Pollen-feeding in thrips (Insecta: Thysanoptera)

Eight species of thrips in three families fed readily on individual grains of pollen. Feeding behaviour is described. Thrips fed on the contents of the grains, but left the pollen wall. In Thrips fuscipennis Halid., the feeding time per grain increased in direct proportion to grain volume up to a grain volume of about 60,000 μm'. but then began to level off. Large grains and tetrads were usually abandoned before all the contents were removed. Mean feeding times ranged from 3 s to 120 s per grain.
Thrips appeared to have alternate periods of feeding and non-feeding. Drops of fluid were sometimes deposited from the end of the abdomen after non-feeding periods. Large amounts of pollen can be consumed; one thrips fed on more than 100 pollen grains in less than 15 min. Pollen-feeding appears to be widespread among flower thrips. The implications for pollination ecology are discussed.     

Egg-hatching in thrips (Insecta: Thysanoptera)

The hatching of eggs of thrips (Insecta: Thysanoptera) was investigated for three thripids, Thrips tabuci Lindeman, Frankliniella fusca (Hinds) and Kakothrips pisivorus (Westwood), and for a phlaeothripid, Haplothrips leucanthemi (Schrank). An embryonic cuticle with hatching spines was found in these thripids, and distinct lids were discovered on eggs of the first two species of thripid. At least one species of phlaeothripid lacks hatching spines. Haplothrips leucanthemi eggs did not have a distinct lid; the eggs split along lines of weakness following the pattern left by the follicle cells.
Kakothrips pisivorus was observed and photographed during hatching. The larva emerged most of the way out of the egg while still enclosed in embryonic cuticle. Expansion and contraction of the pronotum split the embryonic cuticle, which was then forced down to the tip of the abdomen by peristaltic movements, freeing in turn the antennae and legs. The embryonic cuticle was left poking out of the oviposition hole.     

Bizarre flagellum of thrips spermatozoa (Thysanoptera,Insecta)

The flagellum of the thysanopteran spermatozoon has been examined by electron microscopy and computer-aided image analysis. The flagellum consists of 27 microtubular elements that probably are formed as outgrowths from three separate basal bodies. Nine of the elements are normal microtubular doublets that carry dynein arms and nine are doublets without dynein arms. The remaining nine elements are microtubular singlets that apparently bear dynein arms and have the same appearance as A-subtubules of microtubular doublets. The 27 elements are arranged in a fixed pattern that consists of nine groups, each of which begins with a microtubular singlet and ends with an arm-less microtubular doublet. Computer-aided image analysis has shown that the A-subtubules of the doublets and the microtubular singlets have lumens with very similar patterns. The sperm tail is known to have some motility; it generates fast waves running along its length. The amalgamated axonemes hence act as a functional flagellum. The thysanopteran sperm tail is the only type of flagellum known to us that consists of microtubules in a highly asymmetric array.     

New findings on sperm ultrastructure in thrips (Thysanoptera, Insecta)

Sperm ultrastructure of several species in each of the two suborders of Thysanoptera Tubulifera and Terebrantia shows a distinctive and unusual architecture. Members of the whole order share a bizarre axoneme consisting of 27 microtubular elements derived from the amalgamation of 3 (9+0) axonemes present in each spermatid at the beginning of spermiogenesis. The reciprocal shifting of these axonemes along the length of the sperm, together with their possible shortening and overlapping for short distances, could explain why in some species it is never possible to observe the complete set of 27 microtubular elements in any one cross section. Tubuliferan sperm have a small elliptical (in cross section) acrosome extending the length of the sperm. In Bolothrips insularis and Compsothrips albosignatus this structure is larger and is associated with an external, flattened vesicle throughout its length. Terebrantian sperm lack an acrosome, but display for half their length a dense body running parallel to the nucleus. The sperm, in members of this suborder, are also characterized by possession of a small mitochondrion and by the unusual bilobed outline of cross sections through the anterior sperm region, with the nucleus located in one of the two lobes. Structures serving to anchor sperm to the inner surface of the cyst cell have been observed at their anterior tips in the testes of tubuliferans. In B. insularis, an anterior appendage is formed in immature sperm and is maintained in the mature spermatozoon parallel to its long axis in the most anterior region. Such an anchoring structure has not been observed in sperm of the terebrantian species examined, probably because the testis of terebrantians contains only a single cyst of developing gametes.     

Systematics of thrips (Insecta: Thysanoptera) associated with mosses

The systematic relationships between phlaeothripine Thysanoptera species suggest that moss-feeding is an uncommon and highly derived habit. It is restricted to a single sub-tribe, the Williamsiellina, which includes two genera, Lissothrips with 17 species and Williamsiella with 25 species. Although widely distributed, these genera are particularly common in the New World. Structural variation within and between populations of these small wingless insects is discussed and the conclusion reached that species cannot be defined satisfactorily in the common North American L. muscorum -group without experimental rearing. Trisclerothrips is synonymized with Lissothrips , and Prolissothrips, Microlissothrips and Phthirothrips are synonymized with Williamsiella . One specific synonym is established, and four new species are described: L. clayae from Trinidad, L. okajimai from Japan, W. tambopata from Peru and W. zaps from Fiji.     

Ultrastructural analysis of the aberrant axoneme morphogenesis in thrips (Thysanoptera, Insecta)

Thrips spermiogenesis is characterized by unusual features in the differentiating spermatid cells. Three centrioles from which three individual short flagella are initially assembled, make the early spermatid a tri-flagellated cell. Successively, during spermatid maturation, the three basal bodies maintain a position close to the most anterior end of the elongating nucleus, so that the three axonemes are progressively incorporated in the spermatid cytoplasm, where they run in parallel to the main nuclear axis. Finally, the three axonemes amalgamate to form a microtubular bundle. The process starts with the formation of rifts at three specific points in each axonemal circumference, corresponding to sites 1,3,7 and leads to the formation of 9 microtubular rows of different length, i.e. 3 "dyads", 3 "triads" and 3 "tetrads". In the spermatozoon, the nucleus, the mitochondrion and the bundle of microtubules are arranged in a helicoidal pattern. The elongation of the spermatozoon is allowed by the deep anchorage of the spermatid to the cyst cell through a dense mass of material which, at the end of spermiogenesis, becomes a long anterior cylindrical structure. This bizarre "axoneme" does not show any trace of progressive movement but it is able to beat. According to the presence of dynein arms, sliding can take place only within each row and not between the rows. The possible molecular basis underlying the peculiar instability of thrips axonemes is discussed in light of the present knowledge on the organization of the axoneme in mutant organisms carrying alterations of the tubulin molecule.     

Data on the thrips (Insecta,Thysanoptera) fauna of Central Yakutia

A list of 29 species of Thysanoptera belonging to three families from Central Yakutia is given.     

New records of thrips (Thysanoptera) species in Brazil

This study reports four thrips species from Brazil for the first time: the terebrantians Aptinothrips rufus (Haliday) and Echinothrips caribbeanus Hood; and the tubuliferans Androthrips ramachandrai Karny and Gynaikothrips uzeli (Zimmermann). New data about biological aspects of some of these new records are presented.     

Wolbachia-mediated parthenogenesis in the predatory thrips Franklinothrips vespiformis (Thysanoptera: Insecta)

Wolbachia are bacterial endosymbionts in arthropods and filarial nematodes. They cause thelytoky, which is a form of parthenogenesis in which females produce females without males, in hymenopteran insects. Infection of this parthenogenesis-inducing Wolbachia has been restricted to the order Hymenoptera, but was found in another insect order, Thysanoptera. A parthenogenetic colony of a predatory thrips Franklinothrips vespiformis (Aeolothripidae) possessed B-group Wolbachia. Male progeny were produced from this thrips by heat and tetracycline treatments. Males produced motile sperm, which were transferred to the female spermatheca by mating. However, the mating did not affect the sex ratios of the next generation, suggesting that the sperm do not fertilize the eggs.     

Phylogeny of thrips (Insecta: Thysanoptera) based on five molecular loci

The order Thysanoptera (Paraneoptera), commonly known as thrips, displays a wide range of behaviours, and includes several pest species. The classification and suggested relationships among these insects remain morphologically based, and have never been evaluated formally with a comprehensive molecular phylogenetic analysis. We tested the monophyly of the suborders, included families and the recognized subfamilies, and investigated their relationships. Phylogenies were reconstructed based upon 5299 bp from five genetic loci: 18S ribosomal DNA, 28S ribosomal DNA, Histone 3, Tubulin‐alpha I and cytochrome oxidase c subunit I. Ninety‐nine thrips species from seven of the nine families, all six subfamilies and 70 genera were sequenced. Maximum parsimony, maximum likelihood and Bayesian analyses all strongly support a monophyletic Tubulifera and Terebrantia. The families Phlaeothripidae, Aeolothripidae, Melanthripidae and Thripidae are recovered as monophyletic. The relationship of Aeolothripidae and Merothripidae to the rest of Terebrantia is equivocal. Molecular data support previous suggestions that Aeolothripidae or Merothripidae could be a sister to the rest of Terebrantia. Four of the six subfamilies are recovered as monophyletic. The two largest subfamilies, Phlaeothripinae and Thripinae, are paraphyletic and require further study to understand their internal relationships.     

Modern thrips families Thripidae and Phlaeothripidae in Early Cretaceous amber (Insecta: Thysanoptera)

Two specimens of Thysanoptera with forked sensilla on third and fourth antennal segments were described from the Lebanese Neocomian and the Spanish Albian ambers, and attributed to the new genus Tethysthrips n. gen. in the family Thripidae Stevens 1829. One specimen with a tubular tenth abdominal segment was also discovered in the Lebanese Neocomian amber, and attributed to the new genus Rohrthrips n. gen. belonging to the family Phlaeothripidae Uzel 1895. Thripidae and Phlaeothripidae are nowadays the most species-rich families of Thysanoptera. The present discoveries of Early Cretaceous fossils show how diversified these families and thrips already were at that time. Moreover, this tubuliferan Rohrthrips specimen has plesiomorphies no longer present in the recent genera, in particular on the wings. Therefore it brings new insight in the evolution of Tubulifera.     

The Jurassic thrips Liassothrips crassipes (Martynov, 1927) and its taxonomic position in the order Thysanoptera (Insecta)

The Late Jurassic thrips Liassothrips crassipes (Martynov) is redescribed, and its taxonomic position discussed. It is shown that the male genitalia of Liassothrips are similar to the terebrantian type, while the female genitalia resemble the tubuliferan type. Therefore, the Liassothripidae shows the possible evolutionary pathway of tubuliferan thrips. Liassothrips is treated as the oldest known member of the suborder Tubulifera (previously known beginning from the Eocene), the ancestors of which belonged to the family Aeolothripidae (Terebrantia) rather than Thripidae.     

Habitat‐specific population structure in native western flower thrips Frankliniella occidentalis (Insecta,Thysanoptera)

Invasions by pest organisms are among the main challenges for sustainable crop protection. They pose a serious threat to crop production by introducing a highly unpredictable element to existing crop protection strategies. The western flower thrips Frankliniella occidentalis (Insecta, Thysanoptera) managed to invade ornamental greenhouses worldwide within < 25 years. To shed light on possible genetic and/or ecological factors that may have been responsible for this invasion success, we studied the population genetic structure of western flower thrips in its native range in western North America. Analysis of nucleotide sequence variation and variation at microsatellite loci revealed the existence of two habitat‐specific phylogenetic lineages (ecotypes) with allopatric distribution. One lineage is associated with hot/dry climates, the second lineage is restricted to cool/moist climates. We speculate that the ecological niche segregation found in this study may be among the key factors determining the invasion potential of western flower thrips.     

Identification of the terebrantian thrips (Insecta,Thysanoptera) associated with cultivated plants?in?Java,Indonesia

An illustrated identification key is provided to 49 species of Thysanoptera, Terebrantia that have been found in association with cultivated plants in Java. This is the first published identification system to this group of insects from Indonesia, and includes 15 species not previously recorded from Indonesia, and a further three species not previously recorded from Java. A table is provided indicating the plants from which thrips were taken.     

Isolation and characterization of six polymorphic microsatellite loci in the western flower thrips Frankliniella occidentalis (Insecta,Thysanoptera)

Highly polymorphic microsatellite markers can provide important demographic information on founder events and range expansion following initial introduction of invasive insect species. Six microsatellite loci were isolated from an enriched DNA library in order to study the invasion patterns of the western flower thrips, Frankliniella occidentalis. All loci tested were found to be polymorphic and successfully amplified in all individuals. The number of alleles per locus ranged from five to nine and heterozygosity ranged from 45 to 73%. Some of the loci were also successfully amplified in other thrips species.     

A novel mitochondrial genome architecture in thrips (Insecta: Thysanoptera): extreme size asymmetry among chromosomes and possible recent control region duplication

Background

Multipartite mitochondrial genomes are very rare in animals but have been found previously in two insect orders with highly rearranged genomes, the Phthiraptera (parasitic lice), and the Psocoptera (booklice/barklice).

Results

We provide the first report of a multipartite mitochondrial genome architecture in a third order with highly rearranged genomes: Thysanoptera (thrips). We sequenced the complete mitochondrial genomes of two divergent members of the Scirtothrips dorsalis cryptic species complex. The East Asia 1 species has the single circular chromosome common to animals while the South Asia 1 species has a genome consisting of two circular chromosomes. The fragmented South Asia 1 genome exhibits extreme chromosome size asymmetry with the majority of genes on the large, 14.28 kb, chromosome and only nad6 and trnC on the 0.92 kb mini-circle chromosome. This genome also features paralogous control regions with high similarity suggesting a very recent origin of the nad6 mini-circle chromosome in the South Asia 1 cryptic species.

Conclusions

Thysanoptera, along with the other minor paraenopteran insect orders should be considered models for rapid mitochondrial genome evolution, including fragmentation. Continued use of these models will facilitate a greater understanding of recombination and other mitochondrial genome evolutionary processes across eukaryotes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1672-4) contains supplementary material, which is available to authorized users.     

DNA条形码技术在田间常见蓟马种类识别中的应用

蓟马类害虫种类多、 体型小, 传统的形态学鉴定方法难以快速准确识别。本研究利用DNA条形码通用型引物, 以我国田间常见的25种蓟马为靶标扩增其线粒体DNA细胞色素C氧化酶亚基Ⅰ (mitochondrial cytochrome c oxidase subunit Ⅰ gene, mtDNA COⅠ) 基因 (约650 bp), 通过对靶标片段碱基序列的测序及比对分析, 以邻接法 (NJ法) 构建系统发育树, 并以Kimura双参数模型计算种内、 种间遗传距离。结果表明： 聚类分析与形态学鉴定结果一致, 表现为较长的种间分支和较短的种内分支, 每个单系分支对应一个物种, 同一物种不同单倍型的最初分支自展值均为100%。25种蓟马的种内平均遗传距离为0.0027, 种间平均遗传距离为0.2757, 种间遗传距离为种内遗传距离的102.1倍; 而且种内、 种间遗传距离没有重叠区域。结果说明基于COⅠ基因的DNA条形码技术可以用于不同种类蓟马的快速准确鉴别。     

Application of DNA barcoding technology for species identification of common thrips ( Insecta: Thysanoptera) in China

蓟马类害虫种类多、体型小,传统的形态学鉴定方法难以快速准确识别.本研究利用DNA条形码通用型引物,以我国田间常见的25种蓟马为靶标扩增其线粒体DNA细胞色素C氧化酶亚基Ⅰ(mitochondrial cytochrome coxidase subunit Ⅰ gene,mtDNA CO Ⅰ)基因(约650 bp),通过对靶标片段碱基序列的测序及比对分析,以邻接法(NJ法)构建系统发育树,并以Kimura双参数模型计算种内、种间遗传距离.结果表明:聚类分析与形态学签定结果一致,表现为较长的种间分支和较短的种内分支,每个单系分支对应一个物种,同一物种不同单倍型的最初分支白展值均为100％.25种蓟马的种内平均遗传距离为0.0027,种间平均遗传距离为0.2757,种间遗传距离为种内遗传距离的102.1倍;而且种内、种间遗传距离没有重叠区域.结果说明基于COⅠ基因的DNA条形码技术可以用于不同种类蓟马的快速准确鉴别.     

Wolbachia 在花蓟马中的感染及其与寄主线粒体DNA多样性的关系

【目的】Wolbachia 是一种广泛存在于节肢动物中的胞内共生细菌,影响寄主的生物学特性。花蓟马 Frankliniella intonsa (Trybom)是重要的害虫,对农作物及园林植物造成危害。本研究旨在明确 Wolbachia 在花蓟马中的感染情况,并分析其与寄主线粒体DNA多样性的关系。【方法】采集中国境内26个花蓟马自然种群,运用多位点序列分型技术（multilocus sequence typing, MLST）对其体内 Wolbachia 感染率及株系进行分析;利用线粒体 COI 分子标记研究花蓟马的遗传分化及遗传多样性;通过比较感染和未感染 Wolbachia 个体 COI 数据,探究 Wolbachia 多样性与寄主线粒体DNA多样性之间的关系。【结果】花蓟马中 Wolbachia 的感染率为0%~60%,共检测到5种 Wolbachia 株系（wFint1,wFint2,wFint3,wFint4及wFint5）,均属于B大组且形成一个单系群。Wolbachia感染情况与这些花蓟马种群（除CC, GZ, TA和TY, N<5）的线粒体DNA多样性相关,表现为不感染 Wolbachia 的种群中线粒体DNA单倍型多样性（Hd）与核苷酸多样性（Pi）均高于感染 Wolbachia 的种群,且 Wolbachia 感染率与 Hd 呈显著负相关（ P <0.05）。AMOVA分析表明花蓟马线粒体DNA遗传分化与Wolbachia 感染情况有关。【结论】 Wolbachia 可能在侵染花蓟马种群后出现遗传分化;Wolbachia 感染与寄主线粒体DNA多样性有关。     

New aspect of the “mycetome” of a thrips,Bactrothrips brevitubus Takahashi (Insecta: Thysanoptera)

Morphology and cytochemical properties of “mycetomes” are described in the developing oocytes and eggs of an idolothripine thrips, Bactrothrips brevitubus (Thysanoptera). The “mycetome” is an aggregation of numerous granules of various sizes. We found no membrane encapsulating the aggregation of granules. Two types of granules are distinguishable: the smaller ones filled with electron-dense material and the larger ones with inclusion of myelin-like structures. Each of the granules has a limiting membrane. The limiting membrane is a simple unit membrane but shows no characteristics of cell walls. No nucleoid or nucleoplasm is detected in the granules. The “mycetome” takes up dyes whose specific incorporation into lysosomes has been demonstrated. In addition, a high activity of acid phosphatase is demonstrated in the “mycetome.” These characteristics apparently indicated that the “mycetome” of Bactrothrips brevitubus is an aggregation of lysosomes but not a clump of microorganisms. Thus we propose that the structure being regarded as the mycetome should be renamed the “lysosomal aggregation.” © 1994 Wiley-Liss, Inc.