Thrips Research Articles

RNA interference tools for the western flower thrips, Frankliniella occidentalis

The insect order Thysanoptera is exclusively comprised of small insects commonly known as thrips. The western flower thrips, Frankliniella occidentalis, is an economically important pest amongst thysanopterans due to extensive feeding damage and tospovirus transmission to hundreds of plant species worldwide. Geographically-distinct populations of F. occidentalis have developed resistance against many types of traditional chemical insecticides, and as such, management of thrips and tospoviruses are a persistent challenge in agriculture. Molecular methods for defining the role(s) of specific genes in thrips–tospovirus interactions and for assessing their potential as gene targets in thrips management strategies is currently lacking. The goal of this work was to develop an RNA interference (RNAi) tool that enables functional genomic assays and to evaluate RNAi for its potential as a biologically-based approach for controlling F. occidentalis. Using a microinjection system, we delivered double-stranded RNA (dsRNA) directly to the hemocoel of female thrips to target the vacuolar ATP synthase subunit B (V-ATPase-B) gene of F. occidentalis. Gene expression analysis using real-time quantitative reverse transcriptase-PCR (qRT-PCR) revealed significant reductions of V-ATPase-B transcripts at 2 and 3days post-injection (dpi) with dsRNA of V-ATPase-B compared to injection with dsRNA of GFP. Furthermore, the effect of knockdown of the V-ATPase-B gene in females at these two time points was mirrored by the decreased abundance of V-ATPase-B protein as determined by quantitative analysis of Western blots. Reduction in V-ATPase-B expression in thrips resulted in increased female mortality and reduced fertility, i.e., number of viable offspring produced. Survivorship decreased significantly by six dpi compared to the dsRNA-GFP control group, which continued decreasing significantly until the end of the bioassay. Surviving female thrips injected with dsRNA-V-ATPase-B produced significantly fewer offspring compared to those in the dsRNA-GFP control group. Our findings indicate that an RNAi-based strategy to study gene function in thrips is feasible, can result in quantifiable phenotypes, and provides a much-needed tool for investigating the molecular mechanisms of thrips–tospovirus interactions. To our knowledge, this represents the first report of RNAi for any member of the insect order Thysanoptera and demonstrates the potential for translational research in the area of thrips pest control.

Above Ground Arthropod Diversity in a Tropical Deciduous Forest in Ayodhya Hill, Purulia, India

Arthropods exploiting terrestrial habitats constitute a single major group that represents extreme diversity of forms and functions. The present commentary provides a description of the above ground arthropod species diversity of the tropical deciduous forest in Ayodhya hills, Purulia, West Bengal, India. Species diversity was only considered for this study through random quadrat sampling method. Shannon-Wiener diversity index, equitability among species, relative dominance, species richness and community similarity for the two different habitats were calculated. A total of 289 individuals were recorded which included the insect orders Hymenoptera, Coleoptera, Isoptera, Hemiptera, Diptera, Thysanoptera, Homoptera, Mantodea, and few individuals of class Isopoda, Araneae and Chilopoda. In majority of the quadrats the dominant insect order was Hymenoptera.

Polyploidy versus endosymbionts in obligately thelytokous thrips.

BackgroundThelytoky, the parthenogenetic development of females, has independently evolved in several insect orders yet the study of its mechanisms has so far mostly focussed on haplodiploid Hymenoptera, while alternative mechanisms of thelytoky such as polyploidy are far less understood. In haplodiploid insects, thelytoky can be encoded in their genomes, or induced by maternally inherited bacteria such as Wolbachia or Cardinium. Microbially facilitated thelytoky usually results in complete homozygosity due to gamete duplication and can be reverted into arrhenotoky, the parthenogenetic development of males, through treatment with antibiotics. In contrast, genetically encoded thelytoky cannot be removed and may result in conservation of heterozygosity due to gamete fusion. We have probed the obligate thelytoky of the greenhouse thrips, Heliothrips haemorrhoidalis (Bouché), a significant cosmopolitan pest and a model species of thelytoky in the haplodiploid insect order Thysanoptera. Earlier studies suggested terminal fusion as a mechanism for thelytoky in this species, while another study reported presence of Wolbachia; later it was speculated that Wolbachia plays a role in this thrips’ thelytokous reproduction.ResultsBy using PCR and sequence analysis, we demonstrated that global population samples of H. haemorrhoidalis were not infected with Wolbachia, Cardinium or any other known bacterial reproductive manipulators. Antibiotic treatment of this thrips did also not result in male production. Some individuals carried two different alleles in two nuclear loci, histone 3 and elongation factor 1 alpha, suggesting heterozygosity. However, the majority of individuals had three different alleles suggesting that they were polyploid. Genetic diversity across both nuclear loci was low in all populations, and absent from mitochondrial cytochrome oxidase I, indicating that this species had experienced genetic bottlenecks, perhaps due to its invasion biology or a switch to thelytoky.ConclusionsGeographically broad sampling and experimental manipulation revealed low genetic diversity, absence of Wolbachia but presence of three different alleles of nuclear loci in most analysed individuals of obligately thelytokous H. haemorrhoidalis. This suggests that polyploidy may be involved in the thelytokous reproduction of this thrips species, and polyploidy may be a contributing factor in the reproduction of Thysanoptera and other haplodiploid insect orders.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0304-6) contains supplementary material, which is available to authorized users.

Control of Western Flower Thrips on Gardenia, Summer 2004

Control of Western Flower Thrips on Gardenia, Summer 2004

Diet dependent olfactory response and predation rate of Neoseiulus californicus (Acari: Phytoseiidae) in the presence of Frankliniella occidentalis and Tetranychus urticae

Responses of female predatory mite, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) with different diet experiences were examined in a Y-tube olfactometer. The odor sources were clean air vs. clean bean leaves, clean air vs. Tetranychus urticae (Koch) (Acari: Tetranychidae) infested bean leaves, and T. urticae infested bean leaves vs. clean bean leaves. Female predatory mites that fed on T. urticae as their previous diet for three generations, preferred clean leaves, spider mite infested leaves and again spider mite infested leaves over the alternative odor sources. When N. californicus was fed on T. urticae plus pollen, a significant movement was recorded towards clean leaves rather than clean air, but no significant preference was observed in two other olfactory experiments. Feeding on pollen alone, thrips first instar alone and thrips first instar plus pollen, the predators did not make a significant preference towards the arms in any of the olfactory experiments. Comparing the mean foraging time and predation rate of N. californicus when their prey ( T. urticae ) were experienced in a direct contact with Frankliniella occidentalis with predators whose prey had previousely received signals due to thrips ( F. occidentalis ) presence, we recorded a significantly higher foraging time and consumed prey in the patches where thrips were removed. According to our results, N. californicus is capable of detecting its prey and patches with heterospecific ( F. occidentalis ) and conspecific predators through its diet-based-understanding of chemical cues. Explanations for the olfactory response and foraging behavior of N. californicus are discussed.

Population structure and genetic diversity in Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae): is there a correlation between genetic and geographic proximity?

Gynaikothrips uzeli (Thysanoptera: Phlaeothripidae) is a minuscule insect species, which forms galls, is subsocial, and parthenogenetic. It is associated with Ficus benjamina L. (Moraceae) and has a pantropical occurrence. The paucity of genetic studies on the order Thysanoptera led us to use inter-simple sequence repeat molecular marker to assess intra- and inter-gall, as well as intra- and inter-site, genetic variability and population structure of G. uzeli. Analyses indicated low genetic variability, probably related to haplodiploidy, genetic drift, the galling habit, and the low dispersal ability of G. uzeli. Populations were highly structured, with higher variation within populations than among them. Geographic distance does not appear to affect structure and genetic diversity, the latter being influenced by G. uzeli's bioecological traits, by numerous introductions during a short period, and by a possible recent, common ancestry.

SURVEY AND POPULATION DENSITY OF IMPORTANT INSECTS INFESTING CICHORIUM INTYBUS L. PLANTS DURING TWO SUCCESSIVE SEASONS AT QALUBIA GOVERNORATE , EGYPT

Survey of dominant insects occurred on Cichorium intybus , Asteraceae and their abundance were carried out throughout two successive seasons 2009/2010 and 2010/2011 at Qalubia governorate. The results showed that there are twelve insect species belonging to four orders and nine families were dominant on Chicory plant they were: Order : Diptera { Family Agromyzidae (Liriomyza trifolii (Burg) ,and Family Anthomyidae (Pegomia mixta (Witt.), Order: Hemiptera {Family Aleyrodidae Bemisia tabaci (Genn) , Family Aphididae (Aphis craccivora (Koch) , Aphis gossypii (Glover), and Myzus persicae (sulzer) , Family Cicadellidae (Empoasca spp.), Family Pentatomidae (Nezara viridula) and Family pseudococcidae (Planococcus sacchara (Cockerell), Order Lepidoptera { Family Noctuidae (Agrotis ipsilon (H.) and Spodoptera littoralis (Boisd.) and Order Thysanoptera { Family Thripidae (Thrips tabaci (lind) Population density of five insects infesting Chicory plants C. intybus L. was estimated during 2009 /2010 in the first season and the second season2010 /2011 , the study was insects studied were : L.trifolii ., B. tabaci ., A. gossypii, Empoasca spp., Th. tabaci .The obtained results showed that the white fly B.tabaci recorded the highest number (278.5 and 405.9 individuals / 5 leaves) followed by A. gossypii (2001and 238.7 individuals/5 leaves), Thrips tabaci (117.5 and 165.1 individuals /5 leaves), Empoasca spp (83.7 and 114.6 individuals / 5 leaves) and Liriomyza trifolii (74.8 and 107.6 individuals |5 leaves) during first and second season, respectively.

Innate responses to putative ancestral hosts: is the attraction of Western flower thrips to pine pollen a result of relict olfactory receptors?

Pollinophagy is widely documented in the order Thysanoptera, with representative individuals from six of the nine divergent families known to feed on pollen. Various pollens of the genus Pinus increase the development time, fecundity, longevity, and settling preference of Western Flower Thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Certain species of flower thrips discriminate among pollen types, but no studies have elucidated the olfactory cues that play a role in their pollen preferences. In this study, the volatile organic compounds emitted by pollens of the genus Pinus were elucidated. Various chemicals from pollen headspace elicited electrophysiological responses from WFT antennae. The compound (S)-(-)-verbenone, identified in pollen headspace, attracted WFT in a 4-arm olfactometer. This compound has potential for use in integrated pest management programs against the pest. We present the hypothesis that this polyphagous insect may have retained ancestral ‘relict’ olfactory receptors through the course of evolution, to explain this attraction to pine pollen. This attraction has allowed the insect to find and exploit an unusual nutrient source that significantly increases its fitness. The study demonstrates how fossil record analysis and subsequent evolutionary knowledge can aid in explaining possibilities as to why some insects sense and respond to chemicals that would otherwise seem peculiar to their ecology, allowing insight into the evolutionary forces that may shape insect olfactory systems over time.Electronic supplementary materialThe online version of this article (doi:10.1007/s10886-014-0450-0) contains supplementary material, which is available to authorized users.

Cross-resistance, the stability of acetamiprid resistance and its effect on the biological parameters of cotton mealybug,Phenacoccus solenopsis(Homoptera: Pseudococcidae), in Pakistan

Acetamiprid is a neonicotinoid insecticide that is effective against both soil and plant insects, including insects of the orders Lepidoptera, Coleoptera, Homoptera and Thysanoptera. In order to estimate the effects associated with insecticide exposure and devise better pest management tactics, a field population of Phenacoccus solenopsis was exposed to acetamiprid in the laboratory. Subsequently, cross-resistance and the effects of acetamiprid on the biological parameters of P. solenopsis were investigated. Following five rounds of selection with acetamiprid, P. solenopsis developed a 315-fold greater resistance to this chemical compared with an unexposed control population. The selected population also demonstrated very high to moderate cross-resistance to other tested insecticides. Furthermore, acetamiprid resistance remained unstable when the acetamiprid-selected population was not exposed for a further five generations. The acetamiprid-selected population had a relative fitness of 0.22, with significantly lower survival rate, pupal weight, fecundity, percentage hatching, net reproductive rate, intrinsic rate of natural increase, biotic potential and mean relative growth rate, with prolonged male and female nymphal duration, developmental time from egg to female adult and male and female longevity compared with the control population. P. solenopsis biological parameters are greatly affected by acetamiprid, and it is of significant cost for the insects to counter these effects. This study will be a valuable source of information for further understanding of acetamiprid resistance and for assisting the development of resistance management programmes.

Coupling scanning electron microscopy with DNA bar coding: a novel approach for thrips identification

The small size and cryptic nature of thrips pests often make their monitoring and the identification process difficult. With the aim to obtain accurate identification of various pest species in the order Thysanoptera, a pilot study was conducted on an invasive thrips species Scirtothrips dorsalis Hood in Florida. The specific objective of this pilot study was to assess if the thrips specimens processed to be observed under scanning electron microscopy (SEM) can be further utilized for DNA based assays. Larvae and adults of S. dorsalis were subjected to traditional morphological identification using high resolution SEM prior to their DNA extraction. Sequence results of both mtCO1 and ITS rDNA of individual larva and adult S. dorsalis were found to be in agreement with the taxonomic identification conducted using SEM and each result confirmed the other technique. Our results suggest that steps involved during specimen preparation and observation under SEM does not impact DNA analysis of the sample. The two techniques together could be used for the correct identification of various thrips species using the same specimen. The proof of concept was further tested on three other important thrips species Frankliniella occidentalis (Pergande), F. schultzei (Trybom) and Thrips palmi Karny, which confirmed the robustness of the technique. The technique has broader significance for different areas under entomological sciences especially medical, forensic and taxonomic studies where the samples put under a high beam of ions for investigation are often required for DNA analysis.

Faba Beans are Not a Good Trap Crop for Thrips (Thysanoptera: Thripidae) in Snow Peas in Guatemala

Snow peas intercropped with faba beans in the Guatemalan highlands did not show a reduction in thrips densities compared to snow peas in monoculture, and faba bean does not appear to function as a trap crop. Thrips species composition differed markedly on each host, which may largely explain the results. Thrips tabaci was predominant on snow peas, while Frankliniella occidentalis was the main species on faba beans. El cultivo de arveja china en asocio con haba en el altiplano de Guatemala no produjo reduccion significativa de trips comparado con arveja china en monocultivo. No hubo evidencia que el haba funcione como cultivo trampa. La composicion de especies de trips mostro diferencias marcadas entre hospederos, lo cual ayuda a explicar los resultados. La especie predominante en arveja china fue Thrips tabaci mientras que la especie principal en haba fue Frankliniella occidentalis . View this article in BioOne

Alkaloid metabolism in thrips-Papaveraceae interaction: Recognition and mutual response

Frankliniella occidentalis (Pergande), the Western Flower Thrips (WFT), is a polyphagous and highly adaptable insect of the order Thysanoptera. It has a broad host range but is rarely found on Papaveraceae, which might be due to deterrent effects of alkaloids present in most species of this family. In order to test the adaptive potential of WFT, we investigated its interaction with two Papaveraceae offered as sole feeding source. We found that WFT are able to live and feed on leaves of Eschscholzia californica and Chelidonium majus. Both plants respond to thrips feeding by the enhanced production of benzophenanthridine alkaloids. Furthermore, cell cultures of E. californica react to water insoluble compounds prepared from adult thrips with enhanced alkaloid production. During feeding, WFT take up benzophenanthridine alkaloids from either plant and from an artificial feeding medium and convert them to their less toxic dihydroderivatives. This was shown in detail with sanguinarine, the most cytotoxic benzophenanthridine. A similar conversion is used in plants to prevent self-intoxication by their own toxins. We conclude that WFT causes a phytoalexin-like response in Papaveraceae, but is able to adapt to such host plants by detoxification of toxic alkaloids.

Thrips (Insecta, Thysanoptera) of Iran: a revised andupdated checklist.

In Iran, as a result of recent changes in nomenclature 201 species and one species group of the insect Order Thysanoptera, are here listed in 70 genera and five families. In considering species listed previously from this country, the presence of 7 species is considered not confirmed, and 12 species are excluded from the Iranian list. Problems in the study of Iranian Thysanoptera are discussed briefly.

<span lang="EN-US"><span style="font-family: 'Times New Roman'; font-size: small;">Order Thysanoptera Haliday, 1836. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013) </span></span>

The world fauna of the insect Order Thysanoptera continues to be poorly sampled, with the tropical and subtropical areas of the southern continents inadequately surveyed (Mound 2014), and an almost complete lack of knowledge of the thrips fauna of New Guinea. In Australia, the number of described thrips species has increased from 400 to over 800 in 10 years, published largely in Zootaxa (Mound 2011a; Mound & Masumoto, 2005 & 2009; Mound & Tree, 2011). The number of described thrips species worldwide has increased 1.3% between 2011 (Mound 2011b) and 2013, and the other geographic areas responsible for this descriptive activity are China and South America. However, these numbers do not reflect the numbers of employed or experienced taxonomists, with the major international collections in Frankfurt, London, San Francisco and Washington no longer employing any thrips specialists.

Austral Thysanoptera: 100 years of progress

AbstractAn overview of the present state of knowledge of the insect order Thysanoptera in the four southern continents is provided. Knowledge of thrips biology and host associations has increased considerably in Australia, but not in the other three areas. The rich fauna of South America, particularly the southern areas, remains poorly explored, and faunal relationships across the Austral regions are not well documented.

Galling insects associated with Haloxylon spp. (Bunge) in Abu Dhabi, United Arab Emirates

This article introduces the arthropods that induce galls or are associated with galls in two plant species (Haloxylon persicum and Haloxylon salicornicum) in the Emirate of Abu Dhabi, United Arab Emirates. In connection with a baseline survey conducted to establish species knowledge to assess the habitat and diversity of the flora and fauna in proposed Houbara bustard (Chlamydotis (undulata) macqueeni) release sites of the Western Region of Abu Dhabi, Emirate. The galls were collected and studied to understand the gall-associated arthropods. In the current observation, four different types of galls were observed from stem and leaf portion of the two plant species: Swollen galls and flower-like galls from H. persicum; flower-like galls and spike-like galls from leaves and stem of H. salicornicum. In the present study, we have additionally observed arthropods associated with plant galls from both species ofHaloxylon (gall-associated species). No attempts were made to classify them into further categories like gall inducers or parasitoids of gall-inhabiting insects. The taxon observed in the current study belong to different arthropod groups: 1) Arachnids: Acari and Araneae; 2) insect orders like Hymenoptera: Pteromalidae, Thysanoptera: Thripidae, Hemiptera: Psyllidae, Pseudococcidae, Diptera and Lepidoptera: Pyralidae. Key words: Biodiversity, Haloxylon persicum, Haloxylon salicornicum, gall inducers, inquilines, gall associates, Western Region.

Demographic parameters of Neoseiulus barkeri (Acari: Phytoseiidae) fed on Thrips tabaci (Thysanoptera: Thripidae)

Thrips tabaci Lindeman is a serious pest of cucumber and onion in field and greenhouse conditions in Iran. Neoseiulus barkeri Hughes is an indigenous biological control agent in west of Iran on cucumber and maize that preys on spider mites and T. tabaci and can prevent the outbreak of them. In this study, the demographic parameters of the Iranian population of N. barkeri were determined using 1 st instar larvae of T. tabaci as prey under laboratory conditions at 30±1°C,65±5% RH and photoperiod 8:16 h (D:L). The results showed that N. barkeri successfully developed on 1 st instars larvae of T. tabaci . The developmental times for egg, larva, protonymph, deutonymph and all immature stages were 1.37, 1.03, 1.54, 1.71 and 5.68 days, respectively. Also, 96.66% of eggs hatched and the survival rate for the movable immature stages were 100%. Total prey consumption by protonymphs, deutonymphs and adult female was 2.70, 3.57 and 75.85 individuals, respectively. Adult longevity of the male was recorded as 14.36 days while the females lived longer (20.17 days). The female ratio was 0.62%. The intrinsic rate of increase ( r m ) and the net reproductive rate ( R 0 ) were 0.252 day -1 and 18.70 female offspring, respectively. Our results showed that N. barkeri could be considered as a biological agent for the control of T. tabaci on cucumber. Expanding knowledge on the biological parameters of this predatory mite can help to increase the use of this indigenous biological agent for the control of T. tabaci on cucumber.

A Male-Predominant Cuticular Hydrocarbon, 7-Methyltricosane, is used as a Contact Pheromone in the Western Flower Thrips Frankliniella occidentalis

In a laboratory bioassay, adult female Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) spent more time near filter paper disks that had been exposed to adult males than near unexposed disks; this effect was not observed on disks exposed to adult females. The response could only partly be explained by the known male-produced aggregation pheromone, neryl (S)-2-methylbutanoate, suggesting the presence of an unknown male-produced compound. In gas chromatography/mass spectrometry analyses, 7-methyltricosane was detected on disks exposed to males, but not on disks exposed to females. Extracts of cuticular lipids also showed relatively large amounts of 7-methyltricosane on males, whereas only trace amounts were found on females and none on larvae. Bioassays of synthetic 7-methyltricosane showed that adults responded only after contact. The response to this compound was clearly different from that to n-tricosane or hexane-only controls. Females that contacted 7-methyltricosane on glass beads stayed in the vicinity and frequently raised the abdomen, a behavior that rejects mating attempts by males. Males stayed in the vicinity and wagged the abdomen sideways, a behavior used in fighting between males. This is the first identification of a contact pheromone in the order Thysanoptera.

New Record of Grasshopper (Orthoptera: Acrididae & Romaleidae) Defoliators and Population Dynamics of Insects on Crops ofHeliconiaspp in the Amazon

Despite the expansion of floriculture, little is known about insects associated to this crop in northern Brazil. The objective was to identify the main species of defoliator grasshoppers, associated to crops of Heliconia spp. in the northeastern region of State of Pará, Brazil , in the municipalities of Castanhal, Belém and Benevides, from Aug 2004 to Mar 2005. Representatives with higher abundances in these municipalities were the orders Coleoptera, Thysanoptera, Hemiptera and Orthoptera. The collected species of Orthoptera were Cornops frenatum frenatum (Marshall) and Eutropidacris cristata L. (Orthoptera: Acrididae), Prionolopha serrata L. and Chromacris speciosa Thunberg (Orthoptera: Romaleidae), which present a substantial potential to damage heliconias crop in northeastern Pará, Brazil.

Dissecting the Mode of Maize Chlorotic Mottle Virus Transmission (Tombusviridae: Machlomovirus) by <I>Frankliniella williamsi</I> (Thysanoptera: Thripidae)

Maize chlorotic mottle virus (MCMV) (Tombusviridae: Machlomovirus) has been recorded in Hawaii (Kauai Island) since the early 1990s and has since become one of the most widespread corn viruses in the Hawaiian Islands. In the United States Mainland, MCMV has been reported to be transmitted by six different species of chrysomelid beetles, including the western corn rootworm, Diabrotica virgifera virgifera LeConte. However, none of these beetle species have been reported in Hawaii where the corn thrips, Frankliniella williamsi Hood (Thysanoptera: Thripidae) has been identified to be the main vector. In this study, we developed leaf disk transmission assays and real time reverse transcription-polymerase chain reaction to examine the mode of MCMV transmission by the corn thrips. We showed that thrips transmitted the virus with no evidence for latent periods. Both larvae and adults transmitted the virus for up to 6 d after acquisition, with decreasing rates of transmission as time progressed. There was no evidence that adult thrips that acquired the virus as larvae were competent vectors. Real time reverse-transcription polomerase chain reaction assays showed that viral load was depleted from the vector's body after thrips had access to healthy plant tissue. Depletion of viral load was also observed when thrips matured from larvae to adults. Thrips were able to transmit MCMV after acquisition and inoculation access periods of 3 h. However, transmission efficiency increased with longer acquisition and inoculation access periods. Taken altogether our data suggests that corn thrips transmit MCMV in a semipersistent manner. To our knowledge, this is the first work reporting evidence of a plant virus transmitted semipersistently by thrips.