Search Results (89)

Blueberry is a high-value fruit crop in the United States, with Georgia and Florida serving as important early-season production regions. In these areas, several thrips species (Thysanoptera: Thripidae), including Frankliniella tritici (Fitch), Frankliniella bispinosa (Morgan), and Scirtothrips dorsalis (Hood), have emerged as economically significant pests. While F. tritici and F. bispinosa primarily damage floral tissues, S. dorsalis targets young foliage. Their rapid reproduction, high mobility, and broad host range contribute to rapid population buildup and complicate the management programs. Species identification is often difficult due to overlapping morphological features and requires the use of molecular diagnostic tools for accurate identification. Although action thresholds, such as 2–6 F. tritici per flower cluster, are used to guide management decisions, robust economic thresholds based on yield loss remain undeveloped. Integrated pest management (IPM) practices include regular monitoring, cultural control (e.g., pruning, reflective mulch), biological control using Orius insidiosus (Say) and predatory mites, and chemical control. Reduced-risk insecticides like spinetoram and spinosad offer effective suppression while minimizing harm to pollinators and beneficial insects. However, the brief flowering period limits the establishment of biological control agents. Developing species-specific economic thresholds and phenology-based IPM strategies is critical for effective and sustainable thrips management in blueberry cropping systems. Full article

Thrips flavus (Thysanoptera: Thripidae) is a Eurasian pest that primarily attacks a variety of cash crops such as soybean. Currently, there is insufficient knowledge of thrips-resistance mechanisms in soybeans and a lack of effective thrips-resistant soybean varieties. The objective of this study was to identify the correlation between the pest thrips, T. flavus, resistance levels and morphological structures of soybean varieties. A total of 41 spring soybean varieties were planted in a field in Northeast China. Observations were made regarding the infestation intensity of T. flavus, the morphological structures (compound leaf shape, leaf length, leaf width, leaf surface humidity, trichome density, length, and color), leaf SPAD value, leaf nitrogen content, etc. Specifically, leaf trichome density (regardless of whether it was on the upper or lower surfaces of the upper, middle, or lower leaves), trichome color, and compound leaf shape all showed significant positive correlations with the amount of T. flavus. Additionally, principal component analysis (PCA) indicated that, during the peak flowering stage, leaf width, trichome length, trichome density, SPAD value, and nitrogen content were key factors for evaluating resistance; meanwhile, during the podding stage, leaf length, SPAD value, nitrogen content, and leaf surface humidity made the most significant contributions. Field resistance screening using the number of T. flavus per meter of double rows, the average number of T. flavus per plant, and hierarchical cluster analysis yielded consistent results. The soybean variety “podless-trichome” is a thrips-resistant variety (high resistance), and “Jinong 29” is a thrips-sensitive variety (high sensitivity). This study provides valuable insights into the occurrence of insect resistance to thrips in soybean varieties. Full article

Volatile cues are important in the host detection and discrimination of phytophagous insects, allowing them to find suitable hosts. Here, the electroantennography (EAG) and behavioral responses of female Thrips hawaiiensis to the floral volatiles of different plants, Magnolia grandiflora L. (Magnoliales: Magnoliaceae), Gerbera jamesonii Bolus (Asterales: Asteraceae), Lilium brownii Baker (Liliales: Liliaceae), and Rosa rugosa Thunb. (Rosales: Rosaceae), were studied. Y-tube olfactometer bioassays revealed that M. grandiflora was the preferred host for T. hawaiiensis. Fifty-two compounds were identified from the volatile profile of M. grandiflora by gas chromatography–mass spectrometry analysis, of which β-elemen (15.39%), bicyclogermacren (11.99%), and (E)-α-bisabolene (6.05%) showed the highest relative contents. The EAG bioassays revealed that the antennae of T. hawaiiensis could perceive these tested volatile compounds at different concentrations. In six-arm olfactometer bioassays, T. hawaiiensis showed significant positive responses to β-elemen and (E)-α-bisabolene at various concentrations, and 10 μg/μL was found to be the most attractive concentration for β-elemen, and 50 and 100 μg/μL for (E)-α-bisabolene. Based on the four-arm olfactometer bioassays, β-elemen was more attractive than (E)-α-bisabolene to T. hawaiiensis when compared at their optimal concentrations. Therefore, T. hawaiiensis could perceive and distinguish the floral volatiles from the preferred host plant (M. grandiflora). These findings assist in better understanding the mechanism of host preferences of T. hawaiiensis from a chemoecological perspective. In particular, β-elemen showed the greatest potential to be developed as a novel attractant for the monitoring and control of T. hawaiiensis. Full article

The invasive pest Frankliniella occidentalis (western flower thrip, WFT) severely impacts agricultural production. RNA interference (RNAi) has emerged as a viable alternative to chemical control methods. Trehalose-6-phosphate synthase (TPS) is an important enzyme for the synthesis of trehalose in insects. The TPS gene is a potential target for RNAi-based pest control; however, its efficacy against WFTs remains unclear. Feeding with the synthesized dsFoTPS to WFT significantly increased the mortalities of first- and second-instar nymphs and adults and significantly decreased the number of eggs laid by adults within 72 h; the expression of FoTPS was significantly down-regulated in 24, 48, and 72 h. Ingestion of WFTs on Escherichia coli expressing dsFoTPS led to a marked increase in the total pre-reproductive period; reductions in survival rate, adult longevity, oviposition days, fecundity, peak reproduction value, the intrinsic rate of increase, the finite rate of increase, and the net reproductive rate; and an extension of the mean generation time. TPS gene expression was significantly down-regulated on days 7 and 28. A population simulation of WFTs fed with E. coli expressing dsFoTPS indicated that the population suppression was reduced to 1/34 of the control in 100 d. Oral delivery of E. coli expressing dsFoTPS effectively inhibited the survival, fecundity, and population growth of WFTs, offering a novel approach and rationale for the prevention and control of WFTs. Full article

Tomato spotted wilt virus (TSWV) is a highly destructive plant pathogen and transmitted by several thrips including the western flower thrips, Frankliniella occidentalis. A structural N protein encoded in the viral genome represents the nucleocapsid protein by binding to the viral RNA genome. However, it remains unknown how the RNA-binding protein specifically interacts with the viral RNA from host RNAs in the target cells. To study the molecular basis of N function, we produced the protein in Escherichia coli and the resulting purified recombinant protein was used to investigate the protein–RNA interactions. The recombinant N protein migrated on agarose gel to the anode in the electric field due to its high basic isoelectric point. This electrostatic property led N protein to bind to DNA as well as RNA. It also bound to both single-stranded (ssRNA) and double-stranded RNA (dsRNA). However, when the total RNA was extracted from plant tissues collected from TSWV-infected host, the RNA extract using the recombinant N protein was much richer in the TSWV genome compared to that without the protein. To investigate the specificity of N protein to ssRNA, the three-dimensional structure was predicted using the AlphaFold program and showed its trimeric oligomerization with the binding pocket for ssRNA. This was supported by the differential susceptibility of N protein with ssRNA and dsRNA against RNase attack. Furthermore, a thermal shift assay to analyze the RNA and protein interaction showed that ssRNA strongly interacted with N protein compared to dsRNA. In addition, the N gene was expressed along with the multiplication of the viral RNA genome segments from the segment-specific fluorescence in situ hybridization analysis in different tissues during different developmental stages of the virus-infected F. occidentalis. These results suggest that the functional trimeric N proteins bind to the viral RNA to form a basic nucleocapsid structure at a specific virus-replicating compartment within the host cells. Full article

In southern China, cowpea production is severely threatened by Megalurothrips usitatus due to its fast-evolving resistance to insecticides. The toxicity monitoring of commonly used insecticides against field populations provides key information for the resistance management of pests. In this study, field populations of Megalurothrips usitatus were collected from three locations (QY, YF, MM) in Guangdong, and the sensitivity of these populations against insecticides was determined by using a thrips insecticides bioassay system (TIBS) method. The bioassay results indicated there were sensitivity variances to insecticides between these three field populations. Among these 10 insecticides, spinetoram and spinosad both showed high toxicity against all three field populations. In addition, broflanilide for QY, emamectin benzoate for YF, and emamectin benzoate and cyantraniliprole for MM were suggested as alternate insecticides to alleviate selective pressure from insecticides on field populations. In field experiments, the corrected control efficacy of cyantraniliprole and spinetoram against M. usitatus was over 75% at 7 dpa, which proved to be ideal insecticides for field application. These field-based results provide guidance for chemical control against thrips and can be valuable in proposing appropriate strategies for thrips resistance management. Full article

The western flower thrips, Frankliniella occidentalis, a worldwide insect pest with its polyphagous feeding behavior and capacity to transmit viruses, follows a diurnal rhythmicity driven by expression of the circadian clock genes. However, it remained unclear how the clock signal triggers the thrips behaviors. This study posed a hypothesis that the clock signal modulates cGMP-dependent protein kinase (PKG) activity to mediate the diurnal behaviors. A PKG gene is encoded in F. occidentalis and exhibits high sequence homologies with those of honeybee and fruit fly. Interestingly, its expression followed a diel pattern with high expression during photophase in larvae and adults of F. occidentalis. It is noteworthy that PKG expression was clearly observed in the midgut during photophase but not in scotophase from our fluorescence in situ hybridization analysis. A prediction of protein–protein interaction suggested its functional association with clock genes. To test this functional link, RNA interference (RNAi) of the PKG gene expression was performed by feeding a gene-specific double-stranded RNA, which led to significant alteration of the two clock genes (Clock and Period) in their expression levels. The RNAi treatment caused adverse effects on early-life development and adult fecundity. To further analyze the role of PKG in affecting diurnal behavior, the adult females were continuously observed for a 24 h period with an automatic digitization device to obtain movement parameters and durations (%) in different micro-areas in the observation arena. Diel difference was observed with speed in RNAi-control females at 0.16 mm/s and 0.08 mm/s, in photo- and scotophase, respectively, whereas diel difference was not observed for the PKG-specific RNAi-treated females, which showed 0.07 mm/s and 0.06 mm/s, respectively. The diel difference was also observed in durations (%) in the control females, more strongly in the intermediate area in the observation arena. Speed and durations in the different micro-areas in mid-scotophase were significantly different from most photophase in the control females, while speed was significantly different mainly during late photophase when comparing effects of control and RNAi treatments in each light phase. Three sequential stages consisting of high activity followed by feeding and visiting of micro-areas were observed for the control females. For RNAi-treated females, the three phases were disturbed with irregular speed and visits to micro-areas. These results suggest that PKG is associated with implementing the diurnal behavior of F. occidentalis by interacting with expressions of the circadian clock genes. Full article

Western flower thrips (WFT), Frankliniella occidentalis (Pergande) [Thysanoptera: Thripidae], is a destructive pest of greenhouse ornamentals. Flowering yellow marigolds, Tagetes patula (L.) [Asterales: Asteraceae], have been shown to be attractive to WFT, implicating their suitability as a trap plant. However, functionality may vary in part due to crop variety, the growth stage of the crop in which the marigold trap plant is deployed and whether or not the crop plants have flowers present. The attractiveness of yellow marigolds was tested within several varieties of mature, flowering ornamental bedding plants that were flowering or had their flowers removed: Calibrachoa spp. Petunia spp. Verbena spp., Osteospermum spp., Impatiens haekeri and other marigolds. Trials were conducted in cages under controlled greenhouse conditions for six weeks. The effectiveness of orange vs. yellow marigolds as a trap plant was also assessed. The results showed that WFT were attracted to flowering marigolds and, over time, were present in greater numbers on these than crop plants for all crop species and varieties tested at varying levels of significance. Yellow marigold trap plants were the least effective when deployed within other marigold varieties. In crops with flowers, it took up to five weeks for the number of WFT on trap plants to surpass numbers on crop plants. In contrast, in crop varieties with their flowers removed, trap plants attracted WFT earlier, within one to two weeks, and harbored them in greater numbers over time. Orange, flowering marigolds were a less effective trap plant compared to yellow marigolds. These results confirm that flowering yellow marigolds are attractive to WFT and have potential as a trap plant in greenhouse ornamentals, particularly when crop plants do not have flowers. Full article

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. Full article

Western flower thrips (WFTs) are significant pests affecting various crops globally. Developing sustainable strategies for managing WFTs is essential for improving thrips management. Ethological control methods, particularly those employing volatile organic compounds (VOCs) emitted by plants to influence insect behavior, have emerged as a promising avenue for pest management. Natural hosts such as Alstroemeria provide an intriguing yet underexplored opportunity for developing attractants tailored to WFT management. This study examined the behavioral preferences of WFTs towards flowers of four commercial Alstroemeria cultivars, focusing on variations in VOC profiles. Using headspace solid-phase microextraction (HS-SPME), VOCs were captured in vivo from cultivars with contrasting levels of WFT infestation. Gas chromatography coupled with mass spectrometry (GC-MS) was employed to analyze the VOCs, with linear retention indices aiding compound identification. An untargeted volatile profiling-based comparative analysis revealed key VOCs that differed among cultivars, shedding light on their potential correlation with WFT behavior. Behavioral assays identified three specific VOCs—butyl butyrate, 1-methylnaphthalene, and citronellyl acetate—as influential in attracting WFTs. Attraction responses were concentration-dependent, with two tested concentrations eliciting significant behavioral effects. These findings highlight the potential of these active VOCs as components of novel attractants for WFT management. The results direct future research and the development of tools to integrate ethological strategies into sustainable pest management practices for crops. Full article

Megalurothrips usitatus is an economically important vegetable pest. Because of the growing demand for reducing pesticide use on vegetables, new environmentally friendly strategies for controlling M. usitatus are urgently needed. Insect odorant-binding proteins are prospective targets for screening environmentally friendly odorant attractants for pest control. However, very little is known about OBP genes in M. usitatus. Here, we identified 14 OBPs in the M. usitatus genome using HMMER and BLAST. The chromosomal location showed that these OBPs were widely distributed across eight chromosomes. The analysis of the gene and protein structure characteristics of OBPs in M. usitatus revealed substantial diversity within the OBP gene family. The spatiotemporal expression profiles showed that ten out of 14 MusiOBPs displayed male biased expression, which were highly expressed in antennae, suggesting that they may play a crucial role in the recognition of host plant volatiles and thrips aggregation pheromones. Notably, only MusiOBP8 was significantly higher expressed in female adults, indicating a potential involvement in reproduction. Moreover, MusiOBP7 and MusiOBP13 were highly expressed in the pupae, indicating their possible role in immune responses. These results provide an important foundation for further exploration of the functions of the OBPs in M. usitatus. Full article

As two major pests of cowpea in South China, bean flower thrips [Megalurothrips usitatus (Bagnall)] and flower thrips [Frankliniella intonsa (Trybom)] always occur on the same plant. In this study, the two-sex life table parameters of these two species were investigated on three bean pods: cowpea (Vigna unguiculata L. var. Chunqiu Wujiadou), snap bean (Phaseolus vulgaris L. var. Yonglong 3), and green bean (Phaseolus vulgaris L. var. Linghangzhe) using standard cut bean protocols. Longevity of female adult M. usitatus showed no significant difference on cowpea and snap bean, but was shortest on green bean, with the highest fecundity on snap bean, followed by cowpea and green bean. Longevity and fecundity of female adult F. intonsa were both highest on cowpea, followed by snap bean and green bean. On snap bean, the population parameters (R₀, GRR, T) of M. usitatus were higher than F. intonsa, whereas r and λ were not different, suggesting that M. usitatus were more competitive on snap bean. On cowpea, the population parameters (R₀, GRR, r, λ) of F. intonsa were higher than M. usitatus, suggesting a competitive advantage of F. intonsa on cowpea. To better mimic field conditions, we investigated the survival and fecundity of adult M. usitatus under two distinct scenarios: when they could feed directly on cut surfaces of cowpeas (standard lab protocol), and when they could not. Adult survival of M. usitatus is not significantly influenced by whether or not they fed directly on cut surfaces of cowpeas. However, a notable decrease in fecundity was observed in M. usitatus that fed on surface-covered cut pods. This suggested that direct feeding on cut surfaces of cowpea did have an impact on thrips’ fecundity, offering fresh perspectives for future research into the growth and development of thrips in a laboratory. Our study suggests that experiments involving cut surfaces may be misleading, and further investigations are ongoing to address these concerns. Full article

In Uganda, the common bean (Phaseolus vulgaris) is often infested by a complex of insect pests, but bean flies, aphids, bean leaf beetles, and flower thrips are the most important. Whereas yield losses due to these pests have been established, there is limited information on their population dynamics at different stages of crop growth and their effect on yield and yield components. In order to describe the population dynamics of selected common bean pests at various phases of bean crop growth, and their impact on yield and yield components, a study was carried out in Uganda during the 2016 second rains and the 2017 first rains in three agro-ecological zones. Bean flies, bean aphids, bean leaf beetles, whitefly, striped bean weevil, leafhoppers, and caterpillars were the main insects observed. Pesticide spray schedules were imposed to generate different populations of insect pests whose effects on yield and its components were determined. The findings indicate that spray regimes significantly influenced the abundance of bean flies and leafhoppers, but not the other insect pests. Additionally, except for caterpillars, insect pests were significantly influenced by crop growth stages, but only leafhoppers exhibited a significant negative relationship with grain yield. Furthermore, yield and yield components varied significantly between spray regimes, and there was a significant positive relationship between grain yield and yield components. Our study is important for informing growers on the stage of crop growth at which management tactics such as use of insecticides can be applied for different insect pests. Full article

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. Full article

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. Full article