Search

BACKGROUND: The western flower thrips (WFT), Frankliniella occidentalis (Thysanoptera: Thripidae), is a significant pest in horticulture and ornamental agriculture. While exogenous calcium (Ca) has been shown to confer plant immune responses against thrips, the detailed mechanisms of this interaction remain to be elucidated for improved thrips management strategies. This study aimed to assess the impact of exogenous Ca on WFT feeding behavior and to explore its role in enhancing the defense mechanisms of kidney bean plants against WFT attacks. We compared WFT feeding preferences and efficiency on kidney bean plants treated with H2O or Ca, and examined whether exogenous Ca improves plant defense responses to thrips attack. RESULTS: WFT exhibited less preference for feeding on Ca‐treated plants over H2O‐treated ones. The total duration of WFT's long‐ingestion probes was significantly reduced on Ca‐treated plants, indicating impaired feeding efficiency. Furthermore, WFT infestation activated both jasmonic acid (JA) and salicylic acid (SA) signaling pathways in kidney bean plants, and exogenous Ca application led to elevated levels of endogenous Ca2+ and CaM, up‐regulation of genes associated with JA and SA pathways (LOX, AOS, PAL, and β‐1,3‐glucanase), and increased accumulation of JA, SA, flavonoids, and alkaloids. CONCLUSION: Our findings demonstrate that the application of exogenous Ca enhances endogenous Ca2+, JA, and SA signaling pathways in kidney bean plants. This enhancement results in an up‐regulation of the biosynthesis of flavonoid and alkaloid, thereby equipping the plants with an enhanced defense against WFT infestation. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) is a polyphagous species and can cause damage to many agricultural products such as cotton, strawberries, tomato and ornamental plants. F. occidentalis sucks the sap from the flowers of plants and causes premature flower fall and low yield. In addition, it can cause indirect damage because it is a virus vector. In this study, it was aimed to perform molecular identification of thrips obtained from the flowers of strawberry plants, which have economic importance for Aydın province, by applying PCR-RFLP protocol and to detect the presence of tospoviruses by the RT-qPCR method by obtaining RNA isolates. As a result of the study; it was determined that all species obtained were F. occidentalis. In addition, the presence of tospoviruses transmitted by these insects was also detected. Both methods seem promising to be used in future studies in terms of providing fast and reliable results. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis, poses a significant challenge in global agriculture as a notorious pest and a vector of economically significant orthotospoviruses. However, the limited availability of genetic tools for F. occidentalis hampers the advancement of functional genomics and the development of innovative pest control strategies. In this study, we present a robust methodology for generating heritable mutations in F. occidentalis using the CRISPR/Cas9 genome editing system. Two eye‐colour genes, white (Fo‐w) and cinnabar (Fo‐cn), frequently used to assess Cas9 function in insects were identified in the F. occidentalis genome and targeted for knockout through embryonic microinjection of Cas9 complexed with Fo‐w or Fo‐cn specific guide RNAs. Homozygous Fo‐w and Fo‐cn knockout lines were established by crossing mutant females and males. The Fo‐w knockout line revealed an age‐dependent modification of eye‐colour phenotype. Specifically, while young larvae exhibit orange‐coloured eyes, the colour transitions to bright red as they age. Unexpectedly, loss of Fo‐w function also altered body colour, with Fo‐w mutants having a lighter coloured body than wild type, suggesting a dual role for Fo‐w in thrips. In contrast, individuals from the Fo‐cn knockout line consistently displayed bright red eyes throughout all life stages. Molecular analyses validated precise editing of both target genes. This study offers a powerful tool to investigate thrips gene function and paves the way for the development of genetic technologies for population suppression and/or population replacement as a means of mitigating virus transmission by this vector. [ABSTRACT FROM AUTHOR]

Copyright of Acta Zoologica Lilloana is the property of Fundacion Miguel Lillo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The two-spotted spider mite (TSSM), Tetranychus urticae Koch, and the Western flower thrips (WFT), Frankliniella occidentalis (Pergande), are pests commonly found in strawberry crops and pose significant challenges to production. However, the specific dynamics of their interactions with both healthy and infested plants remain poorly understood. In this study, we aimed to investigate the attraction of TSSM and WFT to volatile compounds emitted by healthy plants versus those of plants damaged by either or both species. Plant choice bioassays were conducted under varying conditions, including both healthy and those previously damaged by both TSSM and WFT. Additionally, behavioral tests were carried out using a Y-tube olfactometer, with extracts obtained via dynamic aeration from the plants in different states. The results revealed distinct preferences: TSSM exhibited a strong attraction to both healthy plants and those previously infested by their own specifics, whereas WFT showed a higher preference for healthy plants and those damaged by TSSM. Consistent behaviors were observed in the bioassays conducted with plant extracts. This research sheds light on the intricate interactions between strawberry plants and these pests and offers insights into the probable sequence of attack when both pests are present concurrently. The findings are valuable when implementing management strategies for these two pests in strawberry cultivation, considering the order in which they appear in the crop to help mitigate the damage caused by infestation in a more precise manner and order. [ABSTRACT FROM AUTHOR]

The western flower thrips (Frankliniella occidentalis) is a significant agricultural pest, causing severe global yield losses due to extensive feeding damage and the transmission of plant pathogenic viruses. Despite recent advancements in RNA interference (RNAi) in thrips species, its application has been mostly limited to the adult stage. Given the crucial role of first instar larval thrips in acquiring and transmitting orthotospoviruses, achieving gene silencing in these larvae is critical for studying virus entry and acquisition. While thoracic and abdominal injections have proven effective in adult thrips, the low post‐injection survival rate hinders their use in larval thrips. This study addresses this challenge by presenting a microinjection methodology to deliver dsRNA into the hemolymph of first instar larval thrips through the coxa, the first proximal segment of the foreleg. This method significantly improved larval survival rate by preventing detrimental damage to the internal tissues. Significant knockdown of V‐ATPase‐B, cytochrome P450 (CYP3653A2), and apolipophorin‐II/I (ApoLp‐II/I) transcripts was confirmed after 48 and/or 72 h post injection (hpi), corresponding to the first and second instar larval stages, respectively. Silencing CYP3653A2 or ApoLp‐II/I significantly increased larval mortality. These findings demonstrate proof‐of‐principle of gene silencing and associated silencing phenotype (mortality) for first instar larval thrips and highlight the essential role of CYP3653A2 and ApoLp‐II/I in larval vitality. Our RNAi‐based tool offers an opportunity to investigate the molecular mechanisms of thrips‐orthotospovirus interactions, as the virus must be acquired by young larval thrips for successful transmission to plants, thus presenting potential targets for thrips pest management. [ABSTRACT FROM AUTHOR]

In order to further understand the species and occurrence dynamics of major pests in peanut fields in Yantai area of Shandong Province, from 2017 to 2020, the pests in peanut fields in Yantai area of Shandong Province were systematically monitored by color plate trapping method. The results showed that the dominant populations of pests in peanut fields in Yantai area were mainly Frankliniella occidentalis, peanut aphids, leafhoppers, Liriomyza and Tabanid. F. occidentalis mostly broke out in July and August, and the number of insects was higher than that in other months. The population density of F. occidentalis was positively correlated with average temperature, average ground temperature and sunshine time, and was significantly correlated with average temperature and average ground temperature. It was negatively correlated with average relative humidity, rainfall and wind speed, but not significant. [ABSTRACT FROM AUTHOR]

Western flower thrips, Frankliniella occidentalis, is a serious worldwide pest of agriculture and horticulture, and its contact pheromone is 7-methyltricosane. Two enantiomers of 7-methyltricosane were synthesized for the first time. The centra of our strategy were chiral auxiliaries to introduce stereocenter, and Wittig coupling to connect two blocks. The overall yields of our synthesis were 29–30% with seven steps. The electroantennogram (EAG) and the contact behavioral responses revealed that (R)-, (S)- and racemic 7-methyltricosane were separately bioactive, and the racemate was the most bioactive in the male arrestant activity and the female EAG test. This result provides valuable insights, showing that the racemate could be used for the support of the control of western flower thrips, which could be more easily prepared relative to more expensive enantiopure pheromone. [ABSTRACT FROM AUTHOR]

Life table parameters of Amblyseius swirskii when Frankliniella occidentalis and Tetranychus urticae were offered solely as diet were investigated. The switching behaviour of this predator was studied on F. occidentalis in the presence of spider mites. The data showed that feeding on the spider mite resulted in significantly longer developmental time compared to thrips. We found a significant effect of prey on the total life span, adult pre-oviposition period (APOP), and total pre-oviposition period (TPOP) of the predatory mite. The length of the oviposition period and the number of laid eggs per female were not affected by the kind of the offered prey. None of population growth parameters was affected by the type of diet except for mean generation time (T). Predators fed on spider mite had a longer T than those reared on thrips. Furthermore, our data illustrated a negative switching in the behaviour of A. swirskii when T. urticae and F. occidentalis were present. In other words, the predator switched from the abundant prey to the rarer prey. The results of this study are needed to understand and forecast the performance of A. swirskii in greenhouse environments where both T. urticae and F. occidentalis can be present. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis, western flower thrips, is an invasive pest that seriously damages economic crops such as vegetables, flowers, and fruit trees because of its high fecundity, short generation cycle, and strong adaptability. Lecanicillium is an important entomopathogenic fungus, characterised by its wide host range, high pathogenicity, and environmental safety. It plays an important role in the environmentally friendly management of F. occidentalis. This study clarifies whether L. attenuatum infects F. occidentalis and affects its reproduction. The results of scanning electron microscope showed that conidia of L. attenuatum were attached to many parts of thrips adult after 1 h of treatment with 10^8 conidia/mL, and most F. occidentalis were covered by hyphae after 72–120 h. The cumulative mortality rate of the second instar larvae of the F1, F2, and F3 generations exceeded 60% on the seventh day post-infection and that of female adults was higher than 90% when treated by L. attenuatum with 10^8 conidia/mL. Simultaneously, L. attenuatum had strong sublethal effects on the surviving thrips. Indeed, the number of eggs deposited and the lifespan of female adults decreased considerably after the second instar larvae of F. occidentalis were treated with L. attenuatum, and had the impaction on the thrips offspring too. Altogether, our data suggested that L. attenuatum not only exhibited a high degree of pathogenicity towards F. occidentalis second instar larvae and adults but also affected the longevity and reproduction of surviving thrips. [ABSTRACT FROM AUTHOR]

SUMMARY: Although plants harbor a huge phytochemical diversity, only a fraction of plant metabolites is functionally characterized. In this work, we aimed to identify the genetic basis of metabolite functions during harsh environmental conditions in Arabidopsis thaliana. With machine learning algorithms we predicted stress‐specific metabolomes for 23 (a)biotic stress phenotypes of 300 natural Arabidopsis accessions. The prediction models identified several aliphatic glucosinolates (GLSs) and their breakdown products to be implicated in responses to heat stress in siliques and herbivory by Western flower thrips, Frankliniella occidentalis. Bivariate GWA mapping of the metabolome predictions and their respective (a)biotic stress phenotype revealed genetic associations with MAM, AOP, and GS‐OH, all three involved in aliphatic GSL biosynthesis. We, therefore, investigated thrips herbivory on AOP, MAM, and GS‐OH loss‐of‐function and/or overexpression lines. Arabidopsis accessions with a combination of MAM2 and AOP3, leading to 3‐hydroxypropyl dominance, suffered less from thrips feeding damage. The requirement of MAM2 for this effect could, however, not be confirmed with an introgression line of ecotypes Cvi and Ler, most likely due to other, unknown susceptibility factors in the Ler background. However, AOP2 and GS‐OH, adding alkenyl or hydroxy‐butenyl groups, respectively, did not have major effects on thrips feeding. Overall, this study illustrates the complex implications of aliphatic GSL diversity in plant responses to heat stress and a cell‐content‐feeding herbivore. Significance Statement: The function of many metabolites in (a)biotic stress responses is still largely unknown. By integrating large‐scale metabolome and stress‐related phenome data into GWA mapping, we reveal that genes involved in glucosinolate biosynthesis have pleiotropic effects on the responses of Arabidopsis thaliana to heat stress and thrips infestation. [ABSTRACT FROM AUTHOR]

Background: The automation of pest monitoring is highly important for enhancing integrated pest management in practice. In this context, advanced technologies are becoming increasingly explored. Hyperspectral imaging (HSI) is a technique that has been used frequently in recent years in the context of natural science, and the successful detection of several fungal diseases and some pests has been reported. Various automated measures and image analysis methods offer great potential for enhancing monitoring in practice. Results: In this study, the use of hyperspectral imaging over a wide spectrum from 400 to 2500 nm is investigated for noninvasive identification and the distinction of healthy plants and plants infested with Myzus persicae (Sulzer) and Frankliniella occidentalis (Pergande) on bell peppers. Pest infestations were carried out in netted areas, and images of single plants and dissected leaves were used to train the decision algorithm. Additionally, a specially modified spraying robot was converted into an autonomous platform used to carry the hyperspectral imaging system to take images under greenhouse conditions. The algorithm was developed via the XGBoost framework with gradient-boosted trees. Signals from specific wavelengths were found to be associated with the damage patterns of different insects. Under confined conditions, M. persicae and F. occidentalis infestations were distinguished from each other and from the uninfested control for single leaves. Differentiation was still possible when small whole plants were used. However, application under greenhouse conditions did not result in a good fit compared to the results of manual monitoring. Conclusion: Hyperspectral images can be used to distinguish sucking pests on bell peppers on the basis of single leaves and intact potted bell pepper plants under controlled conditions. Wavelength reduction methods offer options for multispectral camera usage in high-grown vegetable greenhouses. The application of automated platforms similar to the one tested in this study could be possible, but for successful pest detection under greenhouse conditions, algorithms should be further developed fully considering real-world conditions. [ABSTRACT FROM AUTHOR]

Spatial and temporal distribution of food resources influences predatory insects' foraging and dispersal behavior. Orius insidiosus (Say) (Hemiptera: Anthocoridae) is a good biological control agent of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), in the strawberry crop and consumes two‐spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), and pollen as well. Augmentative biological control programs may fail if, following release, predators disperse from the crop. We studied the dispersal of O. insidiosus as a function of pollen availability, density of their main prey WFT, and the presence of the alternative prey TSSM, within and between strawberry plants. We found that O. insidiosus remained on the flowers during the 24 h of the assay. The dispersal of predators to a neighboring flower with thrips was approximately six times greater from a flower without pollen than from a flower with pollen. When TSSM was the only prey available, O. insidiosus colonized the leaves, and its dispersal within the plant was greater. At the plot scale, the predator dispersal from the release plant to other plants also depended on the presence of flowering plants and prey. Our results highlight the importance of flowering plants and pollen availability in enhancing the persistence of O. insidiosus in strawberry plants. Releases of this predator in the strawberry crop should be after the beginning of flowering, even at low WFT densities. [ABSTRACT FROM AUTHOR]

Simple Summary: The western flower thrips, Frankliniella occidentalis, is a common pest in many crops worldwide. Predatory mites (Acari: Phytoseiidae) are effective predators of first-instar thrips and have been extensively used for biological control of the pest. However, the short development time of thrips larvae limits the effectiveness of thrips control. Recent studies have shown that some species of phytoseiid mites are capable of consuming thrips eggs embedded in leaf tissue, thereby extending the window for effective predation on F. occidentalis populations. In this study, we aimed to investigate the predatory ability of three phytoseiids native to Southeast Asia and one commercially available species on western flower thrips eggs and compare it with their predation on first instars of the pest. Both at 25 °C and 30 °C, the functional response of all the studied mites was type II to first instars of the thrips, whereas it shifted to type III when thrips eggs were provided. The consumption of first-instar thrips was consistently higher than that of thrips eggs. More thrips eggs were consumed at 30 °C than at 25 °C, whereas predation on larvae was minimally affected by temperature. Our research indicates the potential of the studied mites to contribute to the suppression of F. occidentalis outbreaks in Southeast Asia. The predation capacity and functional responses of adult females of the phytoseiid mites Amblyseius largoensis (Muma), Proprioseiopsis lenis (Corpuz and Rimando), Paraphytoseius cracentis (Corpuz and Rimando), and Amblyseius swirskii (Athias-Henriot) were studied on eggs and first instars of the western flower thrips, Frankliniella occidentalis (Pergande), in the laboratory at 25 °C and 30 °C. At both temperatures, the functional response of all four phytoseiid mites was type II to first instars of the thrips. In contrast, when offered thrips eggs, the functional response was type III. At both temperatures tested, A. swirskii had the highest mean daily consumption of first-instar F. occidentalis, followed by A. largoensis, P. cracentis, and P. lenis. Amblyseius largoensis had the shortest handling time and the highest maximum attack rate when first-instar thrips were the prey. When fed on thrips eggs, A. largoensis had the highest mean daily consumption, followed by A. swirskii, P. cracentis, and P. lenis. On thrips eggs, A. swirskii showed the shortest handling time and highest maximum attack rate. Our findings indicate that all four phytoseiids had a better ability to prey on first-instar larvae of F. occidentalis compared to thrips eggs. At 25 and 30 °C, A. largoensis was the better predator on thrips larvae, whereas A. swirskii was superior in consuming eggs of F. occidentalis. Proprioseiopsis lenis was the inferior predator on both thrips larvae and eggs compared to the other phytoseiids tested. [ABSTRACT FROM AUTHOR]

The encapsulation of essential oils (EOs) in nanostructured lipid carriers (NLCs) represents a modern and sustainable approach within the agrochemical industry. This research evaluated the colloidal properties and insecticidal activity of NLCs loaded with thyme essential oil (TEO-NLC) and rosemary essential oil (REO-NLC) against three common arthropod pests of ornamental flowers: Frankliniella occidentalis, Myzus persicae, and Tetranychus urticae. Gas chromatography–mass spectrometry (GC-MS) analysis identified the major chemical constituents of the EOs, with TEO exhibiting a thymol chemotype and REO exhibiting an α-pinene chemotype. NLCs were prepared using various homogenization techniques, with high shear homogenization (HSH) providing the optimal particle size, size distribution, and surface electrical charge. A factorial design was employed to evaluate the effects of EO concentration, surfactant concentration, and liquid lipid/solid lipid ratio on the physicochemical properties of the nanosuspensions. The final TEO-NLC formulation had a particle size of 347.8 nm, a polydispersity index of 0.182, a zeta potential of −33.8 mV, an encapsulation efficiency of 71.9%, and a loading capacity of 1.18%. The REO-NLC formulation had a particle size of 288.1 nm, a polydispersity index of 0.188, a zeta potential of −34 mV, an encapsulation efficiency of 80.6%, and a loading capacity of 1.40%. Evaluation of contact toxicity on leaf disks showed that TEO-NLC exhibited moderate insecticidal activity against the western flower thrips and mild acaricidal activity against the two-spotted spider mite, while REO-NLC demonstrated limited effects. These findings indicate that TEO-NLCs show potential as biopesticides for controlling specific pests of ornamental flowers, and further optimization of the administration dosage could significantly enhance their effectiveness. [ABSTRACT FROM AUTHOR]

Abstract Background The western flower thrips (WFT), Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), is an important polyphagous pest in both greenhouses and fields. Due to its wide range of host plants and short life cycle, the pest causes overwhelming damage and has led to the destruction of many crops. The combined use of entomopathogenic microorganisms could be an important option to overcome the difficulties in controlling WFT. The virulence of thirty local entomopathogen isolates was tested on WFT, and possibilities of combined application for WFT control were investigated. Results All isolates were virulent for both the second larval stage and the adult stage of WFT. Serratia marcescens Se9 was the most virulent bacterial isolate with a mortality of 54 and 69.6% against the second larval and the adult stages of WFT, respectively. The LC50 values of the Se9 isolate were determined to be 4 × 106 cfu/ml for the second larval stage and 6.3 × 106 cfu/ml for the adult stage. Among the fungal isolates, Metarhizium flavoviride As18 showed a mortality rate of 92.1 and 74.5% against the second larval and the adult stages of WFT, respectively. The LC50 value was determined to be 1.6 × 104 and 7.1 × 104 conidia/ml for the second larval and adult stages of WFT, respectively. The combined application of S. marcescens Se9 and M. flavoviride As18 at different concentrations generally performed better than single treatments, indicating an additive or synergistic interaction. While the single treatment with S. marcescens and M. flavoviride caused a mortality of 20.4 and 49.5%, respectively, the combined application (S. marcescens LC25; M. flavoviride 100 × LC25) resulted in a mortality of 95.7% of the second larval stage. Similarly, the combined application caused 96% mortality in the adult stage, while the single treatments with S. marcescens and M. flavoviride caused 11.3 and 61.3% mortality, respectively. Conclusion The study showed that the combined application of S. marcescens (LC25) and M. flavoviride (LC25 × 100) resulted in synergism against both second larval and adult stages of WFT. This is the first study to show that the combination of S. marcescens and M. flavoviride had synergistic potential to suppress the WFT population. In future studies, these microorganisms should be formulated together as biopesticides and tested under greenhouse or field conditions.

Omnivores obtain resources from more than one trophic level, choosing food based on quantity and quality. They usually engage in intraguild predation (IGP) when prey is scarce. Orius laevigatus is an example of omnivore that becomes superior predator of the predatory mite Amblyseius swirskii when released in a combined system under low levels of the preferred prey, the thrips Frankliniella occidentalis. Here, we test two genetically enhanced O. laevigatus strains for bigger size and better fitness feeding on pollen (BIG30 and 2POL-11, respectively), hence with a wider dietary diversification, to elucidate the potential effects on prey preference and IGP on the predatory mite, in comparison with a commercial population of O. laevigatus. To do that, predation rates were registered on adult phytoseiids solely or in a choice situation at different availability ratios of adult thrips under laboratory conditions. The effect of pollen as supplemental food on IGP and prey preference was examined, too. We found that our two enhanced lines killed up to 9% less predatory mites and fed preferably on adult thrips, compared to the commercial population. While BIG30 showed a significantly higher total predation rate, killing up to 150% more adult thrips, 2POL-11 is defined as an efficient user of resources, switching between different prey and pollen showing low IGP. Pollen supplementation had a significant effect on reducing IGP, but only for 2POL-11 the influence on prey preference was significant. The theory of intraguild predation and the impact of prey switching on food webs and biological control strategies are also discussed. [ABSTRACT FROM AUTHOR]

Arthropod pests cause significant problems in agricultural crops all around the world. As chemical pesticide use becomes less desired, there is a need for alternative methods of pest control. Inspired by the natural adhesiveness of arthropod trapping plants, we examined the effectiveness of adhesive droplets made from oxidised and cross-linked plant-derived oils for control of western flower thrips. Two filter paper droplet adhesiveness assays and three detached chrysanthemum leaf assays were carried out to test efficacy against thrips. Suspensions containing adhesive droplets and other constituents were applied to filter papers and leaves via spraying or dipping. On filter papers, droplets made from oxidised rice germ oil (RGO) of different sizes caught 40–93% of thrips. Droplets made of a mixture of sunflower, olive, and linseed oil (MIX) caught up to 94% of thrips. Likewise, adhesive droplet-treated filter papers showed higher thrips mortality than untreated or control solution-treated filter papers. On chrysanthemum leaves, thrips were caught by both RGO (up to 40%) and MIX droplets (up to 20%) and thrips damage and reproduction were reduced. On MIX-treated leaves, thrips mortality was also increased. Within treatments, droplets of different size classes occurred and larger droplets were more effective at catching thrips in general. Droplets were also robust to rinsing with water, which is of importance for their application in horticulture. In conclusion, adhesive droplets made from edible plant oils show potential for use in control of western flower thrips. [ABSTRACT FROM AUTHOR]

Zoophytophagous predators can induce plant defence responses through phytophagous feeding. Since the zoophytophagous bug Orius sauteri lays eggs into plant tissues, we hypothesised that its oviposition behaviour may also induce plant defence responses with a negative impact on subsequent herbivore attacks. Pre-inoculation of O. sauteri females on tomato plants significantly reduced the fitness and reproduction of Frankliniella occidentalis, which also preferred the non-inoculated plants in indoor micro-environments. In the field, O. sauteri pre-inoculation also caused reduced population growth of F. occidentalis. All these tendencies were weaker with male compared to female O. sauteri pre-inoculation. Next, a transcriptome analysis showed that the MAPK signalling pathway, the plant hormone signal transduction and plant-pathogen interaction of defence-related pathways were significantly enriched in plants inoculated with O. sauteri females compared to untreated plants. We showed that three key genes of the JA pathway, allene oxide synthase (AOS), jasmonate ZIM-domain 2 (JAZ2), and proteinase inhibitor 1 (PI-1), were upregulated. This is evidence of plant defence activation, the likely mechanism by which O. sauteri pre-inoculation (through feeding and oviposition activities) reduced F. occidentalis fitness in the laboratory and population densities by almost three times in a greenhouse experiment. This mechanism could be promoted in IPM strategies through the early introduction of zoophytophagous biocontrol agents activating crop plant defences to enhance biological pest control. [ABSTRACT FROM AUTHOR]

Blue sticky traps contribute substantially to monitoring the western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), in greenhouses. Although sticky traps can detect the initial presence of thrips reliably, an estimation of the actual thrips density in the crop by counting number of thrips on the traps is often not accurate. To overcome this issue, we compared blue sticky traps and newly developed sticky LED-enlightened traps in combination with the commercial thrips kairomone Lurem-TR under commercial growing conditions. Therefore, an experiment was conducted in cucumber, Cucumis sativus L. (Cucurbitaceae), crop stands in greenhouse cabins investigating the correlation between thrips caught on (LED) traps and the thrips density in the crop for an accurate and reliable thrips monitoring. Additionally, experiments aiming to understand underlying mechanisms of thrips orientation towards traps in different scenarios were conducted under controlled conditions. Results show that thrips catches on sticky LED enlightened coloured traps correlated strongly positive with number of thrips in the crop, especially at low thrips population densities. Adding Lurem to this trap type further improved accuracy of the correlation in the greenhouse cabin experiment. Moreover, LED traps with and without Lurem were more attractive towards thrips in small follow-up experiments compared to standard blue sticky traps. The results are discussed in the context of general orientation of thrips and its behaviour towards visual and olfactory cues when considering different scenarios. Our study shows the successful integration of blue LEDs into an existing trapping system and underlines the advantages compared with standard sticky plates. In conclusion, sticky LED enlightened coloured traps have a potential as an improved thrips monitoring device that might improve pest management decisions. [ABSTRACT FROM AUTHOR]

The plant immune system has evolved to sense and respond to potential threats. When an insect attacks a plant, endogenous molecules called damage-associated molecular patterns (DAMPs) are released into the apoplast, triggering a cascade of intracellular signals. Extracellular DNA (eDNA) is a DAMP signal which activates the plant's immune responses. However, our understanding of whether the detection of eDNA can lessen the damage caused by herbivores is still restricted. Here, we demonstrate that eDNA treatment in Arabidopsis leaves induced plant resistance against the herbivorous insect Frankliniella occidentalis without compromising the plant's growth. The number of leaves, rosette diameter, fresh weight, and other growth-related parameters in eDNA-treated plants was comparable to water-treated plants. Besides, eDNA treatment reduced the feeding symptoms of F. occidentalis on Arabidopsis leaves. We further found that enhanced resistance in eDNA-treated plants was accompanied by callose accumulation in the affected area, and using the callose-deficient mutant pmr4-1, we demonstrated the positive role of callose in eDNA-induced resistance (eDNA-IR). Additionally, the induction in the jasmonic acid (JA)-signaling marker genes LOX2 and AOS, and the higher accumulation of Jasmonyl-isoleucine (JA-Ile) and JA revealed the role of jasmonates in eDNA-IR. Finally, we demonstrated that the JA signaling mediates callose deposition in eDNA-treated plants by using the JA response mutant jar1-1. These results advance our knowledge of the ability of eDNA to trigger plant resistance and the underlying mechanisms involved in eDNA-IR. [ABSTRACT FROM AUTHOR]

Simple Summary: Thrips constitute one of the main nectarine pests, with damage either in flowering or before harvesting (silvering). Nectarine orchards under organic and integrated management were sampled in Lleida (Baix Segre intensive production area) 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 and damage during fruit maturation. Fifteen species were collected in Lleida, and 10 species were collected in Girona. Organic orchards in Lleida showed lower populations and silvering damage levels than 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. 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. [ABSTRACT FROM AUTHOR]

Bottom-up effects are major ecological forces driving crop-arthropod pest interactions in agroecosystems. Light is an important resource for plants, alters plant growth traits and trade-off their defensive ability through the bottom-up effects. In this study, we measured the effects of red (R), blue (B), red-blue (RB) and white (W, control) light on the growth traits of tomato plants and their defensive ability against whitefly Bemisia tabaci and western flower thrips Frankliniella occidentalis. Compared to the control, red, blue and red-blue light significantly affected the growth and defensive ability of tomato plants but to differing effects. Red light promoted plant height and stem diameter of tomato plants, inhibited photosynthetic traits and leaf thickness, which significantly decreased the fecundity of B. tabaci and F. occidentalis, and reduced the feeding and oviposition preference of B. tabaci. Blue light decreased the growth of tomato plants but increased photosynthetic parameters and leaf thickness and inhibited the fecundity of B. tabaci. Red-blue light was closest to the white control, slightly reducing growth of tomato plants but increasing leaf thickness and significantly decreasing the feeding and oviposition preference of F. occidentalis. These results indicated that red, blue and red-blue light had certain inhibitory effects on the performance of B. tabaci and F. occidentalis, and blue light also suppressed the growth and biomass accumulation of tomato plants. In conclusion, red and red-blue light reduced the performance of herbivores and optimally improve plant yield and quality in greenhouses. [ABSTRACT FROM AUTHOR]

Maize lethal necrosis is attributed to the accumulation of maize chlorotic mottle virus (MCMV), an invasive virus transmitted by insect vectors. The western flower thrips (WFT) can shift host to maize, thus promoting the spread of MCMV. However, our understanding of the characteristics and interactions involved in the transmission of MCMV is still limited. This study finds that non-viruliferous WFTs showed a 57.56% higher preference for MCMV-infected maize plants compared to healthy maize plants, while viruliferous WFTs showed a 53.70% higher preference for healthy maize plants compared to MCMV-infected maize plants. We also show for the first time that both adults and larvae of WFT could successfully acquire MCMV after 1 min of acquisition access period (AAP), and after 48 h of AAP, WFT could transmit MCMV in an inoculation access period of 1 h without a latent period. Both adults and larvae of WFT can transmit MCMV for up to 2 days. Furthermore, the decreasing number of viruliferous WFTs and transmission rates as time progressed, together with the transcriptomic evidence, collectively suggest that WFTs transmit MCMV in a semi-persistent method, a mode of transmission requiring minutes to several hours for acquisition access and having a retention time of several hours to a few days. Additionally, β-myrcene can attract WFTs significantly and is detected in Nicotiana benthamiana plants transiently expressing MCMV CP (coat protein), which is consistent with results in MCMV-infected maize plants through the metabolomic profiling and the preference analyses of WFT. Therefore, this study demonstrates the indirect interaction between MCMV and WFT by inducing maize to synthesize β-myrcene to attract insect vectors. The exploration of specific interactions between MCMV and WFT could help to expand the mechanism studies of virus--vector--host plant interaction and put forward a new insight for the combined control of MCMV and WFT through the manipulation of plant volatiles and key insect genes. [ABSTRACT FROM AUTHOR]

For scientific purpose, 3D traps mimicking a botanical flower organ in five varieties of shape, three varieties of sizes and two colors (blue and yellow) were created to monitor the emergence of western flower thrips Frankliniella occidentalis Pergande. A methodology has been developed for their application to cucumbers, second crop, in greenhouse conditions at the experimental base of "Opora Zaden Bulgaria" Ltd. in the village of Tsalapitsa. The effect of the traps was observed along the height of the stem at three points from the soil surface, at equal distances (15 cm, 30 cm and 45 cm). Reported results are based on placement of traps along the plant stem, size and color of the trap. Fixing the traps up to a height of 45 cm, in three points along the stem of the plant has a positive effect on reducing the population of western flower thrips (F.occidentalis). The best efficiency for monitoring the pests was achieved when placing the flower model traps at a height of 15 cm from the soil surface. In addition to western flower thrips, the presence of tomato mining moth (Tuta absoluta Meyrick) and bioagents was recorded in the traps. The color of the flower model trap affects the monitoring result. The yellow color is attractive to all types of pests and bioagents in the greenhouse, and the blue color only attracts thrips. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis, commonly known as the western flower thrips (WFT), is one of the world's most significant cosmopolitan pests. This pest infests many ornamental species, including Alstroemeria, leading to substantial economic losses. F. occidentalis damages flowers, transmits viruses, and causes the rejection of shipments for exports. Farmers have observed variations in the occurrence of F. occidentalis among different Alstroemeria cultivars. It is hypothesized that differences in flower color and odor among cultivars may influence the host-choice behavior of this insect, potentially explaining the observed variations in incidence and damage in the field. To test this hypothesis, we analyzed one year's worth of sampling data for the occurrence of the WFT complex in a commercial Alstroemeria greenhouse crop. This analysis identified cultivars with high and low thrips incidences. The 'Himalaya' and 'Whistler' cultivars exhibited the highest incidence, while the 'Shakira' and 'Nora' cultivars showed the lowest incidence values. To investigate the potential role of host odors in these field incidence differences, we conducted behavioral tests (choice, non-choice, and repellency) using glass boxes where visual stimuli were blocked. These tests confirmed a differential attraction response of thrips to the flowers of Alstroemeria cultivars, although all cultivars were viable options for WFT choice. Preferences under laboratory conditions differed from the incidence observed in the greenhouse, ruling out a repellency effect of some cultivars on insects. This study provides evidence that differential emissions from Alstroemeria flowers can influence host selection by WFT, a phenomenon that warrants further in-depth exploration in future studies. [ABSTRACT FROM AUTHOR]

Orthotospovirus tomatomaculae (tomato spotted wilt virus, TSWV) is transmitted by the western flower thrips, Frankliniella occidentalis. Epoxyoctadecamonoenoic acids (EpOMEs) function as immune-suppressive factors, particularly in insects infected by viral pathogens. These oxylipins are produced by cytochrome P450 monooxygenases (CYPs) and are degraded by soluble epoxide hydrolase (sEH). In this study, we tested the hypothesis that TSWV modulates the EpOME level in the thrips to suppress antiviral responses and enhance its replication. TSWV infection significantly elevated both 9,10-EpOME and 12,13-EpOME levels. Following TSWV infection, the larvae displayed apoptosis in the midgut along with the upregulated expression of four caspase genes. However, the addition of EpOME to the viral treatment notably reduced apoptosis and downregulated caspase gene expressions, which led to a marked increase in TSWV titers. The CYP and sEH genes of F. occidentalis were identified, and their expression manipulation using RNA interference (RNAi) treatments led to significant alternations in the insect's immune responses and TSWV viral titers. To ascertain which viral factor influences the host EpOME levels, specialized RNAi treatments targeting genes encoded by TSWV were administered to larvae infected with TSWV. These treatments demonstrated that NSS expression is pivotal in manipulating the genes involved in EpOME metabolism. These results indicate that NSs of TSWV are crucially linked with the elevation of host insect EpOME levels and play a key role in suppressing the antiviral responses of F. occidentalis. [ABSTRACT FROM AUTHOR]

The western flower thrips, Frankliniella occidentalis, is a serious pest causing both direct feeding damage and indirect harm by transmitting the tomato spotted wilt virus. A spraying double‐stranded RNA (dsRNA) targeted at the vacuolar‐type ATPase (vATPase) gene was developed and demonstrated high insecticidal activity in the laboratory but less effective in field applications. To improve control efficacy under field conditions, three strategies were explored in this study. First, to identify a more efficient RNA interference (RNAi) target, dsRNA specific to the Snf7 gene was tested alongside dsRNA targeting vATPase, and both were found to be similarly effective in controlling the thrips. Second, to elucidate the factors contributing to dsRNA resistance, dsRNA‐degrading enzymes were annotated and their physiological roles in diminishing RNAi efficacy were investigated. Third, to suppress the dsRNA degradation from the dsRNase activities and protect it in field conditions, the dsRNA was encapsulated with chitosan. This formulation enhanced the dsRNA's resistance to environmental stressors such as ultraviolet light and the digestive enzymes in the thrips' gut. Additionally, the chitosan formulation specifically increased the RNAi efficacy, likely by facilitating more efficient entry into the target cells, thus bolstering the insecticidal activity of the dsRNA. The formulated dsRNA was applied on F. occidentalis infesting the hot peppers in a greenhouse at a concentration of 500 ppm, demonstrating an 82.4% control efficacy compared with 59.2% control efficacy observed with the application of naked dsRNA. This study further demonstrated an enhancement in the spectrum of control by combining dsRNAs specific to three distinct thrips species, while the mixture showed no adverse effects on non‐target insects, such as the lepidopteran Spodoptera exigua. Collectively, these findings reveal that the chitosan formulation of dsRNA not only improves control efficacy under field conditions but also broadens the control spectrum against three different thrips pests. [ABSTRACT FROM AUTHOR]

Tenvermectin B is a patented novel macrocyclic lactone insecticide independently developed in China. In order to develop its potential market and delay the emergence of resistance, the insecticidal activities of tenvermectin B to 10 pest varieties, such as Plutella xylostella, Pyrausta nubilalis, and Hyphantria cunea, were performed by leaf dipping method. The activities against Aphis gossypii, Tetranychus urticae, and Liriomyza sativae were conducted by spraying method. Sun Yunpei's cotoxicity (CTC) method was used to evaluate the synergistic effect of the mixtures of tenvermectin with thioacetamide, chlorfenapyr, and indoxacarb on P. xylostella, and the optimal ratio was employed for field efficacy assay. The bioassay showed that tenvermectin B had higher control activity against P. xylostella, P. nubilalis and T. urticae, compared with abamectin, the LC50 values were 0.115, 0.043, and 0.012 mg/L, respectively. Tenvermectin B also displayed high activity against Mythimna separata, H. cunea, Cnaphalocrocis medinalis, Frankliniella occidentalis and A. gossypii, the LC50 values ranged from 0.337-9.784 mg/L. Mixture screening showed that tenvermectin B with neither thiotraniliprole nor indoxacarb had synergistic effect on P. xylostella. The mixture of tenvermectin B and chlorfenapyr showed significant synergy against P. xylostella, with a CTC value of 178.59 at the optimal ratio of tenvermectin B to chlorfenapyr as 1 : 14 (m : m). The result of the field trial indicated that at 7 d and 14 d after treatment, the control efficacies of the mixture against P. xylostella were over 80% at the dosage of 75 g a.i./hm². Our study demonstrated that tenvermectin B had a broad insecticidal spectrum, with excellent activity against P. xylostella, T. urticae, A. gossypii, etc., showing promising potential for development and application. The mixture of tenvermectin B and chlorfenapyr (1 : 14) showed a synergistic effect and could be further developed for P. xylostella control to delay the emergence of resistance. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis (Pergande) is a typical omnivorous insect that feeds on host plants, pollens and mite eggs, and poses a threat to crops worldwide. The insulin signalling pathway (ISP) is a typical nutrient‐sensitive pathway that participates in the regulation of various functions in insects. Serine/threonine kinases (AKTs) and phosphoinositide‐dependent kinases (PDKs) are key components of the ISP. In this study, the FoAKT and FoPDK genes in F. occidentalis were cloned, and the effects of three foods on their expression were determined. The expression of FoAKT and FoPDK in the thrips fed on kidney bean leaves supplemented with pine pollen or mite eggs was higher than in those primarily fed on leaves alone. Meanwhile, the fecundity of thrips fed on leaves supplemented with pine pollen was highest. In addition, RNA interference‐mediated knockdown of FoAKT and FoPDK decreased vitellogenin (Vg) content and Vg expression in females, shortened ovariole length, delayed egg development and reduced fecundity and offspring hatching rates. Furthermore, the synthesis of juvenile hormone (JH) was reduced, and the contents of glucose, trehalose, glycogen and trehalase were affected. These results suggest that FoAKT and FoPDK regulate the reproduction of F. occidentalis by regulating Vg and JH production as well as carbohydrate metabolism. [ABSTRACT FROM AUTHOR]

A number of studies have indicated the potential role of secondary metabolites, referred to as 'resistance factors', in plant defence against insect pests. Nevertheless, it remains unclear which metabolites serve as predictors of resistance in chrysanthemum cultivars against thrips. In the present study, the phenolic compounds of chrysanthemum leaves at different ontogenetic stages were analysed using high-performance liquid chromatography (HPLC). Furthermore, the relative epidermal flavonol contents in the leaves were quantified using the Dualex® Scientific 4 sensor, and the suitability of this non-destructive method for the rapid discrimination of resistance levels was evaluated. The results demonstrated that the most notable discrepancies in phenolic metabolite profiles were observed in the older leaves and the vegetative state of the chrysanthemum plants. Multiple discriminant analysis was conducted using HPLC-analysed metabolites to predict the importance of metabolites in resistant, susceptible, or highly susceptible plants in the vegetative stage. The results demonstrated that multiple metabolites, rather than a single metabolite, are responsible for thrips resistance in chrysanthemum. However, the relative flavonol content did not reflect the HPLC-analysed flavonoid glycosides or hydroxycinnamic acid derivatives, indicating that the Dualex® sensor is not a suitable device for determining resistance levels in chrysanthemums. Testing is required to extend and analyse the results in greater depth. [ABSTRACT FROM AUTHOR]

Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) is an important generalist predator used to control several important crops' pests such as spider mites, whiteflies, and thrips. In this study, the lethal concentrations of Mentha piperita L. (Lamiaceae) and Laurus nobilis L. (Lauraceae) essential oils (EOs) were calculated on the adult stage of the Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). The side effects of EOs were investigated on the functional response of A. swirskii on F. occidentalis 1st instar larvae. The females of A. swirskii were exposed to sublethal concentrations (LC30 and LC50) of EOs for 12 h with the fumigant exposure method. In the control, the treatment was performed by using Triton X-100 (0.02). Treated predatory mites were selected randomly, and transferred to the experimental arenas containing 2, 4, 8, 16, 32, and 64 thrips. The predators were kept in the experimental arenas for 24 h at 25 ± 1 °C, 60 ± 10% RH, and a photoperiod of 16: 8 h (L: D). Results indicated that A. swirskii exhibited a type II functional response, regardless of EOs applications. The shortest (1.62 ± 0.046 h) and the longest (1.91 ± 0.049 h) handling times, were recorded in the control and the LC50 treatment of M. piperita EO, respectively. There was not a significant difference between attack rate coefficients (α) under sub-lethal concentrations. Based on the results, the two EOs have the potential to be used in F. occidentalis management, but their side effects on A. swirskii should be considered in IPM programs. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis (Thysanoptera: Thripidae) are insect pests of global economic importance due to the damage they cause to the agricultural sector. Its control is framed in Integrated Pest Management (IPM) programs, with chemical control being the most used conventional tool for the control of said arthropods. One of the factors why its control is unsuccessful in the crops where it is present is the high selection pressure to which they are subjected due to the irrational use of chemically synthesized insecticides, which causes loss of sensitivity or resistance to many insecticide molecules. Accordingly, the present investigation evaluates the effectiveness of the biorational insecticide Spinosad, 48 % concentrated suspension in combination with two surfactant adjuvants, one from the organosilicon group and the other from the group of ethoxylated alcohols. The bioassay was executed under a completely randomized design (DCA) with seven treatments that included an absolute control and dosages of Spinosad with and without adjuvants, each with 5 repetitions in experimental units of 10 adults of thrips F. occidentalis. The application of the treatments was carried out by two modes of entry: treated surface (ingestion) and direct contact (topical), where mortality variables were evaluated three and seven days after application, additionally an analysis of variance (ANOVA) was carried out, to determine significant statistical differences (p>0,05) between the treatments, Tukey's multiple comparison test was used (p>0,05), concluding that the effectiveness of Spinosad treatments together with adjuvants increases compared to the control and Spinosad without adjuvants. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Entomology is the property of Chinese Journal of Applied Entomology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Agriscientia is the property of Revista AgriScientia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The heavy metal, cadmium (Cd) is an increasingly serious issue in agricultural ecosystems, mediating bottom-up effects on plants, herbivores and natural enemies. We measured how Cd modifies interactions between tomato Solanum lycopersicum, western flower thrips Frankliniella occidentalis, and the predatory bug Orius sauteri by examining Cd effects on the growth of tomato, the fitness of western flower thrips, and the survival and behavior of predators. The photosynthetic parameters of Pn (net photosynthetic rate), Gs (stomatal conductance), Ci (intercellular CO2 concentration), and Tr (transpiration rate) of tomato plants significantly decreased with the increase of Cd concentration. The total survival number of western flower thrips fed on tomato plants treated with different concentrations of Cd was significantly lower than that of the control, and sex ratios (female/male) gradually increased with the increase of Cd concentration. The numbers of thrips predated by O. sauteri on tomato plants treated with high concentrations of Cd (2.0 or 4.0 mg/L) were significantly reduced by the second day. Cadmium was accumulated and bioconcentrated in the roots, stems, leaves of tomato plants, and transferred to F. occidentalis, and O. sauteri. Cadmium translocated in significant quantities from roots to the stems and leaves of tomato plants, and from the tomato leaf to F. occidentalis. However, there was minimal (non-significant) transfer of Cd from F. occidentalis to O. sauteri. The presence of Cd significantly reduced the growth of tomato plants, the fitness of F. occidentalis, and the predation efficiency of O. sauteri. Collectively, Cd can mediate bottom-up effects on tomato, thrip, and predatory bug along food chain, potentially interrupting pest biological control in tomato in heavy metal-contaminated ecosystems.

The Western Flower Thrips (Frankliniella occidentalis) constitutes a significant threat to rose greenhouses in Colombia. An eco-friendly approach to managing this pest involves using the predatory bug Orius insidiosus. The pest and its predator’s food search and selection mechanisms are influenced by ecological interactions mediated by volatile organic compounds (VOCs) emitted during plant–pest interactions. To investigate the role of VOCs in the foraging and host-selection behaviors of O. insidiosus, we conducted functional response assays in greenhouses and olfactometry experiments in laboratory settings. These experiments used flowers from two rose cultivars, with and without female adult thrips, over 24, 48, and 72 h. Functional response analysis revealed a shift in O. insidiosus foraging behavior based on the duration of thrips interaction with rose flowers, transitioning from a Type II to a Type III functional response between 24 and 48 h in the ‘Freedom’ cultivar. The maximum consumption rates increased significantly, from 7.98 individuals at 24 h to 16.18 individuals at 48 h, before slightly decreasing to 14.37 individuals at 72 h. This shift coincided with an increase in O. insidiosus preference for thrips-infested ‘Freedom’ flowers over time, with selection proportions rising from 0.37 at 24 h to 0.46 at 72 h, suggesting a learning effect on prey-searching behavior mediated by VOCs. Olfactometry analyses revealed that O. insidiosus did not respond to the same VOCs that attracted F. occidentalis during flower infestation. However, O. insidiosus responded to certain VOCs likely associated with floral resources such as nectar and pollen, which also attract pollinators and zoophytophagous predators. This observation suggests a potential overlap in the chemical cues used by O. insidiosus for distinct ecological purposes. These findings highlight the complex chemical ecology underlying predator–prey interactions in agroecosystems and underscore the importance of considering VOCs in shaping the foraging behavior of natural enemies and their interactions with insect pests.

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. [ABSTRACT FROM AUTHOR]

Western flower thrips, Frankliniella occidentalis (WFT), is one of the most destructive insect pests of vegetables and ornamental crops globally. Ultraviolet-C (UV-C) exposure has been shown to reduce populations of arthropod pests, including whiteflies and two-spotted spider mites, but has not been fully assessed for WFT. The goal of this study was to determine if UV-C radiance could be a viable strategy for inclusion in integrated pest management (IPM) programs for WFT. The objectives were to (1) assess the relationship among UV-C dose (irradiance × duration) and mortality of WFT adults and second instar larvae, (2) determine the effect of UV-C on WFT fecundity and egg hatch, and (3) assess the effect of the WFT lethal dose of UV-C on three WFT-prone ornamental plants. A UV-C dose is measured in Joules, which equals power (watts) × exposure time. A dose-dependent relationship between UV-C exposure and mortality of WFT larvae and adults was observed. At the doses of 0.98 and 0.68 J/cm2 (5 and 4 min exposure, respectively), 50% of the larvae died within 24 and 48 h, respectively. The UV-C dose needed to achieve 50% mortality was higher for adults than larvae, occurring at 5.2 and 4.4 J/cm2 (35 min and 25 min exposure, respectively) within 72 and 120 h, respectively. The number of eggs laid by surviving WFT subjected to UV-C treatment was less than by those that were untreated, and the egg-laying period was significantly shorter among those treated with UV-C. When leaves containing WFT eggs were exposed to UV-C doses known to cause 30–40% mortality in adults, 86–98% fewer eggs hatched compared to untreated controls. Ornamental plants exposed to UV-C doses lethal to eggs, second instars, and adult WFT either showed no damage, or when damage occurred, plants recovered within 14–30 days. Additional studies under controlled greenhouse conditions are needed to elucidate the effectiveness of UV-C radiance against WFT over time and its compatibility with biological control and other IPM practices. [ABSTRACT FROM AUTHOR]

We explored the effects of elevated CO2 on the population performance and interspecific interactions of three thrips pests. The dominance of the three thrips in the field was Frankliniella occidentalis ≈ Frankliniella intonsa > Thrips hawaiiensis. The performance of these thrips, alone and in combination, was evaluated in the laboratory under elevated CO2 (800 μl L−1) and ambient CO2. Compared with ambient CO2, elevated CO2 significantly accelerated the developmental rates and decreased the survival rates of all thrips species. Significant differences in fecundity, intrinsic rate of increase (rm), and net reproductive rate (R0) were observed among these thrips, and their values were significantly increased in F. occidentalis but decreased in F. intonsa and T. hawaiiensis under elevated CO2, compared that in the ambient CO2 treatments. In treatments where thrips species coexisted, F. occidentalis and F. intonsa accounted for similar proportions of the population, and both were dominant over T. hawaiiensis within 10 generations under ambient CO2. Under elevated CO2, F. occidentalis was the dominant species and completely displaced F. intonsa and T. hawaiiensis by the ninth or eighth generation. Where the three species coexisted, no displacement occurred within 10 generations, but the pattern of dominance shifted to F. occidentalis > F. intonsa > T. hawaiiensis. Our results show that the population development of F. occidentalis benefits from elevated CO2 and that it can become the dominant species in interspecific interactions with native thrips species. Thus, compared with native thrips species, F. occidentalis has greater adaptability and competitive capacity under elevated CO2, and it may become a more dangerous crop pest under environmental change in the future. [ABSTRACT FROM AUTHOR]

Simple Summary: Thrips are among the most damaging insect pests affecting greenhouse horticulture crops. Research on biological control of these pests has focused on the dominant species, western flower thrips (WFT). However, a second species, onion thrips (OT), has become more prevalent in greenhouse ornamentals in Ontario, and biocontrol strategies for WFT do not control OT sufficiently to prevent crop losses. Although thrips' natural enemies have been tested against OT alone, there are few studies examining how effective they are for OT compared to WFT. We conducted several laboratory trials examining the relative efficacy of several natural enemies typically used in thrips biocontrol, including predators, parasitic nematodes, and a fungal-based biopesticide. All of the natural enemies tested were at least as effective at killing OT as they were for WFT in the laboratory, indicating that they all have the potential to manage both species equally well. Possible explanations why this potential is not realized in commercial greenhouse operations are explored. Thrips biocontrol research in greenhouse crops has focused primarily on western flower thrips (WFT; Frankliniella occidentalis). However, recent outbreaks of onion thrips (OT; Thrips tabaci) in Ontario, Canada, demonstrate that biocontrol-based IPM programs for WFT do not control OT sufficiently to prevent crop losses. A lack of comparative studies makes it difficult to determine which program components for WFT are failing for OT. We conducted several laboratory trials examining the extent to which commercial biocontrol products kill OT compared to WFT. These included phytoseiid mites (Amblyseius swirskii, Neoseiulus cucumeris, Amblydromalus limonicus, Iphiseius degenerans), a large generalist predator (Orius insidiosus), an entomopathogenic fungus (Beauveria bassiana strain GHA), and entomopathogenic nematodes (Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora). In no-choice trials, A. swirskii and O. insidiosus consumed more OT than WFT (first instars and adults, respectively). In choice trials, A. swirskii, N. cucumeris, and O. insidiosus consumed more OT than WFT. Steinernema feltiae caused higher mortality in OT than WFT. There was no difference in mortality between thrips species exposed to other biocontrol agents. This suggests available tools have the potential to manage OT as well as WFT. Possible explanations why this potential is not realized in commercial settings are explored. [ABSTRACT FROM AUTHOR]

The Western flower thrips (WFT), Frankliniella occidentaliss (Pergande) (Thysanoptera: Thripidae), is the main pest of many vegetables and ornamental plants in greenhouses in Antalya province (southwestern part of Turkey). The objectives of this study were: (i) to isolate indigenous Entomopathogenic fungi (EPFs) from naturally infected individuals of WFT in the coastal area of Antalya, where greenhouse cultivation is intensively done, (ii) to identify EPF isolates using DNA sequencing, and (iii) to assess the effectiveness of the isolates against various developmental stages [larvae (1st and 2nd instars), pupa and adult (only females)] of WFT under laboratory conditions. In pathogenicity assays, all isolates were tested at three different conidial concentrations (1 × 105, 1 × 106 and 1 × 107 conidia/ml), using the spray method. Two Beauveria bassiana (Balsamo) Vuillemin (Deuteromycota: Hyphomycetes) isolates (M48 and M49) and Isaria fumosorosea Wise formerly [formerly known as Paecilomyces fumosoroseus (Wise) (Ascomycota: Hypocreales)] isolate (M50) were the most pathogenic, causing 100% mortality of WFT larvae within 7–10 days at the highest concentration (1 × 107 conidia/ml). These three isolates also caused a mortality of more than 85% in the pupae of WFT. The Lecanicillium psalliotae (Treschew) Zare & W. Gams (Ascomycota: Hypocreales) isolate (DOA3) was the most virulent against adult females of WFT, causing 100% morality at the highest concentration 10 days after treatment. The current study's findings suggested that certain EPF extracted from WFT cadavers may provide an important foundation for the creation of bioproducts, as well as a possible alternative technique for regulating WFT. [ABSTRACT FROM AUTHOR]

The generalist predator Orius similis plays a crucial role in controlling the pests Frankliniella occidentalis (Pergande) and Tetranychus urticae Koch. To assess the effectiveness of O. similis in controlling these pests in bean field, we conducted field surveys and used DNA molecular analysis to quantitatively measure the levels of predation on each prey. Field surveys conducted from June 18 to August 7, 2021, showed a linear increase in the population densities of O. similis, F. occidentalis, and T. urticae. The population density of F. occidentalis and T. urticae peaked on July 16, whereas that of O. similis peaked on July 23. The highest positive rate for F. occidentalis and T. urticae was observed on July 23 and 16, respectively. The positive detection rate to F. occidentalis was significantly higher than that of T. urticae (t = 7.659, df = 14, P < 0.0001). The DNA half-lives of F. occidentalis and T. urticae were estimated at 4.44 and 2.60 h, respectively, based on the positive detection rates of both preys during the digestion time in O. similis. These results suggest that molecular intestinal content analysis can be effectively used to quantitatively evaluate the control effect of O. similis on F. occidentalis and T. urticae. [ABSTRACT FROM AUTHOR]

Frankliniella occidentalis (Pergande) and Megalurothrips usitatus are invasive and native thrips species, respectively, that cause serious damage to bean plants. We investigated the effects of avermectin on the interspecific competition between these thrips species and the underlying metabolic mechanism. The results showed that F. occidentalis was more resistant to avermectin than M. usitatus, and it subsequently replaced M. usitatus with or without avermectin treatment. This replacement under avermectin stress occurred after one generation, which was one less than that under no avermectin stress. The P450 activity in F. occidentalis was significantly higher than that in the control at any time point, including F1 generation. In M. usitatus, it was significantly higher than that in the control over three short time intervals after avermectin treatment. The P450 activity in M. usitatus was significantly higher than that in F. occidentalis at 72 h, but an opposite effect was observed in the F1 generation. Although CYP6-3 expression in both F. occidentalis and M. usitatus was generally significantly inhibited, it was substantially upregulated at 72 h in F. occidentalis and in the F1 generation of M. usitatus respectively. Under avermectin stress CYP6-3 expression was significantly lower in M. usitatus than in F. occidentalis at 72 h, whereas it was the opposite at other time points. The two thrips species exhibited enhanced metabolic detoxification of pesticides via increased activity of detoxifying enzyme. This resistance was persistent in F. occidentalis but only temporary in M. usitatus. Our results suggest that avermectin stress accelerates the competitive replacement of M. usitatus by F. occidentalis. [ABSTRACT FROM AUTHOR]

Thrips are significant pest of crops, vegetables, and fruiting trees, and various species of thrips can infest citrus at fruit formation as well as new leaf sprouts. Thrips presence and damage can significantly reduce the export value of fruits, making them a major concern for citrus growers. Field studies were conducted to investigate the biodiversity and abundance of citrus thrips on an early fruiter citrus cultivar in experimental and commercial orchards of Morocco. In this study, we investigated the abundance, economic importance, dynamics, and seasonal fluctuations of citrus thrips in relation to citrus phenology. We identified four species of thrips that infest citrus orchards, including Frankliniella occidentalis, Pezothrips kellyanus, Scirtothrips sp, and Aeolothrips sp. Our results showed that the quantitative peak of thrips occurred during the blooming stage, and that the number of thrips caught on sticky traps during bloom could be a suitable predictive method for estimating final fruit damage. The population dynamics of thrips species were found to depend on several biotic and abiotic factors, including temperature, rainfall, and chemical interventions. We also observed that some citrus varieties were more susceptible to thrips attacks than others, with Washington navel and Maroc late being the most infested orchards with infestation rates of 32% and 24%, respectively. Our findings provide important insights into the abundance, economic importance, and seasonal fluctuations of citrus thrips, which can inform the development of effective control strategies to mitigate their damage in citrus orchards. [ABSTRACT FROM AUTHOR]

BACKGROUND: Insects utilize trehalases (TREs) to regulate energy metabolism and chitin biosynthesis, which are essential for their growth, development, and reproduction. TREs can therefore be used as potential targets for future insecticide development. However, the roles of TREs in Frankliniella occidentalis (Pergande), a serious widespread agricultural pest, remain unclear. RESULTS: Three TRE genes were identified in F. occidentalis and cloned, and their functions were then investigated via feeding RNA interference (RNAi) and virus‐induced gene silencing (VIGS) assays. The results showed that silencing FoTRE1‐1 or FoTRE1‐2 significantly decreased expression levels of FoGFAT, FoPGM, FoUAP, and FoCHS, which are members of the chitin biosynthesis pathway. Silencing FoTRE1‐1 or FoTRE2 significantly down‐regulated FoPFK and FoPK, which are members of the energy metabolism pathway. These changes resulted in 2‐fold decreases in glucose and glycogen content, 2‐fold increases in trehalose content, and 1.5‐ to 2.0‐fold decreases in chitinase activity. Furthermore, knocking down FoTRE1‐1 or FoTRE1‐2 resulted in deformed nymphs and pupae as a result of hindered molting. The VIGS assay for the three FoTREs revealed that FoTRE1‐1 or FoTRE2 caused shortened ovarioles, and reduced egg‐laying and hatching rates. CONCLUSION: The results suggest that FoTRE1‐1 and FoTRE1‐2 play important roles in the growth and development of F. occidentalis, while FoTRE1‐1 and FoTRE2 are essential for its reproduction. These three genes could be candidate targets for RNAi‐based management and control of this destructive agricultural pest. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The immature development and reproduction of the predatory mites Amblyseius largoensis (Muma), Proprioseiopsis lenis (Corpuz and Rimando), and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) were investigated using both thrips eggs and first instars of the western flower thrips, Frankliniella occidentalis Pergande, as prey in a controlled laboratory environment at 25 °C and 60% relative humidity. When provided with thrips eggs as food, A. largoensis exhibited a notably shorter immature development period for both males (7.05 days) and females (6.51 days) as compared with A. swirskii (8.05 and 7.19 days, respectively) and P. lenis (8.10 days and 7.05 days, respectively). Amblyseius largoensis also displayed a higher oviposition rate (2.19 eggs/female/day) than A. swirskii and P. lenis (1.79 and 1.78 eggs/female/day, respectively). Moreover, it exhibited the highest fecundity (25.34 eggs/female), followed by P. lenis (24.23 eggs/female) and A. swirskii (22.86 eggs/female). These variations led to A. largoensis having the highest intrinsic rate of increase (rm) at 0.209, followed by A. swirskii at 0.188, and P. lenis at 0.165. However, when the predatory mites were provided with first instars of F. occidentalis, A. swirskii demonstrated a faster immature development period for both males (7.67 days) and females (7.59 days) as compared with P. lenis (9.00 days and 7.86 days, respectively) and A. largoensis (8.47 days and 8.61 days, respectively). While the oviposition rates of P. lenis (1.92 eggs/female/day) and A. swirskii (1.90 eggs/female/day) were similar when feeding on this prey, A. largoensis produced fewer eggs (1.83 eggs/female/day). Further, A. swirskii exhibited the highest fecundity (31.93 eggs/female), followed by A. largoensis (25.71 eggs/female) and P. lenis (23 eggs/female). Consequently, the intrinsic rate of increase (rm) on thrips first instars was highest in A. swirskii (0.190), followed by A. largoensis (0.186), and P. lenis (0.176). In summary, our findings indicate that in terms of life history parameters A. largoensis performs optimally when feeding on thrips eggs, whereas A. swirskii performs best when preying on the mobile first instars of the thrips. These insights into the dietary preferences and reproductive capabilities of the studied predatory mite species have important implications for their potential use as biological control agents against F. occidentalis in agricultural settings. [ABSTRACT FROM AUTHOR]

Sweet pepper is a crop that benefits from phytosanitary treatments with low environmental impact, especially the successful control of pests through the introduction of biological control agents in greenhouses. However, predators that naturally occur in these surroundings often enter greenhouses. The precise roles of these natural predators and their interactions with the introduced predatory insects and mites are often unknown. This study investigated the relationships between Nesidiocoris tenuis, which is naturally present, and Amblyseius swirskii and Orius laevigatus, which are two species of generalist predators released for the control of multiple pests. This study was conducted for two years on 13 commercial sweet pepper crops in various types of greenhouses (tunnels and traditional greenhouses) in Sicily. The environmental complexity value (ECV) for each site was estimated based on 18 points detected around the site according to the different habitats that occurred at each coordinate. The results showed that the occurrence of N. tenuis in greenhouses, independently of their typology (tunnel or traditional greenhouse), was mainly promoted by the greater diversification of habitats immediately surrounding the pepper crops (in a circular area with a diameter of 500 mt), with an increase in its density during the crop season. Moreover, N. tenuis–O. laevigatus's co-occurrence in flowers suggested that they were not impacted by each other's presence and that their co-occurrence had a significant effect on pest reduction, although their co-occurrence was density-dependent. As an intraguild predator, N. tenuis competed with O. laevigatus for Frankliniella occidentalis when many predators were present. In addition, N. tenuis also competed with A. swirskii when they both occurred in flowers at a higher density. This study highlights the importance of pepper plant flowers in promoting a higher occurrence of juvenile forms of N. tenuis within flowers. Amblyseius swirskii colonized the plants in 3 weeks, distributing itself almost uniformly over the leaves with a clear control action against not only Bemisia tabaci but also F. occidentalis when present on the flowers. Thus, this concurrent analysis of several commercial pepper sites within the same production area suggests that, even with similar pest control plans, the diverse variability in the presence of natural enemies must be considered when selecting control strategies for pepper crop pests and that N. tenuis, favored by complex surrounding habitats, contributes actively to pest reduction. [ABSTRACT FROM AUTHOR]