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

Toxicity and Efficacy of Thirty Insecticides Against Thrips flavus in Northeast China: Laboratory, Semifield, and Field Trials

In soybean fields across Northeast China, Thrips flavus Schrank (Thysanoptera, Thripidae) populations are increasing, posing a significant threat to soybean production. The aim of this study was to evaluate the toxicity, insecticide efficacy, and field performance of thirty insecticides against T. flavus. Laboratory bioassays revealed that fenthion (LC50 = 2.26 mg/L), sulfoxaflor (LC50 = 4.28 mg/L), cyetpyrafen (LC50 = 4.94 mg/L), and imidacloprid (LC50 = 6.16 mg/L) exhibited the highest toxicity against T. flavus. Pot experiments were subsequently conducted to assess insecticide efficacy. Seven days after application at the highest tested concentration, the insecticide efficacy of fenthion, sulfoxaflor, chlorantraniliprole, bifenazate, and malathion achieved 100% control efficacy. The four insecticides were selected for field trials based on their high toxicity and insecticide efficacy. Seven days after application, the field efficacy of fenthion at 11.25 g a.i.·hm-2, sulfoxaflor at 1.19 g a.i.·hm-2, cyetpyrafen at 8.10 g a.i.·hm-2, and imidacloprid at 11.25 g a.i.·hm-2 exceeded 80%. Thus, these four insecticides hold strong potential for integrated management of T. flavus. Overall, the findings provide a valuable reference for developing chemical control strategies against this pest.

Advancements in Life Tables Applied to Integrated Pest Management with an Emphasis on Two-Sex Life Tables

Life tables are indispensable in IPM, offering an analysis of insect population dynamics. These tables record survival rates, fecundity, and other parameters at various developmental stages, enabling the identification of key factors that affect population numbers and the prediction of growth trajectories. This review discusses the application of life tables in agricultural pest management, including the assessment of the pest control capacity of natural enemies, the evaluation of biological agents, and the screening of insect-resistant plant species. In vector insect control, life tables are used to evaluate the transmission risks, model the population dynamics, and interfere with the life cycles of vector insects. For invasive pests, life tables help us to monitor population dynamics and predict future population sizes. In chemical pest control, life tables assist in evaluating the fitness costs of pesticide resistance, guiding insecticide selection, and optimizing application timing. In the final section, we explore future research directions, emphasizing the potential of integrating new technologies such as genomics, ethology, and satellite remote sensing to enhance life table analysis and improve IPM strategies.

An Overview of the Thrips Fauna of the "Góra Bucze" Landscape-Nature Complex in Western Carpathians (Poland)

Although thrips are commonly viewed primarily as agricultural pests [...].

Thrips (Thysanoptera: Terebrantia) in Nectarine Orchards in North-East Spain: Species Diversity and Fruit Damage

Thrips constitute one of the main nectarine pests, with damage either in flowering or before harvesting (silvering). Several species are associated with damage to flowers, but Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) is the main species associated with summer damage in Europe. Tree canopies of nectarine orchards under organic and integrated management were sampled in Lleida and Girona at four key moments of the season (bud burst, full flowering, fruit setting stage, and colorization of the fruit) during 2021 and 2022 to determine the species composition in the area and the damage caused during fruit maturation. Adult individuals in flowers, leaves, and fruit surfaces were collected and identified, and silvering damage to the fruit surface was assessed in the Lleida area. Fifteen species in Lleida and 10 species in Girona were collected from the tree canopy. Organic orchards in Lleida showed lower populations and silvering damage levels when compared with integrated orchards. Thrips fuscipennis Haliday (Thysanoptera: Thripidae) 1836 was the main species in Lleida during harvest, and Frankliniella occidentalis (Pergande) 1895 was the main species in Girona. Due to their predominance, both species were associated with silvering damage during fruit maturation.

Measuring air metagenomic diversity in an agricultural ecosystem

All species shed DNA during life or in death, providing an opportunity to monitor biodiversity via environmental DNA (eDNA). In recent years, combining eDNA, high-throughput sequencing technologies, bioinformatics, and increasingly complete sequence databases has promised a non-invasive and non-destructive environmental monitoring tool. Modern agricultural systems are often large monocultures and so are highly vulnerable to disease outbreaks. Pest and pathogen monitoring in agricultural ecosystems is key for efficient and early disease prevention, lower pesticide use, and better food security. Although the air is rich in biodiversity, it has the lowest DNA concentration of all environmental media and yet is the route for windborne spread of many damaging crop pathogens. Our work suggests that ecosystems can be monitored efficiently using airborne nucleic acid information. Here, we show that the airborne DNA of microbes can be recovered, shotgun sequenced, and taxonomically classified, including down to the species level. We show that by monitoring a field growing key crops we can identify the presence of agriculturally significant pathogens and quantify their changing abundance over a period of 1.5 months, often correlating with weather variables. We add to the evidence that aerial eDNA can be used as a source for biomonitoring in terrestrial ecosystems, specifically highlighting agriculturally relevant species and how pathogen levels correlate with weather conditions. Our ability to detect dynamically changing levels of species and strains highlights the value of airborne eDNA in agriculture, monitoring biodiversity changes, and tracking taxa of interest.

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.

Chromosome-level genome assembly of the western flower thrips Frankliniella occidentalis

The western flower thrips Frankliniella occidentalis (Thysanoptera: Thripidae) is a global invasive species that causes increasing damage by direct feeding on crops and transmission of plant viruses. Here, we assemble a previously published scaffold-level genome into a chromosomal level using Hi-C sequencing technology. The assembled genome has a size of 302.58 Mb, with a contig N50 of 1533 bp, scaffold N50 of 19.071 Mb, and BUSCO completeness of 97.8%. All contigs are anchored on 15 chromosomes. A total of 16,312 protein-coding genes are annotated in the genome with a BUSCO completeness of 95.2%. The genome contains 492 non-coding RNA, and 0.41% of interspersed repeats. In conclusion, this high-quality genome provides a convenient and high-quality resource for understanding the ecology, genetics, and evolution of thrips.

Characterisation of a Novel Insect-Specific Virus Discovered in Rice Thrips, Haplothrips aculeatus

Insects constitute the largest proportion of animals on Earth and act as significant reservoirs and vectors in disease transmission. Rice thrips (Haplothrips aculeatus, family Phlaeothripidae) are one of the most common pests in agriculture. In this study, the full genome sequence of a novel Ollusvirus, provisionally named "Rice thrips ollusvirus 1" (RTOV1), was elucidated using transcriptome sequencing and the rapid amplification of cDNA ends (RACE). A homology search and phylogenetic tree analysis revealed that the newly identified virus is a member of the family Aliusviridae (order Jingchuvirales). The genome of RTOV1 contains four predicted open reading frames (ORFs), including a polymerase protein (L, 7590 nt), a glycoprotein (G, 4206 nt), a nucleocapsid protein (N, 2415 nt) and a small protein of unknown function (291 nt). All of the ORFs are encoded by the complementary genome, suggesting that the virus is a negative-stranded RNA virus. Phylogenetic analysis using polymerase sequences suggested that RTOV1 was closely related to ollusvirus 1. Deep small RNA sequencing analysis reveals a significant accumulation of small RNAs derived from RTOV1, indicating that the virus replicated in the insect. According to our understanding, this is the first report of an Ollusvirus identified in a member of the insect family Phlaeothripidae. The characterisation and discovery of RTOV1 is a significant contribution to the understanding of Ollusvirus diversity in insects.

A chromosome-level genome for the flower thrips Frankliniella intonsa

The flower thrips Frankliniella intonsa (Thysanoptera: Thripidae) is a common insect found in flowers of many plants. Sometimes, F. intonsa causes damage to crops through direct feeding and transmission of plant viruses. Here, we assembled a chromosomal level genome of F. intonsa using the Illumina, Oxford Nanopore (ONT), and Hi-C technologies. The assembled genome had a size of 209.09 Mb, with a contig N50 of 997 bp, scaffold N50 of 13.415 Mb, and BUSCO completeness of 92.5%. The assembled contigs were anchored on 15 chromosomes. A set of 14,109 protein-coding genes were annotated in the genome with a BUSCO completeness of 95.0%. The genome contained 491 non-coding RNA and 0.57% of interspersed repeats. This high-quality genome provides a valuable resource for understanding the ecology, genetics, and evolution of F. intonsa, as well as for controlling thrips pests.

Rapid and Repeated Climate Adaptation Involving Chromosome Inversions following Invasion of an Insect

Following invasion, insects can become adapted to conditions experienced in their invasive range, but there are few studies on the speed of adaptation and its genomic basis. Here, we examine a small insect pest, Thrips palmi, following its contemporary range expansion across a sharp climate gradient from the subtropics to temperate areas. We first found a geographically associated population genetic structure and inferred a stepping-stone dispersal pattern in this pest from the open fields of southern China to greenhouse environments of northern regions, with limited gene flow after colonization. In common garden experiments, both the field and greenhouse groups exhibited clinal patterns in thermal tolerance as measured by critical thermal maximum (CTmax) closely linked with latitude and temperature variables. A selection experiment reinforced the evolutionary potential of CTmax with an estimated h2 of 6.8% for the trait. We identified 3 inversions in the genome that were closely associated with CTmax, accounting for 49.9%, 19.6%, and 8.6% of the variance in CTmax among populations. Other genomic variations in CTmax outside the inversion region were specific to certain populations but functionally conserved. These findings highlight rapid adaptation to CTmax in both open field and greenhouse populations and reiterate the importance of inversions behaving as large-effect alleles in climate adaptation.

Multiple independent origins of duplicated mitochondrial control regions indicate an apomorphy in the Thysanoptera (Insecta)

The mitochondrial genome (mitogenome) of thrips is characterized by the presence of control region (CR) duplication. However, the evolution pattern of duplicated CRs in thrips is still unclear. In this study, the multiple independent origins of duplicated CR indicated that the CR duplication was not an ancestral state for Thysanoptera. The macroevolutionary pattern suggested that the earliest CR duplication event occurred in the middle Cretaceous (94.85 Ma) coincided with rearrangement events forming the ancestors of Aeolothripidae, but much later than that forming the ancestors of the suborder Terebrantia. The mitogenome with duplicated CRs showed a higher rate of gene rearrangement. The sequence similarity of the CR copies and divergence time were negatively correlated, indicating age-related deterioration of mitochondrial function. No significant differences were found in the mitochondrial DNA, the P123 and P4FD between the single and multiple-CR charactered mitogenomes, which suggested that the duplicated CRs may not affect the replication process in thrip mitogenome. The mitogenomes with duplicated CRs (mean: 0.0088 subs/s/my) show a significantly increased evolutionary rate than that with a single one (mean: 0.0058 subs/s/my). However, it seems that this higher evolutionary rate did not have adaptive mechanisms in Terebrantia. We speculated that the duplicated CRs may cause a more intense production of energy by mitochondria, and an accelerated mutation and substitution rate is expected in such mitogenomes. Our study provided new insights into the presence of CR duplications and their evolution in the mitogenomes of thrips.

Moderate Grazing Promotes Arthropod Species Diversity in an Alpine Meadow

Livestock grazing is an important tool used in grassland land management practices. Studies have substantially addressed the effect of grazing on plant species diversity, revealing that moderate grazing increases plant species diversity. However, few studies have dealt with the relationship between grazing and arthropod species diversity, which remains unclear. Here, we hypothesize that moderate grazing promotes arthropod species diversity because arthropods are directly or indirectly dependent on plant diversity. In this study, we conducted a two-year plant and arthropod survey from 2020 to 2021 at four levels of grazing intensity, i.e., nongrazing (as a control), light grazing, moderate grazing, and heavy grazing, of the long-term grazing experiment starting in 2016. The data show that plant species diversity peaked in the moderate grazing treatment, and herbivore species diversity was positively correlated with plant species diversity (and hence peaked in the moderate grazing treatment). Moderate grazing promoted parasitoid species diversity, which was positively correlated with herbivore species diversity. However, predator species diversity did not significantly differ among the four treatments. In addition, saprophage species diversity decreased, whereas coprophages increased with increasing grazing levels, such that species richness (but not species diversity of detritivores statistically) was highest in the moderate grazing treatment. Consequently, the species diversity of arthropods as a whole peaked at the moderate grazing level, a phenomenology that is consistent with the intermediate disturbance hypothesis. Considering that moderate grazing has been found to increase plant species diversity, facilitate soil carbon accumulation, and prevent soil erosion, we suggest that moderate grazing would maximize multi-functional ecosystem services.

A new species of Neohydatothrips (Thysanoptera: Sericothripinae) from China

Neohydatothrips stachyurus sp. n. is described from Guizhou, China. Morphologically, this new Sericothripinae species is characterized by the shape of blotch on pronotum and the distribution of microtrichia on abdominal segments. The distribution of Neohydatothrips species from China also is discussed.

Interspecific and intraspecific variation in susceptibility of two co-occurring pest thrips, Frankliniella occidentalis and Thrips palmi, to nine insecticides

BACKGROUND

Field control of pest thrips mainly relies on insecticides, but the toxicity of insecticides can vary among thrips species and populations. In this study, we examined the susceptibility of multiple field populations of two thrips pests, Frankliniella occidentalis, and Thrips palmi, that often co-occur on vegetables, to nine insecticides belonging to seven subgroups.

RESULTS

The highest level of variation in susceptibility among F. occidentalis populations was for spinetoram (73.92 fold difference between most resistant and most susceptible population), followed by three neonicotinoids (8.06-15.99 fold), while among T. palmi populations, it was also for spinetoram (257.19 fold), followed by emamectin benzoate, sulfoxaflor, and acetamiprid (23.64-45.50 fold). These findings suggest evolved resistance to these insecticides in some populations of the two thrips. One population of F. occidentalis had a particularly high level of resistance overall, being the most resistant for five of the nine insecticides tested. Likewise, a population of T. palmi had high resistance to all nine insecticides, again suggesting the evolution of resistance to multiple chemicals. For F. occidentalis, the LC₉₅ values of most populations were higher than the field-recommended dosage for all insecticides except chlorfenapyr and emamectin benzoate. For several T. palmi populations, the LC₉₅ values also tended to be higher than recommended dosages, except in the case of emamectin benzoate and spinetoram.

CONCLUSIONS

Our study found interspecific and intraspecific variations in the susceptibility of two thrips to nine insecticides and multiple resistance in some populations, highlighting the need for ongoing monitoring and resistance management. © 2023 Society of Chemical Industry.

The Terebrantia (Insecta: Thysanoptera) of the Maltese Islands

Thirty-nine species of terebrantian Thysanoptera belonging to four families and 22 genera are here recorded from the Maltese Islands. Of these, 33 represent new records to this archipelago. Thrips were collected from 65 different locations over a seven-year period, covering the main habitat types found across the Maltese Islands, namely steppe, garigue, maquis and woodland, but also sand dunes and saltmarshes as well as roadsides, private and public gardens, greenhouses and cultivated fields. An illustrated dichotomous key to identify the Terebrantia of the Maltese Islands is presented. Chorological data for the species researched in the current study shows that the majority of these insects are of a European Mediterranean origin, though the geographical distribution of some of them extends to Africa and the Middle East. Seven species associated with agricultural commodities were found to be of alien origin; however they were locally found in small numbers and do not pose a threat to horticulture.

A remarkable new genus of Thripinae (Thysanoptera, Thripidae) without anteocellar setae from India

Nandithrips pouzolziaegen. et sp. nov. (Thripidae, Thripinae) is described from the flowers of Pouzolzia petandra subsp. wightii (Urticaceae) found in Nandi hills, Karnataka, India. This new genus is characterised by an apomorphy, ocellar setae pairs I and II are both absent, and also has a unique discontinuous pore plate distribution, with a single circular or oval pore plate medially on abdominal sternites II and V–VII of males. Partial mitochondrial cytochrome c oxidase subunit 1 (mtCOI) gene sequence of N. pouzolziae was sequenced and the annotated sequence was submitted to NCBI GenBank.

Variation in the toxicity of a novel meta-diamide insecticide, broflanilide, among thrips pest species and developmental stages

BACKGROUND

Thrips pests cause increasing damage to crops around the world. Widespread usage of some insecticides against thrips has now led to the evolution of resistance to several active ingredients, and new insecticides are required. This study examined the toxicity of the novel insecticide broflanilide to multiple populations of several thrips pests.

RESULTS

Bioassays showed that thrips populations had LC₅₀ values ranging from 0.5 to almost 300 mg·L^-1 . A population of Frankliniella occidentalis had the highest LC₅₀ value at 290.63 mg·L^-1 , while a population of Echinothrips americanus had the lowest LC₅₀ value at 0.51 mg L^-1 . LC₅₀ values among seven populations of Thrips palmi ranged from 2.5689 to 23.6754 mg·L^-1 , indicating intraspecific variation in toxicity. In this species, the toxicity of broflanilide was relatively higher in adults than in larvae. More than 90% of eggs of T. palmi could not develop into larvae when treated with 5-50 mg L^-1 broflanilide. Compared to five commonly used insecticides, broflanilide showed relatively high toxicity to T. palmi. Field control tests with T. palmi showed that control efficacy (from 90.44% to 93.14%) was maintained from day three to day 14 after treatment with 22.5 and 45 ga.i hm^-1 broflanilide.

CONCLUSION

Broflanilide is potentially a useful insecticide for controlling Thrips hawaiiensis, Frankliniella intonsa, Megalurothrips usitatus. E. americanus, and some populations of T. palmi. However, the variation in toxicity of this insecticide to different species, populations, and developmental stages indicates that target species and life stages may need to be carefully considered. © 2022 Society of Chemical Industry.

Thysanoptera as predators: their diversity and significance as biological control agents

Some species of thrips have evolved predatory behaviours, with their reported prey range including thrips, mites, scale-insects, whitefly, psyllid nymphs, and eggs of moths and beetles. However, our current understanding of the biology and potential of these thrips as biological control agents is insufficient, limiting our understanding of their role in pest management. This paper assesses published information on the diversity of predatory thrips and the available biological data on their diet breadth. About 100 species within three different families - Aeolothripidae, Phlaeothripidae and Thripidae - seem likely to be predatory, although some conclusions are speculative. Both facultative and obligate predators can be found among the species with prey records. Obligate predators feed primarily on arthropod tissues, whereas facultative predators consume plant tissues in addition to prey. Quantitative information regarding developmental biology, longevity and fecundity, was obtained for only 11 species. Obligate predators, particularly members of Scolothrips and Franklinothrips, are efficient biological control agents. To better augment the use of predatory thrips in pest management, further increased investment in mass rearing, life history and ecological studies, including interactions with other organisms and their habitat, are needed on these natural enemies. © 2022 Society of Chemical Industry.

The genus Helionothrips (Thysanoptera, Panchaetothripinae) in China, with two new species and an identification key

With 28 listed species Helionothrips Bagnall is the most species-rich genus within the subfamily Panchaetothripinae. Problems are discussed with several character states used for species discrimination: fore wing color; thoracic sculpture; sense cone length on antennal segment IV; male sternal pore plates. An identification key is provided to 15 species of Helionothrips known in China, including H. pallidus sp. n. and H. phragmitesi sp.n. from Southwestern China.  

Molecular Studies of Relationships and Identifications Among Insects of the Subfamily Panchaetothripinae (Thysanoptera, Thripidae)

The Panchaetothripinae comprises 42 genera and 146 species of leaf-feeding thrips, some of which are horticultural pests. We examined representatives of the 18 genera that include most of these pests. For species delimitation, we used DNA barcoding to produce171 sequences for 40 morphospecies. Most species were found to be monophyletic, although cryptic diversity was evident in 8 presumptive species. A multilocus molecular phylogenetic assessment was based on one mitochondrial (COI) and three nuclear loci (EF-1α, ITS2, and 28S) from 132 specimens (18 genera and 33 species), representing all genera and ~82% of species in China. Maximum likelihood (ML) and Bayesian inference (BI) confirmed monophyly of each genus with strong support. Monophyly of tribes Panchaetothripini and Monilothripini were refuted, but the well supported tribe Tryphactothripini was confirmed. Rhipiphorothrips was recovered as a sister to the remainder of the genera of Panchaetothripinae combined. Both analyses revealed two major clades. Clade A comprised the majority of the genera, including tribe Tryphactothripini. Clade B included only four genera of which two, Helionothrips and Caliothrips, are particularly species rich. The relationships of some genera remain unresolved.

The genus Odontothrips in Iran with two new species (Thysanoptera: Thripidae)

Host-plant associations among the 38 species of Odontothrips Amyot & Serville, and features of various structural characters in this genus, are discussed. An illustrated key to 9 species occurring in Iran is provided. Two new species are described from Iran based on specimens on flowers of various Fabaceae. O. bezii sp. n. is close to O. mongolicus Pelikan, and O. pitkini sp. n. is considered as the second species in the genus that has a tooth on the distal inner side of antennal segment II.