Rust Mite Research Articles

Acaricide resistance mechanisms and host plant responses in the tomato specialist Aculops lycopersici.

The mite Aculops lycopersici is a major tomato pest with extremely reduced gene families involved in chemoreception and detoxification. How this limited detoxification toolbox affects the evolution of resistance to acaricides in tomato russet mite(s) (TRM) remains enigmatic. Moreover, although a tomato specialist, TRM has been observed on other Solanaceae and Convolvulaceae plant species, raising questions about transcriptional plasticity underlying host exchange. We identified a field strain with strongly decreased susceptibility to both abamectin and spiromesifen. We detected target-site resistance caused by mutations at conserved positions in two glutamate-gated chloride channels (GluCl), as well as four overexpressed detoxification genes. We then examined transcriptional responses after host shift from tomato to two Solanaceae (potato and black nightshade) and two Convolvulaceae (sweet potato and hedge bindweed) species, as more challenging host plants. Transcriptional responses varied significantly between host plant families, with key differentially expressed genes (DEGs) related to proteolytic, metabolic and detoxification processes. Last, we also identified DEGs encoding for secreted proteins potentially involved in TRM-host plant interactions. Despite a limited detoxification toolbox, A. lycopersici might quickly evolve target-site resistance, probably facilitated by strong selection pressure on the genetic variation associated with enormous population size in field settings. Responses to host plant changes include plasticity in genes related to digestion and detoxification, while most responsive genes are of unknown function and remain to be investigated. © 2024 Society of Chemical Industry.

Predatory mites as potential biological control agents for tomato russet mite and powdery mildew on tomato

Predatory mites as potential biological control agents for tomato russet mite and powdery mildew on tomato

OUTCOMES OF PHYTOSANITARY MONITORING IN THE CITRUS PLANTATIONS OF ADJARA-GURIA

Phytosanitary monitoring conducted in 2023 across citrus plantations in the Adjara-Guria region in Georgia indicated an unfavorable situation. The damage caused by mites was particularly severe, with the citrus rusty (silver) mite (Phyllocoptruta oleivorus Ashm.) and the citrus red mite (Panonychus citri McGregor) observed at the highest intensity (3 points). Both old and younger plants were found to be infested by these pests. A widespread distribution of scale insects was also recorded, including the citrus rust mite (P. oleivorus Ashm.), citrus red mite (P. citri McGregor), yellow scale (Aonidiella citrina Coq.), citrus mussel scale (Lepidella beckii Newman), Japanese maple scale (Lopholeucaspis japonica Cockerell), tortoise wax scale (Ceroplastes japonicus Green), wax scale (Ceroplastes sinensis Del Guercio), brown soft scale (Coccus hesperidum L.), cottony camellia scale (Pulvinaria floccifera Westwood), citrus cottony scale (Pulvinaria aurantii Cockerell), citrus whitefly (Dialeurodes citri Ashm.), citrus blackfly (Aleurocanthus woglumi Ashby), woolly whitefly (Aleurothrixus floccosus Maskell), and citrus spiny whitefly (Aleurocanthus spiniferus Quaintance). The citrus blackfly, citrus spiny whitefly, and woolly whitefly were identified as particularly problematic. In Georgia, they are registered as quarantine pests.. KEYWORDS :Citrus, Mites, Monitoring, Pest, Scale insects

Within-plant distribution and rapid assessment of sugarcane rust mite population on sugarcane canopy

Sugarcane rust mite (SRM), Abacarus sacchari, has been recognized in Florida since 1983. However, no detection technique had been developed yet, whereas a reliable, effective, and efficient technique is important in a mite management practice. The purposes of this study were to determine the within-plant distribution and to develop a sampling technique for SRM. The study was carried out in sugarcane fields naturally infested with the mite population. The mite distribution was identified with the visual direct counting technique and the imprinting technique. Subsequently, the effectiveness and reliability of both techniques were evaluated. The results showed that the within-plant distribution of mite populations was more concentrated in the middle canopy than in the upper or lower canopies. Furthermore, the mite sampling of the middle portion of the leaf could represent the entire mite population on the plant. More importantly, the imprinting technique was reliable, especially when the third or fourth (+3 or +4) fully expanded leaf was taken as sample, resulting in relative variation (RV) as low as 12.9% and 12.4%, respectively; therefore, the imprinting technique is a promising technique for population monitoring programs.

Molecular Methods for the Simultaneous Detection of Tomato Fruit Blotch Virus and Identification of Tomato Russet Mite, a New Potential Virus–Vector System Threatening Solanaceous Crops Worldwide

Tomato fruit blotch virus (ToFBV) (Blunervirus solani, family Kitaviridae) was firstly identified in Italy in 2018 in tomato plants that showed the uneven, blotchy ripening and dimpling of fruits. Subsequent High-Throughput Sequencing (HTS) analysis allowed ToFBV to be identified in samples collected in Australia, Brazil, and several European countries, and its presence in tomato crops was dated back to 2012. In 2023, the virus was found to be associated with two outbreaks in Italy and Belgium, and it was included in the EPPO Alert list as a potential new threat for tomato fruit production. Many epidemiologic features of ToFBV need to be still clarified, including transmission. Aculops lycopersici Massee (Acariformes: Eriophyoidea), the tomato russet mite (TRM), is a likely candidate vector, since high population densities were found in most of the ToFBV-infected tomato cultivations worldwide. Real-time RT-PCR tests for ToFBV detection and TRM identification were developed, also as a duplex assay. The optimized tests were then transferred to an RT-ddPCR assay and validated according to the EPPO Standard PM 7/98 (5). Such sensitive, reliable, and validated tests provide an important diagnostic tool in view of the probable threat posed by this virus–vector system to solanaceous crops worldwide and can contribute to epidemiological studies by simplifying the efficiency of research. To our knowledge, these are the first molecular methods developed for the simultaneous detection and identification of ToFBV and TRM.

Pest categorisation of Calepitrimerus baileyi.

The EFSA Panel on Plant Health performed a pest categorisation of Bailey's rust mite, Calepitrimerus baileyi Keifer (Acariformes: Eriophyidae), following the commodity risk assessment of Malus domestica plants from Türkiye performed by EFSA, in which C. baileyi was identified as a pest of possible concern to the European Union. This mite is not listed in Annex II of Commission Implementing Regulation (EU) 2019/2072. The eriophyid is known to occur in Africa, America, Asia, Europe (Greece and Serbia) and Oceania on Malus spp., which is the only confirmed host genus for C. baileyi. Plants for planting of Malus spp. are the main potential pathway for entry into the EU. However, plants for planting of the genus Malus Mill. are considered as high-risk plants (EU 2018/2019) and therefore prohibited from entering the EU unless granted a country-specific derogation. This is the case for the import of Malus spp. plants for planting from Serbia ((EU) 2020/1361 corrected by 2022/1309). Therefore, this derogation could provide a plausible entry pathway for C. baileyi into the EU. Climatic conditions and the ample availability of the host, Malus spp., in the EU are conducive for establishment, as proven by the occurrence of C. baileyi in Greece. However, the species is not reported as having an impact in Greece, despite reports of damage outside the EU. Measures to prevent further entry and spread of C. baileyi in the EU are available. C. baileyi satisfies all the criteria that are within the remit of EFSA to assess for it to be regarded as a potential Union quarantine pest. However, uncertainties about the distribution of C. baileyi within the EU and its impact on apples in the EU are considered key and affect the confidence of conclusions for this categorisation.

Incidence of eriophyid mites (Acariformes: Eriophyidae) and predatory mites (Parasitiformes: Phytoseiidae) in Florida citrus orchards under three different pest management programs.

The abundance and diversity of eriophyid and phytoseiid mites in south and central Florida were assessed in six citrus orchards under three different pest management systems, conventional, organic, and untreated. Tree canopy, ground cover, and leaf litter were sampled every two months in two groves foreach of the three pest management systems from April 2019 to February 2021. The citrus rust mite, Phyllocoptruta oleivora (Ashmead) represented 95 to99% of the rust mites sampledin each grove except in one untreated orchard where it accounted for 45% of the samples (n = 938 total P. oleivora mounted specimens). The pink citrus rust mite, Aculops pelekassi (Keifer) was present in organic and untreated orchards at 5% and 28%, respectively, but absent from conventional orchards (n = 134 total A. pelekassi mounted specimens). Twenty-nine species of phytoseiid mites were identified from 1778 specimens. Thirteen species were present in the canopy, fifteen in the ground cover, and eighteen in the leaf litter with some common species among these habitats. In the tree canopy, Typhlodromalus peregrinus (39%), Euseius spp. (25%), and Iphiseiodes quadripilis (19%) were the dominant species. Typhlodromalus peregrinus (43%), Typhlodromips dentilis (25%), and Proprioseiopsis mexicanus (13%) were the major species in the ground cover. Species richness was lower in organic orchards (3.0) compared to conventional and untreated orchards (5.0 and 4.7, respectively). In the leaf litter, Amblyseius curiosus (26%), Proprioseiopsis carolinianus (15%), Chelaseius floridanus (14%), and Amblyseius tamatavensis (12%) were the most common species. Shannon index was significantly higher in conventional orchards (1.45) compared to organic and untreated orchards (1.02 and 1.05, respectively). Evenness was also higher in conventional orchards (0.86) compared to organic and untreated (0.72 and 0.68, respectively). Finding of several phytoseiids in abundance across pest management programs suggest the need for identifying their role in pest suppression particularly mites.

First Report of Hirsutella thompsonii as an Entomopathogenic Fungus of Hemp Russet Mite (Aculops cannabicola) in Kentucky

Hemp russet mite (HRM, Aculops cannabicola) is one of the most damaging indoor pests of hemp ( Cannabis sativa). In 2021, HRM was identified in hemp research trials at the University of Kentucky. Beginning in September, large numbers of darkened (black/brown), dead HRM were observed on leaves. Fungi resembling Hirsutella thompsonii were isolated from symptomatic HRM. Fungal identity was confirmed by sequencing a fragment of the internal transcribed spacer (ITS) of the rDNA. To validate pathogenicity, HRM-infested hemp leaves were inoculated with H. thompsonii. Infection was confirmed by day 8 of the experiment. Twenty-eight percent of the HRM in the inoculated treatment became black/brown by day 14. Considering limited options for management of HRM on indoor hemp production, further research is warranted to improve understanding of the potential use of H. thompsonii as a management tool.

Field evaluation of the efficacy of copper nanoparticles against mites associated with orange trees.

Phytophagous mites are dangerous pests, causing economic losses to the world's crops. Nanotechnology is a promising field for pests and disease management, and enhancement of agricultural productivity. The aim of the study was to evaluation of the effectiveness of copper nanoparticles (CuNP) against all stages of eriophyid mite, the citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) and tetranychid mite, the citrus brown mite Eutetranychus orientalis (Klein) (Acari: Tetranychidae), and Tenuipalpid mite, the false spider mite, Brevipalpus obovatus Donnadieu (Acari: Tenuipalpidae). This includes its impacts on predacious mites, Amblyseius swirskii Athias-Henriot and Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae), on orange trees under field conditions. Five different concentrations of copper nanoparticles (40, 80, 160, 240, and 320 ppm), as well as the control (well water) were examined. The obtained results indicated that the mortality rate of both phytophagous and predacious mites was associated with an increase in the concentrations of copper nanoparticles. Copper nanoparticles were significantly effective in killing P. oleivora, E. orientalis and B. obovatus with minimal effects on A. swirskii and E. scutalis. The mortality percentage was 15.24, 20.32, 46.32, 78.97 and 86.37% for P. oleivora, 6.87, 9.86, 28.91, 56.30 and 77.52% for E. orientalis and 8.38, 23.50, 48.83, 68.80 and 84.08% for B. obovatus while the mortality percentage was 0.00, 0.56, 5.83, 9.91 and 15.19% for A. swirskii and 0.44, 3.96, 6.93, 8.63 and 21.39% for E. scutalis one week after exposure to 40, 80, 160, 240 and 320 ppm of copper nanoparticles, respectively. Moreover, the results showed that copper nanoparticles caused a reduction in the percentage of eggs hatching. The percentages of larvae hatching from eggs were 96.29, 80.00, 64.13, 45.66 and 32.17% for P. oleivora, 97.38, 83.28, 69.41, 48.01 and 35.29 for E. orientalis and 96.60, 76.92, 56.38, 40.55 and 33.28% for B. obovatus one week after exposure to copper nanoparticles at 40, 80, 160, 240 and 320 ppm respectively, compared with the control (well water). According to the results, the use of copper nanoparticles significant effect on reducing the population of phytophagous mites associated with orange trees, with low detrimental effects on predatory mites.

The predatory mite Pronematus ubiquitus curbs Aculops lycopersici damage under greenhouse conditions.

The tomato russet mite, Aculops lycopersici, is a major worldwide pest infesting tomato crops for which only few control methods are available. At present, no commercialized beneficial organism has proven to be an effective biological control agent of the pest. As there is a strong need to develop alternatives to synthetic insecticides, we assessed the efficacy of an iolinid mite, Pronematus ubiquitus, as a preventive method against A. lycopersici in comparison with a curative treatment in a replicated experiment in the greenhouse. After pre-establishment of P. ubiquitus supplied with cattail pollen, followed by infestation of A. lycopersici, the predator was able to reduce pest populations by 98% as compared with control plants. Probably due to lack of food and high temperature, the number of P. ubiquitus decreased during the season and so the Eriophyid population rose, along with crop damage. The sulphur treatment could stop the progress of A. lycopersici, but their population levels remained high. Pronematus ubiquitus has great potential to prevent the establishment of the tomato russet mite. Even if a curative treatment affects the pest mite, the use of a preventive method is preferable as such insecticides/acaricides are harmful for beneficials and are applied after symptom appearance, when the pest pressure is already high. Despite the need to optimise management of the predator throughout the season, P. ubiquitus proved to be able to establish successfully on tomato plants. © 2023 Society of Chemical Industry.

Occurrence of Tegolophus brunneus and Phyllocoptruta oleivora (Acari: Eriophyidae) on the main citrus belt of Brazil and the differential toxicity of the acaricides to these species.

Many mites of the family Eriophyidae are important pests worldwide. In citrus crops, the eriophyid Phyllocoptruta oleivora stands out for the economic losses caused. The pest's injuries cause the darkening of leaves, twigs, and fruits, making them unfit for the fresh fruit market and affecting plant productivity. Another species that causes similar symptoms was described in Brazil recently, the brown citrus rust mite, Tegolophus brunneus. Although studies have not been performed with this species, growers and technicians have attributed the rise in rust damages in Brazil to T. brunneus, affirming that this mite is more aggressive and resistant to acaricides than P. oleivora. In this study, the distribution of T. brunneus in the main Brazilian citrus belt and the differential toxicity of the acaricides sulfur and abamectin were evaluated for both species. Infested fruits were collected from different orchards in many municipalities, covering the main citrus species and cultivars grown, aiming to show the main T. brunneus hosts. It was observed that only plants of Tahiti acid lime (Citrus latifolia) were infested by T. brunneus, whereas P. oleivora infested all citrus cultivars and species evaluated (Citrus spp.). In our study, T. brunneus and P. oleivora were never observed coinfesting the same fruit/leaf or plant. The acute toxicity test of sulfur and abamectin as acaricides showed that T. brunneus has greater tolerance to abamectin than P. oleivora. However, the acute toxicity of sulfur was similar for both species. These results showed T. brunneus specificity to infest Tahiti acid lime, causing important damage to this crop, and suggest that attention should be paid to managing this mite using abamectin.

Observation and restriction of Aculops lycopersici dispersal in tomato layer cultivation

The tomato russet mite Aculops lycopersici has become a challenging pest in tomato production in the EU. The number of available acaricides is low, and the efficacy of biological control is limited. With this study, we aim to understand better the unhindered dispersal dynamics and develop a method to reduce dispersal on plants.To better understand the dynamics of A. lycopersici dispersal in layered tomato cultivation under practical conditions, a first trial was carried out. The trial confirmed that first A. lycopersici symptoms in practical cultivation usually occur in the lower or the middle third of tomato plants and then move upwards on plants. It was observed that plants, for a limited period of time often are able to grow new healthy leaves in the same pace as existing leaves, mostly in the lower and middle part of the plant are damaged by A. lycopersici. This is possible due to the fast growth rate of hybrid tomato varieties in layer cultivation. To test if the observed effect can be supported by further slowing down the upwards movement of the pest, a second trial was conducted. Here, the stems of inoculated tomato plants were blocked weekly for A. lycopersici by applying a ring of insect glue 15 cm below the tip of the plants. This stem blockage severely impaired the only active dispersal mode of A. lycopersici: walking. The growth of new plant material, when the method is applied, is able to exceed the speed with which A. lycopersici destroys plant material in layered tomato cultivation. This resulted in significantly less plant damage and prevented fruit damage on all treated plants. The approach of manipulating the plant stem and thereby restricting the movement of the mite on tomato plants could potentially be exploited for plant protection purposes under practical conditions.

Modelling the interaction between a pest (Aculops lycopersici), two predators (Pronematus ubiquitus and Macrolophus pygmaeus) and climate variables: a 3-year greenhouse study in a tomato crop.

The tomato russet mite, Aculops lycopersici, is a major pest in tomato crops, causing damage through leaf and stem browning, defoliation and russeting of fruit. Biological control of this mite on tomato plants is difficult. While several phytoseiid mites feed on the pest, they cannot survive, move, or reproduce on tomato plants due to the presence of glandular trichomes. Pronematus ubiquitus has recently been identified as a biocontrol agent of A. lycopersici in tomato crops, but the predator-prey interaction between these two species is not well studied. In this paper, we present a validated logistic regression predator-prey model based on a 3-year study supplemented with additional datasets. Besides the predator and the prey, this model takes into account an extra generalist predator, Macrolophus pygmaeus, and various climate parameters. The population trend of A. lycopersici is best explained by the presence of the predator P. ubiquitus, the relative humidity and the fact that the crop was lit or unlit using artificial light. P. ubiquitus has proved to be an efficient biocontrol agent of A. lycopersici. For P. ubiquitus the presence of M. pygmaeus, the vapour pressure deficit, the number of light hours and radiation explained the population trend best. For both the predator and the prey density-dependent interactions were identified. Model outcomes are discussed in detail. Our study provides insights into the potential use of P. ubiquitus as a biocontrol agent for A. lycopersici in tomato crops in combination with M. pygmaeus. However, we highlight the importance of considering the presence of other predators and environmental conditions when developing integrated pest management strategies. © 2023 Society of Chemical Industry.

Citrus Pest Quick Guide: Citrus Rust Mite and Pink Citrus Rust Mite (Phyllocoptruta oleivora Ashmead) (Aculops pelekassi Keifer)

This publication is a brief description of the life cycle and damage of citrus rust mite and pink citrus rust mite. It is one publication in a series of quick guides to citrus pests. Each fact sheet is designed to be a quick reference of citrus pests for both residential and commercial industry audiences.

Suppression of hemp russet mite, Aculops cannabicola (Acari: Eriophyidae), in industrial hemp in greenhouse and field.

Hemp russet mite, Aculops cannibicola Farkas (Acari: Eriophyidae), is one of the key pests of hemp, Cannabis sativa L. (Rosales: Cannabaceae). Hemp russet mite feeds primarily on new growth and can reach high densities, frequently exceeding a thousand mites per leaf, and leading to a decrease in yield and quality of cannabinoids. The objective of this experiment was to determine the efficacy of reduced-risk pesticides used in organic crop protection as well as conventional insecticides in managing hemp russet mites in a greenhouse and field. Hemp (var. Unicorn) was exposed to leaves heavily infested with hemp russet mites, and once mite densities reached an average of 50 mites per leaf, the following insecticides were applied to the plants: abamectin, etoxazole, fenpyroximate, rosemary oil, and 2 concentrations of a mineral oil. An application of sulfur was also included in the field experiment. Treatments were replicated 9 times in the greenhouse and 6 times in the field. Each of the pesticides significantly reduced hemp russet mite densities in the greenhouse, with all treatments resulting in significant decrease in mite populations 10 days after the initial treatment that persisted until the end of the experiment. On the other hand, only fenpyroximate, sulfur, and rosemary oil provided strong and effective suppression of the mites in the field. This is the first study to test these products against hemp russet mites in hemp, and our outcomes indicate that several pesticides available for organic crop production can provide effective control of the pest.

Development of a real-time PCR assay for detection of hemp russet mite (Aculops cannabicola).

Of the many arthropod species affecting hemp (Cannabis sativa L.) cultivation in the United States, one species of particular importance is the hemp russet mite (Aculops cannabicola, HRM). Hemp russet mite is a microscopic arthropod which feeds on all parts of hemp plants. Due to its minute size, HRM can proliferate undetected for a long time, complicating management efforts and causing serious economic losses. DNA sequencing and PCR assays can facilitate accurate identification and early detection of HRM in infested-plants. Therefore, a real-time SYBR Green based species-specific PCR assay (quantitative PCR, qPCR) was developed for the identification of HRM DNA by amplification of a 104 bp Internal Transcribed Spacer 1 (ITS1) sequence. The detection limit was estimated to be approximately 48 copies of the HRM marker gene sequence. The real-time-PCR assay is rapid, detects all life stages of mite under 2 hours. A 10-fold serial dilution of the plasmid DNA containing the ITS1 insert were used as standards in the real-time PCR assay. The quantification cycle (Cq) value of the assay showed a strong linear relationship with HRM DNA with R2 of 0.96. The assay was tested against several commonly found hemp pests including two-spotted spider mite and western flower thrips to determine specificity of the assay and to show that no non-target species DNA was amplified. The outcomes of this research will have important applications for agricultural biosecurity through accurate identification of HRM, early detection and timely deployment of management tactics to manage and prevent pest outbreaks.

Biology and management of hemp russet mite (Acari: Eriophyidae).

Hemp is rapidly becoming a crop of global agricultural importance, and one of the more serious pests of this crop is hemp russet mite (HRM) Aculops cannabicola (Acari: Eriophyidae). Significant knowledge gaps presently exist regarding critical aspects of pest biology, quantification of crop damage, and efficacy of pesticides. Here we assessed the role of cannabidiol (CBD) on HRM performance, efficacy of sulfur treatments in field trials, and effect of hot water immersion with and without surfactants in reducing HRM counts on hemp cuttings. We found that HRM fecundity was reduced on a high-CBD cultivar compared with a low-CBD cultivar in detached leaf assays. In contrast, HRM fecundity and survival were not impacted when reared on high-CBD diet in artificial feeding assays. This suggests that cannabinoids other than CBD may aid in reduction of mite populations on the high-CBD cultivar. Sulfur sprays reduced HRM populations by up to 98% with the greatest effects seen in plants receiving dual applications, one during the vegetative period in July and the second at the initiation of flowering in August. Yields of plants treated with sulfur increased by up to 33%, and there was a further increase in cannabinoid production by up to 45% relative to untreated plants. Hot water immersion treatments with and without surfactant solution reduced HRM on infested hemp cuttings, and no phytotoxicity was observed. This study provides novel approaches to mitigating HRM at multiple stages in hemp production.

Assessing the impact of piercing-sucking pests on greenhouse-grown industrial hemp (Cannabis sativa L.).

Cannabis sativa or hemp, defined as <0.3% total tetrahydrocannabinol (THC), is a specialty crop in the United States, of particular interest among growers in the southeastern United States to replace tobacco production. Tetranychus urticae (twospotted spider mite), Aculops cannabicola (hemp russet mite), Polyphagotarsonemus latus (broad mites), and Phorodon cannabis (cannabis aphids) are considered the most significant pests in greenhouse grown hemp. Mite and aphid injury can cause cupping and yellowing of leaves, resulting in leaf drop, and reduced flower and resin production. We sought to understand the effects of feeding by T. urticae and Myzus persicae (green peach aphid), as a proxy for P. cannabis, on the concentration of economically significant cannabinoids through a series of experiments on greenhouse grown plants. First, we compared the variability of chemical concentrations in samples collected from individual plants versus pooled samples from 5 plants, and found that chemical concentrations in single plants were similar to those in pooled plant samples. Next, we compared chemical concentrations prior to arthropod infestation and post infestation. When evaluating the mite feeding damage in 2020, cannabinoids in plants infested with high densities of T. urticae increased more slowly than in uninfested control plants or plants infested with low T. urticae densities. In 2021, the concentration of tetrahydrocannabinol did not differ significantly between treatments. Cannabidiol increased more slowly in plants with low T. urticae densities when compared to uninfested controls but did not differ from the high T. urticae densities 14 days after infestation.

Mode of dispersal of the sugarcane rust mite (Abacarus sacchari) in the sugarcane field

ABSTRACT The sugarcane rust mite (SRM), Abacarus sacchari, infests sugarcane in the Everglades Agricultural Area in southern Florida. Reddish-brown symptoms associated with SRM feeding on leaves appear in April and reach their peak in August-September. Mite dispersal plays an important role in habitat colonization. However, SRM dispersal in sugarcane fields has not yet been explored because of its microscopic size. This study aimed to determine the role of aerial dispersal in the colonization of sugarcane fields. Mite dispersal was studied by measuring aerial mites and mite population on the sugarcane canopy with the elimination of possible ambulatory movement among plants. In addition, the potential dispersal using ambulatory movement as well as precipitation was also investigated. The result suggests that aerial dispersal was the most important method for SRM dispersal. Moreover, females predominated airborne mites, comprising approximately 90% of those measured with 60% gravidity. This strong female bias and its high gravidity in airborne mites further demonstrate the potential role of aerial dispersal in the colonization of sugarcane fields.

The toxic effects of some acaricides on the tomato russet mite and its predator Amblyseius swirskii Athias-Henriot, 1962 (Acari: Phytoseiidae)

The tomato russet mite, Aculops lycopersici (Massee, 1937) (Acari: Eriophyidae) is a common pest of tomatoes. The predatory mite, Amblyseius swirskii Athias-Henriot, 1962 (Acari: Phytoseiidae), can control A. lycopersici populations. To integrate biological and chemical control of A. lycopersici, side effects of the lethal concentrations of acaricides, as a predator, on A. swirskii should be considered. The lethal concentrations of 14 acaricides for A. lycopersici were determined under laboratory conditions at Bursa Uludağ University during 2017-2018. To understand the toxic impacts of the acaricides on juveniles and females of A. swirskii, the LC99 values for A. lycopersici of each acaricide were applied to A. swirskii. The reproduction reduction effects of the LC99 values were also assessed. Quite low concentrations of abamectin, milbemectin, pyridaben, azadirachtin and sulphur were found to be toxic for A. lycopersici. Based on the side effect scale, the LC99 values of abamectin, acequinocyl, bifenazate, fenproximate, fenbutatin oxide, hexythiazox, milbemectin and sulphur that killed A. lycopersici were found to be slightly toxic to both females and juveniles of A. swirskii. The results of this comparative toxicological study have showed that more field studies should be conducted to evaluate the effectiveness of using low concentrations of acaricides with A. swirskii in combination for controlling A. lycopersici.