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Background: Red spider mite, Tetranychus truncatus Ehara (Acari: Tetranychidae) infests many agriculture and horticulture crops in India, but to date it had not been found damaging cultivated groundnut. During 2022-23, the incidence of this species was high in many groundnut growing regions of Tamil Nadu. Identification of the species is highly essential for effective management of the particular pest. Hence, the aim of this research was to identify the mite species infesting groundnut crop and describe the damage caused. Methods: Survey was carried out all over Tamil Nadu and samples of mite infested groundnut leaves were collected from field based on damage symptoms, observed and examined under Stereo zoom microscope, microslides were prepared using Hoyer's medium and taxonomic characters were studied under phase contrast microscope. Molecular analysis was done by genomic DNA isolation, PCR amplification, sequencing and BLAST performed to check the identity with GenBank Sequences. ITS2 primer was used. Result: Red spider mite species, T. truncatus was identified first time in groundnut through both morphological characters and molecular tools. Female: Idiosomal setae longer than the interval between their longitudinal bases and gradually tapers distally. Diamond-shaped pattern of striae between e1 and f1 setal bases. Tarsus I with 4 tactile setae proximal to proximal duplex setae. Male: Aedeagus with tiny terminal knob, apparently truncate with a slight indentation on the dorsal margin. [ABSTRACT FROM AUTHOR]

Simple Summary: Tetranychus truncatus (Acari: Tetranychidae) is the dominant pest on many crops in China. The resistant strain cultivated by pyridaben in our laboratory showed higher adaptability to high temperature than the susceptible strain. Antioxidant enzymes can reduce the damage of reactive oxygen species (ROS) caused by high temperature. Therefore, the antioxidant enzyme genes of T. truncatus were screened, and their biological information was analyzed. The expression patterns of antioxidant enzyme genes in two strains of T. truncatus under high temperature stress were determined by RT-qPCR method, and their functions were verified by RNA interference (RNAi) technology. The experimental results provide a theoretical basis for understanding the occurrence of agricultural mites under the background of climate warming and applying gene regulation technology to control T. truncatus in the future. Tetranychus truncatus (Acari: Tetranychidae) has caused serious economic losses on some crops (soybean, corn, and cotton) in China, and has developed resistance to most acaricides. Our laboratory study found that T. truncatus was resistant to pyridaben and also adapted to high temperature (34–40 °C). High temperature stress may cause arthropods to produce a large amount of reactive oxygen species (ROS), causing oxidative damage. Antioxidant enzymes, as the main antioxidants, can reduce the damage caused by excessive ROS in arthropods. In order to study the adaptation mechanism of the pyridaben-resistant strain of T. truncatus to high temperature and the role of antioxidant enzyme genes under high temperature stress, four antioxidant enzyme genes, TtSOD, TtPOD3, TtPOD4, and TtGSTs2, were screened according to the transcriptome sequencing data of pyridaben-susceptible and -resistant strains in T. truncatus. Firstly, the phylogeny and structure analyses of these four genes were carried out. Then, real-time quantitative PCR (RT-qPCR) technology was used to analyze the gene expression patterns of antioxidant enzymes in two strains of T. truncatus at three different high temperature ranges (34 °C, 38 °C, and 42 °C). The results showed that the expression levels of four antioxidant enzyme genes of two strains of T. truncatus were induced by high temperature stress, and the expression levels of antioxidant enzyme genes were significantly different in each development state. The gene expression of antioxidant enzyme genes in resistant strains at the adult stage was significantly higher than that in susceptible strains. After the TtSOD and TtPOD4 genes of adult mites of the resistant strain were silenced by RNA interference (RNAi) technology, the mortality rate of mites with TtPOD4 gene silencing reached 41.11% after 96 h at 34 °C, which was significantly higher than that of the control and TtSOD gene silencing. It has been confirmed that the TtPOD4 gene plays a key role in the adaptation of pyridaben-resistant strain of T. truncatus to high temperature. It lays a theoretical foundation for revealing the thermal adaptation mechanism of T. truncatus. [ABSTRACT FROM AUTHOR]

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

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

With a generally warming global climate, the number of Tetranychus truncatus specimens in the Hexi region in China has been increasing. As ectotherms, the growth and development of T. truncatus are greatly affected by changes in environmental temperature. The effect of heatwaves on organisms depends on a delicate balance between damage and repair periods. Therefore, we simulated nine patterns of periodically recurring changes in the frequency of high-temperature days using an intraday gradual temperature change model to study and compare the effects on the development and reproduction of pyridaben-sensitive and -resistant strains of T. truncatus. The results showed that the influence of the frequency of high-temperature days on developmental stages, longevity and fecundity was different between the two strains. The egg and immature stages of the sensitive strain were all affected by hot days, whereas the adult stage was less affected by the frequency. The egg stage of the resistant strain was less affected; it was mainly affected in the immature and adult stages. Under the moderate condition of increasing the proportion of days at normal temperature, the longevity of the resistant strain gradually increased and reached a maximum at a 1:3 frequency, and then it decreased with the increase in high-temperature days. The longevity of the sensitive strain was less affected by frequency, and there was no significant difference between most treatment and control groups. In addition, both sensitive and resistant strains were able to complete growth and development under all nine frequencies of high-temperature days, but the reproductive rate was lower than it was at normal temperatures, indicating that both strains of T. truncatus adapted to high temperatures at the expense of reduced reproduction rates. This lays a key theoretical foundation for predicting the occurrence of agricultural pest populations under the background of climate warming and developing appropriate control strategies. [ABSTRACT FROM AUTHOR]

Two local isolates of P. luminescens (NCBI GenBank Accession numbers ON627692, and ON627695) were evaluated for their bio-efficacy against the spider mite Tetranychus truncatus in the laboratory. Different concentrations (104 to 108 CS/CFS mL-1) of cell suspension (CS) and cell-free supernatant (CFS) of the bacterial isolates obtained by centrifugation (4000 rpm for 20 min) were topically applied on eggs and adults of spider mites. The observations on ovicidal as well as adulticidal activity of bacterial isolates were recorded at 24, 48, and 72 h intervals. The bacterial isolates showed significant ovicidal and adulticidal properties for both CS and CFS after 72 h of treatment application. The isolate CNT1 recorded 84.00 and 58.67% mortality of eggs and 100 and 97.33% mortality of adults, respectively, for CS and CFS, at 108 mL-1 concentration. At the same concentration, the isolate ODA showed 44.00 and 84.00% mortality of eggs and 98.67 and 100% mortality of adults, respectively, for CS and CFS. The study identified two bacterial isolates of P. luminescens with appreciable acaricidal properties that can be exploited as a potential biocontrol agent against spider mite pests of crops. [ABSTRACT FROM AUTHOR]

Temperature is an important factor influencing the physiological activities of agricultural pests. Therefore, understanding pest physiological activities and the molecular response to high-temperature stress is of paramount importance for pest management. Tetranychus truncatus Ehara (Acari: Tetranychidae) is a harmful organism, that may cause serious harm to crops such as corn and cotton in high-temperature environments. Cytochrome P450 (CYP450) is induced by high-temperature stress, and it plays an important role in the resistance of spider mites to high temperatures. Because of their role in high-temperature tolerance, the cytochrome P450 genes of the spider mite are attracting more and more attention. In this study, we identified and analyzed CYP450 genes in T. truncatus to investigate their potential roles in growth and development and the resistance to high-temperature stress. Based on phylogenetic and structural analyses, we identified 17 CYP450 genes in T. truncatus. RNA-seq and real-time quantitative PCR (RT-qPCR) revealed differential expression patterns of these genes at different developmental stages and levels of high-temperature stress resistance. The RNA interference results of selected CYP450 showed that when TtCYP3A2 and TtCYP4V2 were silenced by feeding on dsRNA, respectively, the high-temperature resistance of T. truncatus was decreased, which indicated that the expression of these two CYP450 genes in this species may be related to high-temperature tolerance. Our results provide potential evidence for the response of spider mites to high-temperature stress and help to improve the understanding of T. truncatus's ability to resist high-temperature stress. [ABSTRACT FROM AUTHOR]

Tetranychus truncatus (Acari: Tetranychidae) has caused serious economic losses on some crops (soybean, corn, and cotton) in China, and has developed resistance to most acaricides. Our laboratory study found that T. truncatus was resistant to pyridaben and also adapted to high temperature (34–40 °C). High temperature stress may cause arthropods to produce a large amount of reactive oxygen species (ROS), causing oxidative damage. Antioxidant enzymes, as the main antioxidants, can reduce the damage caused by excessive ROS in arthropods. In order to study the adaptation mechanism of the pyridaben-resistant strain of T. truncatus to high temperature and the role of antioxidant enzyme genes under high temperature stress, four antioxidant enzyme genes, TtSOD, TtPOD3, TtPOD4, and TtGSTs2, were screened according to the transcriptome sequencing data of pyridaben-susceptible and -resistant strains in T. truncatus. Firstly, the phylogeny and structure analyses of these four genes were carried out. Then, real-time quantitative PCR (RT-qPCR) technology was used to analyze the gene expression patterns of antioxidant enzymes in two strains of T. truncatus at three different high temperature ranges (34 °C, 38 °C, and 42 °C). The results showed that the expression levels of four antioxidant enzyme genes of two strains of T. truncatus were induced by high temperature stress, and the expression levels of antioxidant enzyme genes were significantly different in each development state. The gene expression of antioxidant enzyme genes in resistant strains at the adult stage was significantly higher than that in susceptible strains. After the TtSOD and TtPOD4 genes of adult mites of the resistant strain were silenced by RNA interference (RNAi) technology, the mortality rate of mites with TtPOD4 gene silencing reached 41.11% after 96 h at 34 °C, which was significantly higher than that of the control and TtSOD gene silencing. It has been confirmed that the TtPOD4 gene plays a key role in the adaptation of pyridaben-resistant strain of T. truncatus to high temperature. It lays a theoretical foundation for revealing the thermal adaptation mechanism of T. truncatus.

The study evaluated the efficacy of solvent fractions of Mexican marigold, Tagetes minuta against the spider mite, Tetranychus truncatus. The dried and pulverized botanical was subjected to sequential extraction using three solvents viz., hexane, chloroform and water in the increasing order of polarity. Solvent fractions were evaluated for their ovicidal and adulticidal activities against T. truncatus in the laboratory at five different concentrations viz., 0.025, 0.05, 0.1, 0.15 and 0.2 %. Results indicated that only hexane fraction at higher concentrations of 0.15 and 2.0 % exhibited significant ovicidal action, causing 100.00 and 81.33 per cent egg mortality, respectively. However, all the fractions recorded significant adulticidal effect at higher concentrations with hexane fractions at 0.2 and 0.15 % recording significantly higher adult mortality (>90 %), followed by chloroform fraction. The best concentrations of the three solvent fractions identified in the laboratory study were evaluated against T. truncatus on amaranthus, in a pot culture experiment. Fourteen days post treatment, hexane fraction at 0.2 % reduced mite population by 88.78 per cent and was superior to neem oil emulsion at 2% (76.44 % reduction), which was on par with chloroform and aqueous fractions. Results of the study identified Mexican marigold as a potential candidate in mite pest management, which may be further validated through multi-locational field trials. [ABSTRACT FROM AUTHOR]

Tetranychus truncatus Ehara (Acari: Tetranychidae) has become one of the major phytophagous pests in China in recent years, and is found on a wide range of host plants. However, little information is available on the population performance of this arthropod pest on potatoes. In this study, we explored the population growth of T. truncatus on two drought-tolerant potato (Solanum tuberosum L.) cultivars under laboratory conditions using the age-stage, two-sex life table. Tetranychus truncatus completed its entire life history on both potato cultivars tested, Holland 15 and Longshu 10. There was no significant difference between two potato cultivars in developmental duration. Tetranychus truncatus had shorter adult longevity (20.61 days), adult female longevity (20.41 days), and total female longevity (33.66 days) on Longshu 10 than Holland 15 (21.16 days, 21.19 days, and 34.38 days, respectively). However, it exhibited a higher preadult survival rate, higher fecundity (F = 88.32 eggs per female), and relatively higher population parameters when reared on Longshu 10 than on Holland 15 (F = 75.70 eggs per female). Growth projection also showed that the population size of T. truncatus on Longshu 10 (expand 750-fold) was larger than that on Holland 15 (expand 273-fold) after 60 days. Our results demonstrate that the drought-sensitive potato variety, Holland 15, is relatively resistant to T. truncatus compared with the drought-tolerant variety, Longshu 10, and suggest that T. truncatus exhibited a trade-off between longevity and reproduction on both potato cultivars. Our findings provide information on population prediction, which may aid the management of this pest mite species of potatoes. [ABSTRACT FROM AUTHOR]

The potential of aqueous and methanol extracts of ten botanicals were evaluated against the egg and adult of the spider mite Tetranychus truncatus Ehara, under laboratory conditions. The extracts showed no or negligible ovicidal action, but significant adulticidal action; among the aqueous extracts, A. squamosa (5, 7.5 and 10%), C. papaya (10%) and B. monnieri (10%) caused significantly maximum mortality, while it was methanolic extracts of A. calamus, C. papaya (1 and 2%) and A. marmelos (2%) which revealed maximum mortality with adults. [ABSTRACT FROM AUTHOR]

Beauveria bassiana is an entomopathogenic fungus that causes the white muscadine disease in insects. The majority of entomopathogenic fungi are soil and insect borne, 15 soil samples were collected from seven different locations during 2021, from January to December. Similarly, during 2022, March to December, 15 fungus-infected insect specimens were collected from five different locations hence soil and insect samples from various ecosystems were collected. As a result, 30 B. bassiana isolates from 11 different geographical areas were identified using morphological characteristics and multilocus sequence data in this investigation. The taxonomical positions of the isolates were determined using morphological characteristics and phylogenetic inferences based on three loci (Internal Transcribed Sequence, Elongation Factor-1a, and B. bassiana chitinase 1). In phylogenetic analysis of B. bassiana, the Maximum Likelihood analytical method produced distinct tree topology when compared to Neighborjoining and minimum evolution. Three isolates viz., Bb3, Bb7 and Bb20 were found closely linked with reference isolate (KTU-24) and other showed the higher population diversity among them. The genetic distances of 30 B. bassiana isolates revealed that 15 were not closely related (D varied from 0.003 to 0.036). The pathogenicity of B. bassiana isolates from various hosts along with one commercial formulation (Beveroz) was assessed against Tetranychus truncatus under in vitro conditions by a completely randomized design (CRD) experiment. The same experiment was repeated thrice to confirm the pathogenicity of B. bassiana against T. truncatus. Later, the collected T. truncatus mortality data was converted into corrected mortality by using the Abbott formula and the values were examined using analysis of variance (ANOVA) in SPSS 23.0 software. Duncan's Multiple Comparison Test was also done to compare the percentage mortality rates among the 30 B. bassiana isolates. The recorded results showed that the Bb6, Bb15 and Bb12 isolates caused significantly higher mortality of T. truncatus, i.e., 97.73, 96.73 and 94.50% respectively, than the other isolates. This study showed the relativeness among the B. bassiana isolates and establishes their bio-efficacy against T. truncatus, which further can be used for commercialization as bio-pesticide. [ABSTRACT FROM AUTHOR]

Beauveria bassiana is an entomopathogenic fungus that causes the white muscadine disease in insects. The majority of entomopathogenic fungi are soil and insect borne, 15 soil samples were collected from seven different locations during 2021, from January to December. Similarly, during 2022, March to December, 15 fungus-infected insect specimens were collected from five different locations hence soil and insect samples from various ecosystems were collected. As a result, 30 B. bassiana isolates from 11 different geographical areas were identified using morphological characteristics and multilocus sequence data in this investigation. The taxonomical positions of the isolates were determined using morphological characteristics and phylogenetic inferences based on three loci (Internal Transcribed Sequence, Elongation Factor-1α, and B. bassiana chitinase 1). In phylogenetic analysis of B. bassiana, the Maximum Likelihood analytical method produced distinct tree topology when compared to Neighbor-joining and minimum evolution. Three isolates viz., Bb3, Bb7 and Bb20 were found closely linked with reference isolate (KTU-24) and other showed the higher population diversity among them. The genetic distances of 30 B. bassiana isolates revealed that 15 were not closely related (D varied from 0.003 to 0.036). The pathogenicity of B. bassiana isolates from various hosts along with one commercial formulation (Beveroz) was assessed against Tetranychus truncatus under in vitro conditions by a completely randomized design (CRD) experiment. The same experiment was repeated thrice to confirm the pathogenicity of B. bassiana against T. truncatus. Later, the collected T. truncatus mortality data was converted into corrected mortality by using the Abbott formula and the values were examined using analysis of variance (ANOVA) in SPSS 23.0 software. Duncan’s Multiple Comparison Test was also done to compare the percentage mortality rates among the 30 B. bassiana isolates. The recorded results showed that the Bb6, Bb15 and Bb12 isolates caused significantly higher mortality of T. truncatus, i.e., 97.73, 96.73 and 94.50% respectively, than the other isolates. This study showed the relativeness among the B. bassiana isolates and establishes their bio-efficacy against T. truncatus, which further can be used for commercialization as bio-pesticide.

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

Heritable symbionts play an essential role in many aspects of host ecology in a temperature-dependent manner. However, how temperature impacts the host and their interaction with endosymbionts remains largely unknown. Here, we investigated the impact of moderate (20°C) and high (30 and 35°C) temperatures on symbioses between the spider mite Tetranychus truncatus and two maternally inherited endosymbionts (Wolbachia and Spiroplasma). We found that the thermal tolerance of mites (as measured by survival after heat exposure) was lower for mites that were singly infected with either Wolbachia or Spiroplasma than it was for co-infected or uninfected mites. Although a relatively high temperature (30°C) is thought to promote bacterial replication, rearing at high temperature (35°C) resulted in losses of Wolbachia and particularly Spiroplasma. Exposing the mites to 20°C reduced the density and transmission of Spiroplasma but not Wolbachia. The four spider mite strains tested differed in the numbers of heat shock genes (Hsps) induced under moderate or high temperature exposure. In thermal preference (Tp) assays, the two Wolbachia-infected spider mite strains preferred a lower temperature than strains without Wolbachia. Our results show that endosymbiont-mediated spider mite responses to temperature stress are complex, involving a combination of changing endosymbiont infection patterns, altered thermoregulatory behavior, and transcription responses.

[Objective] To evaluate the predation preference of Amblyseius andersoni (A. andersoni), a new recorded species, to different prey.[Methods] The predation preference of female adults of A. andersoni to different states of Bemisia tabaci (B. tabaci) and Tetranychus truncatus (T. truncatus) was analyzed by means of predation quantity and predation preference test combined with Cain evaluation index.[Results] In the predation quantity test, for B. tabaci, the highest average daily predation and total predation of A. andersoni was observed in 1st instar nymph, which were 7.19±0.59 and 113.29±7.95, respectively; for T. truncatus, the highest average daily predation and total predation of A. andersoni was observed in larvae, which were 12.00±2.18 and 186.71±7.18, respectively. In the predation preference test, the predation quantity of A. andersoni against 1st instar nymph of B. tabaci was 7.90±1.22, the predation quantity of A. andersoni against egg of B. tabaci was 2.50±0.59, and the Cain index (D) was 3.16>1; the predation quantity of A. andersoni against larvae of T. truncatus was 17.35±1.80, and the predation quantity of A. andersoni against egg of T. truncatus was 15.60±2.99, and the Cain index (D) was 1.11>1;the predation quantity of A. andersoni against 1st instar nymph of B. tabaci was lower in comparison with larvae of T. truncatus, and the Cain index (D) was 0.51<1.[Conclusion] Compared with B. tabaci, A. andersoni showed higher predation preference to T. truncatus, especially for larvae of T. truncatus. [ABSTRACT FROM AUTHOR]

Heritable symbionts play an essential role in many aspects of host ecology in a temperature-dependent manner. However, how temperature impacts the host and their interaction with endosymbionts remains largely unknown. Here, we investigated the impact of moderate (20°C) and high (30 and 35°C) temperatures on symbioses between the spider mite Tetranychus truncatus and two maternally inherited endosymbionts (Wolbachia and Spiroplasma). We found that the thermal tolerance of mites (as measured by survival after heat exposure) was lower for mites that were singly infected with either Wolbachia or Spiroplasma than it was for co-infected or uninfected mites. Although a relatively high temperature (30°C) is thought to promote bacterial replication, rearing at high temperature (35°C) resulted in losses of Wolbachia and particularly Spiroplasma. Exposing the mites to 20°C reduced the density and transmission of Spiroplasma but not Wolbachia. The four spider mite strains tested differed in the numbers of heat shock genes (Hsps) induced under moderate or high temperature exposure. In thermal preference (Tp) assays, the two Wolbachia -infected spider mite strains preferred a lower temperature than strains without Wolbachia. Our results show that endosymbiont-mediated spider mite responses to temperature stress are complex, involving a combination of changing endosymbiont infection patterns, altered thermoregulatory behavior, and transcription responses. [ABSTRACT FROM AUTHOR]

Wolbachia‐induced reproductive regulation in hosts has been used to control pest populations, but little is known about the molecular mechanism underlying Wolbachia regulation of host genes. Here, reproductive regulation by Wolbachia in the spider mite Tetranychus truncatus was studied at the molecular level. Infection with Wolbachia resulted in decreasing oviposition and cytoplasmic incompatibility in T. truncatus. Further RNA‐seq revealed genes regulated by Wolbachia in T. truncatus. Real‐time quantitative polymerase chain reaction (qPCR) showed that genes, including chorion protein S38‐like and Rop were down‐regulated by Wolbachia. RNA interference (RNAi) of chorion protein S38‐like and Rop in Wolbachia‐uninfected T. truncatus decreased oviposition, which was consistent with Wolbachia‐induced oviposition decrease. Interestingly, suppressing Rop in Wolbachia‐infected T. truncatus led to increased Wolbachia titres in eggs; however, this did not occur after RNAi of chorion protein S38‐like. This is the first study to show that chorion protein S38‐like and Rop facilitate Wolbachia‐mediated changes in T. truncatus fertility. In addition, RNAi of Rop turned the body colour of Wolbachia‐uninfected T. truncatus black, which indicates that the role of Rop is not limited to the reproductive regulation of T. truncatus. [ABSTRACT FROM AUTHOR]

[Objective] Based on the hyperspectral reflectance of the canopy damaged by Tetranychustrrncates, a model for estimating the water content of the jujube canopy was constructed. [Method] Based on the spectral reflectance and water content of the jujube (Ziz-iphusjuba) canopy, Analyze the correlation between the first-order differential spectrum of the jujube canopy and the water content under the damage of the spider mite, and screen the sensitive bands of the hyperspectral water content of the jujube canopy, and use the regression models of linear function, quadratic function and exponential function to construct the intercept A hyperspectral estimation model of jujube canopy water content under the damage of spider mites. [Result] The jujube canopy water content decreases with the decrease of spectral reflectance, which is significantly negatively correlated with the level of pests. Using canopy first-order differential spectrum D1102 The multivariate linear stepwise regression model established in the combined bands of D974 and D990 has the best fit, with R2 reaching 0.618, RMSE and RE being 3.428 and 3.900%. [Conclusion] It shows that it is feasible to invert canopy water content by using hyperspectral technology. It has important practical significance in forest pest monitoring. [ABSTRACT FROM AUTHOR]

Wolbachia and Spiroplasma are intracellular bacteria that are of great interest to entomologists, because of their ability to alter insect host biology in multiple ways. In the spider mite Tetranychus truncatus, co‐infection of Wolbachia and Spiroplasma can induce cytoplasmic incompatibility (CI) and fitness costs; however, little is known about the effect of co‐infection at the genetic level and the molecular mechanisms underlying CI. In this study, we explored the influence of the two symbionts on male mite host fitness and used RNA sequencing to generate the transcriptomes of T. truncatus with four different types of infection. In total, we found symbiont‐infected lines had a higher hatch proportion than the uninfected line, and the development time of the uninfected line was longer than that of the other lines. Co‐infection changed the expression of many genes related to digestion detoxification, reproduction, immunity and oxidation reduction. Our results indicate that co‐infection of Wolbachia and Spiroplasma confers multiple effects on their hosts, and helps illuminate the complex interactions between endosymbionts and arthropods. [ABSTRACT FROM AUTHOR]

The bacterial communities of arthropods play important roles in the growth and development of their hosts, such as by providing nutrition or protecting against parasites and pathogens. However, for Tetranychus truncatus, a major crop pest, very little is known about its bacterial community. To understand the effects of the bacterial community in T. truncatus, mites were fed bean leaves that had been soaked in different concentrations of tetracycline hydrochloride (5 mg to 5 g per L). Antibiotic treatment had a negative impact on the fitness of T. truncatus, decreasing its fecundity and longevity. However, we could not exclude the possibility that the decrease in fecundity was due to a toxic effect of the antibiotic. 16S rRNA genes analyses showed that the antibiotic treatment did not significantly affect the diversity of bacterial species, but it did significantly change their relative abundances. Furthermore, predicted functions of microbiota were also changed with antibiotic treatment and the most abundant genes were related to metabolism. Our research revealed that the antibiotic induced change of bacterial communities mostly decreased the fecundity of T. truncatus, although we couldn't totally exclude the direct toxin of antibiotics on spider mites. [ABSTRACT FROM AUTHOR]

BACKGROUND Herbivore‐associated bacterial symbionts can change plant physiology and influence herbivore fitness. The spider mite Tetranychus truncatus is a notorious pest harboring various bacterial symbionts; however, the effect of bacterial symbionts on host plant physiology remains unclear. Here, we investigated whether infection with the endosymbionts Wolbachia and Spiroplasma altered spider mite performance on tomato plants and affected plant‐induced defenses. RESULTS: Wolbachia and Spiroplasma were mainly located in the gnathosoma and ovaries of their spider mite hosts. Wolbachia and Spiroplasma significantly improved spider mite reproductive performance in cultivated and wild‐type tomato. However, in plants deficient in jasmonic acid (JA) and salicylic acid (SA), there were no significant differences in reproduction between spider mites infected with Wolbachia and Spiroplasma and uninfected mites. The results indicated that the reproduction benefits conferred by endosymbionts may relate to plant defenses. Both spider mites infected with Wolbachia and Spiroplasma and uninfected mites induced similar levels of JA and SA accumulation in tomato, whereas tomato plants damaged by spider mites infected with both Wolbachia and Spiroplasma showed lower expression levels of JA‐ and SA‐responsive genes than those damaged by uninfected spider mites. In addition, mites infected with Wolbachia and Spiroplasma mites consumed more tomato amino acids compared to uninfected spider mites, which may have contributed to host fecundity. CONCLUSIONS: Our results suggest that the reproduction benefits conferred by endosymbionts may be associated with changes in plant defense parameters and the concentrations of plant amino acids. The results highlight the importance of endosymbionts in interactions between spider mites and their host plants. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A field study was conducted to evaluate the efficacy of horticultural mineral oil (HMO), combination of HMO + neem oil and neem oil 2 per cent along with a synthetic acaricide, Spiromesifen 240SC and an untreated control against Tetranychus truncatus on okra during March, 2018. The plots treated with HMO at 2.5 (92.60%) and 3.0 per cent (93.90%) as well as combination treatments HMO 2.5 per cent + neem oil 2.0 per cent (94.14%) and HMO 3.0 per cent + neem oil 2.0 per cent (96.79%) recorded significant reduction in mite population and were superior to plots treated with either spiromesifen (91.08%) or neem oil alone at 2.0 per cent (90.42%). The high efficacy of HMO against the spider mite T. truncatus brought out in the study suggests that HMO can be an effective tool for mite management in vegetable crops. [ABSTRACT FROM AUTHOR]

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

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Understanding pest species composition and their geographic distribution of important spider mites is fundamental and indispensable to establish an integrated pest management program. From a long-term survey during 2008–2017 in mainland China, we found that Tetranychus truncatus was the most frequently sampled Tetranychus spider mite (48.5%), followed by T. pueraricola (21.2%), T. kanzawai (12.5%), T. urticae (red) (5.7%) and T. urticae (green) (4.5%). Among them, T. truncatus was the major mite pest in the north of China. T. kanzawai was the dominant species in the Middle and Lower Reaches of the Yangtze River Region and T. pueraricola was the most important species in the southwest region. Other common and serious pests include Amphitetranychus viennensis (6.8%) and Panonychus citri (3.8%). This pattern was largely different from that in 2002–2004, when T. urticae (green and red) was believed to be the most serious mite pest. The factors involved in the change of species composition are not clear and need more exploration. We suggested that the increasing corn planting range may be partly responsible for the conversion of dominant species from other spider mites to T. truncatus. Further research on the mechanisms underlying the change of dominant species will help develop integrated management strategies. [ABSTRACT FROM AUTHOR]

Knowledge about the prey preference of polyphagous predators is important for determining their ability to suppress pest insects. Tetranychus truncatus (Tetranychidae), Tetranychus turkestani (Tetranychidae), and Thrips tabaci (Thripidae) often coexist in crops. Neoseiulus bicaudus (Wainstein) is a native predatory mite that was recently observed in the Xinjiang Uygur Autonomous Region of northwest China. The objective of this study was to assess the potential of N. bicaudus as a bio-control agent against the three pest species mentioned above. The results showed that N. bicaudus protonymphs, deutonymphs, and adults can be effective biological control agents for the three pest species. Neoseiulus bicaudus at all three developmental stages exhibited a Holling's Type II (convex) functional response to the prey. Neoseiulus bicaudus exhibited no preference between T. truncatus adults and T. turkestani adults, irrespective of the prey ratio. In comparison, N. bicaudus clearly preferred first-instar T. tabaci larvae to T. turkestani adults. The results of this study suggest that N. bicaudus could help control T. truncatus, T. turkestani, and T. tabaci. Among these pests, N. bicaudus may be most effective for first-instar T. tabaci. [ABSTRACT FROM AUTHOR]

The prevalence of the endosymbiont Wolbachia and its effects on mitochondria variation were analyzed in seven natural populations of Tetranychus truncatus Ehara (Trombidiformes: Tetranychidae) in current study. Five Wolbachia strains (wtru1, wtru5, wtru7, wtru8, and wtru12) were detected based on the surface protein of Wolbachia (wsp) sequence data and the multiple locus sequences typing data, suggesting that multiple separate invasions have occurred. Part of mitochon-drial cytochrome oxidase subunit I gene was sequenced from infected individuals revealing 10 different haplotypes. As predicted, the haplotype and nucleotide diversity were lower in infected individuals than that in uninfected individuals. Furthermore, phylogenetic and analysis of molecular variance analyses revealed that the distribution of mtDNA haplotypes is not associated with geography. Rather, it is strongly concordant with infection status. These data support the hypothesis that Wolbachia infection can affect the genetic structure and diversity of the host mites. [ABSTRACT FROM AUTHOR]

Tetranychus truncatus Ehara is a phytophagous spider mite that is now one of the most important pests of agricultural and economic crops in East and Southeast Asia. However, population genetics and other studies of T. truncatus have been impeded by the lack of microsatellite markers, which are expensive and time-consuming to identify. Previous studies indicated a high potential of cross-amplification of microsatellites in Tetranychus species, meaning that the microsatellite flanking sequences are sufficiently homologous among Tetranychus species that the primers for one species may work in another species. Here, we tested 205 primer pairs designed from the whole genome sequence of Tetranychus urticae Koch, a sister species of T. truncatus, for microsatellite markers in three populations of T. truncatus in China (N = 94). About half (102) of these primer pairs yielded the desired PCR products, 36 of which revealed polymorphism in T. truncatus. Each of the 36 markers harbored between 2 and 23 alleles, with a mean polymorphic information content of 0.589 (0.119-0.922 range). The mean observed and expected heterozygosity across loci and the three populations were 0.468 and 0.628, respectively. Of the 36 primer pairs, 22 also worked in Tetranychus piercei, but only a few of them worked in T. ludeni and T. phaselus. Cross-amplification is thus a cost-effective way to develop microsatellite markers, which can be of great value in population genetics studies. [ABSTRACT FROM AUTHOR]

Tetranychus macfarlanei(Tm-BB) Baker & Pritchard andTetranychus truncatus(Tt-BJ) Ehara (Acari: Tetranychidae) were recently found in Bangladesh as pests in many crops. The susceptibility of eggs of both species to 14 acaricides and of adults to 11 acaricides was examined in the laboratory, using a rotary spray tower. LC50values in female adults of Tm-BB and Tt-BJ indicated high susceptibility to all acaricides, except chlorfenapyr; LC50of chlorfenapyr in Tm-BB was approximately 10 times higher than the recommended concentration (492 mg/l vs. 50 mg/l). Ratios of LC90values and the recommended concentrations (i.e. resistance factor (RF)) indicated 117.07 and 1.16 fold resistance in Tm-BB adults against chlorfenapyr and spirodiclofen, respectively, whereas Tt-BJ appeared to be resistant to tebufenpyrad (RF = 1.65). The RF value of spirodiclofen in Tt-BJ adults was 0.90, suggesting that this should not be used for control of this species, to avoid the further development of resistance. Eggs of both spider mites proved highly susceptible to all the acaricides at the LC50level. However, RF-ratios based on assays with eggs indicated resistance against chlorfenapyr (1.43) in Tm-BB and fenpyroximate (6.03) in Tt-BJ. RF-ratios of chlorfenapyr (0.87) and milbemectin (0.74) in Tt-BJ eggs suggest these acaricides should be avoided for control of this species. Finally, acequinocyl, bifenazate, clofentezine, cyenopyrafen, cyflumetofen, etoxazole, fenbutatin oxide, hexythiazox and spiromesifen were found to be most effective for control of Tm-BB and Tt-BJ. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome ofTetranychus truncatusEhara (Acari: Tetranychidae) is a typical circular DNA with length of 13,089 bp (GenBank accession number: KM111296). The genome contains all 13 protein-coding genes (PCGs), an A + T-rich region, two rRNA genes and 22 tRNA genes. The A + T content of the mitochondrial genome is 84.5%. The AT-skew is positive (0.032) while the GC-skew is negative (−0.058). The gene arrangement is conserved inT. urticae, Panonychus citriandP. ulmiwhich are in the same family (Tetranychidae). The A + T-rich region is only 43 bp in length with high A + T content (97.7%). All the PCGs start with typical ATD codons. Eight PCGs have complete TAA stop codons, while five PCGs have an incomplete stop codon (T). [ABSTRACT FROM AUTHOR]

Double infections of Wolbachia and Spiroplasma are frequent in natural populations of Tetranychus truncatus , a polyphagous mite species that has been a dominant species in China since 2009. However, little is known about the causes and ecological importance of such coexistences. In this study, we established T. truncatus strains with different infection types and then inferred the impact of the two endosymbionts on host reproduction and fitness. Double infection induced cytoplasmic incompatibility, which was demonstrated by reduction in egg hatchability of incompatible crosses. However, doubly infected females produced more eggs relative to other strains. Wolbachia and Spiroplasma did not affect host survival, whereas doubly infected females and males developed faster than other strains. Such reproduction and fitness benefits provided by double infections may be associated with the lower densities of each symbiont, and the quantitative results also confirmed competition between Wolbachia and Spiroplasma in doubly infected females. These symbiont-conferred beneficial effects maintain stable prevalence of the symbionts and also help drive T. truncatus outbreaks in combination with other environmental factors.

Knowledge about the prey preference of polyphagous predators is important for determining their ability to suppress pest insects. Tetranychus truncatus (Tetranychidae), Tetranychus turkestani (Tetranychidae), and Thrips tabaci (Thripidae) often coexist in crops. Neoseiulus bicaudus (Wainstein) is a native predatory mite that was recently observed in the Xinjiang Uygur Autonomous Region of northwest China. The objective of this study was to assess the potential of N. bicaudus as a bio-control agent against the three pest species mentioned above. The results showed that N. bicaudus protonymphs, deutonymphs, and adults can be effective biological control agents for the three pest species. Neoseiulus bicaudus at all three developmental stages exhibited a Holling's Type II (convex) functional response to the prey. Neoseiulus bicaudus exhibited no preference between T. truncatus adults and T. turkestani adults, irrespective of the prey ratio. In comparison, N. bicaudus clearly preferred first-instar T. tabaci larvae to T. turkestani adults. The results of this study suggest that N. bicaudus could help control T. truncatus, T. turkestani, and T. tabaci. Among these pests, N. bicaudus may be most effective for first-instar T. tabaci., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)