Monitoring insecticide resistance in Australian Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) detects fipronil and spinosad resistance

Abstract  Insecticide resistance monitoring using a Potter precision spray tower with discriminating concentration and log dose probability techniques underpins the Australian insecticide management strategy for Frankliniella occidentalis Pergande. Abamectin, acephate, chlorpyrifos, dichlorvos, dimethoate, endosulfan, fipronil, malathion, methamidophos methidathion, methiocarb, methomyl, pyrazophos and spinosad are recommended for use against F. occidentalis but abamectin, methiocarb and pyrazophos are the only chemicals where insecticide resistance has not been detected. Although not registered, chlorfenapyr was effective against F. occidentalis and should be pursued for that purpose. In contrast, chlorpyrifos, dichlorvos and malathion resistance were detected at low to moderate levels throughout the study period putting their sustainable use for F. occidentalis control in doubt . Although it appears that acephate, dimethoate, endosulfan, fipronil, methamidophos, methidathion and spinosad remain effective, some populations contained a small percentage of thrips that survived exposure to a concentration that killed 100% of the susceptible strain. Subsequent laboratory selection of one such population separately with fipronil and spinosad caused an increase in resistance to these insecticides. These products must now be considered at risk. This is the first report of fipronil or spinosad resistance in populations of F. occidentalis.     

Insecticide resistance in Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) collected from horticulture and cotton in Turkey

Abstract  The sensitivity of three reference strains of the western flower thrips Frankliniella occidentalis from Australia, Israel and Turkey was evaluated and their response did not differ significantly and so they are considered typical of susceptible F. occidentalis . Field strains of F. occidentalis from Antalya, Turkey were tested for resistance against five classes of insecticide during the years 2001–2003. Difference in the field strains response to abamectin, endosulfan, malathion and methomyl was low (<3.0-fold) and in many cases not significant. However, all strains were likely resistant to cypermethrin (1.6- to 12.2-fold at LC₅₀ (lethal concentration)). The established agricultural practices and ecosystem patterns in the Antalya province are assumed to contribute to delay in insecticide resistance in F. occidentalis .     

Pyrethroid resistance in Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and implications for its management in Australia

Abstract  The study was conducted to characterise the underlying resistance mechanisms responsible for high levels of pyrethroid resistance in Frankliniella occidentalis (Pergande) in Australia. Seven commercially available pyrethroids (acrinathrin, alpha-cypermethrin, bifenthrin, deltamethrin, esfenvalerate, permethrin and tau-fluvalinate) were evaluated against seven F. occidentalis strains collected from ornamentals, fruit and vegetables in three states of Australia. A Potter spray tower was used to test for pyrethroid resistance and all field strains were found to be resistant, with resistance ratios ranging from 15-fold deltamethrin to 1300-fold tau-fluvalinate. The two most resistant strains were further tested for detoxification enzymes that could be involved in resistance. Three synergists, piperonyl butoxide (PBO), diethyl maleate (DEM) and profenofos, which, respectively, inhibit the enzymes cytochrome P-450 monooxygenases, glutathione S -transferases and esterases, were used. The synergism data indicate that multiple mechanisms may be involved in pyrethroid resistance in Australian populations of F. occidentalis . Among the three synergists, PBO considerably reduced pyrethroid resistance in the selected strains compared with DEM and profenofos. The practical implication for PBO use to suppress pyrethroid resistance in F. occidentalis is elaborated.     

入侵昆虫西花蓟马的潜在适生区分析

本文在分析西花蓟马生物学特性及其世界分布的基础上,采用CLIMEX软件及提供的气候匹配性分析和位置比较分析两种分析模型,结合我国634个气象站点的数据,预测西花蓟马在我国的潜在分布区。结果表明,西花蓟马在生态气候指数EI≥3的地区爆发危害风险性较大。西花蓟马在我国的广东、海南、安徽、福建、江苏、山东、广西、贵州、河南、湖北、陕西、四川、云南、重庆等省市具有广泛的适生区; 其适宜生存的北界分布在中国年平均温度10℃等温线、1月份平均温度-8℃等温线以及年平均极端最低温度-20℃等温线附近; 而新疆、青海、西藏、黑龙江、吉林、辽宁、内蒙古等省或自治区为不适应生存区。     

Initial verification of the resistance management strategy for Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) in Australia

Shortly after the initial detection of western flower thrips (WFT), Frankiniella occidentalis (Pergande), in Australia during 1993 a resistance management strategy based on the alternation of chemical groups was implemented. This study aimed to verify this strategy by field testing α-cypermethrin against WFT with and without chemical alternation. Up to 114 times α-cypermethrin resistance (at LC50) was detected and resistance increased with and without chemical alternation; however, chemical alternation did significantly reduce numbers of thrips compared with a nonalternation strategy. Resistance has the potential to undermine the sustainable use of those chemicals to which there is no current detectable resistance. Consequently, chemicals with a high frequency and level of resistance against WFT need to be identified through monitoring and quickly eliminated from WFT chemical control recommendations.     

Ultrastructure of the midgut and the adhering tubular salivary glands of Frankliniella occidentalis (Pergande) (Thysanoptera : Thripidae)

The ultrastructure of the midgut and the tubular salivary glands of Frankliniella occidentalis (Thysanoptera : Thripidae) is described. The microvilli have 2 different types of glycocalyx: in the anterior part of the midgut they are surrounded by a myelin-like membrane; in the posterior region, the microvilli have numerous rod-like projections arranged to form a continuous layer. Microfilaments longitudinally cross each microvillus; the microfilaments contain F-actin. Tubular salivary glands flank the midgut but do not fuse with it. The distal part of these glands have microvillated cells containing large amounts of electron-transparent material. The cells of the proximal part are lined with a thin cuticle.     

Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) chemical control: residues associated with the three consecutive spray strategy

Abstract  Chemical control of western flower thrips Frankliniella occidentalis requires three consecutive applications of the same pesticide, 3–6 days apart. Initially, pesticides recommended for western flower thrips control were based on established maximum residue limits (MRLs) from previously established use on pests other than F. occidentalis , rather than product efficacy against F. occidentalis . Moreover, MRLs were based on a single application rather than three consecutive sprays. Chemical residues associated with the three-spray strategy were not quantified. Here those residues are quantified and the scope for rate increases is further tested, as laboratory bioassays suggest that some current permit rates may be too low to be effective. At established withholding periods (WHPs), current permit rate applications of abamectin (0.018 g/L) on strawberry and tomato, and methidathion (0.5 g/L) and endosulfan (0.666 g/L) on lettuce produced residues above the current Australian MRL. Results indicated that a higher than the current permit rate for endosulfan (2.0 g/L) could be sustained on cucumber and strawberry at established WHPs, but would require an extension to the current WHP. Similarly, a modest increase in methidathion (1.0 g/L) rate on tomato could be practical, again with a WHP extension. In each instance additional supporting data are required to accurately quantify the proposed WHP extensions.     

Genetics of spinosad resistance in Frankliniella occidentalis (Thysanoptera: Thripidae)

The genetic basis of spinosad resistance was investigated in the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). The resistant strain, selected in the laboratory for spinosad resistance from a pool of thrips populations collected in Almeria (southeastern Spain), showed a very high resistance to spinosad (356,547-fold based on LC50 values) compared with the laboratory susceptible strain. Mortality data from reciprocal crosses of resistant and susceptible thrips indicated that resistance was autosomal and not influenced by maternal effects. Analysis of probit lines from the parental strains and reciprocal crosses showed that resistance was expressed as an almost completely recessive trait. To determine the number of genes involved, a direct test of monogenic inheritance based on the backcrosses suggested that resistance to spinosad was probably controlled by one locus. Another approach, which was based on phenotypic variances, showed that nE, or the minimum number of freely segregating genetic factors for the resistant strain, equaled 0.59.     

西花蓟马的SCAR分子检测技术

西花蓟马Frankliniella occidentalis （Pergande）是一种世界性入侵害虫,寄主范围广,危害严重,2003年首次在我国发生危害,并有进一步扩散蔓延的趋势。针对蓟马类害虫虫体微小、形态相似,难以准确快速区分的问题,采用特征序列扩增区域（SCAR）标记技术,以西花蓟马及与之同域发生的其他种类蓟马为对象,筛选出1对西花蓟马特异性引物（FOMF/FOMR）,其扩增片段大小为320 bp。种特异性检测结果显示,该对引物只对西花蓟马的基因组DNA具有扩增能力,对同域发生的花蓟马F. intonsa （Trybom）、禾花蓟马F. tenuicornis （Uzel）、烟蓟马Thrips tabaci L. 等41种蓟马不具有扩增效果。该对引物不仅对不同虫态的西花蓟马具有扩增能力,而且在西花蓟马发生地的寄主植物组织内亦检测到了其卵的存在。同时,该检测技术灵敏度高,对成虫的最低检出阈值为1/160头。本检测技术在口岸检疫以及花卉、蔬菜和种苗调运中的害虫检测和监测中具有重要意义。     

Mechanisms of resistance to spinosad in the western flower thrip, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

Cross‐resistance, resistance mechanisms, and mode of inheritance of spinosad resistance were studied in the western flower thrip, Frankliniella occidentalis (Pergande). Spinosad (naturalyte insecticide) showed low cross‐resistance to prothiophos (organophosphorus insecticide) and chlorphenapyr (respiratory inhibitor) showed some cross‐resistance to thiocyclam (nereistoxin). The synergists PBO (piperonyl butoxide), DEM (diethyl maleate), and DEF (s, s, s‐tributyl phosphorotrithioate) did not show any synergism on the toxicity of spinosad in the resistant strain (ICS), indicating that metabolic‐mediated detoxification was not responsible for the spinosad resistance, suggesting that spinosad may reduce sensitivity of the target site: the nicotinic acetylcholine receptor and GABA receptor. Following reciprocal crosses, dose‐response lines and dominance ratios indicated that spinosad resistance was incompletely dominant and there were no maternal effects. The results of backcross showed that spinosad resistance did not fit a single‐gene hypothesis, suggesting that resistance was influenced by several genes.     

Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) chemical control: insecticide efficacy associated with the three consecutive spray strategy

Abstract  After the initial 1993 discovery of Frankliniella occidentalis , western flower thrips, in Australia, temporary chemical control permits were issued to facilitate their insecticidal control. However, these permits were based on established endemic pests of Australian horticulture rather than demonstrated efficacy against F. occidentalis , and laboratory bioassays of Australian field-collected F. occidentalis suggested that some permit application rates were too low to be effective. In 2002 and 2003 field-based trials were carried out in strawberry and lettuce to collect field-generated efficacy data to verify the laboratory conclusions. It was found that by increasing field application rates above the existing permit rate, efficacy was increased, but not for all insecticides and not for all thrips life stages. Increasing the rate of abamectin and endosulfan in strawberry increased control of adults and larvae and increasing the rate of endosulfan in lettuce increased efficacy against larvae only. Spinosad was effective at both rates tested in strawberry, suggesting that the current permit rate could be reduced. The ability to use reduced rates may be useful if used in combination with Integrated Pest Management programs.     

Mechanisms associated with methiocarb resistance in Frankliniella occidentalis (Thysanoptera: Thripidae)

Biochemical mechanisms associated with methiocarb resistance were examined in laboratory-selected and field populations of the western flower thrips, Frankliniella occidentalis (Pergande). Seven populations were examined and they differed in their susceptibility to methiocarb by 30 times. Including the synergists piperonyl butoxide, a cytochrome P-450 monooxygenase inhibitor, or S,S,S-tributylphosphorotrithioate, an esterase inhibitor, in the methiocarb bioassays partially suppressed resistance in the most resistant populations. In vitro assays of general esterase, glutathione S-transferase, and acetylcholinesterase activities showed increased activity in some of the resistant populations and increased activity of the enzymes after methiocarb selection on one of the populations. Assays of acetylcholinesterase sensitivity to inhibition by methiocarb, dichlorvos, and eserine suggested insensitive acetylcholinesterase in two of the resistant populations. These results indicate that methiocarb resistance in F. occidentalis was polyfactorial and involved detoxification and altered target site. None of the biochemical assays showed interpopulation enzymatic differences strongly correlated with the level of methiocarb resistance. The possibilities for developing rapid biochemical diagnostic assays to detect methiocarb resistance in F. occidentalis are discussed.     

Starvation period and age affect the response of female Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) to odor and visual cues

The effects of starvation or age on the walking or flying response of female Frankliniella occidentalis to visual and/or odor cues in two types of olfactometer were examined in the laboratory. The response of walking thrips starved for 0, 1, 4, or 24h to an odor cue (1microl of 10% p-anisaldehyde) was examined in a Y-tube olfactometer. The take-off and landing response of thrips (unknown age) starved for 0, 1, 4, 24, 48 or 72h, or of thrips of different ages (2-3 days or 10-13 days post-adult emergence) starved for 24h, to a visual cue (98 cm(2) yellow sticky trap) and/or an odor cue (0.5 or 1.0 ml p-anisaldehyde) was examined in a wind tunnel. More thrips walked up the odor-laden arm in the Y-tube when starved for at least 4h (76%) than satiated thrips (58.7%) or those starved for 1h (62.7%, P<0.05). In the wind tunnel experiments the percentage of thrips to fly or land on the sticky trap increased between satiated thrips (7.3% to fly, 3.3% on trap) and those starved for 4h (81.2% to fly, 29% on trap) and decreased between thrips starved for 48 (74.5% to fly, 23% on trap) and 72 h (56.5% to fly, 15.5% on trap, P<0.05). Fewer younger thrips (38.8%) landed on a sticky trap containing a yellow visual cue of, those that flew, than older thrips (70.4%, P<0.05), although a similar percentage of thrips flew regardless of age or type of cue present in the wind tunnel (average 44%, P>0.05).     

Chemical Control System of Frankliniella occidentalis (Thysanoptera: Thripidae) in Greenhouse Eggplant

Systems of chemical control were implemented in a plastic greenhouse to control mainly Frankliniella occidentalis (Pergande) in eggplant with several effective eligible groups of insecticides, spraying insecticide singly with new mode of action or in sequence with conventional. The system consisted of three phase of strategy to cope with initial population build up, sporadic pests and F. occidentalis population control. To check the effectiveness of the control system it was evaluated phytotoxicity, the residual toxicity, spraying frequency, insecticidal spectrum against Tetranychus urticae Koch, and Liriomyza trifolii (Burgess), and marketable quality and yield. Spraying singly with abamectin or imidacloprid gave high yields with low damage to the eggfruits. Furthermore abamectin 1.8 emulsifiable concentrate (Ec) showed wide range of insecticidal activity against T. urticae and L. trifolii with slightly less spraying frequency.     

入侵害虫西花蓟马及其他8种常见蓟马的分子鉴定

用PCR产物直接测序法对入侵害虫西花蓟马和其他8种蓟马的线粒体 COⅠ基因433 bp片段测序，获得62个个体的序列。分子数据分析显示： 种内个体间平均遗传距离在0～0.005之间，2003年在北京发现的西花蓟马与欧洲等地区报导的西花蓟马不存在明显的遗传差异； 9种蓟马种间平均遗传距离为0.213。构建的NJ树可以很好的显示蓟马的聚类，物种各单元型最初分支自展值均达到100%。结果表明，基于PCR及直接测序技术的分子鉴定可以达到准确鉴定蓟马物种之目的。     

Management of Frankliniella occidentalis (Thysanoptera: Thripidae) with granular formulations of entomopathogenic fungi

Western flower thrips (WFT), Franklinella occidentalis, is a major pest of ornamentals. Mycotized millet grains with entomopathogenic fungi applied to soil of potted marigold plants were tested to target the soil-dwelling stages of thrips. Two experimental fungal isolates, (Beauveria bassiana [ARS7060] and Metarhizium anisopliae [ERL1171]), were compared with the registered B. bassiana strain GHA [commercialized as BotaniGard®] and untreated controls in greenhouse caged trials. Mycotized millet grains were mixed into the upper surface of the potting soil in pots of flowering ‘Hero Yellow’ marigolds (4 g/pot). One week after application five mated WFT females were released onto each plant (four plants per cage). At 8 weeks post-infestation, the mean total number of thrips per plant was 81% and 90% less in the ERL1171 and ARS 7060 treatments, respectively, than in the control. The mean numbers of thrips per plant for the control and GHA treatments were not significantly different. Plant damage was 60% less on plants treated with the experimental fungi than the control and GHA treatments. At 10 weeks post-application, 75–90% of WFT collected from the treatments of the experimental fungi were infected with the fungal species applied. These results demonstrate that soil applications of entomopathogenic fungi can reduce WFT populations significantly and prevent major damage.     

Suppressing Establishment of Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) in Cucumber Crops by Prophylactic Release of Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae)

Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) is the most damaging pest of protected cucumbers in the UK and reliable control measures are required that are compatible with other components in the IPM programme. Although the predatory mite, Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae), has been used for thrips control for many years, results against F.occidentalis in cucumbers during the early 1990s were frequently unacceptable. Three experiments in 1994/95 evaluated a prophylactic approach to the control of F.occidentalis. This involved placing one A. cucumeris culture sachet on each plant immediately after planting. F. occidentalis was released in all crops to ensure that the biocontrol measure received a severe test. Treatment was compared to untreated controls and the delayed release of culture sachets. The cultures remained active and produced populations of A. cucumeris on leaves for at least nine weeks. Establishment of F. occidentalis populations was almost entirely suppressed when the culture sachets were placed immediately after planting. Thrips damage was reduced compared to untreated controls when introduction of culture sachets was delayed by 2-4 weeks but this increased the risk of control failure.     

Internal anatomy and morphology of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) with special reference to interactions between thrips and tomato spotted wilt virus

The internal morphology of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) (WFT), a primary vector of tomato spotted wilt virus (TSWV), was shown to bear certain similarities to other thrips species, particularly in the composition of the piercing-sucking feeding structures. Striking differences were observed in number, position and ducting of the salivary glands, the morphology of the alimentary canal and the number and arrangement of the malpighian tubules between the WFT and other studied Thysanopterans. These differences provide support for the conclusion that internal morphologies may vary widely in this order, and perhaps among species in the same genus. The results of our investigation support the need for more detailed studies of other thrips species, particularly in light of the potential importance morphological characteristics may play in governing the capacity of thrips species to serve as vectors of TSWV.