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Melon thrips, Thrips palmi, represent a significant threat to plants, inducing necrosis and acting as vectors for numerous plant viruses. Entomopathogenic fungi present a promising avenue for the management of melon thrips populations resistant to conventional chemical treatments. In this work, an adult colony of melon thrips was exposed to Beauveria bassiana strain JEF-350, and the ensuing transcriptional response of the infected thrips was scrutinized to elucidate their reactions during fungal pathogenesis. Utilizing Illumina sequencing, RNA samples were extracted from untreated thrips as well as from thrips continuously infected for 2 and 4 days, each with three biological replicates. While no notable alterations in gene expression were observed between the untreated control and thrips infected for 2 days, those infected for 4 days exhibited a plethora of differentially expressed genes. Specifically, in the thrips infected for the extended period, pathways associated with lysosomal function and insect hormone biosynthesis were notably repressed, while others such as serine and glycine metabolism, Toll and Imd, and circadian rhythm pathways displayed heightened activity. Noteworthy downregulation was observed in numerous lysosomal hydrolase genes encoding glycosidases, sulfatases, and lipases, particularly glycosidases. Furthermore, certain genes related to hydrolase precursors within the Golgi apparatus exhibited heightened expression levels but failed to progress toward hydrolase biosynthesis. Upstream regulation of juvenile hormone biosynthesis was augmented, yet downstream genes were significantly downregulated, leading to a disruption in juvenile hormone production. Similarly, while cytochrome P450 genes in the downstream of ecdysone biosynthesis were upregulated, expressions of cholesterol desaturase and cytochrome P450 genes in the upstream were inhibited, consequently dampening ecdysone biosynthesis. The observed differential targeting of organs or pathways by B. bassiana JEF-350, in contrast to conventional chemicals primarily affecting neurotransmission and energy production, suggests its potential efficacy in managing resistant thrips populations. Consequently, integrating JEF-350 into the chemical spray regimen or incorporating it into tank-mix formulations with chemical insecticides emerges as a pragmatic approach within the realm of integrated pest management strategies. Key points: • Beauveria treatment inhibited lysosomal function and hormone synthesis in thrips. • Thrips serine/glycine metabolism, Toll and Imd, and circadian rhythm pathways were activated. • Upstream functions of thrips hormone biosynthesis increased, while downstream functions were suppressed. • Regarding biosynthesis of metabolites, this fungus targets other pathways with resistance management. [ABSTRACT FROM AUTHOR]

Jasmonic acid (JA) is a regulator of plant resistance to phytophagous insects, and exogenous JA treatment induces plant insect resistance. This study investigated the mechanism of exogenous JA-induced resistance of Hemerocallis citrina Baroni (daylily) to Thrips palmi at the biochemical and molecular levels. Daylily leaves sprayed with JA showed significantly higher levels of secondary metabolites—tannins, flavonoids, and total phenols, and activity of defense enzymes—peroxidase, phenylalanine ammonia lyase, polyphenol oxidase, and protease inhibitor (PI) than control leaves; the most significant effects were observed with 1 mmol L−1 JA. Owing to an improved defense system, significantly fewer T. palmi were present on the JA-treated plants than control plants. The JA-treated leaves had a smoother wax layer and fewer stomata, which was unfavorable for insect egg attachment. The differentially expressed genes (DEGs) were significantly enriched in insect resistance pathways such as lignin and wax biosynthesis, cell wall thickening, antioxidant enzyme synthesis, PI synthesis, secondary metabolite synthesis, and defense hormone signaling. A total of 466 DEGs were predicted to be transcription factors, mainly bHLH and WRKY family members. Weighted gene co-expression network analysis identified 13 key genes; TRINITY_DN16412_c0_g1 and TRINITY_DN6953_c0_g1 are associated with stomatal regulation and lipid barrier polymer synthesis, TRINITY_DN7582_c0_g1 and TRINITY_DN11770_c0_g1 regulate alkaloid synthesis, and TRINITY_DN7597_c1_g3 and TRINITY_DN1899_c0_g1 regulate salicylic acid and ethylene biosynthesis. These results indicate that JA treatment of daylily improved its resistance to T. palmi. These findings provide a scientific basis for the utilization of JA as an antagonist to control T. palmi in daylily. [ABSTRACT FROM AUTHOR]

Thrips pests are causing increasing damage to many crops, including vegetables, fruits, and ornamental plants. RNA interference (RNAi) has been recognized as a potential approach for thrips control. However, the RNAi of thrips is often restricted by the lack of efficient dsRNA delivery method. Here, we developed a nanocarrier-mediated dsRNA oral delivery system for efficient RNAi in the melon thrips, Thrips palmi. We first determined RPL17 and EF1α as the optimal reference genes among different developmental stages, tissues, adult ages, and starvation treatments. Two aminopeptidase N genes, TpAPN2 and TpAPN3, expressed at a relatively high level in the midgut, were selected as target genes for RNAi. In our delivery system, dsRNA solutions were absorbed by cucumber leaves and delivered to thrips by feeding. Naked dsRNAs exhibited no RNAi effect, whereas the nanocarrier SPc (star polycation)-loaded dsRNAs induced a 43.7% and 48.9% decrease in the expression levels of TpAPN2 and TpAPN3, respectively. Inhibited functions of TpAPN2 and TpAPN3 resulted in 36.0% and 53.9% reduction in the feeding amount and 28.5% and 35.5% decrease in egg production, respectively. Co-silencing of TpAPN2 and TpAPN3 led to a mortality of 48.3%, higher than the single-RNAi of TpAPN2 (23.3%) and TpAPN3 (30%). The newly developed dsRNA delivery system is easy to manipulate with improved RNAi efficacy, providing a powerful tool for gene functional study of thrips. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated the effectiveness of soluble silicon fertilizer (SiO2) in protecting dendrobium orchids from thrips pest complexes and fungal pathogens to enhance yield and quality. Over a nine-month greenhouse trial in Hawaii, three dendrobium varieties ('Uniwai Supreme', 'Uniwai Mist', and 'Uniwai Royale') received alternating weekly applications of soluble silicon fertilizer (50 mg Si/plant/application) via either soil drench and/or foliar methods. The primary objectives were to assess the impact of soluble silicon fertilizer on marketable yield, spray length, thrips and fungal damage, and plant vigor. The results revealed significant benefits of silicon fertilization across all varieties. 'Uniwai Supreme' exhibited the most substantial increase in marketable yield (73.0%) and 'Uniwai Mist' had the least increase in marketable yield, with a 50.6% increase compared to untreated controls. These findings have practical implications for orchid cultivation and pest management practices, demonstrating the potential of soluble silicon to improve orchid health and productivity by reducing pest damage. By mitigating the impact of thrips and fungal pathogens, silicon fertilization can contribute to more sustainable orchid production methods. Ultimately this research supports the adoption of silicon supplementation as a strategy to enhance Integrated Pest Management (IPM) tactics and promote environmentally friendly agriculture. The effects of soluble silicon fertilization on monocots and dicots have been widely studied. However, little is known regarding its effects on protecting epiphytes against insect and fungal pests. The efficacy of silicon fertilizer to reduce damage by thrips pest complexes, namely: Thrips palmi Karny, Frankliniella occidentalis Pergande, Chaetanaphothrips orchidii Moulton, and Chaetanaphothrips signipennis Bagnall (Thysanoptera: Thripidae), and the fungal pathogens: Botrytis cinerea Persoon (Helotiales: Sclerotiniaceae) and Fusarium spp. Link (Hypocreales: Nectriaceae) was examined during a nine-month greenhouse trial in Hawaii. The trial assessed yield, quality, and pest damage across three common varieties of dendrobiums. All replicates received additional soluble silicon fertilizer applications alternating weekly between soil drench and foliar (50 mg Si/plant) applications. Yield, quality, and spray length, pest damage, plant vigor, SPAD, and leaf temperature were measured. Data were analyzed using a generalized linear model (glm) with repeated measures followed by post-hoc pair-wise comparisons in R, version 4.3.1. Treatment effects were significant at p < 0.001 for the majority of the explanatory variables including: marketable yield, spray length, thrips damage, and fungal damage. Overall, the lavender variety ('Uniwai Supreme') benefited the most from silicon applications with a 73.0% increase in marketable yield, compared to the white variety ('Uniwai Mist'), which had an increase of 50.6% marketable sprays in contrast to its untreated control. Si benefits conferred to the purple variety ('Uniwai Royale') were intermediate to the lavender and white varieties. Although the magnitude of Si benefits varied among the varieties, all dendrobium varieties significantly benefited from silicon fertilization. [ABSTRACT FROM AUTHOR]

Melon thrips, Thrips palmi (Thysanoptera: Thripidae), is a serious insect pest in crop productions, and synthetic chemicals are frequently used to control them. However, this practice causes residual issue in nature and makes melon thrips acquire strong resistance. To overcome these problems, a group of entomopathogenic fungi could be used as an alternative for controlling melon thrips. In this work, a total of 100 fungal isolates from soil in four different regions of Korea were isolated and subjected to virulence assays against melon thrips. Twenty‐five highly virulent fungal isolates, which showed 100% mortality 6 days after treatment, were determined. Liquid‐cultured filtrates of the selected isolates were further used to investigate their insecticidal activity against melon thrips, and of the 25 selected isolates finally seven isolates including Metarhizium spp. and Fusarium spp. showed high insecticidal activity in a dose‐dependent manner. Under a thermal stress at 121°C, culture filtrates of the seven isolates still kept their insecticidal activities. When liquid‐cultured spores were exposed to 45°C, spores of Fusarium isolates were resistant to the thermal stress, but those of Metarhizium isolates were susceptible to the stress. The culture filtrates of Fusarium isolates did not show any phytotoxicity to the tomato plants, followed by no phytotoxicity of liquid‐cultured spores, although mycotoxins need to be further clearly characterized. This work suggests that entomopathogenic Fusarium isolates are competitive in virulence against melon thrips and production of insecticidal metabolites compared to Metarhizium, and particularly attractive in sporal resistance against thermal stress, significantly stronger than Metarhizium. [ABSTRACT FROM AUTHOR]

Jasmonic acid (JA) is a regulator of plant resistance to phytophagous insects, and exogenous JA treatment induces plant insect resistance. This study investigated the mechanism of exogenous JA-induced resistance of Hemerocallis citrina Baroni (daylily) to Thrips palmi at the biochemical and molecular levels. Daylily leaves sprayed with JA showed significantly higher levels of secondary metabolites—tannins, flavonoids, and total phenols, and activity of defense enzymes—peroxidase, phenylalanine ammonia lyase, polyphenol oxidase, and protease inhibitor (PI) than control leaves; the most significant effects were observed with 1 mmol L−1 JA. Owing to an improved defense system, significantly fewer T. palmi were present on the JA-treated plants than control plants. The JA-treated leaves had a smoother wax layer and fewer stomata, which was unfavorable for insect egg attachment. The differentially expressed genes (DEGs) were significantly enriched in insect resistance pathways such as lignin and wax biosynthesis, cell wall thickening, antioxidant enzyme synthesis, PI synthesis, secondary metabolite synthesis, and defense hormone signaling. A total of 466 DEGs were predicted to be transcription factors, mainly bHLH and WRKY family members. Weighted gene co-expression network analysis identified 13 key genes; TRINITY_DN16412_c0_g1 and TRINITY_DN6953_c0_g1 are associated with stomatal regulation and lipid barrier polymer synthesis, TRINITY_DN7582_c0_g1 and TRINITY_DN11770_c0_g1 regulate alkaloid synthesis, and TRINITY_DN7597_c1_g3 and TRINITY_DN1899_c0_g1 regulate salicylic acid and ethylene biosynthesis. These results indicate that JA treatment of daylily improved its resistance to T. palmi. These findings provide a scientific basis for the utilization of JA as an antagonist to control T. palmi in daylily.

Thrips are serious pests of Hemerocallis citrina Baroni (daylily), affecting crop yield and quality. To defend against pests, daylily has evolved a set of sophisticated defense mechanisms. In the present study, induction of systemic resistance in Hemerocallis citrina ‘Datong Huanghua’ by Thrips palmi feeding was investigated at both biochemical and molecular levels. The soluble sugar content of daylily leaves was significantly lower than that in control check (CK) at all time points of feeding by T. palmi, whereas the amino acid and free fatty acid contents started to be significantly lower than those in CK after 7 days. Secondary metabolites such as tannins, flavonoids, and total phenols, which are harmful to the growth and reproduction of T. palmi, were increased significantly. The activities of defense enzymes such as peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO) were significantly increased, and the degree of damage to plants was reduced. The significant increase in protease inhibitor (PI) activity may lead to disrupted digestion and slower growth in T. palmi. Using RNA sequencing, 1,894 differentially expressed genes (DEGs) were identified between control and treatment groups at five timepoints. DEGs were mainly enriched in secondary metabolite synthesis, jasmonic acid (JA), salicylic acid (SA), and other defense hormone signal transduction pathways, defense enzyme synthesis, MAPK signaling, cell wall thickening, carbohydrate metabolism, photosynthesis, and other insect resistance pathways. Subsequently, 698 DEGs were predicted to be transcription factors, including bHLH and WRKY members related to biotic stress. WGCNA identified 18 hub genes in four key modules (Purple, Midnight blue, Blue, and Red) including MYB-like DNA-binding domain (TRINITY_DN2391_c0_g1, TRINITY_DN3285_c0_g1), zinc-finger of the FCS-type, C2-C2 (TRINITY_DN21050_c0_g2), and NPR1 (TRINITY_DN13045_c0_g1, TRINITY_DN855_c0_g2). The results indicate that biosynthesis of secondary metabolites, phenylalanine metabolism, PIs, and defense hormones pathways are involved in the induced resistance to T. palmi in daylily.

We evaluated the effectiveness of vapor heat treatment on Thrips palmi Karny, Bemisia tabaci(Gennadius), and colonies of powdery mildew, Sphaerotheca fuliginea(Schlechtendal)Pollacci, on greenhouse melon seedlings. Air was gradually heated to a set temperature(48°C)over 45 min while the relative humidity was maintained at 95%. The set temperature was then held for 8 min. The numbers of T. palmi adults and larvae, B. tabaci adults, and colonies of powdery mildew were lower on seedlings held at 48°C for 8 min than on untreated seedlings. The hatchability of T. palmi and the ratio of emerged adults were lower on treated than on untreated seedlings. Treatment at 48°C for 8 min did not visibly damage the seedlings. These results suggest that vapor heat treatment at 48°C for 8 min can effectively reduce the population densities of T. palmi eggs, larvae, pupae, and adults, B. tabaci adults, and powdery mildew on greenhouse melon seedlings. [ABSTRACT FROM AUTHOR]

BACKGROUND: Ultraviolet (UV) interferes with the vision, flight initiation, dispersal, host, and population dispersion of herbivorous insects. Hence, UV‐blocking film has recently been developed as one of the most potential tools to control pests under tropical greenhouse conditions. In this study, we investigated the effects of UV‐blocking film on the population dynamics of Thrips palmi Karny and the growth status of Hami melon (Cucumis melo var. reticulatus) in greenhouses. RESULTS: By comparing thrips populations in greenhouses covered with UV‐blocking films with those covered with ordinary polyethylene films, we found that the UV‐blocking film effectively reduced the thrips population within 1 week and continued to control the population, meanwhile the quality and yield of melon in UV‐blocking greenhouses also had a substantial increase. CONCLUSION: The UV‐blocking film remarkably inhibited the population growth of thrips and greatly improved the yield of Hami melon cultivated in UV‐blocking greenhouse compared with the control greenhouse. Overall, UV‐blocking film is a very powerful potential tool for green pest control in the field, enhancing the quality of tropical fruits, and providing a new wind vane for sustainable green agriculture in the future. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The effects of soluble silicon fertilization on monocots and dicots have been widely studied. However, little is known regarding its effects on protecting epiphytes against insect and fungal pests. The efficacy of silicon fertilizer to reduce damage by thrips pest complexes, namely: Thrips palmi Karny, Frankliniella occidentalis Pergande, Chaetanaphothrips orchidii Moulton, and Chaetanaphothrips signipennis Bagnall (Thysanoptera: Thripidae), and the fungal pathogens: Botrytis cinerea Persoon (Helotiales: Sclerotiniaceae) and Fusarium spp. Link (Hypocreales: Nectriaceae) was examined during a nine-month greenhouse trial in Hawaii. The trial assessed yield, quality, and pest damage across three common varieties of dendrobiums. All replicates received additional soluble silicon fertilizer applications alternating weekly between soil drench and foliar (50 mg Si/plant) applications. Yield, quality, and spray length, pest damage, plant vigor, SPAD, and leaf temperature were measured. Data were analyzed using a generalized linear model (glm) with repeated measures followed by post-hoc pair-wise comparisons in R, version 4.3.1. Treatment effects were significant at p < 0.001 for the majority of the explanatory variables including: marketable yield, spray length, thrips damage, and fungal damage. Overall, the lavender variety (‘Uniwai Supreme’) benefited the most from silicon applications with a 73.0% increase in marketable yield, compared to the white variety (‘Uniwai Mist’), which had an increase of 50.6% marketable sprays in contrast to its untreated control. Si benefits conferred to the purple variety (‘Uniwai Royale’) were intermediate to the lavender and white varieties. Although the magnitude of Si benefits varied among the varieties, all dendrobium varieties significantly benefited from silicon fertilization.

The tomato industry in South Florida (USA) is seriously affected by recently emerging Tomato chlorotic spot virus (TCSV). Western flower thrips, Frankliniella occidentalis (Pergande), and common blossom thrips, Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae), are the two known vectors of TCSV in Florida. In the present study, the presence of thrips vectors and TCSV in 24 flowering ornamental plant species was observed in South Florida. The two thrips vectors, as well as melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), were abundant in the area; they were observed with a range from high (83.1 per sample of 10 flowers) in Hibiscus rosa‐sinensis L. to low (3.7 per sample of 10 flowers) in Catharanthus roseus (L.) G. Don in a nursery study. In a subsequent greenhouse study, we selected seven species of ornamentals, among which the species with the highest thrips abundance, and planted them next to tomato, to determine their effects on TCSV incidence and thrips abundance in tomatoes. Tomatoes with Portulaca oleracea L. next to them showed a higher number of TCSV‐infected plants (4.25 plants per plot in 2017, and 3.25 plants per plot in 2018) compared to tomatoes with some of the other ornamentals next to them. We report the presence of TCSV through reverse transcriptase polymerase chain reaction (RT‐PCR) analysis in Lantana camara L., H. rosa‐sinensis, Mandevilla spec., Gazania linearis (Thunb.) Druce, Hemerocallis spec., Agastache spec., and P. oleracea. Identification of alternative hosts of TCSV and thrips vectors can be helpful to evaluate the ongoing management programs and develop future programs in local tomato‐growing areas. [ABSTRACT FROM AUTHOR]

We evaluated the effectiveness of using an indigenous generalist predatory mite, Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae), to control Thrips palmi Karny (Thysanoptera: Thripidae) in greenhouse melons. In a growth chamber experiment, the density of T. palmi was lower on plants exposed to 20 N. barkeri per plant than on plants grown without a biological control. In a greenhouse experiment, the density of T. palmi was lower in the N. barkeri release plots than in the no-release plots. These results suggest that N. barkeri is an effective biological control agent against T. palmi. [ABSTRACT FROM AUTHOR]

Sap sucking insects like thrips, aphids, mealybugs, whiteflies exploit the sugar rich phloem for growth and development. The excess sugar in the phloem sap creates osmotic imbalance leading to loss of water from haemolymph to gut lumen. In order to maintain osmolarity, sap sucking insects have developed structural adaptation (filter chamber) and also excrete excess sugar as honeydew through various orifices. The excreted honeydew is known to play very vital ecological role such as natural enemy calling (attracting parasitoids). In this regard scanty information is available on this important aspect for different sap sucking insects. In this study we are reporting for the first time on the composition of honeydew from the major horticultural thrips, Thrips palmi reared on French bean (Phaseolus vulgaris). LC-MS-MS analysis revealed the presence of 15 different sugars majorly inositol, fructose, maltose, glucose and sorbitol @ (130.9 ±0.47μg); (95.1±0.45μg); (60.7 ±0.28μg); (54.2 ±0.40μg) and (28.1 ±0.35μg), respectively.

Abstract The melon thrips, Thrips palmi, is an increasingly important pest of vegetables in northern China. Some populations have developed resistance in the field to the insecticide spinetoram. Understanding the origin and dispersal of insecticide‐resistant populations can shed light on resistance management strategies. In this study, we tested susceptibility of seven greenhouse populations of T. palmi to spinetoram collected from a small area of about 300 km2 in Shandong Province and examined population genetic structure across the area based on a segment of mitochondrial cox1 gene and 22 microsatellite loci to infer the possible origin and dispersal of insecticide resistance. Levels of resistance to spinetoram differed among seven populations, which included one population with high resistance (LC50 = 759.34 mg/L), three populations with medium resistance (LC50 ranged from 28.69 to 34.79 mg/L), and three populations with low resistance (LC50 ranged from 7.61 to 8.97 mg/L). The populations were genetically differentiated into two groups unrelated to both levels of resistance and geographic distance. The molecular data indicated high levels of gene flow between populations with different levels of resistance to spinetoram and low gene flow among populations with the same level of resistance, pointing to a likely separate history of resistance evolution. Resistance levels of two tested populations to spinetoram decreased 23 and 4.6 times after five generations without any exposure to the pesticide. We therefore suspect that resistance of T. palmi most likely evolved in response to local applications of the insecticide. Our study suggests that the development of resistance could be avoided or resistance even reversed by reducing usage of spinetoram.

Abstract Background To date, four thrips vectors have been reported to transmit five different tospoviruses in India. Their identification at an early stage is crucial in formulating appropriate pest management strategies. Since morphometric key-based thrips identification based on the adult stage is time-consuming, there is a need to develop diagnostic tools which are rapid, accurate, and independent of developmental stages. Here, we report a multiplex PCR assay to identify four major thrips vectors viz. Thrips palmi, T. tabaci, Scirtothrips dorsalis, and Frankliniella schultzei present in India. Results Cytochrome oxidase subunit III and internal transcribed spacer region 2 were utilized to design species-specific primers. Of 38 pairs of primers tested, primer pairs AG35F-AG36R, AG47F-AG48R, AG87F-AG88R, and AG79F-AG80R amplified 568 bp, 713 bp, 388 bp, and 200 bp products from the DNA templates of T. palmi, S. dorsalis, T. tabaci, and F. schultzei, respectively at same PCR conditions. The specificity of the primer pairs was validated with a large number of known specimens and no cross-reactivity was observed with other thrips species. The multiplex PCR assay with a cocktail of all the four primer pairs detected four thrips vectors efficiently and could discriminate all of them concurrently in a single reaction. Conclusion The multiplex PCR reported in this study could identify the major thrips vectors reported in India. The assay will be useful in ascertaining distribution profile of major thrips vectors, disease epidemiology, screening large samples, and quarantine.

Abstract Biological invasions of pests into climatically unsuitable areas can be facilitated by human‐regulated environments, in which case there may be an impact on genetic structure through population processes and/or adaptation. Here, we investigated the population genetic structure of an invasive agricultural pest, Thrips palmi, in China, which has expanded its distribution range through using greenhouses. Early invaded populations showed a relatively higher level of genetic diversity than recently expanded greenhouse populations. Strong population genetic structure corresponded to a pattern of isolation by distance, with no recent gene flow and low historical gene flow among populations, reflecting limited ongoing dispersal. A genetic signature of population expansion was detected in early invaded populations and three northern populations from greenhouses, suggesting that the greenhouse environments facilitated expansion of this species. Redundancy analysis showed that the independent effects of environment and geography could explain 51.68% and 32.06% of the genetic variance, respectively. These findings point to climate‐ and greenhouse‐related spatial expansion, with the potential for adaptation by T. palmi. They emphasize the contribution of human‐regulated environments on the successes of this invasive species, a situation likely to apply to other invasive species that use greenhouse environments.

Abstract The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high‐risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Thailand, taking into account the available scientific information, including the technical information provided by the Department of Agriculture of Thailand. The risk mitigation measures proposed in the technical dossier from Thailand were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packing house, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Thailand, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,496 and 10,000 M. charantia fruits/10,000 will be free from T. palmi.

Abstract The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high‐risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Sri Lanka, taking into account the available scientific information, including the technical information provided by the National Plant Quarantine Service of Sri Lanka. The risk mitigation measures proposed in the technical dossier from Sri Lanka were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packing house, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Sri Lanka, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9831 and 10,000 M. charantia fruits/10,000 will be free from T. palmi.

Abstract The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Mexico, taking into account the available scientific information, including the technical information provided by the National Service of Health, Safety and Agrifood Quality (Senasica) of Mexico. The risk mitigation measures proposed in the technical dossier from Mexico were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packinghouse, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Mexico, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,492 and 10,000 M. charantia fruits per 10,000 will be free from T. palmi.

Abstract The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as ‘High risk plants, plant products and other objects’. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Honduras, taking into account the available scientific information, including the technical information provided by the National Service of Agrifood Health and Safety (SENASA) of Honduras. The risk mitigation measures proposed in the technical dossier from Honduras were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packinghouse, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Honduras, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,406 and 10,000 M. charantia fruits per 10,000 will be free from T. palmi.

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. M. charantia fruits originating from countries where Thrips palmi is known to occur qualify as high‐risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Suriname, taking into account the available scientific information, including the technical information provided by the National Plant Protection Organization of Suriname. The risk mitigation measures proposed in the technical dossier from Suriname were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packinghouse, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Suriname, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 8,652 and 10,000 M. charantia fruits per 10,000 will be free from T. palmi. [ABSTRACT FROM AUTHOR]

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Honduras, taking into account the available scientific information, including the technical information provided by the National Service of Agrifood Health and Safety (SENASA) of Honduras. The risk mitigation measures proposed in the technical dossier from Honduras were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packinghouse, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Honduras, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,406 and 10,000 M. charantia fruits per 10,000 will be free from T. palmi. [ABSTRACT FROM AUTHOR]

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high‐risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Thailand, taking into account the available scientific information, including the technical information provided by the Department of Agriculture of Thailand. The risk mitigation measures proposed in the technical dossier from Thailand were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packing house, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Thailand, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,496 and 10,000 M. charantia fruits/10,000 will be free from T. palmi. [ABSTRACT FROM AUTHOR]

The European Commission requested the EFSA Panel on Plant Health to prepare and deliver risk assessments for commodities listed in Commission Implementing Regulation (EU) 2018/2019 as 'High risk plants, plant products and other objects'. Momordica fruits originating from countries where Thrips palmi is known to occur qualify as high risk plants. This Scientific Opinion covers the introduction risk for T. palmi posed by fruits of Momordica charantia L. imported from Mexico, taking into account the available scientific information, including the technical information provided by the National Service of Health, Safety and Agrifood Quality (Senasica) of Mexico. The risk mitigation measures proposed in the technical dossier from Mexico were evaluated taking into account the possible limiting factors. An expert judgement is given on the likelihood of pest freedom taking into consideration the potential pest pressure in the field, the risk mitigation measures acting on the pest in the field and in the packinghouse, including uncertainties associated with the assessment. For T. palmi on M. charantia fruits from Mexico, an expert judgement is given on the likelihood of pest freedom following the evaluation of the risk mitigation measures acting on T. palmi, including any uncertainties. The Expert Knowledge Elicitation indicated, with 95% certainty that between 9,492 and 10,000 M. charantia fruits per 10,000 will be free from T. palmi. [ABSTRACT FROM AUTHOR]

Putative mechanisms underlying spinosyn resistance have been identified in controlled studies on many species; however, mechanisms underlying field-evolved resistance and the development of a molecular diagnostic method for monitoring field resistance have lagged behind. Here, we examined levels of resistance of melon thrips, Thrips palmi Karny (Thysanoptera:Thripidae), to spinetoram as well as target site mutations in field populations across China to identify potential mechanisms and useful molecular markers for diagnostic and quantifying purposes. In resistant populations, we identified the G275E mutation, which has previously been linked to spinosyns resistance, and F314V mutation, both located in the α 6 subunit of the nicotinic acetylcholine receptor. There was a strong correlation between levels of spinetoram resistance and allele frequency of G275E mutation in field-collected populations (r 2 = 0.84) and those reared under laboratory conditions for two to five generations (r 2 = 0.91). LC50 ranged from 0.12 to 0.66 mg/liter in populations without G275E mutation, whereas it ranged from 33.12 to 39.91 mg/liter in most populations with a G275E mutation frequency more than 90%. Our results indicate that the field-evolved resistance of T. palmi to spinetoram in China is mainly conferred by the G275E mutation. The frequency of the G275E mutation provides a useful diagnostic for quantifying resistance levels in field populations of T. palmi. [ABSTRACT FROM AUTHOR]

Different species of thrips can occur in the same location and on the same plant. However, variation among dominant thrips species in their susceptibility to insecticide remains unclear. In this study, we evaluated the susceptibility of Frankliniella occidentalis, Thrips palmi and Frankliniella intonsa, three common thrips on vegetables, to spinetoram, from 12 geographical areas across China. Thrips palmi showed the lowest susceptibility to spinetoram (LC50 ranged from 0.1192 to 117.6707 mg L−1), while F. intonsa showed the highest susceptibility (LC50 ranged from 0.0044 to 0.6476 mg L−1). Field-evolved resistance to spinetoram was found for T. palmi and F. occidentalis, resulting in 987.17-fold and 323.77-fold differences in toxicity within each of these species, respectively. The Shouguang populations of T. palmi and F. occidentalis had the highest overall levels of resistance, with LC50 values of 117.6707 mg L−1 and 11.4290 mg L−1, respectively. Levels of susceptibility in southern populations of F. intonsa were low compared to northern populations of this species in China. In conclusion, our study highlighted variation in susceptibility of thrips to spinetoram, both among species and among geographical areas. The results should help the implementation of management tactics, and they provide insights into the displacement of thrips species in fields. [ABSTRACT FROM AUTHOR]

Plant viruses can modify the performance and behavior of insect vectors to maximize their transmission rates. Whether viruses can evolve to mediate their insect vectors' interspecific competition is poorly understood. Here, we used two vectors of tomato zonate spot virus (TZSV), one native species (Thrips palmi) and one exotic species (Frankliniella occidentalis), to investigate this in laboratory and field experiments. TZSV infection increased the population growth of its insect vectors when the thrips species were isolated from one another. When both species coexisted, F. occidentalis displaced T. palmi on both TZSV-infected and uninfected plants. However, on TZSV-infected plant, F. occidentalis completely displaced T. palmi more rapidly (within 14 days) than on uninfected plants. Our results also revealed that reproductive interference occurred between the two thrips species, whereas TZSV-infected pepper significantly decreased the reproductive interference of T. palmi to F. occidentalis. When F. occidentalis and T. palmi co-occurred in Jinning County, Yunnan Province, we found a rising trend of natural proportions of F. occidentalis in the TZSV-infected pepper fields, suggesting that TZSV-infected pepper enhanced the competitive advantage of F. occidentalis over T. palmi in the field. Together, our findings demonstrate a plant virus that plays an important role in the competitive displacement of its insect vectors. [ABSTRACT FROM AUTHOR]

Thrips are serious pests of Hemerocallis citrina Baroni (daylily), affecting crop yield and quality. To defend against pests, daylily has evolved a set of sophisticated defense mechanisms. In the present study, induction of systemic resistance in Hemerocallis citrina 'Datong Huanghua' by Thrips palmi feeding was investigated at both biochemical and molecular levels. The soluble sugar content of daylily leaves was significantly lower than that in control check (CK) at all time points of feeding by T. palmi , whereas the amino acid and free fatty acid contents started to be significantly lower than those in CK after 7 days. Secondary metabolites such as tannins, flavonoids, and total phenols, which are harmful to the growth and reproduction of T. palmi , were increased significantly. The activities of defense enzymes such as peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO) were significantly increased, and the degree of damage to plants was reduced. The significant increase in protease inhibitor (PI) activity may lead to disrupted digestion and slower growth in T. palmi . Using RNA sequencing, 1,894 differentially expressed genes (DEGs) were identified between control and treatment groups at five timepoints. DEGs were mainly enriched in secondary metabolite synthesis, jasmonic acid (JA), salicylic acid (SA), and other defense hormone signal transduction pathways, defense enzyme synthesis, MAPK signaling, cell wall thickening, carbohydrate metabolism, photosynthesis, and other insect resistance pathways. Subsequently, 698 DEGs were predicted to be transcription factors, including bHLH and WRKY members related to biotic stress. WGCNA identified 18 hub genes in four key modules (Purple, Midnight blue, Blue, and Red) including MYB-like DNA-binding domain (TRINITY&#95;DN2391&#95;c0&#95;g1, TRINITY&#95;DN3285&#95;c0&#95;g1), zinc-finger of the FCS-type, C2-C2 (TRINITY&#95;DN21050&#95;c0&#95;g2), and NPR1 (TRINITY&#95;DN13045&#95;c0&#95;g1, TRINITY&#95;DN855&#95;c0&#95;g2). The results indicate that biosynthesis of secondary metabolites, phenylalanine metabolism, PIs, and defense hormones pathways are involved in the induced resistance to T. palmi in daylily., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Sun, Shen, Chen, Ma, Yang, Liu and Li.)

The behaviour of 5th instar nymphs and adult males and females of anthocorid bug, Orius insidiosus preying on adult Thrips palmi was studied. Adult O. insidiosus males spent longest time in motion compared with 5th instar nymphs and adult females. First encounter of prey was shortest for 5th instar nymphs but not significantly different from that of adult females. The distance travelled to 1st prey by 5th instar nymphs was significantly shortest compared to both adult male and female O. insidiosus. However, speed of arrival to 1st prey did not significantly differ among the three stages of O. insidiosus examined. Mean time spent by O. insidiosus 5th instar nymphs and adult females on 1st, 2nd, 3rd and 4th prey encounters was not significantly different. However, adult males of O. insidiosus spent significantly less time on 4th prey encounter compared with 1st - 3rd prey encounters. [ABSTRACT FROM AUTHOR]

The melon thrips, Thrips palmi, is an increasingly important pest of vegetables in northern China. Some populations have developed resistance in the field to the insecticide spinetoram. Understanding the origin and dispersal of insecticide‐resistant populations can shed light on resistance management strategies. In this study, we tested susceptibility of seven greenhouse populations of T. palmi to spinetoram collected from a small area of about 300 km2 in Shandong Province and examined population genetic structure across the area based on a segment of mitochondrial cox1 gene and 22 microsatellite loci to infer the possible origin and dispersal of insecticide resistance. Levels of resistance to spinetoram differed among seven populations, which included one population with high resistance (LC50 = 759.34 mg/L), three populations with medium resistance (LC50 ranged from 28.69 to 34.79 mg/L), and three populations with low resistance (LC50 ranged from 7.61 to 8.97 mg/L). The populations were genetically differentiated into two groups unrelated to both levels of resistance and geographic distance. The molecular data indicated high levels of gene flow between populations with different levels of resistance to spinetoram and low gene flow among populations with the same level of resistance, pointing to a likely separate history of resistance evolution. Resistance levels of two tested populations to spinetoram decreased 23 and 4.6 times after five generations without any exposure to the pesticide. We therefore suspect that resistance of T. palmi most likely evolved in response to local applications of the insecticide. Our study suggests that the development of resistance could be avoided or resistance even reversed by reducing usage of spinetoram. [ABSTRACT FROM AUTHOR]

In order to contrast the fitness of Thrips palmi Karny reared on two of its hosts plants, Brassica oleracea L. leaves and Phaseolus vulgaris L. beans, life tables were constructed for T. palmi individuals reared on the two hostplants at 25°C using the age–stage, two-sex life table. The durations of the egg, first instar larva, pupa, and total immature stages of T. palmi reared on P. vulgaris were significantly longer than those reared on B. oleracea , whereas the adult preoviposition period, female adult longevity, and number of oviposition days of T. palmi reared on B. oleracea were significantly longer/greater than those on P. vulgaris. The fecundity (F) of T. palmi reared on B. oleracea (159.71 offspring/female) was significantly higher than in females reared on P. vulgaris (F = 122.98 offspring/female) despite the higher proportion of female adults that emerged on P. vulgaris. Although there were no significant differences in the intrinsic rate of increase (r), finite rate (λ), net reproductive rate (R 0), and mean generation time (T) between the two populations, computer projection showed that the T. palmi population will increase faster when reared on B. oleracea than on P. vulgaris. Our results demonstrate that population projection based on life table data is potentially an important tool in pest management. Furthermore, we used the bootstrap technique to demonstrate the variable effect that survival rate and fecundity at different ages can have on population parameters. [ABSTRACT FROM AUTHOR]

Thrips are tiny insects from the order Thysanoptera (Hexapoda: Condylognatha), including many sap‐sucking pests that are causing increasing damage to crops worldwide. In contrast to their closest relatives of Hemiptera (Hexapoda: Condylognatha), including numerous sap‐sucking species, there are few genomic resources available for thrips. In this study, we assembled the first thrips genome at the chromosomal level from the melon thrips, Thrips palmi, a notorious pest in agriculture, using PacBio long‐read and Illumina short‐read sequences. The assembled genome was 237.85 Mb in size, with 1,324 contigs and a contig N50 of 567 kb. All contigs were assembled into 16 linkage groups assisted by the Hi‐C technique. In total, 16,333 protein‐coding genes were predicted, of which 88.13% were functionally annotated. Among sap‐sucking insects, polyphagous species (e.g., T. palmi and Bemisia tabaci) usually possess more detoxification genes than oligophagous species (e.g., Diaphorina citri). The polyphagous thrips genomes characterized so far have relatively more detoxification genes in the GST and CCE families than polyphagous aphids, but they have fewer UGTs. HSP genes, especially from the Hsp70s group, have expanded in thrips compared to other hemipterans. These differences point to different genetic mechanisms associated with detoxification and stress responses in these two groups of sap‐sucking insects. The expansion of these gene families may contribute to the rapid development of pesticide resistance in thrips, as supported by a transcriptome comparison of resistant and sensitive populations of T. palmi. The high‐quality genome developed here provides an invaluable resource for understanding the ecology, genetics, and evolution of thrips as well as their relatives more generally. [ABSTRACT FROM AUTHOR]

The effects of red-light irradiation and a reflective sheet cover on the population density of two thrips species（Thysanoptera: Thripidae）, the melon thrips（Thrips palmi Karny）and the onion thrips （Thrips tabaci Lindeman）, were investigated on eggplant and cucumber in a greenhouse in 2014 and 2015. Red fluorescent lamps were illuminated from above the plants and a light reflecting sheet was placed on the ridges of the treated plots. A greenhouse without either material was set up as a control plot. The population densities of the two thrips species on eggplant and T. palmi on cucumber were significantly lower in the treated plots than in the control plot. [ABSTRACT FROM AUTHOR]

To develop an augmentative biological control programme for Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and Thrips palmi Karny (Thysanoptera: Thripidae) using Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), we studied the life history traits of a Japanese strain of N. tenuis reared on B. tabaci and T. palmi in controlled environments. The lower developmental threshold during the nymphal period was far higher than those estimated for Spanish, Moroccan, and Iranian strains, indicating that the Japanese strain is better adapted to higher temperatures than the other three strains tested. The intrinsic rate of increase rm was highest at 30 °C and lowest at 20 °C. The rm value for individuals reared on T. palmi at 25 °C was lower than that for individuals reared on B. tabaci at the same temperature. Implications of these results for the biological control of B. tabaci and T. palmi in greenhouses are discussed. [ABSTRACT FROM AUTHOR]

Background: To date, four thrips vectors have been reported to transmit five different tospoviruses in India. Their identification at an early stage is crucial in formulating appropriate pest management strategies. Since morphometric key-based thrips identification based on the adult stage is time-consuming, there is a need to develop diagnostic tools which are rapid, accurate, and independent of developmental stages. Here, we report a multiplex PCR assay to identify four major thrips vectors viz. Thrips palmi, T. tabaci, Scirtothrips dorsalis, and Frankliniella schultzei present in India. Results: Cytochrome oxidase subunit III and internal transcribed spacer region 2 were utilized to design species-specific primers. Of 38 pairs of primers tested, primer pairs AG35F-AG36R, AG47F-AG48R, AG87F-AG88R, and AG79F-AG80R amplified 568 bp, 713 bp, 388 bp, and 200 bp products from the DNA templates of T. palmi, S. dorsalis, T. tabaci, and F. schultzei, respectively at same PCR conditions. The specificity of the primer pairs was validated with a large number of known specimens and no cross-reactivity was observed with other thrips species. The multiplex PCR assay with a cocktail of all the four primer pairs detected four thrips vectors efficiently and could discriminate all of them concurrently in a single reaction. Conclusion: The multiplex PCR reported in this study could identify the major thrips vectors reported in India. The assay will be useful in ascertaining distribution profile of major thrips vectors, disease epidemiology, screening large samples, and quarantine. [ABSTRACT FROM AUTHOR]

Transmission efficiencies of capsicum chlorosis virus (CaCV) were investigated for four thrips species (Thysanoptera: Thripidae), Frankliniella occidentalis (Pergande), Frankliniella intonsa (Trybom), Thrips palmi (Karny), and Thrips tabaci Lindeman infesting green pepper in Japan. The first-instar larvae of the thrips were allowed to feed on CaCV-infected green pepper leaves for 24 h. The transmission of CaCV by thrips was examined using a petunia leaf disk assay. CaCV was transmitted by four male (8.70%) and four female (3.88%) T. palmi, but the virus was not transmitted by adults of any other species. In a second transmission assay, 10 adult T. palmi that had fed on infected leaves as larvae were released to healthy green pepper seedlings. After 21 days, the seedlings were examined and 50% of them showed symptoms of CaCV infection. RT-PCR confirmed that they were infected with the virus. The viruliferous rate of adult T. palmi was 60%, while CaCV was not detected in adults of the other three species. These results suggest that T. palmi is capable of being a new vector of CaCV. [ABSTRACT FROM AUTHOR]

[Display omitted] • This study tested phenotypic changes in heat and cold tolerance of Thrips palmi. • Rapid heat hardening at 35 °C slightly increased CTmax but decreased it at 31 °C. • Heat acclimation for 2 and 4 days significantly increased CTmax at 35 °C. • Cold hardening and acclimation increased cold tolerance. • Space for heat stress induction is narrower than for cold stress induction. Extreme temperatures threaten species under climate change and can limit range expansions. Many species cope with changing environments through plastic changes. This study tested phenotypic changes in heat and cold tolerance under hardening and acclimation in the melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), an agricultural pest of many vegetables. We first measured the critical thermal maximum (CT max) of the species by the knockdown time under static temperatures and found support for an injury accumulation model of heat stress. The inferred knockdown time at 39 °C was 82.22 min. Rapid heat hardening for 1 h at 35 °C slightly increased CT max by 1.04 min but decreased it following exposure to 31 °C by 3.46 min and 39 °C by 6.78 min. Heat acclimation for 2 and 4 days significantly increased CT max at 35 °C by 1.83, and 6.83 min, respectively. Rapid cold hardening at 0 °C and 4 °C for 2 h, and cold acclimation at 10 °C for 3 days also significantly increased cold tolerance by 6.09, 5.82, and 2.00 min, respectively, while cold hardening at 8 °C for 2 h and acclimation at 4 °C and 10 °C for 5 days did not change cold stress tolerance. Mortality at 4 °C for 3 and 5 days reached 24.07 % and 43.22 % respectively. Our study showed plasticity for heat and cold stress tolerance in T. palmi , but the thermal and temporal space for heat stress induction is narrower than for cold stress induction. [ABSTRACT FROM AUTHOR]

Biological invasions of pests into climatically unsuitable areas can be facilitated by human‐regulated environments, in which case there may be an impact on genetic structure through population processes and/or adaptation. Here, we investigated the population genetic structure of an invasive agricultural pest, Thrips palmi, in China, which has expanded its distribution range through using greenhouses. Early invaded populations showed a relatively higher level of genetic diversity than recently expanded greenhouse populations. Strong population genetic structure corresponded to a pattern of isolation by distance, with no recent gene flow and low historical gene flow among populations, reflecting limited ongoing dispersal. A genetic signature of population expansion was detected in early invaded populations and three northern populations from greenhouses, suggesting that the greenhouse environments facilitated expansion of this species. Redundancy analysis showed that the independent effects of environment and geography could explain 51.68% and 32.06% of the genetic variance, respectively. These findings point to climate‐ and greenhouse‐related spatial expansion, with the potential for adaptation by T. palmi. They emphasize the contribution of human‐regulated environments on the successes of this invasive species, a situation likely to apply to other invasive species that use greenhouse environments. [ABSTRACT FROM AUTHOR]

Capsicum species are commercially grown for pepper production. This crop suffers severely from thrips damage and the identification of natural sources of thrips resistance is essential for the development of resistant cultivars. It is unclear whether resistance to Frankliniella occidentalis as assessed in a specific environment holds under different conditions. Additionally, other thrips species may respond differently to the plant genotypes. Screening for robust and general resistance to thrips encompasses testing different Capsicum accessions under various conditions and with different thrips species. We screened 11 Capsicum accessions (C. annuum and C. chinense) for resistance to F. occidentalis at three different locations in the Netherlands. Next, the same 11 accessions were screened for resistance to Thrips palmi and Scirtothrips dorsalis at two locations in Asia. This resulted in a unique analysis of thrips resistance in Capsicum at five different locations around the world. Finally, all accessions were also screened for resistance to F. occidentalis in the Netherlands using a leaf disc choice assay, allowing direct comparison of whole plant and leaf disc assays. Resistance to F. occidentalis was only partially consistent among the three sites in the Netherlands. The most susceptible accessions were consistently susceptible, but which accession was the most resistant differed among sites. In Asia, one C. chinense accession was particularly resistant to S. dorsalis and T. palmi, but this was not the most resistant accession to F. occidentalis. Overall, resistance to F. occidentalis correlated with S. dorsalis but not with T. palmi resistance in the C. annuum accessions. Damage inflicted on leaf discs reflected damage on the whole plant level. Our study showed that identifying broad spectrum resistance to thrips in Capsicum may prove to be challenging. Breeding programmes should focus on developing cultivars suitable for growing in defined geographic regions with specific thrips species and abiotic conditions. [ABSTRACT FROM AUTHOR]

The study was conducted to evaluate the effect of bio-pesticides and chemical insecticides namely Novastar 56EC, Stargate 48SC, Confidor 70WG, Actara 25aWG, Tracer 45SC, Ecomec 1.8EC, Bioneem plus 1EC to control thrips infesting mung bean in the experimental field of Sher-e-Bangla Agricultural University during November 2017 to February 2018. An untreated control observation was also evaluated. Efficacy of the treatments differed significantly and showed effective results in reduction of thrips population and infestation on mung bean at vegetative and reproductive growth stages of the plant. Stargate 48SC (clothianidin) was the most effective insecticide against the thrips species Megalurothrips usitatus and Thrips palmi with the highest reduction of population on top trifoliate leaves and terminal shoots (100.00 and 89.40%, respectively) at vegetative stage and reduction on flower buds and flowers (86.04 and 85.95%, respectively) at reproductive stage of mung bean. The lowest flower bud and flower infestation (7.22 and 3.41%, respectively) and shedding (4.21 and 1.06%, respectively) by thrips with the highest number of pod (23.80 plant-1), seed (10.20 pod-1), 1000 seed weight (48.40 g) and yield (1026.91 kg ha-1) were also found in Stargate 48SC treated plots followed by Confidor 70WG and Actara 25WG treatments. [ABSTRACT FROM AUTHOR]

A residual contact vial plus water (RCVpW) bioassay method, in which water was supplemented to minimize control mortality, was established to monitor insecticide resistance in field populations of the melon thrips, Thrips palmi. In the RCVpW, median lethal doses (LD 50) of six insecticides commonly used in T. palmi control, were determined at 8 h post-treatment, using a susceptible RDA strain according to the RCVpW protocol. Diagnostic doses for on-site resistance monitoring of the six insecticides, which were determined as doses two-fold higher than required to achieve LD 90 in the RDA strain, were in the range of 0.299 to 164.3 μg−1 cm2. Insecticide resistance levels in five field populations of T. palmi were evaluated to test the applicability of RCVpW in monitoring the pest. Although the RDA strain exhibited 100% mortality to diagnostic doses, field populations showed a reduced mortality in response to all test insecticides, indicating different degrees of resistance. In particular, all test field populations exhibited a significantly low mortality in response to spinosad, suggesting a wide distribution of spinosad resistance. Synergistic bioassay revealed that cytochrome P450-mediated metabolic factor is involved in spinosad resistance in the Korean population. Interestingly, an apparently reduced mortality to emamectin benzoate and chlofenapyr was observed in some field populations, perhaps suggesting uneven distribution of resistance to these insecticides in field populations. Our study showed that the RCVpW protocol can be employed both as an on-site resistance monitoring method for major thrip species, and in the selection of appropriate insecticides for their control. Unlabelled Image • Residual contact vial bioassay assists monitoring of Thrips palmi insecticide resistance. • T. palmi insecticide resistance varies between populations and insecticides. • Insecticide resistance to spinosad is particularly high in tested populations. • Spinosad resistance is associated with cytochrome P450-mediated metabolic factor. [ABSTRACT FROM AUTHOR]

Melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), is a serious pest of vegetable, ornamental, and fruit crops. As a potential component of an integrated pest management (IPM) program, different plastic mulches including white-on-black, black-on-white, black-on-black, two metalized ultraviolet (UV)-reflective mulches, and a no mulch control were evaluated for managing T. palmi on six field-grown vegetable crops (eggplant, cucumber, squash, snap bean, Jalapeno pepper, and tomato) during the Fall of 2015 and 2016. Metalized reflective mulch significantly reduced the number of T. palmi in all vegetable crops compared with the other treatments. The highest numbers of T. palmi were observed on the white-on-black mulch and control treatments. The numbers of adults and larvae were highest on eggplant followed by cucumber, snap bean, squash, and Jalapeno pepper. The lowest numbers of T. palmi were observed on tomato plants. This study indicated that growing vegetable crops on metalized mulch is an effective method of reducing T. palmi populations in vegetable crops and should be considered in IPM programs for this insect species. [ABSTRACT FROM AUTHOR]

[Display omitted] • Actinomycete IMBL-2090 showed high insecticidal activity against T. palmi. • IMBL-2090 was identified to Streptomyces gramineus. • Phenylacetic acid was isolated as main insecticidal compound from IMBL-2090. Thrips palmi, also known as melon thrips, is one of the serious phytophagous sap-sucking insects that not only damages a wide range of crops but also serve as a vector for plant viruses. Actinomycetes have been reported to produce various insecticidal compounds such as spinosad and avermectin, suggesting that secondary metabolites from actinomycetes could be useful biological insecticides. In this study, culture filtrates of 174 actinomycetes isolates were screened for their insecticidal activity against T. palmi. Among them, Streptomyces IMBL-2090 showed superior insecticidal activity with 100% mortality and no acute fish toxicity. Through bioassay-guided fractionation using culture filtrate of IMBL-2090, phenylacetic acid was identified as the major insecticidal substance. These results suggested that Streptomyces IMBL-2090 could be exploited as an effective biological insecticide for control of T. palmi. [ABSTRACT FROM AUTHOR]