Soybean stem fly,Melanagromyza sojae (Diptera: Agromyzidae), on Sumatra: Seasonal incidence and the role of parasitism

Abstract

The density of M. sojae and percentage parasitism was studied in unsprayed soybean at 18 farmers’ field sites in Aceh, North Sumatra and West Sumatra provinces, Indonesia, during 1992 and 1993. M. sojae generally infested soybean throughout the season; infestation was initially low, reached its peak from the fifth till the eighth week after planting and declined towards the end of the season. A complex of seven hymenopterous parasiloids had a high impact on the pest. Parasitism levels built up alongside with host density and remained high until just before harvest. The eucoilid Gronotoma sp. was the most prevalent species during the early and mid‐season; a complex of pteromalids became dominant towards the end of the season. In soybean planted successively at 2‐week intervals, the parasitism level in the first‐planted crop built up slowly, whereas the parasitism level in the third‐planted crop was high from the early crop stage onwards, which suggests that the third‐planted crop benefited from parasitism build‐up in the earlier‐planted crops. The role of parasitoids in controlling beanflies in unsprayed soybean is discussed.     

Changes in biochemistry and cellular ultrastructure support different resistance mechanisms to Phytophthora sojae in nonhost common bean and host soybean

Phytophthora root and stem rot of soybean caused by Phytophthora sojae is a destructive disease affecting soybean production worldwide. In nature, soybean is the only economically important cultivated host of P. sojae. The aim of this study was to explain different resistance mechanisms to P. sojae in nonhost common bean and host soybean as a basis for the control of Phytophthora root and stem rot of soybean via nonhost resistance. Observations and measurements of disease resistance-related variables showed slight differences in structural and biochemical resistance mechanisms between common bean and soybean. P. sojae infection induced a stronger hypersensitive response in nonhost common bean than in host resistant soybean. Moreover, phytoalexin phaseollidin synthesis-related vestitone reductase gene was extremely highly up-regulated, and phytoalexin glyceollin synthesis-related isoflavone reductase gene was slightly less up-regulated in common bean than in soybean, which resulted in a higher level of phaseollidin and a lower level of glyceollin in common bean. Phaseollidin had stronger inhibitory effects on mycelial growth and oospore formation of P. sojae than glyceollin, and more cell wall depositions and callose accumulated in common bean, which are probably related to the stronger resistance of nonhost common bean to P. sojae.     

黑龙江省大豆疫霉根腐病调查与病原分离

１９９６年对黑龙江省东部和中部大豆产区２３个市、县的大豆苗期疫霉根腐病进行了调查、研究,应用ＰＢＮＩＣ疫霉选择性培养基分离大豆疫霉根腐病病原菌,从牡丹江、穆棱、林口和佳木斯豆田具疫霉根腐症状的大豆植株上分离到大豆疫霉根腐病菌,并从根腐病株上单独或与大豆疫霉菌同时分离到终极腐霉菌,研究进一步证实我国黑龙江省有大豆疫霉根腐病。调查发现,大豆疫霉根腐病和终极腐霉根腐病主要发生在土质粘重、土壤含水量高或易积水的田块。     

非寄主和寄主种子分泌物对大豆疫霉活性的影响

为探寻非寄主和寄主种子分泌物中抗病信号分子,通过显微观察,采用菌丝生长速率法和离体接种法对不同种子分泌物处理后大豆疫霉Phytophthora sojae的游动孢子数、孢子囊数、游动孢子释放后残留的空囊数、成囊和未成囊的游动孢子数、萌发和未萌发的胞囊数、菌落直径、卵孢子数进行测量,并计算抑制率,明确非寄主菜豆和寄主大豆抗病品种、感病品种种子分泌物对大豆疫霉游动孢子趋化性、生长发育和侵袭力的影响。结果显示,非寄主菜豆种子分泌物不吸引大豆疫霉游动孢子,显著抑制大豆疫霉孢子囊形成、胞囊萌发和卵孢子产生,抑制率依次为97.3%、73.0%和17.5%,然后溶解胞囊,最终导致游动孢子对下胚轴侵袭力降低,抑制率为67.1%。寄主大豆种子分泌物能吸引大豆疫霉游动孢子,感病品种种子分泌物吸引力高于抗病品种。感病品种种子分泌物对大豆疫霉生长发育无显著影响,但促进大豆疫霉游动孢子侵袭力;抗病品种种子分泌物显著抑制大豆疫霉孢子囊形成、胞囊萌发和卵孢子产生,抑制率依次为86.6%、34.3%和12.8%,然后溶解胞囊,但作用强度小于非寄主菜豆种子分泌物,最终导致游动孢子对下胚轴的侵袭力降低,抑制率为24.2%。表明非寄主菜豆和寄主大豆抗病品种的种子分泌物对大豆疫霉有抑菌活性,大豆疫霉的非寄主和寄主抗病性与种子分泌物有关。     

Race distribution of Phytophthora sojae on soybean in Hyogo, Japan

Since 1987, Phytophthora root and stem rot of soybean [Glycine max (L.) Merr. cv. Tanbakuro], caused by Phytophthora sojae Kaufman and Gerdemann, has been increasing in the Sasayama, Nishiwaki, and Kasai regions in Hyogo, the most famous soybean (cv. Tanbakuro)-producing areas in Japan. In 2002 to 2004, 51 isolates (one from each field) of P. sojae were recovered from 51 fields in Hyogo. These isolates were tested for virulence on six Japanese differential soybean cultivars used for race determination in Japan, and three additional ones containing four Rps genes used in Indiana, USA. Race E was the most prevalent from 2002 to 2004, followed by races A, C, D, and four new races (proposed as races K, L, M, and N). Interestingly, none of the new races had high virulence on the Japanese differential cultivars, compared with other races in each area. One (race N) was avirulent on all six soybean differentials. There was a difference in race distribution on each of three individual areas; race E seemed to be a major component of the P. sojae population in Sasayama, whereas race A and the new race M were the most prevalent in Nishiwaki and Kasai, respectively. Rps6 (cv. Altona) and Rps1a + Rps7 (cv. Harosoy 63) were infected by 90.2% and 33.3% of all isolates, respectively. However, Rps1d (cv. PI103091) was not susceptible to any of the 51 isolates, nor was cv. Gedenshirazu-1. These two soybean cultivars were considered to be potential sources of resistance to breed new resistant cultivars with the desirable characteristics of cv. Tanbakuro for this region.     

大豆疫霉菌部分生物学特性及其药剂筛选研究

采用大豆疫霉菌在不同条件下菌丝生长速度法研究了大豆疫霉菌的部分生物学特性,并应用杀菌剂室内生测、盆栽药剂防效对药效作了评价。研究结果表明,大豆疫霉菌营养生长的最适温度为25～30℃;最适pH为6;光暗交替有利于该菌营养体的生长,在Rye或CA培养基上生长最快。室内药效测定结果表明,烯酰吗啉EC₅₀为0.165 4μg/mL,抑菌效果最好,甲霜灵、甲霜灵.锰锌和氟吗啉.锰锌的EC_{50分别为0.261 00、.451 0和0.984 2μg/mL,效果次之。盆栽试验结果表明,几种药剂在活体条件下对大豆疫病的防治效果较好,并有较长持效期。}     

Coinfection of soybean plants with Phytophthora sojae and soybean cyst nematode does not alter the efficacy of resistance genes

The soybean cyst nematode (SCN) Heterodera glycines and the oomycete Phytophthora sojae are among the most damaging pathogens of soybean worldwide. Resistant cultivars are commonly used to manage these diseases. As it is known that the presence of SCN can facilitate the development of other pathogens, it is important to verify if there is a synergistic activity between SCN and P. sojae. The purpose of this study was to evaluate a possible interaction on susceptible and resistant soybean lines. The plants were inoculated with one or both organisms at different stages (5 or 10 days old). Two levels of SCN inoculum (2,000 and 10,000 eggs/plant) and different timing between SCN and P. sojae inoculation (2, 5, or 8 days) were compared. The results on 5-day-old plants showed that SCN did not influence P. sojae development. The resistant cultivar to P. sojae remained effective (0% mortality) and susceptible cultivars exhibited high mortality (100%) in the presence or absence of SCN. Experiments on 10-day-old plants showed that SCN resistance was not affected by the presence of P. sojae. SCN inoculum density and timing of P. sojae infection did not affect the virulence of these pathogens and the efficacy of resistance genes. However, the number of SCN cysts was decreased by more than 50% (p < .001) when P. sojae was coinfesting the susceptible cultivar. This suggests that P. sojae might indirectly influence SCN development by reducing the root mass. This study confirmed that resistant cultivars remain a valid option for the management of P. sojae and SCN.     

Parasitoid community of the loreyi leaf wormMythimna (Acantholeucania) loreyi: Novel host-parasitoid associations and their efficiency in the eastern mediterranean region of Turkey

The loreyi leaf worm,Mythimna (Acantholeucania) loreyi Duponchel (Lepidoptera, Noctuidae), is a pest of gramineous crops and causes significant economic damage to maize. In field surveys on maize to determine the parasitoid community and its impact on the pest in the eastern Mediterranean region of Turkey, nine parasitoid species were found associated with immature stages ofM. loreyi: The hymenopteran (Braconidae and Ichneumonidae) parasitoidsCotesia (=Apanteles) ruficrus (Haliday),Chelonus oculator Panzer,Meteorus ictericus Nees,Hyposoter didymator (Thunberg),Sinophorus sp.; and the dipteran (Tachinidae) parasitoidsPseudogonia rufifrons Wiedeman,Exorista rossica Mesnil,Gonia picea (Robineau-Desvoidy) andLinnaemya vulpina (Fallen) — the last three recorded for the first time as parasitoids ofM. loreyi in Turkey.C. ruficrus was the dominant parasitoid species, being recovered from 38.5% of the larvae collected and was also the most prevalent species, existing in 91.0% of the fields in whichM. loreyi was found. Total parasitism levels achieved by braconid species was 41.4%, by ichneumonid parasitoids 4.8%, and by tachinid parasitoids 1.9%. In a separate field experiment, seasonal population fluctuations and natural efficiency ofC. ruficrus onM. loreyi were found to be 35.1% and 42.4%, respectively. Population levels ofC. ruficrus were closely related to fluctuations in the population ofM. loreyi, with parasitism ranging between 0 and 77.3% during the study. http://www.phytoparasitica.org posting Aug. 28, 2005.     

大豆疫霉细胞凋亡相关基因的鉴定与表达分析

为探讨大豆疫霉Phytophthora sojae细胞凋亡潜在的调控机制,根据已知的细胞凋亡蛋白,利用在线工具BLASTP、pFAM和SMART在大豆疫霉蛋白组数据库中鉴定细胞凋亡同源蛋白并构建其进化树,通过转录组数据和实时荧光定量PCR技术分析细胞凋亡相关基因在大豆疫霉生长、发育及侵染不同时期的表达情况。结果显示:在大豆疫霉中共鉴定到13个细胞凋亡同源蛋白,包括核酸内切酶G(PsNUC1)、细胞色素c(PsCYCS)、凋亡诱导因子(PsAIF)、丝氨酸蛋白酶(PsHtrA-1、PsHtrA-2和PsHtrA-3)、多聚ADP核糖聚合酶(PsPARP-1、PsPARP-2和PsPARP-3)和TatD核酸酶(PsTatD1、PsTatD2、PsTatD3和PsTatD4)。在进化上,PsNUC1、PsCYCS、PsAIF、PsHtrA-1、PsPARP-1、PsPARP-2、PsPARP-3、PsTatD1和PsTatD2与人及秀丽隐杆线虫Caenorhabditis elegans的同源蛋白亲缘关系较近,而与真菌相关蛋白亲缘关系较远,PsHtrA-2、PsHtrA-3、PsTatD3和PsTatD4与酿酒酵母Saccharomyces cerevisiae相关蛋白相似度更高,说明大豆疫霉细胞凋亡蛋白在进化中发生了较大变异。大豆疫霉细胞凋亡相关基因PsHtrA-1和PsRARP-1在孢子囊阶段诱导表达,PsHtrA-2和PsRARP-2在游动孢子阶段上调表达,PsAIF、PsHtrA-3、PsRARP-1和PsRARP-2在侵染阶段明显诱导表达,PsCYCS在侵染阶段下调表达。细胞凋亡相关基因在大豆疫霉不同阶段的表达模式有较大差异,说明细胞凋亡在大豆疫霉生长、发育及致病过程中具有重要作用。     

Real-time quantitative PCR assays for evaluation of soybean varieties for resistance to the stem and root rot pathogen Phytophthora sojae

Phytophthora root and stem rot caused by Phytophthora sojae is one of the most destructive disease of soybeans in the world. Effective management of the disease depends on selection and use of soybean varieties resistant to the disease. Fast and reliable procedures are vital to screen soybean varieties against the pathogen. Novel real-time quantitative (qPCR) assays were developed for both absolute and relative quantification of P. sojae in infected root tissues. QPCR assays were based on the detection of the internal transcribed spacer (ITS) gene of the pathogen and 18S ribosomal gene of the host plant. Absolute qPCR allowed the detection of as low as 10 femtograms (fg) of P. sojae DNA in soybean roots. Relative qPCR, employing the comparative threshold cycle (Ct) method, was effective and reliable for quantification of P. sojae DNA normalized to plant DNA in infected soybean root tissues. P. sojae DNA quantities detected in both qPCR assays had high correlations with disease severity index (DSI) ratings of soybean varieties. QPCR assays developed in this study were useful for determination of the levels of P. sojae DNA in different varieties of soybean and for evaluation of them for relative resistance to the pathogen.     

The current status of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiiidae) in Turkey and baseline toxicity of some insecticides

Tomato is one of the most important vegetable crops in Turkey, with national production of over 10 million tonnes in 2010. Tuta absoluta (Meyrick) is an important pest of tomato, and was first recorded in Urla District of Izmir Province in the Aegean region of Turkey in August 2009. It has since spread rapidly to the other regions of Turkey and become the main pest of tomato. Since its dispersal, chemical control has been the main method of control. Intensive use of insecticides has led to the development of resistance in T. absoluta. In this study, the baseline toxicity (LC₅₀ values) of some insecticides was determined using a leaf‐dip bioassay method in Antalya and Ankara populations of T. absoluta.     

Zoospore chemotaxis of closely related legume‐root infecting Phytophthora species towards host isoflavones

Phytophthora niederhauserii, P. pisi, P. sojae and P. vignae are closely related species that are pathogenic to various legume plants. While P. sojae and P. vignae are reported to specifically infect soybean and cowpea, respectively, P. pisi is reported to attack pea and faba bean. Phytophthora niederhauserii is considered to have a broad host range. Zoospores of some Phytophthora species are chemotactically attracted to the isoflavones that are secreted by their host plants. The focus of the current study was to determine the chemotaxic behaviour of zoospores from closely related legume‐root infecting Phytophthora species and to investigate the correlation, if any, to host preference as determined by greenhouse pathogenicity tests. The results showed that P. sojae and P. vignae were attracted to the non‐soybean isoflavone prunetin as well as to the soybean isoflavones genistein and daidzein, which is in contrast with their host specificity on soybean and cowpea, respectively. On the other hand, P. pisi and P. niederhauserii were only attracted to prunetin, previously reported to be produced by pea, but not to the isoflavones associated with the non‐host soybean. The lack of responsiveness to genistein and daidzein in P. pisi may represent a recent adaptation to the host specialization towards pea. However, the affinity of P. niederhauserii to prunetin shows that this trait can also be present in taxa not specifically associated with legume hosts.     

Genetic analysis of Phytophthora sojae populations in Fujian, China

Phytophthora sojae is a destructive soilborne pathogen causing seedling damping‐off and root rot of soybean (Glycine max). The goal of this study was to determine the genetic structure of P. sojae populations in Fujian, China. Nine microsatellite markers were used to investigate the genetic variation in 19 P. sojae populations, sampled from Fujian Province and northeastern China (Jilin and Heilongjiang Provinces) between 2002 and 2013. Overall, a low genetic diversity, Hardy–Weinberg disequilibrium, and an index (an index of association) that was significantly different from zero were detected in populations; these results were consistent with self‐fertilization and clonal modes of reproduction for this pathogen. However, using Bayesian Markov chain Monte Carlo approach, principal component analysis and neighbour joining (NJ) algorithm, the Fujian P. sojae populations clustered into three distinct groups, one of which included most isolates of the northeast populations. What is more, significant estimates of pairwise fixation indices (F_ST) were detected between most populations, especially in different clusters. It is hypothesized that the cropping system used, the limited dispersal ability, and human‐mediated gene flow may account for the observed genetic structure of P. sojae populations in Fujian, China. In addition, a high virulence frequency of the pathogen on different cultivars carrying known major R genes for resistance, and a rapid increase in virulence frequency, indicated that these major R genes should not be used to manage seedling damping‐off and root rot diseases of soybean (Glycine max).     

Note: Tachinid parasitoids (Diptera: Tachinidae) of<Emphasis Type="Italic">Mythimna (Acantholeucania) loreyi</Emphasis> in the southeast Anatolian region of Turkey

The loreyi leaf worm,Mythimna (Acantholeucania) loreyi (Duponchel) (Lepidoptera: Noctuidae), is a serious pest of gramineous crops and reduces yields in maize plantations. This study was undertaken to determine the tachinid parasitoid complex ofM. loreyi in the southeast Anatolian region of Turkey. Four tachinid species were found:Pseudogonia rufifrons (Wiedemann),Exorista larvarum (Linnaeus),Drino imberbis (Wiedemann) andLinnaemya neavei Curran were reared from field-collectedM. loreyi larvae. Of the four tachinid speciesM. loreyi is a new host record forE. larvarum andD. imberbis. L. neavei was recorded for the first time in Turkey and was the most frequently encountered parasitoid in this study. Total parasitism level was 7.1% in 2003 and 15.5% in 2004. http://www.phytoparasitica.org posting Jan. 16, 2007.     

大豆疫霉Phytophthora sojae卵孢子在黑龙江省土壤中的越冬存活率

为探究大豆疫霉Phytophthora sojae卵孢子在黑龙江省土壤中的越冬存活率及其与所处土壤深度和媒介的相关性,以增强型绿色荧光蛋白为报告基因,将培养基及病残体中的大豆疫霉卵孢子分别接种到试验田框栽土壤表层下不同深处,检测其卵孢子的越冬存活率,同时在框栽中定量播种不含任何已知抗疫霉根腐病基因的大豆品种Sloan(rps),苗期调查其发病率。结果表明,大豆疫霉卵孢子在黑龙江省土壤中的适生性较强,可在5~15 cm深度土壤中安全越冬,越冬存活率高达81.67%~96.33%。卵孢子越冬存活率与其所处的越冬媒介关系不大,而与土壤深度有关。在5~15 cm范围内,随着土壤深度的增加,卵孢子越冬存活率增加。处于深层土壤中的卵孢子更容易打破休眠,进入萌发前的萌动状态。各处理间卵孢子越冬存活率的显著性差异并未在发病率上表现出来,说明除了土壤深度外,还有其它因素影响发病率。     

A Phytophthora conserved transposon‐like DNA element as a potential target for soyabean root rot disease diagnosis

A transposon‐like element, A3aPro, with multiple copies in the Phytophthora sojae genome, was identified as a suitable detection target for this devastating soyabean root rot pathogen. The PCR primers TrapF1/TrapR1 were designed based on unique sequences derived from the transposon‐like sequence. A 267‐bp DNA fragment was amplified using this primer pair, the specificity of which was evaluated against 118 isolates of P. sojae, 72 isolates of 25 other Phytophthora spp., isolates of Pythium spp. and isolates of true fungi. In tests with P. sojae genomic DNA, detection sensitivities of 10 pg and 10 fg DNA were achieved in standard PCR (TrapF1/TrapR1) and nested PCR (TrapF1/TrapR1 and TrapF2/TrapR2), respectively. Meanwhile, PCR with TrapF1/TrapR1 primers detected the pathogen at the level of a single oospore, and even one zoospore. These primers also proved to be efficient in detecting pathogens from diseased soyabean tissues, residues and soils. In addition, real‐time quantitative PCR (qPCR) assays coupled with the TrapF1/TrapR1 primers were developed to detect and quantify the pathogen. The results demonstrated that the TrapF1/TrapR1 and TrapF2/TrapR2 primer‐based PCR assay provides a rapid and sensitive tool for the detection of P. sojae in plants and in production fields.     

Current status of red palm weevil in Turkey

The red palm weevil Rhynchophorus ferrugineus (Olivier) is the most serious pest of palms in Turkey. Weevil infestation was first detected in Turkey in summer 2005 in parks and gardens of Mersin province, along the Mediterreanean coast of Turkey. Following the discovery of the pest, destruction of infested plant material, prophylactic insecticide chemical treatments, as well as adult weevil trapping were carried out on palm plantations. Traps containing a commercial aggregation pheromone were hung on palm trees at a high density, in order to monitor the pest infestation and reduce the weevil population by mass trapping. A significant decrease in the number of trapped beetles and destruction of infested plant material was observed in 2009 and continued in the following years in several cities in Turkey. Therefore, it has been observed that mass trapping and curative pesticide applications have played a significant role in the suppression of R. ferrugineus populations in palm plantations.     

First record of tomato leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) in Kyrgyzstan

This short note reports the first record of the tomato leaf miner Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) in Kyrgyzstan. This pest was found in February 2017 in greenhouses producing tomatoes, located 15 km from Bishkek. Identification of the pest was carried out in the Plant Protection Department, Çukurova University, Turkey based on the morphology of adults and larvae and the male genitalia. According to initial surveys this pest could be a major threat to tomato production in Kyrgyzstan.     

安徽省大豆疫霉根腐病菌的鉴定及rDNA-ITS序列分析

为明确安徽省夏大豆疫霉根腐病的病原菌种类,对采集自涡阳、怀远、固镇3个县的夏大豆病株及土样分离纯化后获得28株菌株,选取6株代表性菌株,通过形态学观察及核糖体DNA-ITS序列分析对其进行鉴定,并测定了其致病型。结果表明,6株菌株在利马豆培养基上菌落白色,质地均匀;菌丝无隔,致密,具近直角分枝;在10%V8C培养液中,游动孢子囊顶生,不脱落,卵形至椭圆形,无明显乳突,有内层出现象,长宽比大于1.6∶1;同宗配合,在利马豆培养基上单株培养产生大量卵孢子,藏卵器球形,雄器大多侧生;接种合丰35大豆品种后出现典型的大豆疫霉根腐病症状。r DNA-ITS序列分析表明,6株菌株与Gen Bank中大豆疫霉Phytophthora sojae的ITS序列同源性高达100%;菌株GY4、GY8、HY11、HY16、GZ10、GZ21的毒力公式分别为1b,2,3a,3b,4,5,6,7;1b,1d,3a,3b;1d,3a,3b,3c,4,5,6,7;2,3c,4,5,6,7;1b,3a,3c,5,8;3a,3b,5,6,7,8;属于6个不同的致病型。研究表明,这6株菌株均为大豆疫霉。     

草地贪夜蛾侵害我国大豆的风险预警

草地贪夜蛾Spodoptera frugiperda是一种在全世界范围内危害性极强的害虫。2019年初突然侵入我国云南省并迅猛扩散迁移至国内大部分地区,对玉米等作物生产造成重大影响。我国大豆与玉米生产区重合较多,草地贪夜蛾是否会对大豆产生重大危害是一个值得注意的问题。本文从草地贪夜蛾的食性特点和迁移速度以及新生境3个方面评估了此类昆虫可能对我国大豆造成的危害,并对我国大豆生产中草地贪夜蛾的短期和长期预防策略进行了展望,以期为大豆生产中潜在的风险提供预警。