Assessment of loci for DNA barcoding in the genus Thrips (Thysanoptera:Thripidae)

Identification of the juveniles of economically important thrips species on imports by morphology alone can be challenging and culturing is usually required. In the case of EU quarantine species such as Thrips palmi, rapid and accurate identification is essential. DNA barcoding using the Cytochrome oxidase I (COI) gene has become a popular technique for species identification; however, in some invertebrate genera COI has been shown to provide insufficient variability for species discrimination. This study presents a comparison of five different loci to investigate their ability to discriminate a small number of Thrips species. All five loci discriminated the species by neighbour-joining tree and varying degrees of discrimination were determined upon further investigation of the intraspecific and interspecific distances. Two distinct COI clades were observed for T. Palmi and judged to be COI haplotypes when data from the other four additional loci and geographical collection data were taken into consideration. COI was shown to provide sufficient variation to be used in future DNA barcoding efforts within the genus Thrips.     

DNA Barcode Analysis of Thrips (Thysanoptera) Diversity in Pakistan Reveals Cryptic Species Complexes

Although thrips are globally important crop pests and vectors of viral disease, species identifications are difficult because of their small size and inconspicuous morphological differences. Sequence variation in the mitochondrial COI-5ʹ (DNA barcode) region has proven effective for the identification of species in many groups of insect pests. We analyzed barcode sequence variation among 471 thrips from various plant hosts in north-central Pakistan. The Barcode Index Number (BIN) system assigned these sequences to 55 BINs, while the Automatic Barcode Gap Discovery detected 56 partitions, a count that coincided with the number of monophyletic lineages recognized by Neighbor-Joining analysis and Bayesian inference. Congeneric species showed an average of 19% sequence divergence (range = 5.6% - 27%) at COI, while intraspecific distances averaged 0.6% (range = 0.0% - 7.6%). BIN analysis suggested that all intraspecific divergence >3.0% actually involved a species complex. In fact, sequences for three major pest species (Haplothrips reuteri, Thrips palmi, Thrips tabaci), and one predatory thrips (Aeolothrips intermedius) showed deep intraspecific divergences, providing evidence that each is a cryptic species complex. The study compiles the first barcode reference library for the thrips of Pakistan, and examines global haplotype diversity in four important pest thrips.     

Thrips (Thysanoptera) in the Meadows of Kaliningrad Province

The insect order Thysanoptera is one of the less known in Kaliningrad Province. In the course of investigations, plants were collected in May–September of 2013–2016 in the motley-grass communities from 22 localities in different landscape regions of Kaliningrad Province. From the plants in the laboratory a total of 1362 adults of 29 thrips species from three families of two suborders were collected. Thirteen species are recorded from Kaliningrad Province for the first time: Dendrothrips saltatrix, Mycterothrips consociatus, Odontothrips loti, O. meliloti, O. confusus, Platythrips tunicatus, Sericothrips bicornis, Thrips brevicornis, Th. nigropilosus, Th. pillichi, Th. trehernei, Haplothrips niger, and H. leucanthemi. Most of the species revealed are hortobionts, except for Mycterothrips consociatus and Dendrothrips saltatrix which live on deciduous trees. All the species are known from Poland; M. consociatus, O. meliloti, and Th. pillichi are not known from Lithuania. The largest numbers of the species are associated with the plant families Fabaceae, Asteraceae, and Apiaceae; the most widely distributed in Kaliningrad Province are Thrips major, Th. tabaci, Th. fuscipennis, and Frankliniella intonsa.     

Thrips (Thysanoptera) identification using artificial neural networks

We studied the use of a supervised artificial neural network (ANN) model for semi-automated identification of 18 common European species of Thysanoptera from four genera: Aeolothrips Haliday (Aeolothripidae), Chirothrips Haliday, Dendrothrips Uzel, and Limothrips Haliday (all Thripidae). As input data, we entered 17 continuous morphometric and two qualitative two-state characters measured or determined on different parts of the thrips body (head, pronotum, forewing and ovipositor) and the sex. Our experimental data set included 498 thrips specimens. A relatively simple ANN architecture (multilayer perceptrons with a single hidden layer) enabled a 97% correct simultaneous identification of both males and females of all the 18 species in an independent test. This high reliability of classification is promising for a wider application of ANN in the practice of Thysanoptera identification.     

Thrips (Thysanoptera, Insecta) from the Rovno amber, Eocene of Ukraine

Seventy-six thrips were discovered in Rovno amber. Among these, 67 were identified to suborder, 52, to family, 45, to genus, and 41, to species level. In total, five species, six genera, five families, and two suborders are recorded. No undescribed taxa have been found so far. All the identified thrips, except those of the genus Phloeothrips, belong to fossil taxa, previously known only from the Baltic and Bitterfeld ambers. However, the composition of species in the Rovno amber is highly unusual due to domination of Praedendrothrips avus Priesner, 1924. This species, rare in the Baltic amber, constitutes 49% of all the Rovno records. Thus, the Rovno amber, in contrast to the Baltic and Bitterfeld ambers, is characterized by poor taxonomic diversity of thrips and presence of a clearly dominant species.     

A Trichodorus (Triplonchida: Trichodoridae) Nematode from Thrips (Thysanoptera: Panchaetothripinae)

A thrips insect Caliothrips sp. (Thysanoptera: Panchaetothripinae) from persimmon fruit (Ebenaceae: Diospyros sp.) from an unknown origin, possibly Asia, was intercepted in a passenger bag in November 2012 at the Peace Arch Border Crossing from Canada to Blaine, WA, by a USDA-APHIS-PPQ port inspector. Nematodes were attached to the abdomen of the female insect and sent to us in saline. Seven nematodes (five females, two males) were measured and these and others were processed for permanent slides. An adult female and a female juvenile were prepared for PCR. Morphologically these nematodes belonged to the Trichodorus sparsus group, and the 28S rDNA D2-D3 sequence showed greatest similarity to Trichodorus paragiennensis (94%) and T. giennensis (93%), with greatest morphological similarity to the latter species. Among other morphological differences, the innermost uterus width is wider than in related species. Trichodorus spp. are normally found in soil, so this is the first population seen in the atypical habitat of an insect. Morphological and molecular characteristics of Trichodorus sp. are presented, but a putative new species name is not currently advisable because of relatively poor condition of specimens. Ecological associations are also discussed.     

A New Method for Mounting Thrips (Thysanoptera) on Slides

Entomologists that frequently work with thrips often find mounting of their material by well known methods too complicated and slow. A new method is described here that is the shortest possible, and is still very reliable and safe in everyday work.     

Polymorphic microsatellite markers in Thrips hawaiiensis (Thysanoptera: Thripidae)

Thrips hawaiiensis (Morgan, 1913) is an important insect pest of fruits and vegetables. At present, it is primarily distributed in tropical and subtropical area. For a better understanding of the genetic makeup and migration patterns of T. hawaiiensis throughout the world, we isolated 11 novel polymorphic microsatellite loci from an enriched genomic library based on a biotin/streptavidin capture protocol. Genetic parameters were estimated on 80 individual thrips from two natural populations. The results showed that all 11 loci were highly polymorphic; the number of alleles ranged from six to 37, and nine loci demonstrated polymorphic information content (PIC) > 0.5. The observed (H _O) and expected (H _E) heterozygosities ranged from 0.350 to 0.925 and 0.307 to 0.952, respectively. Furthermore, only four locus/population combinations significantly deviated from Hardy–Weinberg equilibrium (HWE). These microsatellite markers have potential utility in population structure and gene flow studies of this species.     

Resistance to Thrips palmi (Thysanoptera: Thripidae) in beans

Resistance in beans, Phaseolus vulgaris L., to the melon thrips Thrips palmi Karny was studied under field conditions at two sites in Colombia. Genotypes were rated for resistance on the basis of visual damage scores, bean production ratings (a visual estimate of pod and seed set), and grain yields. Of 1,138 genotypes tested, only 60 (5.3%) were rated as resistant. Repeated testing allowed us to identify potential sources of resistance in five germplasm accessions (G 02402, G 02852, G 03177, G 03569, and G 04055), one commercial variety ('Brunca'), six elite breeding lines (A 216, DOR 714, EMP 486, FEB 115, FEB 161, and FEB 162), 41 recombinant inbred lines derived from the BAT 881 x G 21212 cross, and seven recombinant inbred lines derived from a cross between DOR 364 and BAT 477. Resistance was not associated with maturity, growth habit, pubescence, and seed color or seed size. In general, correlations between visual damage scores and bean production ratings and between damage scores and yield were high and significant meaning that selection on damage rating is useful to identify genotypes that may have tolerance as a mechanism of resistance. The continuous distribution of damage scores of 139 recombinant inbred lines suggested that the inheritance of resistance to the melon thrips might be quantitative. Overall, resistance levels in beans can be considered as moderate, because none of the genotypes tested received damage scores of <3 on a 1-9 scale and none was ever rated as highly resistant in terms of bean production ratings.     

Functional and Numerical Responses of Three Species of Predatory Phytoseiid Mites (Acari: Phytoseiidae) to Thrips flavidulus (Thysanoptera: Thripidae)

Phytoseiid mites are considered the most effective natural enemies of pest mites. They also have been shown to attack pest thrips. It is unknown, however, whether phytoseiid mites can reduce high densities of Thrips flavidulus (Bagnall). We addressed this question by the study of functional and numerical responses. The aim of this research was to evaluate the potential predation success of the adults of three predatory mites, Neoseiulus cucumeris (Oudemans), Neoseiulus barkeri (Hughes), and Euseius nicholsi (Ehara & Lee), against the first-instar of T. flavidulus in a climatic chamber at five different temperatures. The results showed that the functional responses of those predators reflected the Holling type II functional response and were density dependent and positively related to temperature. For the three predatory mites, predation and successful attack rates increased with increasing temperature up to 26°C, reducing afterward. Handling time had the opposite trend. Reproductive ability also increased with an increase in temperature and prey consumption.     

Transmission of capsicum chlorosis virus by Thrips palmi (Thysanoptera: Thripidae)

Applied Entomology and Zoology - Transmission efficiencies of capsicum chlorosis virus (CaCV) were investigated for four thrips species (Thysanoptera: Thripidae), Frankliniella occidentalis...     

中国小头蓟马属一新种记述（缨翅目：蓟马科）

记述我国蓟马科小头蓟马属1新种Microcephalothrips yanglingensis,sp.nov，模式标本保存在西北农林科技大学昆虫博物馆。     

中国率管蓟马属一新种记述(缨翅目:管蓟马科)

记述中国率管蓟马属1新种——海南率管蓟马Litotetothrips hainanensis,sp．nov．。模式标本保存于西北农林科技大学昆虫博物馆(NWSUAF)。     

Detection of Gene Flow from Sexual to Asexual Lineages in Thrips tabaci (Thysanoptera: Thripidae)

Populations of Thrips tabaci are known to have two sympatric but genetically isolated reproductive modes, arrhenotoky (sexual reproduction) and thelytoky (asexual reproduction). Herein, we report behavioral, ecological and genetic studies to determine whether there is gene flow between arrhenotokous and thelytokous T. tabaci. We did not detect significant preference by arrhenotokous males to mate with females of a particular reproductive mode, nor did we detect significant behavioral differences between arrhenotokous males mated with arrhenotokous or thelytokous females in their pre-copulation, copulation duration and mating frequency. Productive gene transfer resulting from the mating between the two modes was experimentally confirmed. Gene transfer from arrhenotokous T. tabaci to thelytokous T. tabaci was further validated by confirmation of the passage of the arrhenotokous male-originated nuclear gene (histone H3 gene) allele to the F₂ generation. These behavioral, ecological and genetic studies confirmed gene transfer from the sexual arrhenotokous mode to the asexual thelytokous mode of T. tabaci in the laboratory. These results demonstrate that asexual T. tabaci populations may acquire genetic variability from sexual populations, which could offset the long-term disadvantage of asexual reproduction.     

中国大蓟马属一新种记述(缨翅目:蓟马科)

记述中国蓟马亚科1新种：贵州大蓟马Megalurothrips guizhouensis,sp.nov.，模式标本保存在西北农林科技大学昆虫博物馆。     

中国花蓟马属一新种记述(缨翅目:蓟马科)

记述花蓟马属1新种--海南花蓟马 Frankliniella hainanensis Zheng et Feng,sp.nov..模式标本保存在西北农林科技大学昆虫博物馆.