Mite Pests Research Articles

Behavior of Typhlodromus (Anthoseius) recki confronted to a combination of plants and food: pollen, Tetranychus urticae and Aculops lycopersici for companion plant use.

Typhlodromus (Anthoseius) recki feeds on pest mites on tomato plants and its introduction into crops via companion plants, Mentha suaveolens and Phlomis fruticosa, has been recently investigated. This study aims at assessing the predator arrestment behavior, through lab choice tests to determine the effects of (i) prey (Aculops lycopersici and Tetranychus urticae) vs Typha angustifolia pollen deposited on companion plant or Solanum nigrum, (ii) T. urticae vs A. lycopersici on S. nigrum and (ii) M. suaveolens vs P. fruticosa using pollen as food source. The predator position, the number of eggs laid and the number of T. urticae eggs consumed were assessed during 4 days. The predator was more observed on leaf discs with A. lycopersici vs pollen when the pollen was deposited on S. nigrum and M. suaveolens, but was more found on leaf discs with pollen on P. fruticosa. It was equally found on leaf discs with T. urticae vs pollen for all the plants tested. No difference in predator arrestment behavior was noted between A. lycopersici and T. urticae, but a higher proportion was observed on leaf discs with A. lycopersici at the beginning of the experiment than at the end. Finally, the predator was more observed on leaf discs of P. fruticosa than of M. suaveolens. The highest fecundity was observed in systems with pollen and A. lycopersci + pollen, and the lowest with T. urticae + pollen; T. urticae consumption was not different with pollen or A. lycopersici. The predator less arrested on pollen vs A. lycopersici that provides a high fecundity; however, surprisingly it was more attracted to pollen vs a prey T. urticae, questioning the cues perceived by T. (A.) recki. The strong preference for P. fruticosa without prey vs S. nigrum with prey or M. suaveolens with pollen, suggests for the second time for Phytoseiidae, direct effects of plant (may be via odors) and questions the ecological advantages of such a behavior. For practical issues, M. suaveolens would be a better bank plant than P. fruticosa; an arrestment on patches of A. lycopersici within tomato plant is expected even if pollen is present and in case of T. urticae infestation a low dispersal to this prey will probably occur, questioning the interest to use T. (A.) recki in combination with other Phytoseiidae species, specialized in T. urticae predation, as Phytoseiulus persimilis.

Extrafloral nectar from coffee-associated trees as alternative food for a predatory mite.

Plant diversity can enhance natural pest control in agriculture by providing resources and conditions that are not regularly available in conventional crops tonatural enemies of crop pests. Extrafloral nectar-producing plants, for example, might cause reduction of pest densities on neighboring plants because the nectar can increase the performance of natural enemies. Coffee agroforestry systems often contain extrafloral-nectar-producing Inga spp. trees that serve several purposes. Recent studies suggest that they attract and arrest a diversity of natural enemies that contribute to the control of coffee pests. Mites from the Phytoseiid family are key natural enemies of coffee pest mites, but no study has investigated whether Inga extrafloral nectar increases the performance of predatory mites in coffee ecosystems. Thus, here, we assessed whether the extrafloral nectar of Inga edulis Mart. (Fabaceae) can be considered a suitable nutritional resource for the predatory mite Amblyseius herbicolus (Chant), one of the most abundant phytoseiids in coffee crops. We found that feeding on extrafloral nectar allows for development and survival, but not reproduction, of A. herbicolus. Whereas individuals that fed on a diet of nectar during their immature development could subsequently only oviposit after having fed on a pollen diet, individuals that had developed on pollen stopped ovipositing when fed nectar. Our findings suggest that interplanted Inga trees can help to conserve populations of predatory mites in crop ecosystems through the provision of nectar and may boost biological control services. Future research should investigate the effects of extrafloral nectar-producing trees on coffee pest control by these predatory mites.

Molecular target for sprayable double-stranded RNA-based biopesticide against Amphitetranychus viennensis (Acari, Tetranychidae).

Amphitetranychus viennensis, a destructive pest mite of fruit plants in Europe and Asia, poses a serious challenge due to its adaptability and resistance to multiple acaricides. RNA interference (RNAi)-based technologies offer a promising alternative to address this emerging issue. In this study, we screened for candidate genes that can be targeted for spray-induced gene silencing (SIGS). Suppression of AvSrp54k, AveIF4A-1, AvHel31B, AvCOPB2 and AvProsbeta5 led to a significantly higher mortality and caused minor damages to leaf discs in comparison to the controls. Among them, AvCOPB2 and AvProsbeta5 were the best candidates with the highest mortality (>95%) and minimal leaf damages (<13%). Given that LdProsbeta5 is the active ingredient of the first sprayable dsRNA-based biopesticide, Ledprona, against the Colorado Potato Beetle, Leptinotarsa decemlineata, we examined the suitability of AvProsbeta5 in managing A. viennensis. In comparison to the control, A. viennensis population was suppressed by >95% at day-17, and the plant defoliation rate decreased to 0 at day-24. Our combined results not only provide two viable molecular targets for sprayable dsRNA-based biopesticides, but also confirm the practical implications of SIGS in managing A. viennensis, one of the most destructive arthropod pests in orchards and ornamental plants.

A novel encapsulation method for lemongrass essential oil in nanoemulsion and SiO2 nanoparticles against the storage mite Aleuroglyphus ovatus (Acari: Acaridae)

Lemongrass essential oil (LEO), which is extracted from Cymbopogon citratus, has emerged as a promising alternative to traditional synthetic pesticides. In the present study, we fabricated pure LEO and its nanomaterials (nanoemulsion [NE] and SiO2 nanoparticles [NPs]) and investigated their acaricidal effects on Aleuroglyphus ovatus (Acari: Acaridae), a common storage pest mite. A loading capacity (LC) of 57.45% was obtained, showing successful encapsulation of LEO in SiNPs. The contact mortality, fumigant mortality, ovicidal activity, repellent activity, and toxic effects of LEO on A. ovatus were investigated. The median lethal concentration (LC50) values of contact mortality of LEO, LEO-NE, and LEO-SiNPs against adult mites were 0.067, 0.053, and 0.019 mg/cm2, respectively, after 24 h of exposure. Similarly, the corresponding LC50 values of fumigant activity were 0.044, 0.096, and 0.067 mg/cm3, respectively. All products had greater contact and fumigant effects on nymphs and larvae than they did on adults. After 5 days of exposure to the products, LEO-NE and LEO-SiNPs had greater inhibitory effects on hatching than did pure LEO. LEO-SiNPs exhibited a rapid and significant repellent effect at 3 h (82.22%) and were effective even after 24 h (35.56%), indicating their persistent and long-term acaricide activity. A study of toxicity symptom revealed two different manifestations of toxicity in mites after exposure to these products (knock-down type and immobilized type). Taken together, these findings suggest that LEO and its nanomaterials exhibit significant acaricidal activity against A. ovatus.

Genetic and morphological features of some Turkish populations of Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae)

Amblyseius swirskii is one of the most important phytoseiid mites commercialized worldwide for controlling pest mites and small insect pests. The study aims to investigate morphological and genetic variation among seven populations collected from different locations and plant species (cotton, orange) in Türkiye. The DNA sequences (12S rRNA and Cytb mitochondrial DNA markers) were also compared with those of commercial populations. The average genetic distance among the Turkish populations was quite low (0.7% for 12S rRNA and 0.9% for Cytb mtDNA), ranging from 0 to 2.8% and 0 to 1.5%, respectively. The phylogenetic trees show two distinct groups, separated by genetic distances of 0.9% and 1.3% for the 12S rRNA and the Cytb mtDNA fragments, respectively. The genetic differences were not explained by location or host plant. However, specimens from some populations were exclusively or predominantly included in one of the two clades, and commercialized specimens of A. swirskii only included in one clade, along with specimens collected in orange orchards. Specimens from cotton fields and Solanum nigrum, were found in both clades, but in different proportions. Results show a globally low genetic diversity within A. swirskii for the two DNA fragments. The existence of two clades raises questions about the presence of a clade derived from commercial releases. However, this result may be related to other factors. Morphological analyses demonstrated substantial variability among the populations, except for the population sampled from orange in Adana Kozan. Despite this, the morphological and molecular results are relatively consistent.

Orchid Insect and Mite Pests in South Florida

This publication presents information on the most common and damaging arthropod pests of orchids. It is based on literature review and interviews with local nurseries in the Ft. Myers and Naples, Florida, area as well as with local orchid club members. Orchids are one of the most popular plants in the ornamental realm. Extension agents and Master Gardeners need information to help address client questions about orchid ailments and orchid pests.

Presence of a Non-Pest Mite Tarsonemus confusus Ewing (Acari: Tarsonemidae), in Florida Strawberry Fields

This publication aims to benefit growers and Extension agents by increasing awareness of a fungus-feeding mite, Tarsonemus confusus, commonly found in strawberry fields. Tarsonemus confusus may be misidentified as other pest mites. In fact, without help from an expert mite taxonomist, incorrect species identification can be a major concern. Although this mite species typically does not achieve pest status on most crops, an incorrect pest identification may lead to unnecessary application of miticides, triggering a secondary pest outbreak.

Design, Synthesis, and 3D-QASR of Oxazoline Derivatives Containing an S-S Moiety as Potential Acaricide.

To mitigate the detrimental effects of agricultural pest mites on crop yield, an active substructure splicing strategy was employed to modify etoxazole by introducing an S-S moiety. The target products were obtained efficiently via a bilateral disulfurating reagent (DSMO), which was developed by our group. The leaf dip method was used to evaluate the activities of the designed target compounds against the eggs and larvae of the spider mite (Tetranychus cinnabarinus). Most of the target compounds exhibited good efficacy in controlling the larvae and eggs of T. cinnabarinus. Based on these results, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was established to guide the construction of compound 7l. Notably, compound 7l exhibited a better activity against T. cinnabarinus eggs (LC50 = 0.0035 mg/L) compared to etoxazole (LC50 = 0.2990 mg/L). Greenhouse bioassays indicated that compound 7l exhibits excellent acaricidal activity against egg of T. cinnabarinus, which is better than the etoxazole at 1.0 mg/L. Additionally, some of the compounds showed inhibitory effects against Dickeya zeae (D. zeae), Xanthomonas campestris pv campestris (Xcc), Xanthomonas oryzae pvoryza (Xoo), and Xanthomonas oryzae pvoryzicola (Xoc). Furthermore, compounds 7l not only exhibited relatively potent against Plutella xylostella activities (LC50 = 24.0 mg/L) but also had low toxicity (LC50 > 11.0 μg/bee) to Apis mellifera. In conclusion, the current experimental results suggest that oxazoline derivatives containing an S-S moiety have the potential to serve as lead compounds for the development of novel acaricide agents.

RNAi of nuclear receptor E78 inhibits the cuticle formation in the molting process of spider mite, Tetranychus urticae.

The two-spotted spider mite, Tetranychus urticae, is an important pest mite in agriculture worldwide. E78, as a member of the nuclear receptor superfamily and a downstream responsive gene of ecdysteroids, plays a crucial role in regulating physiological behaviors such as development and reproduction in insects. However, its function in mites remains unclear. The aim of this study was to explore how E78 functions in the molting process of spider mites. In this study, reverse transcription quantitative polymerase chain reaction (RT-qPCR) experiments to analyze the expression pattern of TuE78 during the development of Tetranychus urticae, demonstrated that the expression level of TuE78 was higher during the molting state than that after the completion of molting, and it reached a peak expression level when the deutonymph mites entered the molting stage. RNA interference (RNAi)-mediated gene-silencing of TuE78 resulted in 95% deutonymph mite molt failure. A series of analysis under a light microscope, and scanning and transmission electron microscopy revealed that RNAi mites died within the exuvium without ecdysis, and that apolysis had started but the new cuticle was thin and the typical cuticular lamellae were absent, indicating blockage of the post-apolysial processes and explaining molt failure. Hence, transcriptome sequencing confirmed that the expression of cuticle protein and lipid metabolism-related genes was significantly affected after TuE78 silencing. This study demonstrated that TuE78 participates in the molting process of Tetranychus urticae by regulating the post-apolysial processes with the formation of new cuticle and successful ecdysis. This in turn suggests the potential of TuE78 as a target for pest mite control and provides a theoretical basis for further exploration of the molecular regulatory mechanism of spider mite molting. © 2024 Society of Chemical Industry. Published by John Wiley & Sons Ltd.

Spirodiclofen toxicity in Tetranychus urticae and safety to natural enemies Proprioseiopsis asetus and Amblyseius swirskii

Proprioseiopsis asetus and Amblyseius swirskii are excellent natural enemies of plant-feeding mites and small pests. In order to clarify the safety of the acaricide spirodiclofen to the predatory mites P. asetus and A. swirskii, here, we investigated the toxicity of the acaricide on the pest mite T. urticae (nymphs and adult females) and on both species of predatory mites, P. asetus and A. swiskii (eggs, nymphs, and female adults) by using the spray, slide-dip, and leaf residual toxicity methods, compared the selective toxicity and assessed the safety to these natural enemies. The results demonstrated that the corrected mortality in P. asetus and A. swirskii female adults was &lt;5% at recommended spirodiclofen concentrations in the spray method. In the leaf residual toxicity method, P. asetus and A. swirskii egg-hatching rates did not differ significantly from the pure water control group. In the slide-dip method, spirodiclofen lethal concentration 50 (LC50) in P. asetus and A. swirskii female adults was noted to be 9,494.875 and 3,064.187 mg·L−1, respectively. In the spray method, spirodiclofen LC50 in P. asetus and A. swirskii nymphs was found to be 4,292.664 and 1,081.609 mg·L−1, respectively, and that in T. urticae female adults and nymphs was 55.189 and 40.862 mg·L−1, respectively. Spiroclofen selective toxicity ratios (STRs) in P. asetus female adults–T. urticae and P. asetus nymphs–T. urticae were 172.013 and 105.053, respectively, indicating that spiroclofen has a high positive selectivity toward the pest T. urticae and its natural enemy P. asetus. In contrast, spiroclofen STRs in A. swirskiis female adults–T. urticae and A. swirskiis nymphs–T. urticae were 55.522 and 26.470, respectively, indicating spiroclofen has a moderate positive selectivity toward the pest T. urticae and its natural enemy A. swirskii. In the safety evaluation, the spirodiclofen safety factor for P. asetus female adults and nymphs was 158.248–237.37 and 71.544–107.317, respectively, whereas that for A. swirskii female adults and nymphs was 50.070–76.605 and 18.027–27.040 respectively. All spirodiclofen safety factor values were much higher than 5, indicating that spirodiclofen is highly safe for P. asetus and A. swirskii; in particular, spirodiclofen is safer for P. asetus than for A. swirskii.

Acaricidal Efficacy of Abamectin against Tetranychus urticae Populations When Combined with Entomopathogenic Fungi

Tetranychus urticae (Acari: Tetranychidae) is a widespread and serious mite pest that infests tomato plants and causes economic losses worldwide. We investigated the acaricidal efficacy of two isolates of entomopathogenic fungi (EPF) Metarhizium robertsii (WG-7) and Beauveria bassiana (WG-12) alone and in combination with abamectin when applied topically to tomato leaf discs in the laboratory against T. urticae. We also evaluated the establishment and proliferation of T. urticae mite life stages on tomato plants in the greenhouse after application of each of the above treatments. The combination of abamectin with each EPF caused 100% mortality in T. urticae immatures after 2 days while each EPF or abamectin alone caused moderate mortality, not exceeding 74.2% 3 days post-exposure. Complete (100%) mortality of adults was observed after 5 days in leaf discs treated with M. robertsii plus abamectin whereas B. bassiana plus abamectin caused 100% mortality after 7 days. The mean number of eggs, emerged immatures, and adults were significantly reduced on both sides of the leaves (i.e., abaxial and adaxial sides) after using the combined application of M. robertsii or B. bassiana plus abamectin, compared to abamectin alone and controls. Our results reveal that the acaricidal efficacy of abamectin combined with either EPF was significantly better in managing the T. urticae life stages than either treatment alone under greenhouse conditions.

Efficiency of Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) for controlling three plant-feeding mites on guava trees in Egypt

ABSTRACT Tegolophus guavae (Boczek), Brevipalpus phoenicis (Geijskes), and Tetranychus urticae Koch are plant-feeding mite pests that cause severe damage to the foliage and fruits of guava trees in Egypt. The phytoseiid mite, Neoseiulus californicus (McGregor), was released at three densities (100, 200, and 300 predators/tree). The results indicated that the efficiency of N. californicus was significantly influenced by the release rate. The highest mean reduction percentage after six months of release for T. guavae, B. phoenicis, and T. urticae was, respectively, at 300 predators/tree (64.90, 81.15, and 81.11%) in 2021 and (74.89, 83.76, and 83.07%) in 2022. The mean fruit yields (kg/treatment) in the released plots were substantially greater than those in the control (ranging from 8–16%). The current result suggests that releasing N. californicus is a viable option for biological guava mite pest management.

Lemongrass (Cymbopogon citratus) essential oil: an eco-friendly and fast-acting acaricide against the grain pest mite Aleuroglyphus ovatus

ABSTRACT This study was designed to evaluate the acaricidal effect and the mode of action of lemongrass essential oil (LEO) against Aleuroglyphus ovatus. Contact and fumigant mortality indicated that LEO had higher acaricidal activities at a low concentration, and the acaricidal action of LEO was significantly more effective by contact effects than by fumigant bioassay. Repellent rate against A. ovatus at different concentrations of LEO increased with application time. Observation on the toxic symptoms revealed that almost all mites were in immobilized type (IM type) in 30 min, but the symptom of knock-down type (KD type) appeared later. Cuticles of mites killed by LEO exhibited obvious colour change and deformation. Detoxification enzyme activity assay showed that glutathione S-transferase (GST) activity increased in mites treated by LEO compared to the controls. LEO increased catalase (CAT) activity of A. ovatus but inhibited superoxide dismutase (SOD) after 20 h. LEO also increased nitric oxide synthetase (NOS) and inhibited acetylcholine esterase (AChE) activities. Moreover, LEO acted as a fast-acting neurotoxin on A. ovatus. Our results suggest that LEO has an acaricidal potential and is a promising agent in control of A. ovatus.

Ecofriendly Management of Two Spotted Spider Mites on Tomato (Solanum lycopersicum) (Mill) in Eastern Ethiopia

This study was initiated with the objective to evaluate the efficacy of tobacco leaf extract and potentiality of intercropping on TSSM in Eastern Ethiopia. The tomato, tomato + cabbage, tomato + common bean, tomato + onion, tomato + tobacco leaf extract and tomato + karate 5% EC were the treatments used for the trial. The overall result indicated that intercropping and tobacco leaf extract significantly reduced the population of these mite pests compared to sole tomato. The minimum population with infestation was recorded on karate (14.65, 0.79) followed by tomato – tobacco leaf extract (16.50, 0.92) and tomato onion (36.53, 1.74) from intercropping while control was the most in recording maximum population with maximum infestation (94.10, 2.88 respectively). The most population reduction with infestation was observed on tobacco leaf extract compared to untreated plot followed by tomato-onion intercropping. The highest yield (50.73tha-1) was recorded on the tomato-onion intercrops followed by karate 5%EC (43.96tha-1) and tobacco extract (43.65tha-1) while the lowest yield was recorded on head cabbage intercrops (30.10tha-1). The maximum net benefit was obtained from tomato-onion intercrops (688653.45 ETB) whereas the lowest net benefit was recorded on common bean (354176.60 ETB) intercrops. Therefore, tomato onion intercrops and tobacco leaf extract could be considered as the first options in boosting tomato production as an alternative to karate 5%EC and expected as common integrated management of TSSM on tomato.

Expression reduction and a variant of a P450 gene mediate chlorpyrifos resistance in Tetranychus urticae Koch

IntroductionUnderstanding how insects and mites develop resistance to chlorpyrifos is crucial for effective field management. Although extensive research has demonstrated that T. urticae exhibits high resistance to chlorpyrifos, the specific resistance mechanism remains elusive. Investigating this mechanism could provide valuable insights for pest control strategies. ObjectivesThis study aimed to reveal the mechanism of chlorpyrifos resistance in T. urticae. MethodsThe expression level of the CYP392D8 gene in T. urticae strains were analyzed using real- time quantitative PCR and western blot techniques. Functional validation of CYP392D8 was conducted through RNAi and heterogeneous expression. The production of chlorpyrifos-oxon in both resistant and susceptible strains were quantified using LC-MS/MS. Furthermore, the metabolic capabilities of CYP392D8 variants were verified using HPLC-MS and molecular docking. ResultsThe results showed the expression of CYP392D8 was reduced in some Chinese resistant populations and mites with knocked down CYP392D8 showed decreased susceptibility to chlorpyrifos. Chlorpyrifos-oxon, the active metabolite of chlorpyrifos, was generated when chlorpyrifos was incubated with recombinant CYP392D8 protein in vitro. And a higher efficiency of chlorpyrifos-oxon formation was observed with the CYP392D8-S variant from susceptible mites compared to the CYP392D8-R variant from resistant mites. After treatment with low doses of chlorpyrifos, susceptible mite extracts produced substantial amounts of chlorpyrifos-oxon, while resistant mites only showed trace amounts. In addition, molecular docking studies showed that CYP392D8-S had a higher binding capacity to chlorpyrifos than the CYP392D8-R variant. ConclusionThis study reveals a mechanism of insecticide resistance due to the bioactivation reduction in combination with the sequence variation in a pest mite. These findings provide an important theoretical bias for management strategies of mites in the field and comprehensive control.

Sublethal Effects Induced by a Cyflumetofen Formulation on Honeybee Apis mellifera L. Workers: Assessment of Midgut, Hypopharyngeal Glands, and Fat Body Integrity.

Worldwide, both cultivated and wild plants are pollinated by the honey bee, Apis mellifera. Bee numbers are declining as a result of a variety of factors, including increased pesticide use. Cyflumetofen controls pest mites in some plantations pollinated by bees, which may be contaminated with residual sublethal concentrations of this pesticide, in nectar and pollen. We evaluated the effects of a sublethal concentration of a cyflumetofen formulation on the midgut, hypopharyngeal gland, and fat body of A. mellifera workers orally exposed for 72 h or 10 days. The midgut epithelium of treated bees presented digestive cells with cytoplasm vacuoles and some cell fragmentation, indicating autophagy and cell death. After being exposed to the cyflumetofen formulation for 72 h, the midgut showed a higher injury rate than the control bees, but after 10 days, the organs had recovered. In the hypopharyngeal gland of treated bees, the end apparatus was filled with secretion, suggesting that the acaricide interferes with the secretory regulation of this gland. Histochemical tests revealed differences in the treated bees in both exposure periods in the midgut and hypopharyngeal glands. The acaricide caused cytotoxic effects on the midgut digestive cells, with apical protrusions, plasma membrane rupture, and several vacuoles in the cytoplasm, features of cell degeneration. In the hypopharyngeal glands of the treated bees, the secretory cells presented small electron-dense and large electron-lucent secretory granules. The fat body cells had no changes in comparison with the control bees. In conclusion, the cyflumetofen formulation at sublethal concentrations causes damage to the midgut and the hypopharyngeal glands of honey bee, which may compromise the functions of these organs and colony fitness. Environ Toxicol Chem 2024;43:2455-2465. © 2024 SETAC.

Acaricidal potential of Bidens pilosa in the control of the red palm mite

Raoiella indica Hirst, 1924 (Prostigmata: Tenuipalpidae), is one of the leading pest mites on plants of the Arecaceae family, especially palm and banana trees. This species has a high reproductive capacity and rapid dissemination, but the control methods available for this species are still limited. Therefore, this work aimed to evaluate the acaricidal effect of blackjack (Bidens pilosa) on adult individuals of R. indica. The experiment was conducted in a completely randomized design, using the plant structures of blackjack to prepare the extracts. The experimental units consisted of coconut leaf discs (4 cm), with moistened cotton at the bottom of the Petri dish (10.0 × 1.2 cm), and around the disc to maintain turgidity and prevent mites from escaping. Spraying was carried out on 12 adult females of R. indica per sample unit, with seven repetitions for each concentration, using an airbrush with a constant pressure of 1.3 psi and 1 mL of solution per repetition plate. The acaricidal effect was evaluated 12, 24, 36, 48, 60, and 72 hours after spraying. The mortality of R. indica was proportional to the increase in the concentration of the blackjack plant extract, and the lethal concentrations obtained, CL50 and CL 90, were estimated between 1.49% and 4.19%, indicating the acaricidal potential of B. pilosa. Phenolic compounds were the majority of compounds found in this study.

Transcriptomic landscapes reveal development-related physiological processes in the two-spotted spider mite, Tetranychus urticae.

The two-spotted spider mite (Tetranychus urticae Koch, TSSM) is recognized as one of the most problematic spider mite pests. However, the precise gene expression patterns across its key developmental stages remain elusive. Here, we performed a comprehensive transcriptome analysis of TSSM eggs, nymphs and adult females using publicly available RNA sequencing (RNA-seq) data to elucidate the overarching transcriptomic differences between these developmental stages. Principal component analysis and hierarchical clustering analysis unveiled distinct separations among samples across different developmental stages, regardless of their Wolbachia infection status. Differential expression analysis revealed 4,089,2,762, and 1,282 core genes specifically enriched in eggs, nymphs, and adults, respectively. KEGG and GO enrichment analyses showed upregulation of genes in eggs are associated with proteolysis, Wnt signaling pathway, DNA transcription, RNA biosynthetic and metabolic processes, as well as protein folding, sorting, and degradation pathways. Meanwhile, nymphs exhibited increased abundance of genes related to chitin/amino sugar metabolic processes, G protein-coupled receptor signaling pathways, monoatomic ion transport, and neurotransmitter transport pathways. Pathways involving sphingolipid and carbohydrate metabolic processes, proteolysis, lipid transport, and localization were particularly enriched in older females. Altogether, our findings suggest that the egg stage exhibits higher activity in cell differentiation processes, the nymph stage is more involved in chitin development, and the adult stage shows increased metabolic and reproductive activity. This study enhances our understanding of the molecular mechanisms underlying TSSM development and paves the way for further research into the intricate physiological processes of TSSM.

Ambulatory dispersal of Typhlodromus (Anthoseius) recki Wainstein (Acari: Phytoseiidae) along Solanceae stem.

Tomato crops are attacked by several pests, including mites. While the main predatory mites are not effective enough to control mite pests, recent studies have shown encouraging results with the European endemic phytoseiid Typhlodromus (Anthoseius) recki. The first objective of the study was to assess the ability of this species to disperse along the tomato stem, considering six genotypes of Solanum lycopersicum, S. peruvianum and S. cheesmaniae with contrasted trichome numbers and types of stem trichomes, accuratetly characterised in a previous study. The second objective was to determine how predator morphological traits can explain dispersal along the tomato stem. For this, ambulatory dispersal ability of females (stem crossing rate success, hesitation and escape behavior, mobility periods) was tested in lab conditions on the eight Solanum genotypes, at four period of time after the predator introduction (10, 25, 55 and 100min), with a video observation of 5min at each period. The females were then mounted on slides and body length and width (at the fore hind, middle and back parts) measured. No effect of the tomato genotypes was observed on the dispersal ability of the predator. However, specimens that succeeded in crossing the stem, had a higher percentage of mobility time (79.36%) than those that failed (43.60%). Furthermore, body width at midbody (DSW2) and dorsal shield length (DSL) were negatively correlated with dispersal ability. The mean DSL and DSW2 of the females that succeed to cross were 342.3 and 160.9μm, respectively vs. 345.6 and 164.9μm, for females that did not succeed. This suggests that the more slender and relatively small the specimens, the more are mobile and able to successfully cross the stem. The number of glandular trichomes type (GT) VI and to a lesser extent GT I and IV, and non-glandular trichomes (NGT) II&III appear to limit dispersal. The GT VI seems to have a repellent effect. On the opposite, the number of NGT V were positively correlated with high mobility and stem crossing rates. Assuming that the main barrier to biological control efficiency is dispersal along tomato stems, these preliminary results should have implications for biological control success. The proportion of mites with 'optimal dimensions' appears to be low and further studies should be undertaken to better assess the proportion of mites with such ideal dimensions in different populations and also to determine whether these morphological traits are associated with different feeding abilities and/or abiotic conditions.

Evaluation of the temperature adaptation of three rubber tree pest mites based on their two-sex life table.

To determine the optimal temperature range for the development and reproduction of three spider mites (Eotetranychus sexmaculatus, Eotetranychus orientalis, and Oligonychus biharensis), this study investigated their developmental period, survival rate, lifespan, and reproduction under five temperatures, 21, 24, 27, 30, and 33°C, to predict and control in the field. With the gathered data, a two-sex life table was constructed for each of them. The results revealed that as the temperature increased, both O. biharensis and E. orientalis displayed a gradual reduction in their generation period. Furthermore, an inverse relationship was observed between lifespan and temperature for all three spider mite species. When examining the survival rates at varying temperatures, E. sexmaculatus exhibited the highest rate (98%) at 33°C, while E. orientalis and O. biharensis demonstrated their highest survival rates at 24°C, reaching 90% and 100% respectively. Regarding reproduction, O. biharensis displayed the highest oviposition rates at 30°C with an average of 17.45 eggs per individual. Conversely, E. sexmaculatus and E. orientalis exhibited the highest oviposition rates at 33°C, averaging at 15.22 and 21.38 eggs per individual respectively. Significantly higher intrinsic growth rates were observed for O. biharensis and E. orientalis at 33°C, with rates of 0.22 and 0.26 respectively. In contrast, E. sexmaculatus demonstrated the highest intrinsic growth rate at 27°C. The temperature of 27°C was more suitable for the growth of the E. sexmaculatus, while 33°C was the optimal temperature for the E. orientalis and O. biharensis. The current findings provide valuable guidance for the control and prevention of these three spider mites.