Tetranychus Urticae Research Articles

Indirect effects of plasma-activated water irrigation on Tetranychus urticae populations

AbstractPlasma-activated water (PAW) is receiving increased attention as a booster of seed germination and seedling vigor, and some studies have described use of PAW to manage crop pathogens. Here, we examined physicochemical properties of two PAWs (referred to as PAW 6.0 and 9.4 min with atmospheric plasma jet) and assessed “their indirect effects” (applied as supplementary irrigation) on host suitability of tomato plants (Solanum lycopersicum L.) to two-spotted spider mites (Tetranychus urticae Koch). Exposure of water to cold plasma significantly lowered pH and increased concentrations of H2O2, NO2−, and NO3−. Supplementary PAW irrigations elicited significant increases in leaf composition of several elements (N, P, K S, Ca, and Mg), leaf reflectance, plant size, and trichome densities (except non-glandular trichomes on the adaxial surface). Preference bioassays revealed significant avoidance of settling and reduced oviposition by two-spotted spider mites on leaf discs from PAW-irrigated plants compared to those from untreated control plants. Performance bioassays showed a significant decrease in two-spotted spider mite populations on PAW-irrigated plants. Results presented in this study provide comprehensive support to the hypothesis that indirect effects of supplementary PAW irrigation significantly reduce host plant suitability to two-spotted spider mites. PAW 6.0 may be slightly better than PAW 9.4, and this difference in performance is discussed in this study. Applications of PAW as supplementary irrigation are likely highly compatible with other IPM tactics and should be considered an innovative and sustainable component in twenty-first-century pest management.

Metabolomic responses of tea [Camellia sinensis (L.) O. Kuntze] leaves to red spider mite [Oligonychus coffeae (Nietner)] and tea mosquito bug [Helopeltis theivora Waterhouse] infestation: a GC–MS-based study

BackgroundThe tea plant, Camellia sinensis (L.) O. Kuntze, is an evergreen leafy plant whose tender leaves are used in the manufacturing of the world’s second most consumed beverage—tea. The production and consumption of tea worldwide have continually increased over the decades. All parts of the plant—leaf, stem, root, flower and seed, are fed upon by insect pests. This study elucidates the metabolomic changes occurring in tea leaves in response to infestation by two major pests in tea gardens: red spider mites and tea mosquito bugs. These pests significantly impact both the quantity and quality of tea production. The secondary metabolites produced by the tea due to pest attack has been analysed using GC–MS analysis in the laboratory.ResultsMostly fatty acid derivatives were biosynthesized as secondary metabolites due to pest attack as revealed from the result. In both infestations, methyl stearate was found to be produced along with increased chromatographic peaks of compounds such as caffeine, methyl palmitate, methyl linoleate, and stigmasta-7,25-dien-3-ol. In comparison with respective control samples (leaf with no pest attack), the one attacked by red spider mite showed eighteen exclusive metabolites, whereas tea mosquito bug infested leaf showed six such exclusive metabolites.ConclusionsSome metabolites were found to be either increased or decreased in their amount in both the samples. The increased compounds were reported with insecticidal and pesticidal properties with respect to respective controls. Some metabolites were markers of pest attacks i.e. plant defense mechanism induced phytochemicals according to the literature as discussed in this research.

Effect of Methyl Jasmonate on the Performance of Tetranychus evansi Baker & Pritchard, 1960 (Acari: Tetranychidae) and Phytoseiulus longipes Evans, 1968 (Acari: Phytoseiidae) on Tomato Plants

Inducible anti-herbivore defenses in plants are predominantly regulated by jasmonic acid (JA). The red spider mite Tetranychus evansi Baker & Pritchard, 1960 (Acari: Tetranychidae) is an invasive pest known for its detrimental impact on tomato plants and other Solanaceae crops. Here, we investigated the extent to which T. evansi and the predatory mite Phytoseiulus longipes Evans, 1968 (Acari: Phytoseiidae) are affected by induced JA-defenses. Initially, we artificially induced the JA-response in tomato plants using exogenous methyl jasmonate (MeJA) and subsequently assessed the effect of JA defenses on spider mite by evaluating mortality and oviposition rates. Our findings revealed a higher mortality and lower oviposition rates on plants treated with MeJA compared to non-treated control plants. Furthermore, we examined the predatory mite's predation rates on spider mite eggs produced on MeJA-treated and non-treated tomato plants. The results showed a reduced predation on T. evansi eggs derived from MeJA-treated plants, indicating a potential negative impact of JA-induced defenses on the predator's performance. Finally, we released five predatory females on T. evansi-infested tomato plants treated and non-treated with MeJA, monitoring the predator population density for three generations. Predator population was not affected, as the abundance of larvae and adults was not significantly different between treatments. These findings underscore the negative impact of JA defenses on herbivores and highlight the trade-off it may pose on natural enemies.

Evaluation of chemical acaricides against the two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae) in geothermal greenhouses in southern Tunisia

The two-spotted spider mite, Tetranychus urticae (Koch) (Acari: Tetranychidae), represents a major threat to geothermal greenhouses in southern Tunisia, causing considerable damage to geothermal crops. In this study, we evaluated the efficacy of new chemical acaricides against T. urticae infesting tomato crops under heated greenhouses: Cyflumetofen, Cinnamaldheyde, Fenazaquin, Pyridaben, Abamectin + Spinosad and Diafenthiuron. The results showed that all acaricides had a significant effect on the reduction of eggs and motile forms of T. urticae, although the reference treatment based on Diafenthiuron varied between 84.40% and 100%. In conclusion, this study highlights the efficacy of several acaricides in managing T. urticae populations, offering promising prospects for effective control of this mite in heated greenhouse crops.

Spider mite herbivory induces an abscisic acid-driven stomatal defense.

Arthropod herbivory poses a serious threat to crop yield, prompting plants to employ intricate defense mechanisms against pest feeding. The generalist pest two-spotted spider mite (Tetranychus urticae) inflicts rapid damage and remains challenging due to its broad target range. In this study, we explored the Arabidopsis (Arabidopsis thaliana) response to T. urticae infestation, revealing the induction of abscisic acid (ABA), a hormone typically associated with abiotic stress adaptation, and stomatal closure during water stress. Leveraging a FRET-based ABA biosensor (nlsABACUS2-400n), we observed elevated ABA levels in various leaf cell types post-mite feeding. While ABA's role in pest resistance or susceptibility has been debated, an ABA-deficient mutant exhibited increased mite infestation alongside intact canonical biotic stress signaling, indicating an independent function of ABA in mite defense. We established that ABA-triggered stomatal closure effectively hinders mite feeding and minimizes leaf cell damage through genetic and pharmacological interventions targeting ABA levels, ABA signaling, stomatal aperture, and density. This study underscores the critical interplay between biotic and abiotic stresses in plants, highlighting how the vulnerability to mite infestation arising from open stomata, crucial for transpiration and photosynthesis, reinforces the intricate relationship between these stress types.

Ultrastructure of silk threads of the water spider Argyroneta aquatica (Clerck, 1757) (Araneae, Cybeidae) in comparison with that of some mites

Silk of the water spider Argyroneta aquatica (Clerck, 1757) was obtained in the laboratory in the form of a capturing web irrespective of the formation of a diving bell and egg cocoon. Silk threads were examined by light microscopy, scanning (SEM), and transmission electron microscopy (TEM) as well as by atomic force (AFM) microscopy. Based on the diameter and internal organization, the silk threads have been divided into five types—a-, b-, c-, d-, and e-types interlaced freely in the thread bundles taken for examinations. Threads of all types are infinitely long, non-branched, round in shape, uniform in width through their course, and rarely found to be ruptured. Threads of the a-type are mostly straight, up to 1,000 nm in diameter, and composed of a fibrillary wall enveloping an electron-dense vacuolated core, which may be occasionally absent. The wall may also become lost, leaving a single core substance surrounded by a slightly wrinkled double membrane. Threads of the b-, c-, and d-types are organized nearly identical, being composed of a fine granular electron-light uniform material enveloped by a fine membrane. The diameter of these threads varies from max. 500 nm in the b-type and 120 nm in the c-type to around 50 nm in the d-type. Threads of these types are more convoluted and more numerous than threads of the a-type. Threads of the last kind, the e-type, occur rarely and are significantly larger with a diameter of around 3.5–4.5 µm. They possess the layered membranous wall surrounding a uniformly dense core. The silk of the water mites Limnochares aquatica (L., 1758) and Limnesia maculata (O.F. Müller, 1776) is composed of threads of only one type that closely corresponded to the a-type threads of A. aquatica. Conversely, the silk of the two-spotted spider mite Tetranychus urticae (C.L. Koch, 1836) consists of threads highly correlated with the d-type threads of A. aquatica. This finding shows that in different phylogenetic lineages of arachnids, the mechanisms of silk production are quite similar.

Investigating biological performance, oviposition and diet preference of the twospotted spider mite feeding on various melon genotypes

The twospotted spider mite, Tetranychus urticae Koch, is one of the most dangerous pests for many crops worldwide, including the melon. Here, we raise the hypothesis that the resistance of melon genotypes to the spider mite is associated with the morphological characteristics of the leaves. We determined (i) the feeding preference and oviposition suitability of T. urticae on four melon genotypes, (ii) various biological parameters and population growth rate (ri) of T. urticae on different melon genotypes, (iii) the leaf morphology of the melon genotypes, and (iv) the relationship between the leaf characteristics and resistance to T. urticae. In no choice tests, lower numbers of adults and eggs of T. urticae were found in the genotypes CNPH 06–1047-343, CNPH 11–1071-43, and CNPH 06-1047-341 compared to control (Goldex). Individuals that fed on CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 genotypes had a longer egg incubation time, longer development time, lower immature viability, longer time to reach adult stage (egg–adult) and lower instantaneous rate of increase compared to control. These findings are in line with the fact that these three genotypes had thicker epidermis and greater mesophyll thickness than control genotype “Goldex”. Even the genotypes CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 had higher trichome densities, this morphological characteristic was not related with the resistance to T. urticae. CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 showed antibiosis and antixenosis against T. urticae and that resistance of the melon to T. urticae wss associated with the greater thickness of the leaf epidermis and mesophyll.

Effect of Mammea americana Aqueous Extract on the Control of the Coffee Red Spider Mite

The coffee red spider mite, Oligonychus ilicis, stands out as one of the main pests of Conilon coffee. The use of synthetic chemical control has led to an increase in the population of this mite and a reduction in its natural enemies. Aiming to find viable alternatives, this study aimed to evaluate the acaricidal potential of “abricó” peel extract, Mammea americana, in the management of O. ilicis. Each treatment consisted of 7 repetitions, with 10 individuals per repetition. They were placed in Petri dishes (10.0 x 1.2 cm), containing coffee leaf disks (4 cm diameter) inside, and moistened cotton at the bottom of the dish and around the disks. The peels of M. americana were dried, crushed, and diluted in aqueous solution to obtain extracts at concentrations of 2; 2.57; 3.30; 4.24; 5.45; and 7 %. The application was done by spraying, using an Alfa 2 model airbrush connected to a compressor calibrated with a constant pressure of 1.3 psi. 1 mL of solution of each concentration was applied for each repetition. Distilled water and the surfactant Tween® 80 (0.05 % v/v) were used as control treatments. The acaricidal effect was evaluated 24, 48, and 72 hours after spraying, and the lethal concentrations LC50 and LC90 were calculated. The results of the toxicity tests indicated an increase in the mortality of O. ilicis with the increase in the concentrations of aqueous extracts of M. americana, resulting in 100 % mortality. The LC90 was estimated at 3.83 %. In the chemical analysis of the M. americana extract, the presence of phenolic acids, tannins, and flavonoids was observed at concentrations of 39.150, 40.783, and 0.0349 mg-1, respectively. We conclude that the aqueous extract of M. americana peels demonstrated acaricidal potential in a controlled environment for the coffee red spider mite.

Leaf trichome-mediated predator effects on the distribution of herbivorous mites within a kidney bean plant.

Some predators prefer to settle on leaf patches with microstructures (e.g., trichomes and domatia), leaving traces on the patches. Herbivorous arthropods, in turn, select leaf patches in response to these traces left by predators. It remains unclear whether traces of predators on leaf patches affect the distribution of herbivorous prey within plants through plant microstructure. Therefore, we examined the distribution of herbivorous mite (Tetranychus urticae) and predatory mite (Phytoseiulus persimilis) by investigating their oviposition pattern. We used a kidney bean plant (Phaseolus vulgaris) with two expanded primary leaves and the first trifoliate leaf, focusing on leaf trichomes as the microstructure. The density of trichomes was higher on the first trifoliate leaf than on the primary leaves and on the abaxial surface of the leaves than on the adaxial surface. Adult female P. persimilis laid more eggs on the first trifoliate leaf to the primary leaves. Although adult female T. urticae preferred to oviposit on the abaxial surface of primary leaves, previous exposure of plants to predators diminished this preference. The altered egg distribution would be a response to the traces of P. persimilis rather than eggs of P. persimilis. Our findings indicate that T. urticae reproduces on leaf patches with traces of predators without altering their oviposition preference. Given that the presence of predator traces is known to reduce the reproduction of T. urticae, it may have a substantial effect on the population of T. urticae in the next generations on kidney bean plants.

Combined application of entomopathogenic fungi and predatory mites for biological control of Tetranychus urticae on chrysanthemum.

Most studies on efficacy of fungal pathogens and predatory mites against Tetranychus urticae have been done on individual species in the laboratory. We evaluated fungi and predatory mites separately and together against greenhouse populations of T. urticae on chrysanthemum plants. First, effectiveness of the fungal pathogens Beauveria bassiana (Bb88) and Metarhzium anisopliae (Ma129), was compared; then, effectiveness of the predatory mites Phytoseiulus persimilis and Neoseiulus californicus. Based on the results, N. californicus and isolate Ma129 were selected and evaluated in combination. In all experiments, treatment effects were assessed for eggs and motile stages of T. urticae. The first experiment showed no significant effect of both fungal isolates on T. urticae populations, except on plants initially infested with 20 mites, where more eggs were found in the control compared to the fungal treatments. In the second experiment, both predatory mites were equally effective at reducing T. urticae populations compared with the control, regardless of initial T. urticae population density. The last experiment demonstrated that populations of T. urticae were reduced most when M. anisopliae (Ma129) and N. californicus were applied together, compared with the control and when each natural enemy was applied separately. M. anisopliae (Ma129) and B. bassiana (Bb88) isolates did not have a significant effect reducing T. urticae populations. Both predatory mites reduced T. urticae populations, regardless of T. urticae density. Combined application of M. anisopliae (Ma129) and N. californicus were more effective against T. urticae than the control or when each agent was applied separately. This article is protected by copyright. All rights reserved.

Glutathione S-Transferase Genes Involved in Response to Short-Term Heat Stress in Tetranychus urticae (Koch).

Tetranychus urticae, a globally ubiquitous mite, poses a significant threat to agriculture. Elevated temperatures exacerbate the growth, development, and reproduction of T. urticae, leading to substantial crop damage. In this study, we employed comparative transcriptomic approaches with whole-genome information of T. urticae to identify six Glutathione S-transferase genes (GSTs) implicated in heat stress response. Through comprehensive bioinformatics analyses, we elucidated the tertiary structure and active sites of the corresponding proteins, providing a thorough characterization of these GST genes. Furthermore, we investigated the expression patterns of these six GST genes under short-term heat shock conditions. Our findings unveiled the involvement of T. urticae GST genes in combating oxidative stress induced by heat, underscoring their role in antioxidant defense mechanisms. This study contributes valuable insights into the molecular mechanisms underlying the response of T. urticae to heat stress, laying a foundation for the development of strategies aimed at mitigating its impact in high-temperature environments.

Automated imaging coupled with AI-powered analysis accelerates the assessment of plant resistance to Tetranychus urticae

The two-spotted spider mite (TSSM), Tetranychus urticae, is among the most destructive piercing-sucking herbivores, infesting more than 1100 plant species, including numerous greenhouse and open-field crops of significant economic importance. Its prolific fecundity and short life cycle contribute to the development of resistance to pesticides. However, effective resistance loci in plants are still unknown. To advance research on plant-mite interactions and identify genes contributing to plant immunity against TSSM, efficient methods are required to screen large, genetically diverse populations. In this study, we propose an analytical pipeline utilizing high-resolution imaging of infested leaves and an artificial intelligence-based computer program, MITESPOTTER, for the precise analysis of plant susceptibility. Our system accurately identifies and quantifies eggs, feces and damaged areas on leaves without expert intervention. Evaluation of 14 TSSM-infested Arabidopsis thaliana ecotypes originating from diverse global locations revealed significant variations in symptom quantity and distribution across leaf surfaces. This analytical pipeline can be adapted to various pest and host species, facilitating diverse experiments with large specimen numbers, including screening mutagenized plant populations or phenotyping polymorphic plant populations for genetic association studies. We anticipate that such methods will expedite the identification of loci crucial for breeding TSSM-resistant plants.

Implementation of Ant Colony Optimization and Principal Component Analysis for Early Prediction of Tomato Leaf Diseases: A Feature Reduction Approach

This paper details the implementation of a sophisticated algorithmic framework designed for the early prediction of various tomato leaf diseases, crucial for enhancing crop management and yield. The research deploys image processing techniques to extract pivotal features such as Red Mean, Green Mean, Blue Mean, Height, Width, and Defect Color channels from high-resolution images of tomato leaves. These features serve as indicators for diseases including Bacterial Spot, Early Blight, Late Blight, Leaf Mold, Septoria Leaf Spot, and infestations by Two-spotted Spider Mites. The core of the implementation lies in the integration of Ant Colony Optimization (ACO) with Principal Component Analysis (PCA) for feature reduction, which streamlines the dataset while retaining critical information. This combination not only reduces computational load but also improves the accuracy of the early prediction model. The paper demonstrates the application of this hybrid approach and compares its performance with existing models, emphasizing its efficiency and accuracy in early-stage disease prediction. The findings indicate that the proposed method outperforms traditional techniques, offering a reliable and scalable solution for agricultural disease management.

Early detection of infestation by mustard aphid, vegetable thrips and two-spotted spider mite in bok choy with deep neural network (DNN) classification model using hyperspectral imaging data

Although exclusion measures (e.g., air filters, biosecurity practices) can be employed to prevent occurrence of pest outbreaks, indoors vegetable farms in Singapore are still susceptible to various arthropod pests. Due to strong interest from the industry to pursue pesticide-free production, indoors pest management is often focused on early detection for timely containment and eradication, implying the importance of robust and vigorous pest monitoring programs. In recent years, application of machine vision technologies, especially hyperspectral imaging (HSI), has been studied for their capacity to early detect pest infestation. However, there is a lack of studies conducted in actual indoor environments and on multiple arthropod pests. Thus, this study aimed to non-destructively collect hyperspectral data of bok choy Brassica rapa subspecies chinensis which were healthy or infested with either mustard aphids Lipaphis erisymi, vegetable thrips Echinothrips americanus or two-spotted spider mites Tetranichus urticae in indoor environment to build deep neural network (DNN) classification model for early detection. Based on HSI data of control and infested plants collected daily over a period of two weeks, we found that point percentage change (PPC) values associated with leaf reflectance in 420–440 nm, 500–520 nm, 620–637 nm, 720–800 nm, and 850 nm were sensitive to infestation by the mentioned arthropod pests. Deep Neural Network (DNN) classification models trained on collected HSI data were found to outperform Linear Discriminant Analysis (LDA) and Support Vector Machine (SVM) classification models. DNN models achieved 92.8 ± 0.4 % overall classification accuracy across all days. As early as two days after infestation, DNN models could achieved classification precision values of 96.4 %, 96.9 %, 93.9 % and 100 % for control plants and plants infested with either aphids, spider mites or thrips respectively. These results highlight the feasibility of multiclass early detection of different arthropod pests and the potential of HSI system coupled with DNN classification as an autonomous plant health monitoring tool in indoor crop production.

Morpho-molecular study of entomopathogenic fungi associated with citrus orchard pests in Northern Iran.

Entomopathogenic fungi play a significant role in regulating insect populations in nature and have potential applications in pest management strategies in different regions. Citrus spp. are among the important horticultural products in northern Iran, and the orchards are affected by different insect pests, especially mealybugs. This study aimed to isolate and identify entomopathogenic fungi associated with citrus orchard pests in northern Iran, focusing on Akanthomyces and Lecanicillium species on mealybugs. Through the samples collected from different regions within Guilan province, 12 fungal isolates were collected and identified based on the combination of morphological characteristics and molecular data. Akanthomyces lecanii, A. muscarius, Engyodontium rectidentatum, Lecanicillium aphanocladii and Lecanicillium rasoulzarei sp. nov. were identified. Of these, A. muscarius on Lepidosaphes sp., E. rectidentatum on Coccidae, and L. aphanocladii on Tetranychus urticae are reported as new fungal-host records from Iran. Moreover, a new species, Lecanicillium rasoulzarei, is illustrated, described, and compared with closely related species.

Development of Menthyl Esters of Valine for Pest Control in Tomato and Lettuce Crops.

Menthyl ester of valine (MV) has been developed as a plant defense potentiator to induce pest resistance in crops. In this study, we attempted to establish MV hydrochloride (MV-HCl) in lettuce and tomato crops. When MV-HCl solutions were used to treat soil or leaves of potted tomato and lettuce plants, 1 µM MV-HCl solution applied to potted plant soil was most effective in increasing the transcript level of defense genes such as pathogenesis-related 1 (PR1). As a result, leaf damage caused by Spodoptera litura and oviposition by Tetranychus urticae were significantly reduced. In addition, MV-HCl-treated plants showed an increased ability to attract Phytoseiulus persimilis, a predatory mite of T. urticae, when they were attacked by T. urticae. Overall, our findings showed that MV-HCl is likely to be effective in promoting not only direct defense by activating defense genes, but also indirect defense mediated by herbivore-induced plant volatiles. Moreover, based on the results of the sustainability of PR1 expression in tomato plants treated with MV-HCl every 3 days, field trials were conducted and showed a 70% reduction in natural leaf damage. Our results suggest a practical approach to promoting organic tomato and lettuce production using this new plant defense potentiator.

A novel target-site mutation (H146Q) outside the ubiquinone binding site of succinate dehydrogenase confers high levels of resistance to cyflumetofen and pyflubumide in Tetranychus urticae

Mitochondrial electron transfer inhibitors at complex II (METI-II), also referred to as succinate dehydrogenase inhibitors (SDHI), represent a recently developed class of acaricides encompassing cyflumetofen, cyenopyrafen, pyflubumide and cyetpyrafen. Despite their novelty, resistance has already developed in the target pest, Tetranychus urticae. In this study a new mutation, H146Q in a highly conserved region of subunit B of complex II, was identified in a T. urticae population resistant to all METI-IIs. In contrast to previously described mutations, H146Q is located outside the ubiquinone binding site of complex II. Marker-assisted backcrossing of this mutation in a susceptible genetic background validated its association with resistance to cyflumetofen and pyflubumide, but not cyenopyrafen or cyetpyrafen. Biochemical assays and the construction of inhibition curves with isolated mitochondria corroborated this selectivity. In addition, phenotypic effects of H146Q, together with the previously described H258L, were further examined via CRISPR/Cas9 gene editing. Although both mutations were successfully introduced into a susceptible T. urticae population, the H146Q gene editing event was only recovered in individuals already harboring the I260V mutation, known to confer resistance towards cyflumetofen. The combination of H146Q+I260V conferred high resistance levels to all METI-II acaricides with LC50 values over 5000 mg a.i./L for cyflumetofen and pyflubumide. Similarly, the introduction of H258L via gene editing resulted in high resistance levels to all tested acaricides, with extreme LC50 values (>5000 mg a.i./L) for cyenopyrafen and cyetpyrafen, but lower resistance levels for pyflubumide and cyflumetofen. Together, these findings indicate that different mutations result in a different cross-resistance spectrum, probably also reflecting subtle differences in the binding mode of complex II acaricides.

Microbiome changes in Akanthomyces attenuatus JEF-147-infected two-spotted spider mites

The two-spotted spider mite (Tetranychus urticae Koch) is an agriculturally serious polyphagous pest that has acquired strong resistance against acaricides because of its short life cycle and continuous exposure to acaricides. As an alternative, mite-pathogenic fungi with different modes of action could be used to control the mites. The spider mite has symbiotic microorganisms that could be involved in the physiological and ecological adaptations to biotic stresses. In this study, mite-pathogenic fungi were used to control female adults, and the microbiomes changes in the fungus-infected mites were analyzed. The acaricidal activity of 77 fungal isolates was tested, and Akanthomyces attenuatus JEF-147 exhibited the highest acaricidal activity. Subsequently a dose–response assay and morphological characterization was undertaken For microbiome analysis in female adults infected with A. attenuatus JEF-147, 16S rDNA and ITS1 were sequenced using Illumina Miseq. Infected mite showed a higher Shannon index in bacterial diversity but lower index in fungal diversity. In beta diversity using principal component analysis, JEF-147-treated mites were significantly different from non-treated controls in both bacteria and fungi. Particularly in bacterial abundance, arthropod defense-related Rickettsia increased, but arthropod reproduction-associated Wolbachia decreased. The change in major bacterial abundance in the infected mites could be explained by a trade-off between reproduction and immunity against the early stage of fungal attack. In fungal abundance, Akanthomyces showed up as expected. Foremost, this work reports microbiome changes in a fungus-infected mite and suggests a possible trade-off in mites against fungal pathogens. Future studies will focus on gene-based investigations related to this topic.

The development of an egg-soaking method for delivering dsRNAs into spider mites

Recently, the first sprayable RNAi biopesticide, Ledprona, against the Colorado potato beetle, Leptinotarsa decemlineata, has been registered at the United States Environmental Protection Agency. Spider mites (Acari: Tetranychidae), a group of destructive agricultural and horticultural pests, are notorious for rapid development of insecticide/acaricide resistance. The management options, on the other hand, are extremely limited. RNAi-based biopesticides offer a promising control alternative to address this emerging issue. In this study, we i) developed an egg-soaking dsRNA delivery method; ii) evaluated the factors influencing RNAi efficiency, and finally iii) investigated the potential mode of entry of this newly developed egg-soaking RNAi method. In comparison to other dsRNA delivery methods, egg-soaking method was the most efficient, convenient/practical, and cost-effective method for delivering dsRNAs into spider mites. RNAi efficiency of this RNAi method was affected by target genes, dsRNA concentration, developmental stages, and mite species. In general, the hawthorn spider mite, Amphitetranychus viennensis, is more sensitive to RNAi than the two-spotted spider mite, Tetranychus urticae, and both of them have dose-dependent RNAi effect. For different life stages, egg and larvae are the most sensitive life stages to dsRNAs. For different target genes, there is no apparent association between the suppression level and the resultant phenotype. Finally, we demonstrated that this egg-soaking RNAi method acts as both stomach and contact toxicity. Our combined results demonstrate the effectiveness of a topically applied dsRNA delivery method, and the potential of a spray induced gene silencing (SIGS) method as a control alternative for spider mites.

Trichoscopic Features of Scalp Discoid Lupus Erythematosus versus Lichen Planopilaris: A Systematic Review.

Lichen planopilaris (LPP) and discoid lupus erythematosus (DLE) are primary scarring alopecias that pose diagnostic challenges clinically, where trichoscopy features may provide benefit in delineating these two cicatricial alopecia, and also helps in assessing the evolution and therapeutic response. To date, there are few reviews on dermoscopic findings in differentiating these two alopecias. A systematic literature review was conducted using the PubMed and Google Scholar databases. The search terms included for scalp DLE were 'lupus' OR 'discoid lupus' OR "scalp lupus" and for scalp LPP were "lichen planopilaris" OR "scalp follicular lichen planus" OR "lichen planus follicularis" and were combined with "dermoscopy" OR "dermatoscopy" OR "videodermoscopy" OR "video dermatoscopy" OR "trichoscopy". The differences in the prevalence of dermoscopic features in scalp DLE and LPP were calculated using the Chi-square test. Of 52 articles, 36 (17 LPP, 19 DLE) were eligible for quantitative analysis. We found predominant peripilar tubular casts and perifollicular erythema with the presence of arborizing vessels in the vicinity of these changes, indicating early LPP. In contrast, follicular red dots, speckled brown pigmentation, and hair diameter variability indicated active DLE. Shiny white areas were common in both the groups in late stages. The target pattern of distribution of blue-grey dots, milky red areas, and irregular white fibrotic dots were seen in LPP, and pink-white background, follicular plugs, perifollicular and interfollicular scale, rosettes, chrysalides, and red spider on yellow dots were detected in DLE. Features such as yellow dots and blue-grey structureless areas were nonspecific and did not have a major role in differentiating DLE from LPP. This article provides a comprehensive review of the literature and delineates the trichoscopic differences and peculiarities of scalp DLE and LPP, including the correlation of dermoscopic features with histopathological findings.