, (S)‐limonene inhibited the germination of M. oryzae spores in vitro. OsTPS19 was determined to function as an (S)‐limonene synthase in rice and plays a role in defence against M. oryzae, at least partly, by inhibiting spore germination.     

PAY1 improves plant architecture and enhances grain yield in rice

Plant architecture, a complex of the important agronomic traits that determine grain yield, is a primary target of artificial selection of rice domestication and improvement. Some important genes affecting plant architecture and grain yield have been isolated and characterized in recent decades; however, their underlying mechanism remains to be elucidated. Here, we report genetic identification and functional analysis of the PLANT ARCHITECTURE AND YIELD 1 (PAY1) gene in rice, which affects plant architecture and grain yield in rice. Transgenic plants over‐expressing PAY1 had twice the number of grains per panicle and consequently produced nearly 38% more grain yield per plant than control plants. Mechanistically, PAY1 could improve plant architecture via affecting polar auxin transport activity and altering endogenous indole‐3‐acetic acid distribution. Furthermore, introgression of PAY1 into elite rice cultivars, using marker‐assisted background selection, dramatically increased grain yield compared with the recipient parents. Overall, these results demonstrated that PAY1 could be a new beneficial genetic resource for shaping ideal plant architecture and breeding high‐yielding rice varieties.     

Olfactory cues explain differential attraction of the striped rice stem borer to different varieties of rice plant

In Iranian rice fields, different varieties of rice are cultivated which are differentially impacted by females of the rice stem borer, Chilo suppressalis. To elucidate the role odours may play in their host plant finding behaviour, female Ch. suppressalis were exposed to four varieties of rice plants and their volatiles in a four‐arm olfactometer. In whole plant tests, Ch. suppressalis were significantly attracted to the variety previously characterized as most susceptible, least attracted to one characterized as semisusceptible, and showed no attraction to those varieties characterized as semi‐ and highly resistant. Tests using headspace volatile extracts yielded similar results in the case of the most susceptible variety, but showed no attraction to the semisusceptible and highly resistant varieties, and low attraction to the semiresistant variety. Subsequent analysis of the volatile composition identified a panel of 27 components, some of which were either unique to, or abundantly present in, particular varieties, and may explain the observed variation in their attractiveness. Our findings show that rice plant volatiles can play a role in the host selection behaviour of this pest species, and we suggest compounds which may be important to this process and the future application of volatiles in rice pest management programs.     

A genome‐wide survey reveals abundant rice blast R genes in resistant cultivars

Plant resistance genes (R genes) harbor tremendous allelic diversity, constituting a robust immune system effective against microbial pathogens. Nevertheless, few functional R genes have been identified for even the best‐studied pathosystems. Does this limited repertoire reflect specificity, with most R genes having been defeated by former pests, or do plants harbor a rich diversity of functional R genes, the composite behavior of which is yet to be characterized? Here, we survey 332 NBS‐LRR genes cloned from five resistant Oryza sativa (rice) cultivars for their ability to confer recognition of 12 rice blast isolates when transformed into susceptible cultivars. Our survey reveals that 48.5% of the 132 NBS‐LRR loci tested contain functional rice blast R genes, with most R genes deriving from multi‐copy clades containing especially diversified loci. Each R gene recognized, on average, 2.42 of the 12 isolates screened. The abundant R genes identified in resistant genomes provide extraordinary redundancy in the ability of host genotypes to recognize particular isolates. If the same is true for other pathogens, many extant NBS‐LRR genes retain functionality. Our success at identifying rice blast R genes also validates a highly efficient cloning and screening strategy.     

The role of Bh4 in parallel evolution of hull colour in domesticated and weedy rice

The two independent domestication events in the genus Oryza that led to African and Asian rice offer an extremely useful system for studying the genetic basis of parallel evolution. This system is also characterized by parallel de‐domestication events, with two genetically distinct weedy rice biotypes in the US derived from the Asian domesticate. One important trait that has been altered by rice domestication and de‐domestication is hull colour. The wild progenitors of the two cultivated rice species have predominantly black‐coloured hulls, as does one of the two U.S. weed biotypes; both cultivated species and one of the US weedy biotypes are characterized by straw‐coloured hulls. Using Black hull 4 (Bh4) as a hull colour candidate gene, we examined DNA sequence variation at this locus to study the parallel evolution of hull colour variation in the domesticated and weedy rice system. We find that independent Bh4‐coding mutations have arisen in African and Asian rice that are correlated with the straw hull phenotype, suggesting that the same gene is responsible for parallel trait evolution. For the U.S. weeds, Bh4 haplotype sequences support current hypotheses on the phylogenetic relationship between the two biotypes and domesticated Asian rice; straw hull weeds are most similar to indica crops, and black hull weeds are most similar to aus crops. Tests for selection indicate that Asian crops and straw hull weeds deviate from neutrality at this gene, suggesting possible selection on Bh4 during both rice domestication and de‐domestication.