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The citrus red mite (CRM), Panonychus citri (McGregor) (Acari: Tetranychidae), a worldwide pest chiefly infesting Citrus plants, has spread from Southern China to Northern China. Little information is known about the population performance of CRM on the plants except for citrus trees and pear trees. In order to evaluate the extent of damage might caused by CRM to the fruit trees cultivated in Northern China, the performance of CRM on four Rosaceae species, including three main fruit tree species (pear-Pyrus pyrifolia Nakai cv. Shannongsu, apple-Malus pumila Mill. cv. Fuji, peach-Prunus persica (L.) Batsch cv. Zhongyou 4) cultivated in Shandong Province, Northern China, and one rootstock for grafting apples (crabapple-Malus micromalus Makino) was determined using the age-stage, two-sex life table at laboratory conditions (25 ± 1 °C, 75 ± 5% RH and L16: D8 h photoperiod). The results showed that CRM could complete the whole life cycle on all the four plant species. The development time of larva, protonymph and deutonymph and the survival of immature stage of CRM did not vary among the four plant species. Differences on the egg incubation period explained the total duration of the immature stage among the four plants. The total duration of the immature stage was shorter on pear and peach than on crabapple and apple, but no difference was observed between pear and peach. The mites reared on pear and peach exhibited a higher fecundity, net reproductive rate (R0), intrinsic growth rate (r) and finite rate of increase (λ) and longer longevity of the adult females than on crabapple and apple, but no significant differences between pear and peach, crabapple and apple. The mean generation time (T) of CRM reared on crabapple was the longest, which did not differ significantly on pear, peach and apple. In summary, the cultivars of pear, peach, apple and crabapple used in this study, especially that of peach and pear were suitable for the development and reproduction of CRM. CRM might be a serious risk for the main Rosaceae fruit species in Northern China. [ABSTRACT FROM AUTHOR]

In insects, the juvenile hormone (JH) and 20‐hydroxyecdysone (20E) pathways jointly regulate fecundity, but only methyl farnesoate (MF) and ponasterone A exist in mites. Comparative transcriptomic analysis in Panonychus citri showed that E75B was significantly downregulated when exposed to lufenuron. Knockdown of E75B significantly affects the expression of vitellogenin (Vg), Fushi tarazu factor 1 (Ftz‐f1) and juvenile hormone acid O‐methyltransferase (JHAMT), reducing fecundity in mites. The knockdown of Ftz‐f1 produced a more significant effect than the knockdown of E75B, indicating that the ponasterone A pathway positively regulates fecundity in P. citri. After the knockdown of JHAMT, the expression levels of both Vg and Ftz‐f1 and fecundity were significantly increased, along with the inhibition of Kr‐h1, suggesting that JHAMT was negatively correlated with fecundity in the regulatory network. Knockdown of Kr‐h1 inhibited the expression of Vg and Ftz‐f1 and fecundity, and whether the drop in fecundity is caused by Kr‐h1 or Ftz‐f1 is unclear. Subsequent feeding with MF induced Kr‐h1 and Vg expression, whereas no significant effects were observed for JHAMT and Ftz‐f1. Therefore, the MF pathway stimulates fecundity independently. RNA interference (RNAi) showed that JHAMT and Ftz‐f1 inhibited each other, resulting in opposite effects of MF and ponasterone A pathways on steady‐state fecundity when either factor changed. Meanwhile, JHAMT knockdown led to increased fecundity, indicating that the stimulating effect of the ponasterone A pathway was greater than the inhibiting effect of the MF pathway, and demonstrating the dominant role of the ponasterone A pathway. Therefore, the interaction between JHAMT and Ftz‐f1 may be closely associated with the maintenance of MF–ponasterone A regulatory network homeostasis and is involved in the reduction of fecundity in P. citri induced by exposure to lufenuron. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor), is one of the most important pests of citrus trees. The use of non-selective and wide-spectrum insecticides leads to a reduction in the natural enemy presence against this pest and turns P. citri into a serious pest in citrus orchards. In the present study, the induction of resistance was carried out in two-year-old citrus seedlings using a foliar application of amino acid, humic acid, potassium, vermiwash, and salicylic acid (SA) against P. citri. The data indicated a lower survival rate, longer immature duration, shorter adult longevity, and lower fecundity due to an increase in the resistance of citrus. The developmental time of immature stages, survival, and fecundity was lowest in combined treatments, intermediate in individual treatments, and highest in control and vermiwash treatments. Population growth parameters of P. citri including net reproductive rate, intrinsic rate of increase, finite rate of increase, and generation time were lower when the mites fed on combined treatments, especially on potassium+SA. These results suggest that the application of a combination of fertilizer and SA on citrus trees can lead to a significant reduction in caused damage by citrus red mites. [ABSTRACT FROM AUTHOR]

Panonychus citri (McGregor) is one of the most destructive pests of citrus trees. Its control is difficult because it has developed resistance to some synthetic pesticides. GC-mite is a novel botanical pesticide based on cottonseed, clove, and garlic oils that has shown the potential to control tetranychid mites. This study aimed to evaluate the effects of sublethal concentrations of GC-mite on the life history and biochemical parameters of P. citri. Age-stage life table procedure was used to evaluate the effects of two sublethal concentrations (LC20 = 59.40 μg ml−1 and LC30 = 78.66 μg ml−1) of GC-mite on the development, longevity, and reproduction of P. citri. The biochemical analysis included the content of lipids, carbohydrates and glycogen, esterase, and glutathione S-transferase (GST) activities. The developmental time of treated mites with LC30 was significantly longer than the control but the adult longevity and oviposition days of P. citri treated with both sublethal concentrations decreased. The total fecundity of treated mites decreased with increasing GC-mite concentration applied. The life table analysis showed that sublethal concentrations of GC-mite significantly affected gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), and mean generation time (T). The estimated values of r were significantly lower than the control in LC20 (0.130 day−1) and LC30 (0.117 day−1). The lipids, carbohydrates and glycogen contents as well as esterase and GST activities were significantly lower in mites treated with LC30 concentration, but no significant effect was found in mites treated with LC20 and control. These results suggest that sublethal concentrations of GC-mite had significant effects on both demographic and biochemical parameters of P. citri. [ABSTRACT FROM AUTHOR]

Panonychus citri (McGregor) (Acari: Tetranychidae) is an important pest species in the citrus growing world. Due to broad spectrum chemical pesticides applied on citrus orchards pests, P. citri became an important citrus orchard pest in the north of Iran. In this study, lethal and sub-lethal effects of two biocompatible compounds, citronellol and neem extract, were investigated on different developmental stages of citrus red mite using the potter spray tower method. The results showed that citronellol and neem had high toxicity on egg and larval mite stages with LC50 values of 245.55 and 666.94 mg/L, respectively. The sub-lethal effects of citronellol and neem extract on adult citrus red mite in comparison control significantly reduced fecundity (0.1, 1.5 and 18.03 eggs/female, respectively), fertility (0.066, 1.07 and 17 hatched eggs/female, respectively) and longevity (5.43, 5.86 and 11.83 days, respectively). The results showed appropriate control effects of biomite® and neem extract against early growth stages of the citrus red mite with an environmental protection approach. Therefore, these compounds could be recommended in the program of resistance management of this pest.

This document discusses the identification of common citrus mites. Written by L. M. Diepenbrock, J. D. Burrow, and D. Carrillo and published by the UF/IFAS Entomology and Nematology Department; 2 pp. https://edis.ifas.ufl.edu/in1374

A major pest of citrus orchards in northern regions of Iran is Panonychus citri which is mainly controlled by using chemical acaricides. Knowledge of the lethal and sublethal effects of pesticides on pests is necessary for successful performance of each control programme. In this study, the toxicities of fenazaquin and acequinocyl as well as the effects of the sublethal concentration LC20 and LC30 on demographic and some biochemical traits of P. citri offspring were studied. The results showed that the toxicity of acequinocyl was 2.18 times higher than that of fenazaquin. The developmental time of females was influenced and prolonged by sublethal concentrations of both acaricides. Sublethal concentration effects of both acaricides considerably decreased the total fecundity. A significant reduction was observed in the net reproduction rate (R0), and intrinsic rate of natural increase (r) of the mites exposed to LC20 and LC30 concentrations of both acaricides compared to control. Both acaricides showed a negative impact on the content of lipid, carbohydrate, and glycogen. The LC20 concentration of fenazaquin resulted in an increase in general esterase activity, and both acaricides inhibited glutathione S-transferase (GST) activities. Our findings show that the sublethal doses of both acaricides had adverse effects on the biological and physiological characters of P. citri. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri McGregor (Acari: Tetranychidae) whose control is largely based on the use of acaricides, is a key citrus pest in the world. The lethal and sublethal values of cyflumetofen and spirodiclofen were estimated on citrus red mite. LC20 and LC50 values of cyflumetofen and spirodiclofen were 2.79 and 10.23 ppm, and 2.30 and 7.28 ppm, respectively. LC20 concentration effects of cyflumetofen and spirodiclofen were studied on life table parameters of P. citri females. These two acaricides had significant effects on P. citri biological parameters including developmental time, survival rate, and fecundity. Also, the exposure of females to LC20 considerably reduced net reproductive rate (R0), finite rate of increase (λ) and intrinsic rate of increase (r). The intrinsic rate of increase in females treated with cyflumetofen and spirodiclofen was 0.156 and 0.153 day-1, respectively, and it was 0.183 day-1 for untreated females. The sublethal concentrations affected the citrus red mite life table parameters and consequently may influence the population growth of its future generations. These results provide a baseline for the response of P. citri to cyflumetofen and spirodiclofen pesticides that will aid mite control management in citrus. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri and the two-spotted spider mite, Tetranychus urticae are important pests of citrus orchards and strawberry fields and greenhouses, respectively and their lack of control causes significant damage to the plants. Excessive usage of various types of pesticides has increased the resistance of pests to them. In this research, the contact toxicity of several different biorational and chemical compositions on the eggs and adult stages of these mites was investigated. The treatments included dishwashing liquid 10 ml/L, Dayabon 5, 6, 7, 8, 9 and 10 ml/L, Palizin 1.5, 2 and 2.5 ml/L, Palizin 1.5, 2 and 2.5 + Citrol oil 5 ml/L, Tondexir 2 and 3 + Bartar soap 1 ml/L, Malathion 0.5 ml/L and control (water). At 24, 48 and 72 hours after spraying with different concentrations, dead mites were counted. The results of data analysis showed that there is a significant difference between different treatments on both mites. The highest mortality rate was observed in 72 hours after treatment with Tondexir 3 and 2 ml/L + Bartar soap 1 ml/L, which resulted in mortality of 98.13%, 42.91% in the citrus mite and 84.40% and 82.39% in the two-spotted spider mite, respectively. The results showed that the used botanical pesticides have the ability to control the aforementioned mites at a desirable level and can be a suitable alternative for other high risk acaricides [ABSTRACT FROM AUTHOR]

Cannibalism and intraguild predation (IGP) are two common interactions occurs in animal kingdom which influence their population structure and dynamics. Neoseiulus barkeri (Hughes) and Scolothrips takahashii (Priesner) are important natural enemies of citrus red mite Panonychus citri (McGregor). However, little was known about their interactions and how the availability of extraguild (EG) prey P. citri modulated their interactions. In this study, we determined incidences of cannibalism and intraguild predation of these two predators when different densities of extraguild prey P. citri were available. Our results showed that incidences of both cannibalism and IGP and were significantly reduced in the presence of the extraguild prey. The intraguild predation between N. barkeri and S. takahashii was bidirectional, but N. barkeri was a predominant intraguild predator over S. takahashii. The S. takahashii fed on immobile N. barkeri egg, and N. barkeri fed on inactive prepupa and pupa of S. takahashii, but the conspecifics seldom did. Our results indicated that the interactions of predators decreased significantly when prey was available. The predatory mite N. barkeri was a stronger interspecific competitor. The results of this study may be useful in developing effective biological control strategies against P. citri. [ABSTRACT FROM AUTHOR]

Ecdysteroids regulate molting in arthropods by binding to heterodimers of the ecdysone receptor and retinoid-X-receptor, homologous to the ultraspiracle protein, to induce the expression of downstream signal response genes including the nuclear receptor HR3. However, the detailed expression dynamics of HR3 during molting in spider mites are not yet clear. In this study, the full length of PcHR3 was retrieved based on the genome of citrus red mite, Panonychus citri. The open reading frame is 1707 bp encoding 568 amino acids, which contains a DNA binding domain and a ligand binding domain. Then, the expression pattern of PcHR3 was analyzed throughout the development of the deutonymph by RT-qPCR. The result showed that PcHR3 was mainly transcribed in the late deutonymph stage, when the deutonymph was at least 24 h old and motionless, the critical point at which the mites started molting. Transcription reached the highest level in 32-h-old deutonymphs and decreased by 36 h, where the mites remained in a quiescent state. Further silencing of PcHR3 by leaf-disc-based delivery of dsRNA to 8-h-old deutonymph mites, resulted in retarded development and death of 58% of deutonymphs. In summary, we suggest that PcHR3 regulates the latter stages of molting in P. citri. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri , is a major pest on citrus all around the world. Mitochondrial Electron Transport Inhibitors of complex I (METI-I) acaricides such as fenpyroximate have been used extensively to control P. citri populations, which resulted in multiple reports of METI-I resistant populations in the field. In this study, biochemical and molecular mechanisms of fenpyroximate resistance were investigated in P. citri. Seven populations were collected from Northern provinces of Iran. Resistance ratios were determined and reached up to 75-fold in comparison to a fenpyroximate susceptible population. Cross-resistance to two additional METI-I acaricides, pyridaben and tebufenpyrad, was detected. PBO synergism experiments, in vivo enzyme assays and gene expression analysis suggest a minor involvement of cytochrome P450 monooxygenases in fenpyroximate resistance, which is in contrast with many reported cases for the closely related Tetranychus urticae. Next, we determined the frequency of a well-known mutation in the target-site of METI-Is, the PSST subunit, associated with METI-I resistance. Indeed, the H92R substitution was detected in a highly fenpyroximate resistant P. citri population. Additionally, a new amino acid substitution at a conserved site in the PSST subunit was detected, A94V, with higher allele frequencies in a moderately resistant population. Marker-assisted back-crossing in a susceptible background confirmed the potential involvement of the newly discovered A94V mutation in fenpyroximate resistance. However, introduction of the A94V mutation in the PSST homologue of D. melanogaster using CRISPR-Cas9 did not result in fenpyroximate resistant flies. In addition, differences in binding curves between METI-Is and complex I measured directly, in isolated transgenic and wildtype mitochondria preparations, could not be found. Unlabelled Image • fenpyroximate resistance was investigated in seven Panonychus citri populations from Iran • fenpyroximate resistance ratios reached up to 75-fold and cross-resistance with other METI-I acaricides was observed • synergism experiments, in vivo assays and expression analysis suggest a minor role for P450s in fenpyroximate resistance • a previously reported resistance mutation, H92R in PSST of Complex I, was detected in a highly resistant population • a new mutation, A94V in PSST, was detected in a resistant population but no clear claim regarding its role could be made [ABSTRACT FROM AUTHOR]

Field experiment was carried out to evaluate the efficacy of certain new acaricide molecules against citrus leaf mite Panonychus citri McGregor at the Agricultural College and Research Institute, Madurai during December to March 2019. Among these, fenpyroximate 5EC @1.0 ml/ l led to 85.9% reduction of mites, closely followed by spiromesifen 22.9SC @0.75 ml/ l (83.2 % reduction) and propargite 57EC @ 2.0 ml/ l (79.4% reduction). These treatments also gave higher fruit yield (14.7 t/ ha, 13.9 t/ha, 11.6 t/ha) and increased cost benefit ratio (1:2.8, 1:2.6, 1:2.2), respectively. [ABSTRACT FROM AUTHOR]

Abstract Neuropeptide ecdysis triggering hormone (ETH) plays crucial roles in invertebrates by activating a G protein-coupled receptor (GPCR), the ecdysis triggering hormone receptor (ETHR), which has been intensively investigated in Hexapoda. However, the molecular characterization of ETH and ETHR in Chelicerata remains unknown. In this study, we identified and characterized the full-length cDNA of ETH and ETHR in citrus red mite Panonychus citri (McGregor). Phylogenetic analysis indicated that PcETHR was closely related to the insect ETHR subtype B. A calcium mobilization-based functional assay showed that PcETH activated the PcETHR in a dose-dependent manner. Furthermore, a sharp upregulation of PcETH before ecdysis was observed by quantitative real-time PCR (qRT-PCR), and it revealed a tight correlation of ETH signaling and the molting process. These are the first insights into the molecular characterization of ETH and its receptor in mites as P. citri. Our work provides basic information of the ETH and ETHR in P. citri and lays a solid foundation for further physiological functions to better understand the ETH signaling system in mites. Highlights • Ecdysis triggering hormone (ETH) and its receptor (ETHR) was cloned from P. citri. • Heterologous expression and in vitro functional assay confirmed that PcETHR is activated by ETH in a dose dependent manner. • The PcETH expression showed a tight correlation with the molting process of P. citri. [ABSTRACT FROM AUTHOR]

Citrus red mite, Panonychus citri McGregor is one of the most important pests of citrus orchards in the world. Due to excessive use of chemical pesticides and development of resistance plus their increasing environmental hazards, the use of essential oils has been highly studied. But the low solubility of essential oils in water, oxidation, in addition to their instability in presence of light, humidity and high temperature has diminished their application. Formulation technology is one of the main strategies that can modify the physical properties and the viability of the essential oils in agricultural pest management programs. In this research, the essential oil of Cuminum cyminum L. was encapsulated by in situ polymerization of oil/water emulsion in nano scale and then the effects of nanoencapsulated essential oil (NEO) were analyzed against P. citri. The results showed that LC50 of NEO's contact toxicity was 743.17 ppm over 24 hours. NEO also affected mortality and decreased oviposition rate in P. citri. NEO had deterrence capacity at 300, 500 and 700 ppm. Moreover, NOE had oviposition deterrence, lowering the number of eggs per female compared to the control. Our finding suggests that high-tech formulations including nanoencapsulation technology can be used as botanical pesticides and as alternatives to chemical pesticides.

Introduction: The harmful plant mites not only feed on crops, but also have irreversible damage to humans. The synthetic pesticides can be replaced with natural products for pest control. The agricultural products, health and hygienic of humans can be treated with harmful caused by the mites (Wooley, 1988). The citrus red mite (CRM) Panonychus citri (McGregor) (Acarina: Tetranychidae) is one of the most important herbivorous pests in citrus growth area. For the first time, this pest was reported from Mazandaran province in 1940. The nymph and adult of these pests create identified small, silver and gray spot on leaves and fruits. As a result of feeding, contamination can cause necrosis of leaves, loses of young leaves and reduce the plant freshness. The synthetic of pesticides has been used for controlling of this pest for a long time. The application of non-normative methods for control of the mites can cause pest outbreaks and destroy the natural enemies of the pest. This pest has been resistant to a wide range of pesticides such as; Dicofol, Hexythiazox, Abamectin and Pyrothroids in field conditions. In recent decays, the organic agriculture has been grown dramatically. Lio (2003) has reported that at least 30 countries produce organic citrus fruit. So, for growing organic citrus in Iran, it also suggested to use the low impact pesticides to the environment and the human health. In this research, the comparison toxicity of three botanical pesticides Tondexir (red pepper extract), Sirinol (garlic extract), Palizin (eucalyptus extract) with two common chemical pesticides (Hexythiazox and Fenpyroximate) and common mineral oil has been investigated against adult and protonymph of citrus red mite P.citri. Materials and Methods: The citrus red mite (CRM) has been collected from infected trees from citrus orchard and brought into the lab; after that, the adult and nymphs were separated. The citrus red mite has been reared on citrus leaves in growth chambers with constant condition (25 ±2oC, 16:8 L/D and 60% RH conditions). The primary test has been done to identify the maximum and minimum concentration. For bioassay experiments, the citrus leaves were washed and cleaned with distilled water and prepared in 20 mm diameter leaf disc. The bioassay was carried out using leaf dip methods with different concentration of the following pesticides after primary experiment: Mineral oils (2000, 2828, 4000, 5657 and 8000 ppm), Tondexir (1000, 1368, 1871, 2559 and 3500 ppm), Sirinol (750, 1102, 1620, 2381 and 3500 ppm), Palizin (2000, 2378, 2828, 3364 and 4000 ppm), Hexythiazox (250, 370, 548, 811 and 1200 ppm) and Fenpyroximate (500, 679, 922, 1252 and 1700 ppm). The mortality was recorded at 24, 48 and 72 h after-treatments. All experiments were conducted with three replications. The statistical analyses were performed by SPSS version16.0 software. Results and Discussions: The Probit analysis was shown that the LC50 value of the mineral oils on protunymph and adult of citrus red mite were 1743.6 and 1898 ppm, the LC50 value of the Tondexir were1305.9 and 1549 ppm, the LC50 value of the Sirinol were 666.1 and 693.9 ppm, the LC50 value of the Palizin were 2206 and 1969.2 ppm and the LC50 value of the Hexythiazox were 223.6 and 227.3 ppm at 72 h post-treatments, respectively consequently and the probit analysis was revealed that the LC50 value of the Fenpyroximate on protonymph and adult of citrus red mite were 480 and 439.3 ppm at 72 h post-treatments, respectively. Consistent with our result, the acaricide, Hexythiazox had higher toxicity on adult and protonymph of CRM in comparison to the other pesticides. Among three botanical pesticides, Sirinol has the highest toxicity. Due to the low risk of three botanical pesticides, they should be considered in IPM program. Conclusion: The data analysis of this research was shown that among different compounds, the highest and lowest toxicity on adult and protonymph were obtained with Hexythiazox and Plazin consequently respectively. By comparison the LC50 values, the protonymph was more susceptible than adult. With regards of being low risk and natural products of the botanical pesticides and mineral oils for humans, it is better to use these products to control red mites.

ABSTRACT: Pesticides have been blamed as the principal factor responsible for biological disequilibrium favoring the population increase of Panonychus citri (McGregor) in Brazilian citrus groves. In order to generate subsidies for the integrated management of this pest, we evaluated the lethal and sublethal effects of pesticides used in citrus on P. citri. We tested 18 pesticides by evaluating mortality of adult female, egg viability and adult avoidance. For imidacloprid, pyriproxyfen, dimethoate, deltamethrin, lambda-cyhalothrin and lime sulfur, the principal insecticides used in Brazilian orchards, the oviposition behavior and the incidence of adult females on discontinuous pesticide residues were evaluated. The pesticides which caused adult P. citri mortality were: abamectin (94%), dimethoate (86%), lime sulfur (69%), fenpropathrin (44%), diafenthiuron (25%) and lambda-cyhalothrin (23%). The pesticides affecting egg viability were: fenpropathrin (53%), dimethoate (30%) and lime sulfur (22%). Fenpropathrin, lambda-cyhalothrin and lime sulfur caused repellent effects of 55, 45 and 22%, respectively. P. citri preferred areas untreated with deltamethrin, lambda-cyhalothrin and lime sulfur for oviposition and permanence, but the species could not distinguish areas treated with imidacloprid, pyriproxyfen and dimethoate. The insecticides abamectin, dimethoate and diafenthiuron affected survival and did not cause changes in P. citri behavior. These pesticides should be used mainly in periods P. citri occurs. On the other hand, fenpropathrin, lambda-cyhalothrin, lime sulfur and deltamethrin affect dispersal behavior, oviposition and P. citri incidence and their use should be avoided.

To examine the effect of Citrus Red Mite (CRM) damage on quantitative and qualitative characteristics of Thomson navel orange Citrus sinensis (L.) Osbeck, pairedtreatment experiment, multiple treatment experiment, and regression/correlation methods were used. There were significant differences among the treatments in pairedtreatment and multiple treatment experiments in terms of the average population per leaf of CRM of different life ages and concentration of chlorophyll in the leaves. Also, there were significant differences among the treatments in multiple treatment experiment in terms of the Total Soluble Solids (TSSs) of the fruit extract. In control treatment of the paired-treatment experiment, the highest concentration of chlorophyll (79.13±1.06) was observed when the population density of CRM was 0.48±0.09 per leaf. With increasing the mean number of CRM to 10.59±1.09 per leaf, chlorophyll content was decreased to 62±1.15. Furthermore, the results showed that the storage life of the fruits in treatments with mean number of 6.33±1.8 mites per leaf was significantly reduced. The results of regression and correlation analysis on chlorophyll showed significant and negative relationship between these parameters and CRM population density. The results indicated that increasing the population density of CRM to 10.59±1.09 per leaf at the beginning of the season caused fruit drop and dry twigs. In addition, by increasing population density of CRM to 5.72±0.43 per leaf, the storage capability of the fruits was significantly reduced. [ABSTRACT FROM AUTHOR]

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]

Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased Ro, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves. [ABSTRACT FROM AUTHOR]

Citrus red mite (CRM), Panonychus citri (McGregor) (Acari: Tetranychidae) is one of the important citrus pests in different parts of the world including northern Iran. Population fluctuation and spatial distribution pattern of this pest was studied in Ghaemshahr, northern Iran during 2016-2017 in different initial infestation treatments (pairedtreatment and multiple-treatment experiments) that had been designed for crop loss assessment caused by CRM. Taylor's Power Law and Iwao's Patchiness Regression methods were used to determine the spatial distribution pattern of CRM. The results showed that the highest population density of the pest was during summer of 2016 and 2017 with an average of 127.3 and 91.15 CRM per leaf, respectively, and the population declined in the fall with an average of near zero mites per leaf. The spatial distribution pattern of CRM in both years and both methods was aggregated with an exception in which it was random. It could be concluded that initial infestion with different densities of the pest affected the population fluctuation of the pest during the growing season and somewhat the spatial distribution pattern of CRM. [ABSTRACT FROM AUTHOR]

Panonychus citri and Diaphorina citri are serious citrus pests (mites) in many countries. The predatory mite Neoseiulus cucumeris can prey on both P. citri and D. citri. It is necessary to develop a strategy using predatory mites and selective pesticides that can simultaneously control both pests effectively and sustainably. The toxicities of matrine and abamectin to P. citri, D. citri and N. cucumeris were evaluated in the laboratory. Matrine was highly lethal to D. citri and relatively less toxic to P. citri and N. cucumeris. Abamectin was relatively less toxic to D. citri. The results of the field trials demonstrated the ecological control strategy that combined the release of predatory mites and applications of four matrine sprays from June 2011 to November 2011, which provided better control over P. citri than pesticide applications alone with six sprays during the same period. It achieved similar control levels for D. citri. In Matrine + N. cucumeris orchard, the total number of spiders was significantly larger than that in the Pesticides Only orchard, but the total number of predatory mites was lower. It is inferred that primarily natural enemies and matrine together play a role in controlling citrus pests. [ABSTRACT FROM AUTHOR]

Abstract: Panonychus citri McGregor (“Citrus red mite”) and Phyllocoptruta oleivora Ashmead (“Citrus rust mite”) are key pests of citrus crops in the Chancay valley, Peru, causing dramatical losses in yield and fruit quality. These pest‐mites affect food security in the area, where the small farming prevails, as the citrus crop is the main generating income source for most of households. Small farmers fight against these pest‐mites by spraying nutritional elements on leaves, as it is cheaper and less harmful than using a chemical miticide. Thus, the aim of this work was determining the influence of the foliar application of elements currently used by farmers (Calcium, Magnesium, Zinc, Copper, Iron, Manganese, and Boron) and a mix of all of them at two dosage levels on the population dynamic of these two key citrus pests on tangerine cv. Clemenules, along a whole crop season in the Chancay Valley. Panonychus citri was detected on leaves during the whole crop cycle, while Phyllocoptruta oleivora was visible during the third leaf and bloom shooting period. There were not statistical differences between dosages, but statistical differences were observed between treatments and the control, the latter registering the highest population level of both mites during the whole crop cycle. Application of Cu, Mn, Mg, and Zn did show the lowest P. citri population rates, while Fe, Mix, Cu, Mg, and Zn did show the lowest population levels of P. oleivora. The foliage analysis revealed that the nutritional content of leaves of tangerine trees under study during the crop cycle was mostly at optimal levels, according to the standards for the crop. These results support the current practice of farmers and confirm that the foliar application of microelements represents a potential pesticide alternative method for management/control of citrus mites, lowering production costs, avoiding excessive pesticide applications, and increasing yield and fruit quality. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri, a major citrus pest distributed worldwide, has evolved severe resistance to various classes of chemical acaricides/insecticides including pyrethroids. It is well known that the resistance to pyrethroids is mainly caused by point mutations of voltage-gated sodium channel gene in a wide range of pests. However, increasing number of evidences support that pyrethroids resistance might also be resulted from the integrated mechanisms including metabolic mechanisms. In this study, firstly, comparative analysis of RNA-seq data showed that multiple detoxification genes, including a GSTs gene PcGSTd1, were up-regulated in a fenpropathrin-resistant population compared with the susceptible strain (SS). Quantitative real time-PCR results showed that the exposure of fenpropathrin had an induction effect on the transcription of PcGSTd1 in a time-dependent manner. In vitro inhibition and metabolic assay of recombinant PcGSTd1 found that fenpropathrin might not be metabolized directly by this protein. However, its antioxidant role in alleviating the oxidative stress caused by fenpropathrin was demonstrated via the reversely genetic experiment. Our results provide a list of candidate genes which may contribute to a multiple metabolic mechanisms implicated in the evolution of fenpropathrin resistance in the field population of P. citri. Furthermore, during the detoxification process, PcGSTd1 plays an antioxidant role by detoxifying lipid peroxidation products induced by fenpropathrin. [ABSTRACT FROM AUTHOR]

Solar ultraviolet-B (UVB) radiation and radiant heat have lethal effects on plant-dwelling mites, including spider mites, and their natural enemies, such as phytoseiid mites, leading them to reside on lower leaf surfaces. Panonychus spider mites are outcompeted by Tetranychus spider mites and thus exploit upper leaf surfaces, where they are exposed to both UVB radiation and radiant heat. Panonychus spider mites are thought to produce astaxanthin constitutionally. In this study, we compared carotenoid components, antioxidant capacity, lipid peroxidation, survival, and egg production in wild-type (WTS) and albino-type strains (ATS) of Panonychus citri (McGregor). Four carotenoids (neoxanthin, violaxanthin, lutein, and carotene) and their isomers and esters were identified in both strains, but astaxanthin and its esters were present only in WTS. The singlet oxygen scavenging capacity of lipid-soluble ingredients was greater in WTS than in ATS, whereas the oxygen radical absorbance capacities of hydrophilic ingredients were equivalent between them. Lipid peroxide accumulation was clearly higher in ATS than in WTS under both UVB irradiation (25 °C) and high temperature (35 °C) conditions. The findings are consistent with an antioxidant protective function of astaxanthin in this mite. Survival periods at 38 °C were longer in WTS than in ATS, although no difference was shown at 35 °C or under UVB irradiation. Therefore, astaxanthin accumulation was shown to be a major mechanism for survival under radiant heat, although other mechanisms, such as photoreactivation, might play a major role in survival under UVB radiation. [ABSTRACT FROM AUTHOR]

Development time, survival, reproduction, and sex ratio were determined for the predatory mite Neoseiulus longispinosus (Evans) at six constant temperatures (20, 25, 27.5, 30, 32.5 and 35 °C) reared on citrus red spider mite Panonychus citri (McGregor). No predatory mite reached adulthood at 35°C. All female and male immature stages of N. longispinosus developed significantly faster as the temperature increased from 20 to 30°C, but development slowed down as the temperature exceeded 30 °C. The mean total developmental time of females was longest at 20 °C (9.73 days), followed by 25°C (5.67 days), 27.5°C (4.46 days), and 32.5 °C (4.55 days) and was shortest at 30°C (3.69 days). The oviposition rate and lifetime fecundity were highest at 27.5 °C (2.80 eggs/female/day and 43.76 eggs/female, respectively) and lowest at 20 °C (0.78 eggs/female/day and 21.64 eggs/female, respectively). However, temperature had no influence on the sex ratio of offspring with the proportion of females ranging from 0.62 to 0.65. The intrinsic rate of increase ( r) of N. longispinosus averaged 0.323, 0.303, 0.267, 0.189 and 0.107 females female-1 day-1 at 30, 27.5, 32.5, 25, and 20°C, respectively. These values suggested that the most optimal temperatures for the population growth of N. longispinosus were between 27.5 and 30°C. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri, is one of the most economically and globally destructive mite pests of citrus. Acaricide resistance has been a growing problem in controlling this pest. As the main inhibitory neurotransmitter in organisms, γ-aminobutyric acid (GABA) is synthesized from the amino acid glutamate by the action of glutamate decarboxylases (GADs). In the present study, one novel GAD gene, PcGAD, was identified and characterized from P. citri. The opening reading frame of PcGAD contained 1548 nucleotides that encode 515 amino acids. The subsequent spatiotemporal expression pattern by RT-qPCR revealed that the expression levels of PcGAD were significantly higher in larvae than in adults. Challenging with various concentrations of abamectin resulted in the upregulation of PcGAD transcript levels. Furthermore, biochemical characterization indicated that changes in GAD activity coincided with its mRNA levels. High-performance liquid chromatography confirmed that the GABA contents of P. citri increased upon abamectin treatment. The application of abamectin induces PcGAD expression and activates GAD activity, thereby resulting in an increase in GABA content in P. citri, which contributes to the adaptability of the mite to abamectin challenge. [ABSTRACT FROM AUTHOR]

The predatory mite Neoseiulus barkeri (Hughes) is a good biological control agent for many small sucking pests. We aimed to determine whether rearing long term on alternative prey versus target prey species affected the performance of N. barkeri. Therefore, we investigated the prey preference, life tables, and population parameters of N. barkeri between alternative prey Tyrophagus putrescentiae (Schrank) and three species of spider mites, Tetranychus urticae Koch, Panonychus citri (McGregor), and Eotetranychus kankitus Ehara. We found that N. barkeri preferred the tetranychid mites to the alternative prey. Between the tetranychid mites, the predator consumed more P. citri and E. kankitus than T. urticae. When reared on T. urticae, the total developmental time and longevity of N. barkeri were the longest, whereas the intrinsic rate of increase was the lowest, indicating that the biotic fitness of predatory mite preyed on target of T. urticae was higher than on alternative prey of T. putrescentiae. However, total developmental time, longevity, and fecundity did not differ between N. barkeri reared on T. putrescentiae and P. citri, although these parameters were higher than those for mites reared on E. kankitus, indicating that the predatory mite reared on T. putrescentiae may not be affected to control P. citri, and that coexistence of P. citri and E. kankitus may enhance the control efficiency of N. barkeri. Altogether, our results demonstrated that long-term feeding on the alternative prey T. putrescentiae did not affect the performance of the predatory mite N. barkeri on various target spider mites. [ABSTRACT FROM AUTHOR]

Abamectin is a microbial-derived pesticide widely used for control of agricultural pests. However, sustained use of abamectin has led to the development of resistance in some target species. Previous studies on arthropod resistance to abamectin have mainly used traditional biochemical and molecular approaches. To understand the responses of citrus red mite, Panonychus citri , exposed to abamectin, comparative proteomic analysis was conducted using two-dimensional electrophoresis (2-DE). A total of 26 distinct protein spots were present in response to abamectin exposure. Tandem mass spectrometry (MS/MS) identified 16 proteins that were mainly involved in energy metabolism and detoxification. Some remaining proteins were not identifiable, suggesting that they may be novel. The expression levels of transcripts associated with proteins were analyzed by quantitative reverse transcription PCR (qRT-PCR). Furthermore, to validate the proteomic data obtained in the present study, Western-blot experiment was performed and the expression of sHsp and PcE1 proteins were confirmed, respectively. Biological significance The citrus red mite has developed resistance to many acaricides, including abamectin. In the current study, we used the proteomic approaches involving 2-DE, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF), and MS/MS to document changes in adult P . citri during 24 h of abamectin exposure. Abamectin stress induced a total of 16 differentially regulated proteins. The proteomic results were validated in mRNA expression patterns using qRT-PCR. This is the first analysis of differentially expressed proteins in P . citri exposed to abamectin. The results help clarify the physiological mechanisms of P . citri responses to abamectin exposure. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor), a major citrus pest distributed worldwide, has been found to be resistant to various insecticides and acaricides used in China. However, the molecular mechanisms associated with the abamectin resistance in this species have not yet been reported. In this study, results showed over-expression of a novel glutathione S -transferases (GSTs) gene ( PcGSTm5 ) in abamectin-resistant P. citri . Quantitative real-time PCR analysis showed that the transcripts of PcGSTm5 were also significantly up-regulated after exposure to abamectin and the maximum mRNA expression level at nymphal stage. The recombinant protein of PcGSTm5-pET-28a produced by Escherichia coli showed a pronounced activity toward the conjugates of 1-chloro-2,4 dinitrobenzene (CDNB) and glutathione (GSH). The kinetics of CDNB and GSH and its optimal pH and thermal stability were also determined. Reverse genetic study through a new method of leaf-mediated dsRNA feeding further support a link between the expression of PcGSTm5 and abamectin resistance. However, no direct evidence was found in metabolism or inhibition assays to confirm the hypothesis that PcGSTm5 can metabolize abamectin. Finally, it is here speculated that PcGSTm5 may play a role in abamectin detoxification through other pathway such as the antioxidant protection. [ABSTRACT FROM AUTHOR]

Chitinases are hydrolytic enzymes that are required for chitin degradation and reconstruction in arthropods. In this study, we report a cDNA sequence encoding a putative chitinase ( PcCht1) from the citrus red mite, Panonychus citri. The PcCht1 (564 aa) possessed a signal peptide, a conserver domain, and a chitin-binding domain. Structural and phylogenetic analyses found that PcCht1 had high sequence similarity to chitinases in Tetranychus urticae. Real-time quantitative PCR analyses showed that the transcript levels of PcCht1 peaked periodically in larval and nymph stages. Moreover, significant increase of PcCht1 transcript level in the larvae was observed upon the exposure of diflubenzuron. In contrast, exposures of the larvae to diflubenzuron resulted in the decreased chitin content. Furthermore, through a feeding-based RNA interference approach, we were able to reduce the PcCht1 transcript level by 59.7 % in the larvae, and consequently the treated larvae showed a very low molting rate compared with the control. Our results expanded the understanding of the important role of PcCht1 in the growth and development of P. citri. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor), is a major citrus pest with a worldwide distribution and an extensive record of pesticide resistance. However, the underlying molecular mechanism associated with fenpropathrin resistance in this species have not yet been reported. In this study, synergist triphenyl phosphate (TPP) dramatically increased the toxicity of fenpropathrin, suggesting involvement of carboxylesterases (CarEs) in the metabolic detoxification of this insecticide. The subsequent spatiotemporal expression pattern analysis of PcE1, PcE7 and PcE9 showed that three CarEs genes were all over-expressed after insecticide exposure and higher transcripts levels were observed in different field resistant strains of P. citri. Heterologous expression combined with 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetra-zolium bromide (MTT) cytotoxicity assay in Spodoptera frugiperda (Sf9) cells revealed that PcE1-, PcE7- or PcE9-expressing cells showed significantly higher cytoprotective capability than parental Sf9 cells against fenpropathrin, demonstrating that PcEs probably detoxify fenpropathrin. Moreover, gene silencing through the method of leaf-mediated dsRNA feeding followed by insecticide bioassay increased the mortalities of fenpropathrin-treated mites by 31% (PcE1), 27% (PcE7) and 22% (PcE9), respectively, after individual PcE gene dsRNA treatment. In conclusion, this study provides evidence that PcE1, PcE7 and PcE9 are functional genes mediated in fenpropathrin resistance in P. citri and enrich molecular understanding of CarEs during the resistance development of the mite. [ABSTRACT FROM AUTHOR]

Laboratory experiments were conducted to evaluate the efficacy of the predatory species, Stethorus gilvifrons (Mulsant) (Coleoptera: Coccinellidae) against different stages of the citrus red mite Panonychus citri (McGregor) (Acari: Tetranychidae). Results showed that both larvae and, in particular, adults of the predator were highly efficient in consumption of all mite stages. Efficacy of S. gilvifrons larvae increased from first to the fourth instar. Adult stage of S. gilvifrons seemed to be more voracious than larvae and consumed 78.24 - 80.63% of P. citri offered during the whole life-span of the predator. During its whole life, S. gilvifrons consumed an average of 2666 eggs, 1700.8 larvae, 1285.8 nymphs and 886.6 adults of P. citri. [ABSTRACT FROM AUTHOR]

Anoxia treatment with a deoxidant consisting of iron, calcium chloride and silicon dioxide was evaluated at different temperatures for pest spider mites (Tetranychus urticaeandPanonychus citri) and their natural enemy, the predatory miteNeoseiulus californicus. No spider mite eggs survived when exposed to anoxia for 18 h at 20°C or for 12 h at 25°C, whereas the survival ofN. californicuseggs under these conditions was 53% and 72%, respectively. No adult female spider mites survived when exposed to anoxia for 15 h at 20°C or for 8 h at 25°C, whereas >95% of adultN. californicusfemales survived under these conditions. These results indicate that anoxia has potential as a selective method for controlling pest mites, such asT. urticaeandP. citri, but has little impact on their natural enemy,N. californicus. [ABSTRACT FROM PUBLISHER]

The population fluctuation of Panonychus citri was studied during two successive years on three citrus species at Giza Governorate namely: Lemon (Citrus limon L.), Sweet orange; Navel orange (Citrus sendonensis L.). The obtained results recorded negative correlation between number of mites and average temperature and positive correlation between mite population and average relative humidity. Moreover, the citrus red mite, P. citri has one annual peak of year abundance in March on Lemon trees, while on naval orange and sweet orange, the annual peak occurred in April during two successive years. [ABSTRACT FROM AUTHOR]

The species and varieties of citrus plants that are currently grown can favor the population growth of the citrus red mite Panonychus citri (McGregor) (Prostigmata: Tetranychidae) and alter the pest management programs in citrus groves. In this study we evaluated, in the laboratory, the development and reproduction of P. citri and estimated its life table parameters when reared on four varieties of Citrus sinensis (L.) Osbeck (Valencia, Pera, Natal, and Hamlin), one variety of Citrus reticulata Blanco (Ponkan) and one variety of Citrus limon (L.) Burm. (Sicilian). The incubation period and egg viability were not affected by the host plant. However, the development and survival of the immature stage were significantly lower on Hamlin orange than on Valencia, Pera and Natal oranges, Ponkan mandarin and Sicilian lemon. The fecundity and oviposition period of females were lower on Hamlin orange than on the other hosts. Mites reared on Valencia orange and Sicilian lemon had a higher net reproductive rate ( R), intrinsic growth rate ( r) and finite rate of increase ( λ), and a shorter interval between generations ( T) than on Pera, Natal and Hamlin oranges and Ponkan mandarin. On the other hand, mites reared on Hamlin orange had the lowest R, r and λ and the highest T among the hosts. Based on the results obtained we recommend that for Valencia orange and Sicilian lemon, the mite monitoring programs should be more intense to detect the initial infestation of pest, avoiding the damage in plants and the increase in production costs. [ABSTRACT FROM AUTHOR]

The effective dose of irradiation to control pest mites in quarantine has been studied extensively, but the molecular mechanisms underlying the effects of the irradiation on mites are largely unknown. In this study, exposure to 400 Gy of γ rays had significant (p < 0.05) effects on the adult survival, fecundity and egg viability of Panonychus citri. The irradiation caused the degradation of the DNA of P. citri adults and damaged the plasma membrane system of the egg, which led to condensed nucleoli and gathered yolk. Additionally, the transcriptomes and gene expression profiles between irradiated and non-irradiated mites were compared, and three digital gene expression libraries were assembled and analyzed. The differentially expressed genes were putatively involved in apoptosis, cell death and the cell cycle. Finally, the expression profiles of some related genes were studied using quantitative real-time PCR. Our study provides valuable information on the changes in the transcriptome of irradiated P. citri, which will facilitate a better understanding of the molecular mechanisms that cause the sterility induced by irradiation. [ABSTRACT FROM AUTHOR]

Superoxide dismutase (SOD) is a family of enzymes with multiple isoforms that possess antioxidative abilities in response to environmental stresses. Panonychus citri is one of the most important pest mites and has a global distribution. In this study, three distinct isoforms of SOD were cloned from P. citri and identified as cytoplasmic Cu-ZnSOD ( PcSOD1), extracellular Cu-ZnSOD ( PcSOD2), and mitochondrial MnSOD ( PcSOD3). mRNA expression level analysis showed that all three isoforms were up-regulated significantly after exposure to the acaricide abamectin and to UV-B ultraviolet irradiation. In particular, PcSOD3 was up-regulated under almost all environmental stresses tested. The fold change of PcSOD3 expression was significantly higher than those of the two Cu-ZnSOD isoforms. Taken together, the results indicate that abamectin and UV-B can induce transcripts of all three SOD isoforms in P. citri. Furthermore, PcSOD3 seems to play a more important role in P. citri tolerance to oxidative stress. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri ( McGregor) ( Acari: Tetranychidae), is an important pest worldwide. Previous studies showed that acetyl CoA carboxylase ( ACCase) may be a critical target of spirodiclofen, a recently introduced insecticide. Therefore, we cloned the Pc ACCase gene and obtained a full-length cDNA (Genbank accession number ). The open reading frame was 6 972 bp, coding for 2 323 amino acids. The Pc ACCase protein had a theoretical molecular weight of 262.82 kDa and an isoelectric point of 6.31, and it contained six conserved domains and one low-complexity region. Quantitative real-time PCR showed that spirodiclofen can up-regulate the expression levels of ACCase mRNA during all four developmental stages. [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor) (Trombidiformes: Tetranychidae), a highly destructive pest in citrus groves around the world, has developed resistance to many registered acaricides. Hexythiazox is a selective miticide that has been widely used to control citrus mites in a variety of crops. Forty-six cytochrome P450 mono-oxygenase genes related to general pesticide resistance in other insect species were obtained from the transcriptomes of the hexythiazox-resistant (RR) and hexythiazox-susceptible (SS) strains of P. citri and divided into 4 clans, 15 families and 24 subfamilies. Sequence analyses of each CYP resulted in detection of 3 mutationsin the CYP307A1 gene (841-A to C, 1395-T to C, 1491-T to C) that differed between the 2 strains. Only the change at an amino acid position (278-lysine to glutamine) resulted in a sense mutation. One SNP site was also detected in CYP381A2 (40-A to T) causing a sense amino acid mutation (14-threonine to serine). Seven of these P450s belonged to the CYP2 clan, CYP3 clan and CYP4 clan based on digital gene expression (DGE) library sequencing with a |log2 ratio| value greater than 2, but there were no significant differences revealed by qRT-PCR analysis. This study provides essential information for future research on the hexythiazox-resistance mechanism of P. citri. More methods are needed to further elucidate the molecular mechanisms of resistance to hexythiazox in P. citri. [ABSTRACT FROM AUTHOR]

Panonychus citri McGregor (Trombidiformes: Tetranychidae), the widely distributed citrus red mite, has developed resistance to most registered acaricides. Adaptation of arthropods to extreme environmental conditions has been related to increased expression of their heat shock proteins (HSPs). The objectives of this study were to explore the relationship between HSPs and resistance of Panonychus citri to the acaricide abamectin and the adaptation of Panonychus citri to high temperatures. The full-length cDNA of the HSP90 gene was cloned from an abamectin-sensitive strain of Panonychus citri. This gene consisted of 2,495 nucleotides with a complete open reading frame (ORF) of 2,169 nucleotides. This gene encoded a polypeptide of 721 amino acids with a predicted molecular weight of 83.44 kDa, a theoretical isoelectric point of 5.06, a 3' untranslated region (UTR) of 228 bp, and a 5' UTR of 98 bp. The results of real-time PCR analyses indicated that the expression of the HSP90 gene in P. citri was markedly affected by the concentration of abamectin, the duration of exposure to it and the temperature, suggesting that the up-regulation of the HSP90 gene may play an important role in abamectin resistance and adaptation to high temperatures in Panonychus citri. The results of RNA interference experiments indicated that the HSP90 gene from adult female Panonychus citri was sensitive to down-regulation by double-stranded RNA (0.1-0.2 μg/μL). This study provides a molecular basis for further analysis of the relationships between the HSP90 gene and the resistance of Panonychus citri to abamectin and to high temperatures. [ABSTRACT FROM AUTHOR]

The production and uptake of yolk protein play an important role in the reproduction of all oviparous organisms. Vitellogenin (Vg) is the precursor of vitellin (Vn), which is the major egg storage protein, and vitellogenin receptor (VgR) is a necessary protein for the uptake of Vg into developing oocytes. In this paper, we characterize the full-length Vg and VgR, PcVg1 and PcVgR, respectively, of the citrus red mite Panonychus citri (McGregor). The PcVg1 cDNA is 5748 nucleotides (nt) with a 5553-nt open reading frame (ORF) coding for 1851 amino acids (aa), and the PcVgR is 6090 nt, containing an intact ORF of 5673 nt coding an expected protein of 1891 aa. The PcVg1 aa sequence shows a typical GLCG domain and several K/RXXR cleavage sites, and PcVgR comprises two ligand-binding domains, two epidermal growth factor (EGF)-like regions containing YWTD motifs, a transmembrane domain, and a cytoplasmic domain. An analysis of the aa sequences and phylogenetics implied that both genes were genetically distinct from those of ticks and insects. The transcriptional profiles determined by real-time quantitative PCR in different developmental stages showed that both genes present the same expressional tendencies in eggs, larvae, nymphs, and adults. This suggested that the biosynthesis and uptake of PcVg occurs coordinately. The strong reproductive capacity of P. citri has been hypothesized as an important factor in its resistance; consequently, understanding the molecular mechanisms regulating Vg and VgR are fundamental for mite control. [ABSTRACT FROM AUTHOR]

BACKGROUND The citrus red mite, Panonychus citri ( McGregor), is regarded as one of the most serious citrus pests in many countries and has developed high resistance to pyrethroids as a result of the intensive use of these acaricides. RESULTS The para sodium channel gene of P. citri (named PcNav), containing an entire coding region of 6729 bp, was cloned in this study. Three alternative splicing sites and 12 potential RNA editing sites were identified in PcNav. Thus, exons alt 1 and alt 3-v3 were found to be unique to PcNav. Comparison of field fenpropathrin-resistant ( WZ) and susceptible ( LS) strains identified the point mutation F1538I in IIIS6 of the sodium channel, which is known to confer strong resistance to pyrethroids in mites. Moreover, it was also found that the PcNav mRNA was present during all life stages, and the transcript seems to be more abundant in larvae than in other developmental stages. CONCLUSION These results suggest that the F1538I mutation plays an important role in fenpropathrin resistance in citrus red mites. This is the first study of the sodium channel in P. citri and provides abundant information for further research on the mechanism of pyrethroid resistance. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The citrus red mite, Panonychus citri (McGregor), is an economically important pest on citrus. To better understand the population structure of P. citri, we developed 15 novel polymorphic microsatellites derived from expressed sequence tags (EST). The new microsatellites were assessed in 32 female individuals sampled from Quanzhou (Fujian Province), China. The polymorphic information content ( PIC) for each locus ranged from 0.305 to 0.726, with an average of 0.491. The number of alleles per locus ranged from 2 to 6, with an average of 3.8. The observed and expected heterozygosities ranged from 0.094 to 0.438 and from 0.345 to 0.764, respectively. Significant linkage disequilibrium was detected for three pairs of loci ( PC3 and PC9, PC3 and PC11, PC11 and PC13). Twelve of the 15 loci deviated significantly from Hardy-Weinberg equilibrium ( HWE). The presence of null alleles, inbreeding and the Wahlund effect were considered potential sources of the deviations from HWE. The new polymorphic microsatellites provide a valuable resource for future population genetics studies and management of P. citri. [ABSTRACT FROM AUTHOR]

Acetogenins, a class of natural compounds produced by some Annonaceae species, are potent inhibitors of mitochondrial electron transport systems. Although the cellular respiration processes are an important biochemical site for the acaricidal action of compounds, few studies have been performed to assess the bioactivity of acetogenin-based biopesticides on spider mites, mainly against species that occur in orchards. Using residual contact bioassays, this study aimed to evaluate the bioactivity of an ethanolic extract from Annona mucosa seeds (ESAM) (Annonaceae) against the citrus red mite Panonychus citri (McGregor) (Acari: Tetranychidae), an important pest of the Brazilian citriculture. ESAM is a homemade biopesticide which was previously characterized by its high concentration of acetogenins. It caused both high mortality of P. citri females (LC = 7,295, 4,662, 3,463, and 2,608 mg l, after 48, 72, 96, and 120 h of exposure, respectively) and significant oviposition deterrence (EC = 3.194,80 mg l). However, there was no effect on P. citri female fertility (hatching rate). In addition, the ESAM efficacy (in terms of its LC) was compared with commercial acaricides/insecticides (at its recommended rate) of both natural [Anosom 1 EC (annonin), Derisom 2 EC (karanjin), and Azamax 1.2 EC (azadirachtin + 3-tigloylazadirachtol)] and synthetic origin [Envidor 24 SC (spirodiclofen)]. Based on all of the analyzed variables, the ESAM exhibited levels of activity superior to other botanical commercial acaricides and similar to spirodiclofen. Thus, our results indicate that ESAM may constitute a biorational acaricide for citrus red mite integrated pest management in Brazilian citrus orchards, particularly for local use. [ABSTRACT FROM AUTHOR]

Radio-(60Co), which emits γ rays, has been used worldwide in pest control. The aim of the present study was to analyze the effect of effective-low-power 60Co-γ irradiation on the enzymatic antioxidant system of the citrus red mite Panonychus citri. One day old female adults were exposed to 0.4 kGy 60Co-γ irradiation and on the, 6th h, 1st day, 2nd day, and 5th day post treatment, the mites were euthanized for biochemical analysis. The activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), phenoloxidase (PO) and acetylocholinesterase (AchE) were investigated. POD and CAT activities, as well as SOD were higher in the irradiated mites. We found that exposure to 60Co-γ radiation resulted in increased activities of SOD, CAT, POD and decreased AchE activity. When the recovery time lasted till the 5th day, the activities of POD and PO were significantly lower than the control, whereas the SOD, CAT and AchE activities returned to control levels. Cells possess protein repair pathways to rescue oxidized proteins and restore their functions, but if these repair processes fail, oxidized proteins may become cytotoxic. Our results confirm the hypothesis that low dosages of 60Co-γ irradiation increase the level of oxidative stress in P. citri adults in a short time, causing meanwhile damage and sterility. The results of this study also indicate that stress caused by exposure to irradiation could inhibit the cholinergic system in P. citri. [ABSTRACT FROM AUTHOR]

The citrus red mite ( Panonychus citri) can feed on more than 112 plant species around the world. Endogenous small RNAs ( sRNAs) have proved to be important components of gene regulation in many eukaryotes. Recently, many sRNAs have been shown to be involved in various biological processes, such as development in many animals, including insects; however, to date, no sRNAs have been reported in the citrus red mite. Using Illumina sequencing, several categories of sRNAs were identified, including 594 known micro RNAs ( miRNAs) grouped into 206 families and 31 novel miRNAs in the four developmental stages of citrus red mite. In addition, according to bioinformatics analysis and S- Poly( T) miRNA assays, the expression level of many miRNAs varied among the developmental stages. Furthermore, the prediction of miRNAs target genes and their functional annotation indicated that miRNAs are involved in the regulation of multiple pathways in the citrus red mite. As the first report of the s RNA world in citrus red mite, the present study furthers our understanding of the roles played by sRNAs in the development of citrus red mite and the data may help to develop methods of controlling the pests in the field. [ABSTRACT FROM AUTHOR]

The poultry red mite, Dermanyssus gallinae, is a major pest in egg production, feeding on laying hens. Widely used non-chemical control methods include desiccant dusts, although their persistence under field conditions is often short. Entomopathogenic fungi may also hold potential for mite control, but these fungi often take several days to kill mites. Laboratory experiments were carried out to study the efficacy of 3 types of desiccant dusts, the fungus Beauveria bassiana and combinations of the two control agents against D. gallinae. There was significant synergistic interaction between each of the desiccant dusts and the fungus, with observed levels of mite mortality significantly higher than those expected for an additive effect (up to 38 % higher). Synergistic interaction between desiccant dust and fungus was found also when different application methods were used for the fungus and at different levels of relative humidity. Although increased levels of mortality were reached due to the synergistic interaction, the speed of lethal action was not influenced by combining the two components. The persistence of the control agents applied separately or in combination did not change over a period of 4 weeks. Overall, combinations of desiccant dusts and fungus conidia seem to hold considerable promise for future non-chemical control of poultry red mites. [ABSTRACT FROM AUTHOR]