Biological control of the Western flower thripsFrankliniella occidentalis in cucumber using the entomopathogenic fungusMetarhizium anisopliae

Biological control of the western flower thrips (WFT)Frankliniella occidentalis, using the entomopathogenicMetarhizium anisopliae-7 (M. a-7) strain was studied in three consecutive seasons under greenhouse conditions. Cucumber plants infested with WFT were sprayed with spore suspension of the fungusM. a-7 (0.5 g m^-2), or the soil was treated with dry powder of the fungus (0.5 g m^-2); the control was without fungus application. In the 1997 spring experiment, when the cucumber plants were initially infested with only three or four insects per leaf, the spore suspension spray caused a significant reduction in growth of the thrips population compared with the other treatments and the control. However, in the 1997 summer experiment, when the plants were initially heavily infested with WFT (10–15 insects per leaf), the spray treatment caused only a modest reduction in WFT population growth, and only after 4 weeks of treatment was the reduction significant. In the 1999 experiment, with a low initial WFT population of three or four insects per leaf, the spray treatment was effective in reducing the population growth to a lower level than in the other treatments or control. TheM. a-7 strain was found to be effective in reducing the population growth of WFT under greenhouse conditions, particularly when the initial thrips population was low to moderate. http://www.phytoparasitica.org posting Nov. 4, 2001.     

Seasonal abundance of the western flower thripsFrankliniella occidentalis in the arava valley of Israel

Flowers of 22 plant species grown in the Arava region of Israel were sampled at periodic intervals to study the seasonal abundance ofFrankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Samples were collected from the most common cut-flower and vegetable plant species in this area during 1997 and from pepper in 1996–1998. Western flower thrips (WFT) was detected on 19 of the plant species surveyed, and it reproduced on numerous plant species. WFT counts peaked in late February–April and in October–December. The peak density of WFT during March in our survey corresponded to the peak flowering of cut-flower plants (during spring) and sweet pepper (during autumn). Thrips population was less abundant during autumn than in spring and was very low during summer. The possible reasons for fluctuations in thrips densities are abiotic factors (temperature and relative humidity), and availability of flowering plants. The high temperature (>40°C) and low humidity (∼20%) in summer caused a drastic reduction in WFT populations, although some flowering plant species were available in this season. WFT population remained low until October, when adults appeared in large numbers on flowering pepper. We assume that the thrips had survived the hottest months by aestivation and migrated to the plants when air temperature decreased. In most samples from the cut-flower fields, 84.8% were adult WFT; only during the period from the end of January to March, did the proportion of immature stages in the thrips population increase to 31.6%. Females always outnumbered males (71% females). In pepper fields during the first cropping month the thrips population included 96% adults; from November onwards, the proportions of adults and immatures were almost equal; and females outnumbered males. Organic pepper fields were not infested with thrips because of the presence of the predatory bugOrius albidipennis (Fieber). Contribution from the Agricultural Research Organization. No. 534/00, 2000 series. http://www.phytoparasitica.org posting July 16, 2002.     

Association of the western flower thrips (Frankliniella occidentalis) with cultivated sunflower (Helianthus annuus) in Israel

In 1992 and 1993, sunflower (Helianthus annuus L.) crops in Israel were heavily damaged by the western flower thrips (WFT),Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Adult females appear in the heads of sunflower just as the latter begin to blossom; the population decreases towards completion of anthesis. The damage to kernels is greatest at the periphery of the heads, where flowers appear first, and lowest at the center. Fields sown early in the season (in March) are usually the ones infested most by WFT and suffering the greatest damage. Fields sown one month later are less infested, since predatory bugs of the genusOrius are very active at that time.     

Acquisition of Tomato spotted wilt virus by Adults of Two Thrips Species

ABSTRACT Only larval thrips that acquire Tomato spotted wilt virus (TSWV), or adults derived from such larvae, transmit the virus. Nonviruliferous adults can ingest virus particles while feeding on TSWV-infected plants, but such adult thrips have not been shown to transmit TSWV. Immunofluorescence microscopy was used to show that thrips 1, 5, 10, and 20 days after adult emergence (DAE) fed on TSWV-infected plants acquired TSWV with virus replication and accumulation occurring in both epithelial and muscle cells of Frankliniella fusca (tobacco thrips [TT]) and F. occidentalis (western flower thrips [WFT]), as indicated by immunodetection of the nonstructural (NSs) protein encoded by the small RNA and the nucleocapsid (N) protein, respectively. Adult WFT acquired TSWV more efficiently than TT. There was no significant effect of insect age on TSWV acquisition by TT. In contrast, acquisition by adult WFT at 1 and 5 DAE was higher than acquisition at 10 and 20 DAE. Subsequent transmission competence of adult cohorts was studied by vector transmission assays. All adult thrips tested that had an acquisition access period as an adult were unable to transmit the virus. These results indicate the susceptibility of adult TT and WFT to infection of midgut cells by TSWV and subsequent virus replication and confirm earlier studies that adult thrips that feed on virus-infected plants do not transmit the virus. The role of a tissue barrier in TSWV movement and infection from midgut muscle cells to the salivary glands is discussed.     

The efficacy of spinosad against the western flower thrips, Frankliniella occidentalis, and its impact on associated biological control agents on greenhouse cucumbers in southern Ontario

Insecticides are the most commonly used tactic to control western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), on greenhouse cucumber. However, WFT has developed resistance to several of the insecticides presently in use. In addition, some of these insecticides adversely affect greenhouse biological control agents used to control WFT, resulting in subsequent pest resurgence. Therefore, there is a need to identify novel insecticides with unique modes of action for use in integrated pest management (IPM) programs to effectively control WFT with minimal impact on associated biological control agents. In laboratory bioassays conducted in 2001, immature and adult WFT and three associated greenhouse biological control agents: Amblyseius cucumeris Oudemans (Acarina: Phytoseiidae), Orius insidiosus Say (Hemiptera: Anthocoridae) and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were exposed to direct, direct/residual, and residual contact applications of the novel biopesticide, spinosad (Conserve 120 SC), and the industry standard for whitefly control, endosulfan (Thiodan 50 WP). In all three types of assay, spinosad was effective against immature and adult WFT life stages. It showed low toxicity to A. cucumeris, moderate toxicity to O. insidiosus and high toxicity to E formosa. Greenhouse studies involving exposure of immature and adult WFT and adult biological control agents to cucumber leaves sprayed previously with spinosad supported the laboratory data. Spinosad showed low toxicity to A. cucumeris exposed to leaves 1 day after treatment (DAT), moderate toxicity to O. insidiosus 1 and 8 DAT, and high toxicity to E. formosa up to 28 DAT. These data, along with spinosad's unique mode of action, suggest it would be a valuable reduced-risk control agent for greenhouse cucumber IPM programs.     

西花蓟马对不同颜色的趋性及蓝色粘板的田间效果评价

从18种颜色中筛选出对西花蓟马诱集效果最好的海蓝色,波长为438.2～506.6 nm。并将其研制成为诱虫板商品,田间使用效果优于黄板和国外产蓝板,可用于西花蓟马的防治和种群监测。     

Virulence and efficacy of different entomopathogenic nematode species against western flower thrips (Frankliniella occidentalis)

Virulence and efficacy of five species and strains of the entomopathogenic nematodes of the families Steinernematidae and Heterorhabditidae:Steinernema riobravis, Steinernema feltiae strains Ger. and UK, andHeterorhabditis bacteriophora strains HP88 and IS5, against the prepupal and pupal stages of the western flower thrips (WFT),Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were investigated in the laboratory. Although all these nematodes controlled WFT to some extent, they differed in efficiency. The heterorhabditid nematodeH. bacteriophora strain HP88 was more specific to the soil-inhabiting WFT stages (36–49% thrips mortality). The steinernematid nematodesS. riobravis andS. feltiae strains Ger. and UK had only a slight effect (10% mortality) on prepupal and pupal populations of WFT, andH. bacteriophora strain IS5 had the least effect of all. A possible reason for such species variation is suggested and discussed.     

150亿孢子/g球孢白僵菌可湿性粉剂的研发及对西花蓟马的防治应用

为了研发靶标害虫为西花蓟马的球孢白僵菌杀虫剂,我们首先通过筛选、纯化和复壮获得对西花蓟马高效的真菌菌株;其次,对液-固双相发酵条件和发酵工艺进行优化;然后,改良了产品剂型和配方;最后对产品进行环境和毒性评价。结果显示该产品各项指标均符合国家标准。150亿孢子/g球孢白僵菌可湿性粉剂于2018年在国内获审批登记。喷施1800～3000 g/hm²对辣椒上西花蓟马的防效均为74%以上。推荐用量为2400 g/hm²。该产品的研发和获批登记为西花蓟马的生物防治奠定了坚实的基础。     

The proportion of viruliferous individuals in field populations of Frankliniella occidentalis: Implications for tomato spotted wilt virus epidemics in tomato

Tomato spotted wilt tospovirus (TSWV) infected plants and western flower thrips (Frankliniella occidentalis Perg., WFT) adult population densities were monitored during 1993 and 1994 in field tomatoes in Northeastern Spain. The proportion of viruliferous WFT adults in field populations was quantified. A significant association has been found between early population densities of WFT adult thrips and final TSWV incidence for early transplanted tomato crops. In contrast, for late transplanted tomato crops, whereas similar high final disease incidences of TSWV could be attained, very low WFT adult population densities were always detected. The significantly higher infectious potential of WFT populations collected during the early growth stages of late transplanted tomatoes could be relevant for the TSWV incidences attained in spite of the low thrips numbers detected.     

Note: Extrapolating the use of an entomopathogenic nematode and fungus as control agents forFrankliniella occidentalis toThrips palmi

Little is known regarding non-chemical control measures againstThrips palmi Karny. Since entomopathogenic fungi and nematodes have been found to be active against thrips species such asFrankliniella occidentalis Pergande, comparative bioassays were conducted to determine the extent to which they also show activity againstT. palmi. Significant mortality of the larvae of the species was recorded following treatment withLecanicillium muscarium (Petch) Zare and Gams, and addition of the wetting agent Agral enhanced pathogenicity toT. palmi. T. palmi pupae were not affected byS. feltiae. The potential for use of these agents againstT. palmi in the field is discussed in the light of these results. http://www.phytoparasitica.org posting Aug. 28, 2005.     

阿维菌素与三种杀虫剂对西花蓟马的联合毒力

阿维菌素是防治西花蓟马的常用药剂,为筛选出对西花蓟马具有增效作用的阿维菌素与其他药剂的混配组合,采用浸叶法测定了阿维菌素、毒死蜱、吡虫啉和吡蚜酮等药剂对西花蓟马2龄若虫的毒力,并通过共毒因子法和共毒系数法分别确定了最佳药剂配伍和最佳复配比例。结果表明,阿维菌素与毒死蜱复配表现出明显的增效作用;阿维菌素与毒死蜱比值为2∶8与8∶2时,增效作用最显著;阿维菌素与吡蚜酮、吡虫啉均表现出拮抗作用。     

Integrated pest management in western flower thrips: past,present and future

Western flower thrips (WFT) is one of the most economically important pest insects of many crops worldwide. Recent EU legislation has caused a dramatic shift in pest management strategies, pushing for tactics that are less reliable on chemicals. The development of alternative strategies is therefore an issue of increasing urgency. This paper reviews the main control tactics in integrated pest management (IPM) of WFT, with the focus on biological control and host plant resistance as areas of major progress. Knowledge gaps are identified and innovative approaches emphasised, highlighting the advances in ‘omics’ technologies. Successful programmes are most likely generated when preventive and therapeutic strategies with mutually beneficial, cost‐effective and environmentally sound foundations are incorporated. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Addition of alarm pheromone to insecticides and the possible improvement of the control of the western flower thrips,Frankliniella occidentalis Pergande (Thysanoptera: Thripidae)

This study represents the first attempt to improve insecticide contact using the dodecyl acetate component of the alarm pheromone of the western flower thrips ( Frankliniella occidentalis Pergande ). Dodecyl acetate dissolved in ethanol was added to both fipronil and maldison and used in three spray applications (7 days apart) against field infestations of F. occidentalis on strawberries in two separate trials. Fipronil alone was highly effective against larvae and to a lesser extent against adults; however, the addition of dodecyl acetate did not significantly enhance thrips mortality. Although maldison was significantly less effective against adults and larvae, the larval mortality rate was significantly increased with the addition of dodecyl acetate. In one trial, dodecyl acetate applied on its own caused a significant reduction in larval numbers. Frequent insecticide applications are recommended for control of F. occidentalis in Australia because of the short-term effectiveness of most insecticides. This may hasten the development of insecticide resistance, which is already evident in F. occidentalis populations across the continent. Hence, either cultural methods, biological control agents or more effective chemicals need to be identified. This study has shown that there is potential for dodecyl acetate to enhance insecticide control of F. occidentalis .     

Evaluation of sticky traps and insecticides to prevent gall induction by Gynaikothrips uzeli Zimmerman (Thysanoptera: Phlaeothripidae) on Ficus benjamina

BACKGROUND: Gynaikothrips uzeli Zimmerman was first detected in North America from galls on weeping fig (Ficus benjamina L.) in 2003. It has been reported from ten states in the continental United States, Hawaii, Trinidad and Costa Rica. Adult thrips induce leaves to fold permanently along the midvein, making it a significant pest of weeping fig. Studies were initiated to determine monitoring methods and establish control recommendations.RESULTS: Comparison of captures of adult G. uzeli on blue, yellow, white and green sticky traps found yellow to be the most effective color. Yellow traps were effective for capturing adult Thripastichus gentilei (del Guercio), a larval parasitoid of G. uzeli. Thrips were first captured around 10:00 h. Captures peaked around 15:00-16:00 h and typically ceased by 21:00 h. Systemic neonicotinoid insecticides applied to container media were ineffective against adult G. uzeli feeding on foliage, and foliar applications of these products provided < or =7 days control. Conventional products provided satisfactory control after 1 day, but efficacy declined thereafter. Bifenthrin provided > or = 14 days residual control of adults.CONCLUSION: This paper represents the first report of monitoring phlaeothripids with sticky traps. Data from multiple trials suggest that products effective against other thrips have limited use against G. uzeli.     

Inheritance of resistance to acrinathrin in Frankliniella occidentalis (Thysanoptera: Thripidae)

BACKGROUND: The western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an economically important pest. The genetic basis of acrinathrin resistance was investigated in WFT. RESULTS: The resistant strain, selected in the laboratory for acrinathrin resistance from a pool of thrips populations collected in Almeria (south-eastern Spain), showed a high resistance to acrinathrin (43-fold based on LC(50) 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 a codominant trait. To determine the number of genes involved, a direct test of monogenic inheritance based on the backcrosses suggested that resistance to acrinathrin was probably controlled by one locus. Another approach, which was based on phenotypic variances, showed n(E), or the minimum number of freely segregating genetic factors for the resistant strain, to be 0.79. CONCLUSION: The results showed that acrinathrin resistance in WFT was autosomal and not influenced by maternal effects, and was expressed as a codominant trait, probably controlled by one locus.     

Note: Does<Emphasis Type="Italic">Liriomyza cicerina</Emphasis> affect the yield of chickpeas (<Emphasis Type="Italic">Cicer arietinum</Emphasis>)?

Liriomyza cicerina (Rondani, 1875) (Diptera: Agromyzidae) is an important pest on chickpea (Cicer arietinum L.) in some regions of Turkey. The objective of this study was to determine whether the populations ofL. cicerina on different varieties of chickpea plants during the 2004 and 2005 production seasons affected yield in Sanliurfa province. The trials were carried out using eight different varieties of chickpea with three replicates. During each season, larval densities on leaves were assessed weekly. TheL. cicerina larval population was lowest on four varieties for both seasons. There were very minor differences in yield among the eight varieties in the production seasons. There was no correlation found between larval density and yield loss. http://www.phytoparasitica.org posting Jan. 14, 2007.     

Associations betweenFrankliniella spp. andOrius niger populations in cotton

The distribution of theFrankliniella speciesF. occidentalis (Pergande) andF. intonsa (Trybom) (Thysanoptera: Thripidae), and of the predatory bugOrius niger (Wolff) (Hemiptera: Anthocoridae), in various organs of the cotton plant, as well as prey — predator interactions between thrips andO. niger, were investigated over 6 years in cotton fields in the eastern Mediterranean region of Turkey. The highest number of larvae ofFrankliniella spp. were found inhabiting bolls, whereas the adults colonized mainly flowers. The majority of predatory bug nymphs were present on leaves, followed by bolls, whereasO. niger adults visited mostly flowers. The thrips larvae were most likely preyed upon on flowers and squares, and bolls were safe plant parts for thrips, with a low predation rate. An intermediate but relatively high predation rate occurred on cotton leaves. In further field experiments, the effects of insecticide treatment on the relationships betweenO. niger andFrankliniella spp. were investigated. These trials revealed that a higher correlation existed between the numbers of adultO. niger in flowers andFrankliniella spp. in non-treated cotton fields than in insecticide-treated fields. The proportions of prey/predator in flowers ranged from 1.53 to 19.28 and were below four thrips per predator at most sampling dates in some of the non-treated cotton fields. It is concluded thatO. niger is an effective predator that can play an important role in suppressing population increase ofFrankliniella spp. in cotton. http://www.phytoparasitica.org posting May 12, 2006.     

Comparative host reactions and Frankliniella occidentalis transmission of different isolates of tomato spotted wilt tospovirus from Spain

The abilities of different isolates of tomato spotted wilt tospovirus (TSWV) collected from northeastern and eastern Spain to infect 10 host species, and to be acquired and transmitted by the western flower thrips (WFT), Frankliniella occidentalis were compared. Two isolates of TSWV from a single source plant could be separated according to the different type of local lesions they induced in Nicotiana glutinosa. Host ranges of the studied TSWV isolates were very similar, but differences were found in the symptoms induced and in their capacity to infect specific hosts systemically. Lycopersicon esculentumDatura stramonium were evaluated for their potential as virus acquisition host species. The proportion of transmitter adult thrips obtained from WFT larvae fed on L. esculentum was greater than from D. stramonium. No differences were detected between TSWV isolates in their ability to be acquired and transmitted by WFT. No evidence was obtained of alterations in TSWV particles which could affect WFT transmissibility due to the repeated mechanical transfers used to clone the isolates. Our findings do not support the existence of pathological effects of TSWV on WFT.     

Esterase inhibition by synergists in the western flower thrips Frankliniella occidentalis

BACKGROUND: Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is among the most important crop pests in the south‐eastern region of Spain. Its increasing resistance to insecticides constitutes a serious problem, and understanding the mechanisms involved is therefore of great interest. Use of synergists to inhibit the enzymes involved in insecticide detoxification is widely used to determine their responsibility for insecticide resistance. However, they do not always act as intended or expected, and caution must be exercised when interpreting synergist results. RESULTS: Laboratory‐selected strains of WFT were used to analyse the effects of the synergists piperonyl butoxide (PBO), S,S,S‐tributyl phosphorotrithioate (DEF) and methiocarb on total esterase activity. Significant differences were found, indicating esterase activity inhibition by DEF, a lower effect for methiocarb and a small inhibition of the activity by PBO. Esterase isoenzyme inhibition by these compounds showed a similar result; this assay revealed an extreme sensitivity of Triplet A (resistance‐associated esterases) to DEF. In an in vivo assay carried out with these compounds at different incubation times, only DEF caused posterior in vitro esterase activity inhibition, with a maximum effect 1 h after treatment. CONCLUSION: In this work, only DEF shows true synergistic inhibition of WFT esterases. Copyright © 2011 Society of Chemical Industry     

Note: First record in crete ofHercinothrips femoralis in greenhouse banana plantations

In 2004 the banded greenhouse thrips,Hercinothrips femoralis (Reuter) (Thysanoptera: Thripidae), was recorded for the first time in greenhouse-grown organic banana in the area of Sitia (northeastern Crete). Banana fruits were severely damaged by the thrips infestation and a typical smoky-red discoloration of the fruit was observed. Pest control was poor using either high-pressure washing with potassium fatty acids, or commercially available thrips predatorsNeoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) andOrius laevigatus (Fieber) (Hemiptera: Anthocoridae). During 2005H. femoralis was also found causing severe damage in conventional banana plantations in Arvi, the main banana-growing area of Crete. http://www.phytoparasitica.org posting Sept. 17, 2006.