Thrips Research Articles

Mitogenomics providing new insights into the phylogenetic structure of subfamily Panchaetothripinae (Thripidae: Terebrantia).

Complete mitochondrial genome of two species of subfamily Panchaetothripinae, Astrothrips tumiceps (16,467bp) and Monilothrips kempi (14,773bp) are generated by Next-Generation Sequencing Method. In this study, the detailed annotation of these mitogenomes as well as comparative analyses are carried out to explore the codon usage, gene composition, andphylogenetic relationship of subfamilies of family Thripidae. Moreover, thegene rearrangement of subfamily Panchaetothripinae of family Thripidaeis also studied. Both the mitogenomes featured by 37 genes including 13 PCGs, 22 tRNAs, 2 rRNAs and with single putative control region with a positive AT-skew and negative GC-skew. trnS1 without DHU arm in both species, trnV without DHU arm in M. kempi, and trnE without TΨC loop in As. tumiceps. Further, codon based comparative analysis depicted the existence of natural selection pressure on all the PCGs in all the subfamilies of family Thripidae. The phylogenetic analyses, using the Bayesian inference (BI) and Maximum likelihood (ML) supported the monophyly of two suborders and family Phlaeothripidae. The family Thripidae is recovered as paraphyletic and subfamily Panchaetothripinae is in sister relationship with family Aeolothripidae and Stenurothripidae rather than the other subfamilies of family Thripidae. The gene order of the order Thysanoptera is highly rearranged, while few members of the subfamily Panchaetothripinae showed similar gene order to family Stenurothripidae. Therefore, this study suggests that the phylogenetic relationship between the subfamily Panchaetothripinae and other families is uncertain, necessitating a whole genome-based study to clarify the position of Panchaetothripinae within the suborder Terebrantia.

Long-term memory in <i>Thrips tabaci</i> (Thysanoptera, Thripidae)

Microinsects are capable of associative learning and memory retention despite significant reduction in the number and size of neurons. Previously, the capabilities of Thrips tabaci (Thysanoptera, Thripidae) for associative learning and the formation of short-term memory have been demonstrated. In this study, an additional training session was added, as well as a time interval between them. Increasing the number of training sessions and spacing these out over time allowed us to demonstrate the persistence of memory traces for up to 24 hours. Thus, for the first time, the presence of consolidated forms of memory in the order Thysanoptera has been revealed.

Updated checklist of the order Thysanoptera in Colombia

We present here the first comprehensive checklist of Thysanoptera in Colombia. This study is based on a literature review, examination of specimens deposited in museums, and fieldwork conducted from 2012 to 2018 across various agroecosystems in the Andean, Caribbean, and Orinoco regions. Our study reports 38 new records of Thysanoptera for Colombia, bringing the total number of documented species to 183.

Diversified Roles of Insects in Essential Ecosystem through Pollination for Achieving Sustainable Goals

Pollination is an ecological process that involves the transfer of pollen from the male to the female part of the flower with the help of various abiotic and biotic pollen dispersal agents and is an essential pre-requisite for fertilization and fruit/seed dispersal. Insects constitute one of the primary groups of pollinating agents, as the association between insects and flowers is well established. As flowers radiated so did the mouthparts of the insects exploiting them. Various insect groups, which are of prime significance in the pollination of agricultural and horticultural crops mainly belong to the orders Hymenoptera (bees, ants and wasps), Diptera (flies, mosquitoes, fungus gnats, midges), Coleoptera (beetles and weevils), Lepidoptera (moths and butterflies), Thysanoptera (thrips), Hemiptera (bugs) and Neuropteran (lace wing flies). This work is mainly based on detailed and through observations/study made from various cash crops viz., Brassica nigra, Coriandrum sativum, Tagetes erecta and Helianthus annuus from North 24 Parganas of South Bengal region.

Insect taxa as biodiversity indicators at selected coastal landscape

For monitoring responses of insect arthropods to disturbance, a dataset of 1831 insects was considered. We studied faunal diversity of insects in terraces habitats located on the coast of Lebanon. Insects were sampled from 12 sites having different habitats with one sampling method of combined pitfall-pan trap. This study resulted in nine insect orders and 129 morphospecies. Hymenoptera was the most abundant order in all habitats (63.57%) followed by the orders Diptera, Homoptera, Coleoptera, Orthoptera, Hemiptera, Lepidoptera, Dictyoptera and Thysanoptera. This coast was classified with medium biodiversity index (D) of 0.51 for insect orders and high D of 0.83 for morphospecies. The highest (D) was in field crops habitat (H1) of 0.64 and 0.91 for insect orders and morphospecies, respectively; followed by scrublands (H3), greenhouse areas (H2) and olive orchards (H4). These results indicated that human intervention was affecting the diversity in natural habitats. Five insect orders: Coleoptera, Dictyoptera, Diptera, Hymenoptera, and Lepidoptera were significantly selected as potential biodiversity indicators in this coastal area. Thus, for monitoring these bioindicators, a protocol based on operating our combined trap method appears practical in design and yield very diverse material with the target of sustaining these insect populations in the coastal area.

Dominant species of radish (Raphanus sativus (L.) convar. radicula (Pers) Sazon.) pests in the Right Bank Forest Steppe of Ukraine

Based on the results of phytosanitary monitoring (2008–2022), the species composition of pests in agroecosystems of radish (Raphanus sativus (L.) convar. radicula (Pers) Sazon.) in the central part of the Right-Bank Forest-Steppe of Ukraine has been specified. In radish crops, 59 species of phytophagous insects, two species of nematodes, and one species of slugs were identified. The harmful entomocomplex structure includes insects from 20 families of 8 orders. Representatives of the orders Coleoptera (17 species), Lepidoptera (16 species), and Homoptera (9 species) dominate the taxonomic structure, collectively occupying 71% in the structure of the harmful entomocomplex. Representatives of the orders Diptera and Orthoptera were presented by species from 6 and 5 families, respectively, and in the entomocomplex structure, they occupied 10% and 8%, respectively. The least species diversity was found for the order Thysanoptera, Hemiptera, and Hymenoptera, which collectively occupied 10% in the structure of the harmful entomocomplex. Sixteen constant species were identified (Plutella maculipennis Curt., Phyllotreta cruciferae Goeze, Phyllotreta undulata Kutsch., Pieris brassicae L., Agrotis segetum Denis&Schiff., Lacanobia oleracea L., Eurydema ventralis Kol., Brevicoryne brassicae L., Delia brassicae Bouche, Athalia rosae L., Delia platura Mg., Ceutorrhynchus quadridens Panz., Delia floralis Fallen, Thrips tabaci Lindeman, Entomoscelis adonidis Pallas, Evergestis extimalis Scop.), which caused significant damage to radish plants throughout the vegetation period. These species were trophically specialized, with 75% being oligophagous and 81% being phytophagous. Flea beetles such as Phyllotreta cruciferae Goeze, Phyllotreta undulata Kutsch., diamondback moth (Plutella maculipennis Curt.), cabbage aphid (Brevicoryne brassicae L.), turnip moth (Agrotis segetum Denis&Schiff.), and armyworm (Lacanobia oleracea L.) were found with high and medium frequencies in the studied agroecosystems, with population densities reaching maximum levels of 60–100% in some years.

Thrips (Insecta: Thysanoptera) Species in Pepper Fields in Tokat Province, Türkiye

Abstract: Thrips (Insecta: Thysanoptera) species in pepper fields was determined in Tokat Province, Türkiye in 2021-2022. The density of thrips began to rise once the leaves emerged in late May, and the collection of thrips species started in June to October. To conduct regular samplings of thrips that were infesting pepper fields, flowers were collected and placed in plastic tubes (50 ml) filled with ethyl alcohol at a concentration of 60%. The densities of thrips populations and the resulting damage caused by thrips attacks on different plant components (such as flowers, leaves, and fruits) were evaluated through the examination of a randomly chosen 25 samples for each plant part during each sampling period. The assessment encompassed various thrips families belonging to the order Thysanoptera, specifically, families, Thripidae, Aeolothripidae, and Phlaeothripidae. A total of 7 Thysanoptera species were identified in this study. The species were Frankliniella occidentalis (Priesner, 1932), Thrips tabaci Lindeman), 1895, Thrips meridionalis (Priesner 1926) and Chirothrips manicatus (Haliday, 1836) in Thripidae family, and Aeolothrips intermedius (Bagnall, 1934) and Aeolothrips fasciatus (Linnaeus, 1758) in Aeolothripidae family, and Haplothrips aculeatus (Fabricius, 1803) in Phlaeothripidae family. Both adult and larval thrips were collected mainly from the flowers sampled In this study, the dominant species was F occidentalis in pepper fields in Tokat Province.

Recognition of Haplothrips jordani (Bagnall); one of the oldest names in the insect Order Thysanoptera.

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Efektivitas Beauvaria bassiana dan Metarhizium anisopliae terhadap Pengendalian Hama Thrips sp. (Thysanoptera: Tripidae) pada Tanaman Cabai Besar (Capsicum annuum L.)

The productivity of chili plants can be reduced due to the disturbance of various Plant Pest Organisms (OPT), one of which is insect pests from the Order Thysanoptera, family Thripidae or better known as Thrips sp. Thrips pests attack plants by sucking the liquid on the leaf surface, especially the young leaves. Symptoms that appear are silvery spots then change color to copper brown, the leaves curl or wrinkle and eventually the plant dies. Control measures that can be used to control or suppress Thrips sp. pest populations. other than using insecticides, namely by utilizing Biological Control Agents (APH) such as the entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana. The fungus B. bassiana infects host insects through physical contact by attaching conidia to the integument. M. anisopliae infection begins with the attachment of M. anisopliae spores to the cuticle of the insect and then the spores of M. anisopliae germinate and penetrate into the insect's body. This study used a field experiment method arranged in a Factorial Completely Randomized Design (CRD) with 2 factors and 4 replications. The first factor was the type of entomopathogenic fungus which consisted of two levels, A1 = Beauveria bassiana, A2 = Metarhizium anisopliae. The second factor was the density of conidia which consisted of 4 types: K1 = 105/ml, K2 = 106/ml, K3 = 107/ml, K4 = 108/ml. The observed data is quantitative data, then it will be analyzed statistically using ANOVA analysis of variance, if there is a significant difference then a follow-up test will be carried out using the DMRT. The effect of factor A1 (B. bassiana) is better than the effect of factor A2 (M. anisopliae) on the mortality of Thrips sp. and the best effect of factor K is on K4 (spore density 108/ml). So it is recommended to use the A1K4 treatment because it is effective on the mortality of Thrips sp. and the effect of factor K4 (spore density of 108/ml) was better than the effect of factors K1 (spore density of 105/ml), K2 (spore density of 106/ml), and K3 (spore density of 107/ml) on the intensity of attack of Thrips sp. So it is recommended to use the K4 treatment because it is effective against the intensity of attacks of Thrips sp.

First report of Groundnut ringspot virus (GRSV) infecting tobacco (Nicotiana tabacum L.) in South Africa.

Tobacco (Nicotiana tabacum L.) is an important industrial crop from the Solanaceae family cultivated for its leaves in approximately 100 countries worldwide. In South Africa (SA), tobacco is grown in five of its nine provinces: Limpopo, North West, Western Cape, Eastern Cape, and Mpumalanga. The producer price for unmanufactured tobacco is approximately US$3570/ton annually (FAO, 2021). Emerging and recurrent plant viruses such as tomato spotted wilt orthortospovirus (TSWV) have seriously affected tobacco production yield and quality. Between November 2018 to April 2019 growing season, large thrips (order Thysanoptera) populations were observed in tobacco fields throughout South Africa's major tobacco-growing areas, and plants were showing severe necrosis, yellowing, stunted growth, ringspot, and leaf curling symptoms, which are usually associated with plant virus infections. The disease incidence was estimated at 30%, as per visual observations. Twenty-two symptomatic leaf tissue samples were collected from tobacco farms in Limpopo, Northwest, and Western cape provinces. Samples were initially screened using the double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with LOEWE®Fast Kit (LOEWE®, Germany), which detectsTSWV, groundnut ringspot orthotospovirus (GRSV), and tomato chlorotic spot orthotospovirus (TCSV). Nineteen of these samples tested positive for orthortospoviruses. Subsequently, a reverse transcription-polymerase chain reaction was performed on all ELISA-positive samples using orthotospovirus-specific primers gM410 & gM870c targeting the NSm gene (Chen et al., 2012). All samples were positive for orthotospoviruses, as indicated by the presence of a 500bp amplicon. Nineteen purified PCR products were sequenced in the forward and reverse directions using Sanger sequencing at the KwaZulu-Natal Research and Innovation Sequencing Platform (KRISP; South Africa). The sequences were aligned using Muscle in MEGA version X (Kumar et al., 2018) to generate the consensus sequences that were then subjected to the standard nucleotide basic local alignment search tool (blastn) on the NCBI website. Blastn analysis showed that 16 of the 19 samples matched TSWV nucleotide sequences, while three of the sequences; LP14 (accession number OL505552), LP18 (accession number OL505553), and NW4 (accession number OL505554), had a nucleotide sequence identity of 96,38%, 96,97% and 97,29% with the GSRV isolate SA-05 (accession number MH742957; Silva et al., 2019) from South Africa, respectively. This is the first report of GRSV infecting tobacco after TSWV was reported in SA. Previously, GSRV was reported on soybean and groundnut in South Africa by Petersen and Morris in (2002) and Silva et al. in (2019). The results from this study lay a foundation for more detailed studies on GRSV, which will result in the development of effective and sustainable control strategies to manage GRSV diseases on tobacco in SA.

DNA Barcodes for thrips species and development of multiplex real-time PCR assay for Frankliniella occidentalis Pergande, Frankliniella panamensis Hood, Thrips palmi Karny and Thrips tabaci Lindeman (Thysanoptera: Thripidae)

ABSTRACT Thrips (Order Thysanoptera) species are agriculturally important pests and vectors of plant disease. These tiny insects are commonly found in all life stages on imported commodities at the New Zealand border. Morphological identification of thrips is able to be performed on adults, but the identification keys for immature stages are inadequate and so DNA barcoding is regularly used for their identification. Here, we have generated cytochrome oxidase I (COI) DNA barcode data for 29 thrips species from 124 individuals, focusing on Frankliniella occidentalis, a dominant species intercepted at New Zealand border, followed by F. panamensis, Thrips palmi and T. tabaci. In addition, a multiplex real-time PCR assay has been developed to target the four thrips species. This assay is intended to facilitate the identification of quarantine interceptions with greater accuracy and faster diagnostic turnaround times, regardless of the developmental stages of the thrips. The developed assay demonstrated a high level of specificity for all the four target species and could detect as few as 10 copies/µL of the target DNA. Linear responses and high correlation coefficients between the amount of DNA and Cq values for each species were also achieved. The method was successfully tested on single egg, larva and adult samples and proved to be applicable for all life stages of the four species. Overall, this study has shown that the developed assay is an effective biosecurity tool for rapid and reliable identification of the target thrips species.

Pest status, molecular evolution, and epigenetic factors derived from the genome assembly of Frankliniella fusca, a thysanopteran phytovirus vector

BackgroundThe tobacco thrips (Frankliniella fusca Hinds; family Thripidae; order Thysanoptera) is an important pest that can transmit viruses such as the tomato spotted wilt orthotospovirus to numerous economically important agricultural row crops and vegetables. The structural and functional genomics within the order Thysanoptera has only begun to be explored. Within the > 7000 known thysanopteran species, the melon thrips (Thrips palmi Karny) and the western flower thrips (Frankliniella occidentalis Pergrande) are the only two thysanopteran species with assembled genomes.ResultsA genome of F. fusca was assembled by long-read sequencing of DNA from an inbred line. The final assembly size was 370 Mb with a single copy ortholog completeness of ~ 99% with respect to Insecta. The annotated genome of F. fusca was compared with the genome of its congener, F. occidentalis. Results revealed many instances of lineage-specific differences in gene content. Analyses of sequence divergence between the two Frankliniella species’ genomes revealed substitution patterns consistent with positive selection in ~ 5% of the protein-coding genes with 1:1 orthologs. Further, gene content related to its pest status, such as xenobiotic detoxification and response to an ambisense-tripartite RNA virus (orthotospovirus) infection was compared with F. occidentalis. Several F. fusca genes related to virus infection possessed signatures of positive selection. Estimation of CpG depletion, a mutational consequence of DNA methylation, revealed that F. fusca genes that were downregulated and alternatively spliced in response to virus infection were preferentially targeted by DNA methylation. As in many other insects, DNA methylation was enriched in exons in Frankliniella, but gene copies with homology to DNA methyltransferase 3 were numerous and fragmented. This phenomenon seems to be relatively unique to thrips among other insect groups.ConclusionsThe F. fusca genome assembly provides an important resource for comparative genomic analyses of thysanopterans. This genomic foundation allows for insights into molecular evolution, gene regulation, and loci important to agricultural pest status.

Disaster Risk Regionalization and Prediction of Corn Thrips Combined with Cloud Model: A Case Study of Shandong Province, China

Corn thrips do serious harm to the yield and quality of corn. In this paper, the Shandong Province of China was taken as the study area. Based on the data of the occurrence of corn thrips in Shandong Province, a risk regionalization model was established by using eight indicators under four categories of hazard, sensitivity, vulnerability and the disaster prevention and mitigation capacity of diseases and pests on a monthly time scale. Firstly, the cloud model was introduced to determine the weight of each indicator, and then the risk regionalization of the corn thrips disaster in Shandong Province was carried out using the weighted percentage method, the weighted comprehensive evaluation method and the natural disaster risk index method. Finally, combined with the collected data, the disaster prediction of corn thrip occurrence degree was realized based on multiple linear regression, genetic algorithm optimized back-propagation neural network and genetic algorithm optimized support vector machine methods. The results show that: (1) the risk of Corn thrips disaster is mainly concentrated in the central and western parts of Shandong Province. Heze City is a high-risk area. Liaocheng City, Dezhou City, Jinan City and Weifang City are relatively high-risk areas. (2) By comparing the prediction accuracy of the three models, it was determined that the genetic algorithm optimized support vector machine model has the best effect, with an average accuracy of 79.984%, which is 7.013% and 22.745% higher than that of the multiple linear regression and genetic algorithm optimized back-propagation neural network methods, respectively. The results of this study can provide a scientific basis for fine prevention of corn thrips in Shandong Province.

Ocorrência e caracterização de galhas de insetos em duas reservas da Amazônia peruana

Abstract An insect gall inventory was carried out in two reserves of the Peruvian Amazon, Allpahuayo-Mishana National Reserve and Quistococha Regional Reserve, both situated in Iquitos, northeastern Peru. Four vegetation types were surveyed between December, 2021 and December, 2022: terra firme forest, white-sand wet forest, and white-sand dry forest in Allpahuayo-Mishana National Reserve, and palm swamp forest in Quistococha Regional Reserve. Overall, we found 262 gall morphotypes, distributed across 75 host species representing 66 plant genera and 30 families. Fabaceae was the plant family with the greatest number of gall morphotypes (n = 48), followed by Calophyllaceae (n = 21) and Euphorbiaceae (n = 20). The plant genera that supported the highest diversity of galls were Caraipa (n = 17), Eschweilera (n = 16), Tapirira (n = 16), Micrandra (n = 14), and Iryanthera (n = 10). The plant species Tapirira guianensis (n = 16), Caraipa utilis (n = 14), Micrandra elata (n = 14), Eschweilera coriacea (n = 11), and Sloanea parvifructa (n = 10) exhibited the highest richness of galls. Among the host plants, C. utilis stands alone as the only species noted as both endemic to the Amazonian region and bearing a Vulnerable (VU) conservation status. The leaves were the most attacked organs (90% of all galls). Most morphotypes are glabrous (89%), green (67%), globoid (53%), and one-chambered (91%). We found galling insects belonging to the orders Diptera, Thysanoptera, Lepidoptera, and Hemiptera. The galling insects of Cecidomyiidae (Diptera) were the most common, inducing 22% of the gall morphotypes. In addition to the gallers, we also observed the presence of successors, cecidophages, and parasitoids. Among the sampled vegetation types, the terra firme forest presented the highest richness of gall morphotypes and host plant species. This is the first systematic inventory of insect galls in this part of the Peruvian Amazon.

Arthropods associated with the lychee erinose mite, Aceria litchii (Acari: Eriophyidae) on lychee trees in Minas Gerais, Brazil.

Lychee fruit production (Litchi chinensis) has been threatened in many regions of the world where the presence has been reported of the litchii erinose mite, Aceria litchii (Keifer). This study aims to identify the arthropod community associated with A. litchii on lychee plants in Minas Gerais, Brazil, and to seek for potential natural enemies associated with this mite pest in this region. We sampled lychee leaves infested with A. litchii in commercial and non-commercial lychee orchards during seven consecutive months, covering the dry and wet seasons of the year. Arthropods found in association with A. litchii on lychee leaves were collected and identified. The results indicate that a great diversity and abundance of mites and hexapods are associated with A. litchii. A total of 985 and 1872 specimens of mites were identified in commercial and non-commercial areas, respectively, belonging to the families Cheyletidae, Cunaxidae, Eupodidae, Iolinidae, Stigmaeidae, Phytoseiidae, Tarsonemidae, Tenuipalpidae, Tetranychidae, Tryophtydeidae, Tuckerellidae, Tydeidae, Winterschmidtiidae and Xenocaligonellidae and the suborder Oribatida. Among them, Phytoseiidae was the most abundant and diverse family with a total of 11 species identified, in which Phytoseius intermedius was the most abundant predatory mite species collected. Minor specimens of hexapods were also been, belonging to the orders Collembola, Blattodea, Coleoptera, Diptera, Hemiptera, Hymenoptera, Psocoptera and Thysanoptera. The presence of a high community of predatory mites in association with A. litchii deserves attention and our results indicate that studies to test the potential of these species and the adoption of management practices that enhance this ecological service must be carried out to achieve satisfactory control of the lychee erinose mite in lychee plants.

The Importance of Urban Green Spaces for Pollinating Insects: The Case of the Metropolitan Area of Port-au-Prince, Haiti

The relative contribution of urban agriculture vs. urban forest remnants to the preservation of insect diversity in large cities, particularly in developing countries in the tropics, remains poorly documented. We assessed the distribution of pollinating insect orders in the densely-populated capital city of Port-au-Prince, Haiti, one of the poorest countries in the world. From early January to late April 2018, a survey was conducted in 16 urban green sites, consisting of eight unexploited, private secondary forest remnants (Fo) and eight agroforestry plantations (Ag) embedded within the urban landscape. At each site, we relied on coloured pan traps as an efficient way to sample pollinating insects during three different 24 hour sampling sessions. Overall, we collected a total of 2,747 pollinating insects, belonging to six different orders (Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, and Thysanoptera). Site area, site elevation, and percentage of built area within a 500 m radius had no significant influence on the total number of insects collected at each site. Insect order richness was significantly higher at Ag sites compared to Fo ones. Although it was not possible to identify all collected insects at the family or species level, we collected two Lepidopteran species of patrimonial interest, the Hispaniolan-endemic Zetides Swallowtail, Battus zetides, and the Jaeger's anetia, Anetia jaegeri, in our pan traps during the course of the survey. We discuss our results in relation to the value of urban green spaces for the conservation of pollinating insects and particular characteristics of the metropolitan area of Port-au-Prince.

The complete mitochondrial genome of Megalurothrips usitatus (Bagnall 1913) (Thysanoptera: Thripidae) and its phylogenetic analysis

Megalurothrips usitatus is a serious pest on Vigna unguiculata. In this study, the complete mitochondrial genome sequence of M. usitatus was characterized and its phylogenetic relationship within the Order Thysanoptera was determined. The mitochondrial genome of M. usitatus was a circular molecule of 15426 bp in length, containing 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and the control region. It showed the typical insect mitochondrial genome arrangement. The AT content of the whole genome was 77.69% and the length of the control region was 567 bp with 78.66% AT content. The Maximum likelihood (ML) phylogenetic analysis based on mitochondrial protein-coding genes of 17 insect speciesshowed that M. usitatus is closest to Frankliniella occidentalis.

Gene arrangement, phylogeny and divergence time estimation of mitogenomes in Thrips.

The metazoan mitogenomes usually display conserved gene arrangement while thrips are known for their extensive gene rearrangement, and duplication of the control region. We sequenced complete mitogenomes of eight species of thrips to determine the gene arrangement, phylogeny and divergence time estimation. All contain 37 genes and one control region, (CR) except four species with two CRs. Duplicated tRNAs were detected in Mycterothrips nilgiriensis and Thrips florum. nad4-nad4L were not found adjacent to each other in Phibalothrips peringueyi and Plicothrips apicalis. Both Bayesian and likelihood phylogenetic analyses of thrips mitogenomes supported the monophyly of two suborders (Terebrantia and Tubulifera) and the two largest families (Phlaeothripidae and Thripidae). Out of seven earlier proposed ancestral gene blocks, six are conserved in Panchaetothripinae, three in Thripinae and two in Phlaeothripidae. Additionally, eight Thrips Gene Blocks were identified, of which, three conserved in Tubulifera, four in Terebrantia, and one only in Aeolothripidae. Forty-two gene boundaries (15 from previous study + 27 new) were identified. The molecular divergence time is estimated for the order Thysanoptera and suggested that these insects may have been diversified from hemipterans in the late Permian period. The most recent ancestors belong to family Thripidae and Phlaeothripidae, which were diversified in upper Cretaceous period and showed higher rates of rearrangement from the ancestral gene order. The current study is the first largest effort to provide the new insights into the mitogenomic features, gene arrangement, phylogeny and divergence time estimation of thrips belonging to the order Thysanoptera.

Problems with the Concept of "Pest" among the Diversity of Pestiferous Thrips.

Simple SummaryThe word “pest” can be interpreted in many ways, ranging from something that causes minor personal irritation to something that results in major economic losses. The various insects that are referred to as thrips are used to discuss the question “what is a pest”. Many species of thrips feed on young leaves and developing fruits, and we emphasize that crop loss and reduced financial yield are more significant than mere presence of a thrips on a crop. The diversity in biology among species of thrips is discussed within the context of their respective families and subfamilies, emphasising that pest behaviour is found in relatively few species of the insect Order Thysanoptera. Almost all of the thrips species that are considered pests are members of a single subfamily of Thripidae, the Thripinae, a group that represents less than 30% of the species in the insect Order Thysanoptera. Three of the five major Families of Thysanoptera (Aeolothripidae, Heterothripidae, Melanthripidae) are not known to include any pest species. The Phlaeothripidae that includes more than 50% of the 6300 thrips species listed includes very few that are considered to be pests. Within the Thripidae, the members of the three smaller subfamilies, Panchaetothripinae, Dendrothripinae and Sericothripinae, include remarkably few species that result in serious crop losses. It is only in the subfamily Thripinae, and particularly among species of the Frankliniella genus-group and the Thrips genus-group that the major thrips species are found, including all but one of the vectors of Orthotospovirus infections. It is argued that the concept of pest is a socio-economic problem, with the pest status of any particular species being dependent on geographical area, cultivation practices, and market expectations as much as the intrinsic biology of any thrips species.

Diversity and relative abundance of insect fauna of apple (Malus domestica borkh) in high density plantation

During the course of study appearance of insect-pests started in the month of March coinciding with pink bud stage of apple. Insects belonging to orders Lepidoptera, Coleoptera, Hemiptera, Thysanoptera, Aracnida and Cucurlionoidae were identified. The relative abundance of insects belonging to order Hemiptera was maximum (32.44 and 32.88) followed by Acarina (23.66 and 22.42%) during 2018 and 2019, respectively. Major insect-pests recoded were Panonychus ulmi, Eriosoma lanigerum and Thrips flavus appeared as major pests in this crop. Maximum population of P. ulmi (5.30/leaf was reported on apple leaves during the month of September. However, the highest percent mean density i.e. 471 and the relative density i.e. 23.05% was reported in P. ulmi followed by T. flavus (385) under high density apple plantation. The Simpson’s Diversity Index were calculated as 0.85 and 0.84, respectively, during 2018 and 2019, which signifies the number of species present, as well as the relative abundance of each species under high density apple plantation.