Scirtothrips Citri Research Articles

Taxonomic changes in Scirtothrips species (Thysanoptera: Thripidae) from México

The twelve species of Scirtothrips known from México are difficult to identify. We present new updates for defining Scirtothrips in that country. The species were re-evaluated using specimens from the National Insect Collection at IBUNAM, México. Visual comparisons of the Scirtothrips holotypes and paratypes were completed and contrasted to the current nomenclature of Central and North America taxa. We proposed synonymy of seven species, but the genus retains the twelve species officially reported in México herein. Scirtothrips citri, Scirtothrips perseae and Scirtothrips dorsalis are crop pests usually recorded. An updated key was developed to identify the Scirtothrips spp. in México.

DNA barcoding, an effective approach for the identification of thrips (Thysanoptera: Thripidae) in citrus orchards

AbstractThrips are serious crop pests with a worldwide distribution. The first step in the design of control methods is accurate species identification. However, the morphological identification of thrips can be complex, especially as there is morphological variation amongst individuals of the same species. Analyzing a fragment of cytochrome c oxidase subunit I (COI) has been used successfully in the identification of insects and other arthropods. Citrus is among the most important crops in the world, and Mexico is one of the largest producers. Despite this, formal reports on the species diversity of thrips found in Mexican citrus orchards are scarce. We explored the species diversity of thrips in selected citrus orchards (of Mexican orange, Key lime and Persian lime), based on morphological taxonomy and on partial sequences of COI. We analyzed 111 thrips specimens, distributed in two genera: Frankliniella, including Frankliniella insularis, Frankliniella invasor and Frankliniella occidentalis; and Scirtothrips, including Scirtothrips citri and Scirtothrips dorsalis. Frankliniella insularis and F. invasor were the most abundant species in Mexican orange (Citrus × sinensis) and Persian lime (Citrus × latofolia) orchards. Scirtothrips dorsalis was the most abundant species in Key lime orchards (Citrus × aurantiifolia). Analysis of molecular variance (AMOVA) and haplotype analyses performed on F. insularis sequences (the most abundant species) showed no significant effect of geographical origin or plant host on its genetic population structure. DNA barcoding is a valuable method to complement the morphological identification of thrips in citrus orchards, allowing more accurate identification to species level.

PRpnp, a novel dual activity PNP family protein improves plant vigour and confers multiple stress tolerance in Citrus aurantifolia.

Under field conditions, plants are often simultaneously exposed to several abiotic and biotic stresses resulting in significant reductions in growth and yield; thus, developing a multi-stress tolerant variety is imperative. Previously, we reported the neofunctionalization of a novel PNP family protein, Putranjiva roxburghii purine nucleoside phosphorylase (PRpnp) to trypsin inhibitor to cater to the needs of plant defence. However, to date, no study has revealed the potential role and mechanism of either member of this protein group in plant defence. Here, we overexpressed PRpnp in Citrus aurantifolia which showed nuclear-cytoplasmic localization, where it functions in maintaining the intracellular purine reservoir. Overexpression of PRpnp significantly enhanced tolerance to salt, oxidative stress, alkaline pH, drought and two pests, Papilio demoleus and Scirtothrips citri in transgenic plants. Global gene expression studies revealed that PRpnp overexpression up-regulated differentially expressed genes (DEGs) related to ABA- and JA-biosynthesis and signalling, plant defence, growth and development. LC-MS/MS analysis validated higher endogenous ABA and JA accumulation in transgenic plants. Taken together, our results suggest that PRpnp functions by enhancing the endogenous ABA and JA, which interact synergistically and it also inhibits trypsin proteases in the insect gut. Also, like other purine salvage genes, PRpnp also regulates CK metabolism and increases the levels of CK-free bases in transgenic Mexican lime. We also suggest that PRpnp can be used as a potential candidate to develop new varieties with improved plant vigour and enhanced multiple stress resistance.

Colored sticky traps for monitoring phytophagous thrips (Thysanoptera) in mango agroecosystems, and their impact on beneficial insects

The capture efficiency of six colored sticky traps (blue, green, orange, purple, white, and yellow) was tested in mango agroecosystems of Mexico with the purpose to: (i) document the diversity of Thysanoptera; (ii) determine the attraction of phytophagous thrips; (iii) assess the impact of these traps on beneficial insects; and (iv) assess the relationship between the density of Frankliniella thrips captured on traps and those found in the inflorescences. The use of colored sticky traps has revealed a great diversity of thrips and beneficial insects in the mango agroecosystem. A total of 16,441 thrips were caught on sticky traps throughout the sampling period, of which 16,251 (98.8%) were thrips adults and 190 (1.2%) larvae. Forty one species of thrips were collected either from sticky traps or from inflorescences. Of these, 32 species feed either on leaves or flowers. Frankliniella cephalica, F. gardeniae and F. invasor, were the most abundant species. Scirtothrips citri and S. manihoti were also captured among other phytophagous thrips. The white trap captured significantly more Frankliniella species and also had the smallest capture of beneficial insects. Yellow traps were the most attractive for Scirtothrips species, with low detrimental effects on insect pollinators, although high impact on natural enemies. Thrips species captured on sticky traps showed a low and non-significantly correlation with respect to the density of thrips in mango inflorescences. Although sticky traps did not predict the density of Frankliniella populations in mango inflorescences, the study represents a substantial progress in the use of color traps in mango agroecosystems. Colored sticky traps would be a good option for monitoring mango thrips to detect them at earlier stages of infestation to implement management tactics and avoid the building-up of thrips populations.

Rind Scarring Caused by Biotic and Abiotic Factors Influences Kinnow Fruit Quality

The relationship between rind scarring [caused by Brevipalpus phoenicis (Geijskes), Scirtothrips citri (Moulton) and wind] and physiochemical parameters was studied in three main kinnow producing zones of Punjab (Abohar, Ludhiana and Hoshiarpur), India. The results showed a nonsignificant increase in TSS value with increase in rind damage (caused by mites + thrips + wind) upto 50% but later on it was significantly decreased with increase in damage from 50 to 100%. Other parameters like vitamin C, phenols (pulp and peel), pectin, total carotenoids and fruit firmness were decreased with the increment in damage and lowest values were observed in 100% damaged fruits but the titrable acidity and sugars (non reducing, reducing & total sugar) parameters were not affected by rind scarring. The wind damaged fruits showed noncomparable data for all studied physiochemical parameters which indicated that wind doesn’t affect the fruit quality. It may also be concluded that only thrips and mites are responsible for deterioration of kinnow fruits quality.

Impacts of Fruit-Feeding Arthropod Pests on Oranges and Mandarins in California.

One of the major challenges facing citrus integrated pest management (IPM) in California is the recent, sharp increase in the acreage of mandarins being planted. The current citrus IPM guidelines have been established from years of experiments and experience in oranges, with no specific guidelines for mandarins. In the absence of research into key arthropod pest effects in mandarins, the assumption that the pest management practices for oranges appropriately transfer for optimal production in mandarins has not been tested. We used a data mining or 'ecoinformatics' approach in which we compiled and analyzed production records collected by growers and pest control advisors to gain an overview of direct pest densities and their relationships with fruit damage for 202 commercial groves, each surveyed for 1-10 yr in the main production region of California. Pest densities were different among four commonly grown species of citrus marketed as mandarins (Citrus reticulata, C. clementina, C. unshiu, and C. tangelo) compared with the standard Citrus sinensis sweet oranges, for fork-tailed bush katydids (Scudderia furcata Brunner von Wattenwyl [Orthoptera: Tettigoniidae]), and citrus thrips (Scirtothrips citri Moulton [Thysanoptera: Thripidae]). Citrus reticulata had notably low levels of fruit damage, suggesting they have natural resistance to direct pests, especially fork-tailed bush katydids. These results suggest that mandarin-specific research and recommendations would improve citrus IPM. More broadly, this is an example of how an ecoinformatics approach can serve as a complement to traditional experimental methods to raise new and unexpected hypotheses that expand our understanding of agricultural systems.

An Ecoinformatics Approach to Field-Scale Evaluation of Insecticide Effects in California Citrus: Are Citrus Thrips and Citrus Red Mite Induced Pests?

Experimental approaches to studying the consequences of pesticide use, including impacts on beneficial insects, are vital; however, they can be limited in scale and realism. We show that an ecoinformatics approach that leverages existing data on pesticides, pests, and beneficials across multiple fields can provide complementary insights. We do this using a multi-year dataset (2002-2013) on pesticide applications and density estimates of two pests, citrus thrips (Scirtothrips citri (Moulton [Thysanoptera: Thripidae])) and citrus red mites (Panonychus citri McGregor [Acari: Tetranychidae]), and a natural enemy (Euseius spp. predatory mites) collected from citrus groves in the San Joaquin Valley of California. Using correlative analyses, we investigated the long-term consequences of pesticide use on S. citri and P. citri population densities to evaluate the hypothesis that the pest status of these species is largely due to the disruption of natural biological control-i.e., these are induced pests. We also evaluated short-term pesticide efficacy (suppression of citrus thrips and citrus red mite populations immediately post-application) and asked if it was correlated with the suppression of Euseius predator populations. Although the short-term efficacy of different pesticides varied significantly, our dataset does not suggest that the use of citrus pesticides suppressed Euseius densities or worsened pest problems. We also find that there is no general trade-off between pesticide efficacy and pesticide risk to Eusieus, such that highly effective and minimally disruptive compounds were available to citrus growers during the studied time period.

Pest categorisation of Scirtothripscitri.

The Panel on Plant Health performed a pest categorisation of the citrus thrips, Scirtothrips citri (Moulton) (Thysanoptera: Thripidae), for the European Union (EU). This is a well‐defined and distinguishable species, occurring in North America and Asia. Its precise distribution in Asia is uncertain. S. citri is a pest of citrus and blueberries and has been cited on over 50 different host species in 33 plant families. Whether all plants reported as hosts are true hosts, allowing population development of S. citri, is uncertain. S. citri feeds exclusively on young actively growing foliage and fruit. It is not known to occur in the EU and is listed in Annex IIAI of 2000/29/EC as a harmful organism. The international trade of hosts, as either plants for planting or cut flowers, provide potential pathways into the EU. However, current EU legislation prohibits the import of citrus plants for planting. Furthermore, measures aimed at the import of plants for planting in a dormant stage (no young foliage or fruits present) with no soil/growing medium attached, decreases the likelihood of the pest's entry via other hosts. Considering that there are regional climatic similarities where S. citri occurs in the USA with climates in the EU, and taking EU host distribution into account, S. citri has the potential to establish in the EU, especially in citrus and blueberry growing regions around the Mediterranean where quality losses in citrus and yield losses in blueberry could occur. Phytosanitary measures are available to inhibit the likelihood of introduction of S. citri from infested countries. Considering the criteria within the remit of EFSA to assess its status as a potential Union quarantine pest (QP) or as a potential regulated non‐quarantine pest (RNQP), S. citri meets with no uncertainties the criteria assessed by EFSA for consideration as a potential Union QP.

Impact of Citrus Thrips (Thysanoptera: Thripidae) on the Growth and Productivity of Southern Highbush Blueberries in California

Citrus thrips, Scirtothrips citri (Moulton), is a foliage-feeding pest of blueberries in the San Joaquin Valley of California. We conducted a 4-yr field study to determine the type and amount of damage caused by this species. Using pesticides, we established gradients of citrus thrips in commercial blueberry fields near Richgrove, CA, in the fall of 2006, 2007, 2009, and 2014. Thrips densities were evaluated weekly for ∼1 mo to determine cumulative thrips-days and correlate levels with the average length of new growth. During all four years of the study, there were significant negative correlations between thrips-days and shoot length (for every 100 thrips-days over a period of 4-5 wk there were reductions in the length of new shoot growth of 0.41 to 2.45 cm, 6.4-10.3%). During the spring following each trial, we evaluated the impact of thrips-days on blueberry yield and quality. During the 2006 trial, there was a significant negative correlation between thrips-days and yield as well as the number of berries per plant, but no yield effect was observed in the other three years of the study. No impacts on fruit quality were found any year. A discussion of the complexity of economic injury levels in blueberries is provided, especially considering that the cost of spraying for citrus thrips (estimated at US$150/ha) is almost irrelevant given crop values often in excess of US$100,000/ha.

Evaluation of <I>Beauveria bassiana</I> for Management of Citrus Thrips (Thysanoptera: Thripidae) in California Blueberries

Citrus thrips, Scirtothrips citri (Moulton), is a plant-feeding pest most widely recognized for causing damage to citrus and mango fruits. This insect has broadened its host range to become a significant pest of commercial blueberries grown in the San Joaquin Valley of California. We evaluated Beauveria bassiana (Balsamo) for control of citrus thrips in blueberries grown under two watering regimes (drip irrigation with and without overhead sprinklers) and using two fungal formulations (commercially available spores in suspension vs. colonized seed) over two sampling periods, that is, for two 3-d periods after treatment. We found significant differences in thrips densities as a function of water regime treatment and fungal formulation. Thrips levels were reduced significantly with both fungal treatments at 3 d after treatment, but at 6 d, only results with colonized seed differed from the control treatment. These data suggest entomopathogenic fungi might be useful for control of citrus thrips on blueberries in particular situations (in organic production or as a resistance management tool) but that traditional pesticides will likely remain the preferred management option.

Investigating Alternatives to Traditional Insecticides: Effectiveness of Entomopathogenic Fungi and <I>Bacillus thuringiensis</I> Against Citrus Thrips and Avocado Thrips (Thysanoptera: Thripidae)

Citrus thrips, Scirtothrips citri (Moulton) (Thysanoptera: Thripidae), is a plant-feeding pest most widely recognized for causing damage to citrus (Citrus spp. L. [Rutaceae]) and mango (Mangifera indica L. [Anacardiaceae]) fruits. This insect has recently broadened its known host range to become a significant pest of California grown blueberries. Avocado thrips, Scirtothrips. perseae Nakahara (Thysanoptera: Thripidae), is a recent, invasive pest of California avocados, Persea americana Mill. (Laurales: Lauraceae). Effective alternatives to traditional pesticides are desirable for both pests to reduce impacts on natural enemies and broaden control options in an effort to minimize pesticide resistance via rotation of control materials. We evaluated Bacillus thuringiensis (Bt) subsp. israelensis proteins (Cyt 1A and Cry 11A, activated and inactivated) and multiple strains (GHA, 1741ss, SFBb1, S44ss, NI1ss, and 3769ss) of Beauveria bassiana (Balsamo) Vuillemin against both species. Avocado thrips and citrus thrips were not susceptible to either Bt protein tested, regardless of activation status. All strains of B. bassiana were able to infect both avocado thrips and citrus thrips. However, the commercially available GHA strain was the most effective strain against both species and had a faster rate of infection then the other strains tested. Citrus thrips were more susceptible than avocado thrips to all B. bassiana strains (LC50 and LC95 of 8.6 x 10(4) and 4.8 x 10(6) conidia per ml for citrus thrips, respectively). Investigation of citrus thrips field control using the GHA strain of B. bassiana is therefore justified.

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP/EPPO Standards Diagnostics Diagnostic

Normes OEPP EPPO Standards Diagnostics Diagnostic

Normes OEPP EPPO Standards Diagnostics Diagnostic

Southern Highbush Blueberries are A New Host forScirtothrips citri(Thysanoptera: Thripidae) In California

Citrus thrips, Scirtothrips citri (Moulton), is a major pest for citrus growers in California (Flint et al. 1991; Morse 1995). Citrus thrips feed on the rind at the stem end of young citrus fruit causing a characteristic ring scar (Morse 1995; GraftonCardwell et al. 1998, 2003). They also feed on the new flush of citrus, causing twisting and abnormal growth (Grafton-Cardwell et al. 1998). Heavy infestations of citrus thrips cause new flush to die and drop from the plant (Grafton-Cardwell et al. 1998). Even though citrus thrips was first described based on the damage it caused on California citrus (Horton 1918), it was obviously present prior to the introduction of citrus in the region, i.e., it is native to California and northwestern Mexico and has been observed on over 50 host plants in California, in particular in association with plants that produce an aromatic oil (Morse 1995). Prior to 1992, highbush blueberries ( Vaccinium corymbosum L.) were not grown commercially in California due to the warm climate (Jimenez et al. 2005; Strik & Yarborough 2005). However, several southern highbush blueberry varieties were developed by crossing northern highbush blueberries with several other Vaccinium species (Jimenez et al. 2005; Strik & Yarborough 2005). Southern highbush blueberries require lower chill hours for bud break and are well adapted to California’s climate (Jimenez et al. 2005). As a consequence, California blueberry acreage dramatically increased after 1992 (Jimenez et al. 2005). In 2005, several growers reported widespread damage to the young foliage of their blueberries that appeared to be associated with thrips. Most of the damage was curling and abnormal growth of the new leaves as well as scarring of new twigs.

Impact of citrus thrips chemical treatments on the predatory mite Euseius tularensis

Abstract: The impacts of four pesticides used for control of citrus thrips, Scirtothrips citri (Moulton), were evaluated in both field and laboratory populations of a predaceous mite, Euseius tularensis Congdon. Abamectin and chlorfenapyr had the least impact of pesticides evaluated on a field population of E. tularensis and predaceous mite levels mirrored those observed in the untreated control but at a slightly depressed level. Spinosad reduced predaceous mites somewhat but they recovered to 50% of the level in the untreated control by the end of the trial. Mite populations were low throughout the trial in plots treated with cyfluthrin. As an overall summary statistic, cumulative predator mite‐days ranged from 73.6% of the level observed in the untreated control with abamectin to 67.1% with chlorfenapyr, 36.8% with spinosad and 11.7% with cyfluthrin. Three additional field trials confirmed abamectin's minimal impact. In laboratory studies of adult female mite mortality on field‐weathered, pesticide‐treated leaves, cyfluthrin caused high mortality on day 1 after treatment and all mites that were not killed were driven off leaf discs until day 21. When mites were placed on leaf discs 1 day after treatment with abamectin, spinosad, or chlorfenapyr, 67.5% of the mites died on chlorfenapyr discs. By 7 days after treatment, no material but cyfluthrin showed a significant impact. Implications to citrus integrated pest management are discussed.

Normes OEPP . EPPO Standards

Normes OEPP . EPPO Standards

Scirtothrips aurantii, Scirtothrips citri, Scirtothrips dorsalis

<i>Scirtothrips aurantii</i>, <i>Scirtothrips citri</i>, <i>Scirtothrips dorsalis</i>

Evaluation of Phloxine B as a Possible Control Agent Against Citrus Thrips (Thysanoptera: Thripidae)

We evaluated the toxicity of phloxine B photoactive dye combined with a cane molasses bait against citrus thrips, Scirtothrips citri (Moulton). Laboratory bioassays conducted under artificial light showed that thrips mortality followed a log-dose probit-response model with an estimated LC50 of 0.0079% dye. Diluted cane molasses plus 0.01% phloxine B then was used as a standard for comparison of eight additional baits, including three formulations of concentrated citrus peel liquor (CCPL1–3). Citrus thrips mortality ranked highest to lowest with CCPL1 and CCPL3 > CCPL2, Mo-Bait and cane molasses > concentrated beet molasses, concentrated cane molasses, hemicellulose extract, and whey. Several commercial surfactants were tested to see if their addition to the standard increased efficacy. Hyper-Active, Kinetic, and Tween 60 at 1% and Cohort, Hyper-Active, Kinetic, and Silwet at 0.25% when added to the standard, reduced citrus thrips mortality, whereas Tween 60 and Dyne-Amic at 0.25% had no effect. Cane molasses with one or 5% phloxine B dye and CCPL1 with 1% dye were sprayed on citrus trees and allowed to weather in the field. Laboratory bioassays conducted after leaves had weathered for up to 8 d indicated that bait-dye toxicity was persistent. Possible use of the bait-dye mixture in commercial control of citrus thrips is discussed.

Predacious Mites for Control of Citrus Thrips,Scirtothrips citri(Thysanoptera: Thripidae) in Nursery Citrus

Abstract Predation on citrus thrips,Scirtothrips citri(Moulton), by four species of predacious mites,Ipheseius degeneransBerlese,Euseius tularensisCongdon,Neosieulus cucumeris(Oudemans), andN. barkeri(Hughes) was studied. In the laboratory,I. degeneransandE. tularensisexhibited a consistently high consumption rate of second-instar citrus thrips (4–5 thrips per mite per day), 68–96% survival, and reproduction of 0.9–2.5 eggs per day during the 5-day experiment. Initially,N. cucumerisexhibited a lower consumption rate as well as lower survival and egg production compared withI. degeneransandE. tularensis;however, these rates increased as the experiment progressed. The fourth species,N. barkeri,responded poorly with respect to all three biological parameters. In experiments using potted citrus in a greenhouse, immature stages of citrus thrips were not always available for predation. Under these circumstances,I. degeneransandE. tularensissurvived well and reduced immature citrus thrips to undetectable levels for the 4-week period after release. In contrast,N. cucumerisandN. barkeriexhibited poor survival and did not fully control citrus thrips. WhenI. degeneransandE. tularensiswere released onto potted citrus trees in a commercial citrus nursery, releases ofI. degeneransreduced citrus thrips for two sampling periods and improved tree height and leaf number comparable with an abamectin insecticide treatment. In contrast,E. tularensisreleases did not control citrus thrips, resulting in less growth of trees. These data suggest thatI. degeneransshows promise for commercial releases and control of citrus thrips in citrus nurseries.