Insecticide resistance management strategies against the western flower thrips, Frankliniella occidentalis

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an economically important pest of a wide range of crops grown throughout the world. Insecticide resistance has been documented in many populations of WFT. Biological and behavioural characteristics and pest management practices that promote insecticide resistance are discussed. In addition, an overview is provided of the development of insecticide resistance in F. occidentalis populations and the resistance mechanisms involved. Owing to widespread resistance to most conventional insecticides, a new approach to insecticide resistance management (IRM) of F. occidentalis is needed. The IRM strategy proposed consists of two parts. Firstly, a general strategy to minimise the use of insecticides in order to reduce selection pressure. Secondly, a strategy designed to avoid selection of resistance mechanisms, considering cross-resistance patterns and resistance mechanisms.     

昆明市白车轴草上蓟马种群动态调查

对昆明市白车轴草上蓟马种类及其周年种群动态进行了调查。白车轴草上蓟马主要有西花蓟马(Fran-kliniella occidentalis)、丽花蓟马(F.intonsa)、八节黄蓟马(Thrips flavidulus)、端大蓟马(Megalurothrips distalis)、稻单管蓟马(Haplothrips aculeatus)和烟蓟马(T.tabaci),有时会出现黄胸蓟马(T.hawaiiensis)、玉米黄呆蓟马(Anaphothrips obscurus)、苏丹呆蓟马(A.sudanensis)和云南纹蓟马(Aeolothrips yunnanensis)。本文分析了前6种蓟马的周年种群动态,重点阐述了外来有害生物西花蓟马,该虫主要在3~6月发生,是此期间白车轴草上的蓟马优势种。     

Quantification of imidacloprid toxicity to avocado thrips, Scirtothrips perseae Nakahara (Thysanoptera: Thripidae), using a combined bioassay and ELISA approach

A competitive ELISA (enzyme-linked immunosorbent assay) technique was evaluated for quantifying titres of imidacloprid in homogenates of leaf discs sampled from avocado plants treated with systemic applications of imidacloprid 240 g litre(-1) SC (Admire). Matrix effects were evident with undiluted leaf tissue homogenates, but these were effectively eliminated by dilution of homogenates in water. In a field trial conducted in a commercial nursery, there was an excellent correlation between imidacloprid residues within leaves and avocado thrips (Scirtothrips perseae Nakahara) mortality. However, with subsequent sampling over a 2-month period, the relationship between mortality and apparent imidacloprid concentration became less robust, suggesting that the material was being degraded within the plant to non-toxic metabolites. Nevertheless, assessments of thrips mortality on leaves that had been recently treated with imidacloprid established a lower threshold of activity for imidacloprid residues of 6 ng cm(-2) leaf. Limitations on the use of ELISA to quantify the impact of systemic insecticides on pest populations are discussed.     

Transmissibility of four tospoviruses by a thelytokous population ofThrips tabaci from Liguria, Northwestern Italy

Studies were carried out on a population ofThrips tabaci Lindeman (Thysanoptera: Thripi-dae) from Liguria to assess its sex-ratio and its ability to transmit four tospoviruses: tomato spotted wilt (TSWV), impatiens necrotic spot, tomato chlorotic spot and groundnut ringspot. The population was composed of females only (therefore thelytokous). The first instar larvae were allowed to acquire the virus for 48 h on infected leaves of datura, basil or pepper, and then reared on cucumber until emergence, which medially occurred 9.5 days after hatching. Transmission capacity was checked using two inoculation access periods (lAPs) of 48 h each on pepper leaf disks.T. tabaci was able to transmit TSWV isolate P105 with an efficiency of 16.7% and 4.4% in the first and second IAP, respectively, and TSWV isolate BR-01 with an efficiency of 2.0%. The onion thrips did not transmit the three other tospoviruses. During the IAPs, almost all adults fed on the leaf disks, producing evident silvery scars. The presence of tospovirus nucleocapsids in thrips was assayed by Triple Antibody Sandwich (TAS) and cocktail ELISA. Not all adults that had transmitted TSWV were positive in the tests, whereas some non-transmitter individuals proved positive. For each of the other tospoviruses, some thrips were positive in at least one test, although none was able to transmit the virus.     

洛阳市玉米蓟马发生规律及防治措施

通过观察研究，澄清了玉米蓟马在洛阳市的优势种为禾蓟马和稻管蓟马，明确了影响发生的主 要因子是降雨、日照、玉米播期和栽培措施等，提出了可行的综合防治措施。     

Seasonal abundance of different stages of the citrus thrips,Scirtothrips aurantii, on two mango cultivars in South Africa

The citrus thrips,Scirtothrips aurantii Faure (Thysanoptera: Thripidae), is a pest of mango in South Africa. The aim of the study was to monitor the different stages ofS. aurantii in mango orchards throughout the year. Populations ofS. aurantii were monitored using different methods,i.e., yellow sticky traps, dispersal/emergence traps, counts on fruit and in flowers. Eggs and emergence holes on the new leaves were recorded. The number of adults increased at the end of flowering (September) and remained at high levels until fruiting (November). Low numbers were present from May to August. Much higher population levels were present during 1995/96 than during the 1996/97 season. There was higher infestation present on the cultivar ‘Sensation’ than on ‘Zill’.S. aurantii was present on the fruit for only a short period (less than 10 weeks) during the season and the population was maintained on flush that was present throughout the year.     

40个苜蓿品种(系)对蓟马田间抗性评价

以受害指数为标准,在兰州对来自国内外40个苜蓿品种(品系)进行了田间抗蓟马评价试验。田间蓟马种类以牛角花齿蓟马为主,占田间蓟马混合种群数量的80%以上。结果表明,所有苜蓿品种(品系)的受害指数分布范围为65.89%~88.03%,受害指数在70%以下的有天水、Super7、L287、Eureka和豫县;天水苜蓿抗性最强,受害指数最小,为65.89%,与其他品种有显著差异;准葛尔受害指数最高,为88.03%。对不同品种苜蓿的受害指数与株高和虫口数量的相关分析表明,受害程度与株高及虫量无关。同时,本研究也提出了田间苜蓿受蓟马为害的测定标准及抗性评价方法。     

兰州地区蔬菜蓟马种类调查

对兰州地区蔬菜上的蓟马种类进行了采集调查和室内鉴定,结果表明,该地区蔬菜上有蓟马20种,分别属于2亚目,3科,6属,蓟马科Thripidae 4属16种,纹蓟马科Aeolothripidae 1属1种,管蓟马科Phlaeothripidae 1属3种.其中甘肃新记录种有11种,有害蓟马15种,天敌1种.同时,在该地区未发现已侵入中国的西方花蓟马Frankliniella occi-dentalis.根据鉴定结果,编制了兰州地区蔬菜蓟马种类成虫检索表.     

甘蔗种质对甘蔗蓟马的耐害性研究

通过自然种群接虫方法,开展12个甘蔗种质对蓟马的耐害性评价。结果表明,不同甘蔗种质虫害水平存在较大差异,其中‘云蔗15-507’为害最轻（虫害指数为13.33%）,‘云蔗14-1010’为害最重（虫害指数为73.33%）。相关分析结果显示,虫害指数与卷叶率相关性最强(R=0.9758),蓟马成虫数与虫害指数、卷叶率呈弱相关关系。耐害性由强到弱划分,可将12个甘蔗种质分为4个耐害等级,其中‘云蔗135-507’、‘云蔗15-1679’和‘云蔗14-1289’为1级,‘云蔗11-3898’和‘云蔗14-1215’为2级,‘云蔗14-1208’、‘云蔗15-1692’、‘云蔗13-1821’和‘云蔗12-1185’为3级,‘粤糖93-159’、‘云蔗13-1182’和‘云蔗14-1010’为4级。对耐害性甘蔗种质相关生理生化指标分析结果表明,虫害指数与多酚氧化酶(PPO)活性、超氧化物歧化酶(SOD)活性呈显著的负相关关系,与过氧化氢酶(CAT)活性有弱的正相关相系,与苯丙氨酸解氨酶(PAL)活性、过氧化物酶(POD)活性及丙二醛(MDA)含量等无相关关系。     

Evaluation of Gossypium arboreum L. Germplasm for resistance to thrips

Summary As part of a project to assess the U.S. Asiatic Cotton Germplasm Collection as a source of genes for pest resistance, forty-three accessions of Gossypium arboreum L. were evaluated for resistance to thrips. Thrips, Thysanoptera spp., are a minor, but widespread pest on cotton, G. hirsutum L. and G. barbadense L. Accessions were planted in free-choice field tests in 1988, 1989, and 1990 at the Cotton Branch Experiment Station, Marianna, Arkansas. Damage ratings, based on a scale of 0 (no damage) to 7 (severe damage), were made approximately one month after planting. Relative score was computed by dividing the rating of each accession by the rating of the reference, G. hirsutum Stoneville 506. The relative score averaged over all G. arboreum accessions by year varied with the year, but was less than 100 (relative score for Stoneville 506) in each case. When data were combined for all three years, twenty-five accessions were significantly better than Stoneville 506. Introgression of the better accessions into G. hirsutum is now in progress.Abbreviations NPGS National Plant Germplasm System - STV 506 G. hirsutum Stoneville 506