Control Of Two-spotted Spider Mite Research Articles

Grafting increases superoxide dismutase and catalase activity to overcome the impact of the two-spotted spider mite on eggplant growth and productivity

Grafting vegetable crops is considered a valuable tool for improving the yield and quality of fruits under various stress conditions. This study aimed to assess the influence of grafting eggplant Solanum melongena (cv. A338) onto Solanum torvum rootstock (cv. STT3) on the incidence of the two-spotted spider mite Tetranychus urticae (TSSM). An experimental study was conducted to investigate the defense response elicited, as assessed by measuring the activities of antioxidant enzymes like superoxide dismutase (SOD) and catalase (CAT), as well as hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) and chlorophyll contents in grafted and non-grafted eggplants under different TSSM infestation levels (10, 30 and 50 adults per plant). In addition, the effect of grafting on plant growth and yield of eggplant was evaluated. According to the findings of the present study, grafted plants had a lower density of TSSM than non-grafted plants. The number of eggs, nymphs, and adults on grafted plants was 40.11%, 31.71%, and 27.54%, respectively, lower than on non-grafted plants. With increasing TSSM density, the activities of CAT and SOD were increased at varying degrees. In terms of SOD activity, the grafted plants outperformed both the non-grafted scion and rootstock at all TSSM densities. In addition, the results demonstrated that plants with greater CAT activity were able to maintain a lower H<sub>2</sub>O<sub>2</sub> content and vice versa. The lower negative impacts on photosynthetic pigments demonstrated that grafted plants on S. torvum were more resistant to mite-induced damage to chlorophyll and carotenoids as mite density elevated. The grafted plants were superior in vegetative growth, and the total fruit weight was found to be two times higher than non-grafted plants. The features modified by grafting, such as the increased activities of SOD and CAT, can alleviate the impact of TSSM. Therefore, grafting could constitute a valuable tool when combined with other strategies of Integrated Pest Management (IPM) in the two-spotted spider mite control programs.

Beauveria bassiana submerged spores for control of two-spotted spider mite (Tetranychus urticae Koch (Acari: Tetranychidae)): production, stability, and virulence.

In this study, IBCB 66, IBCB 868, and CBMAI 1306 isolates of Beauveria bassiana were grown in liquid culture for 4days, leading to elevated submerged spores (SS) levels. The influence of the addition of different glycerol concentrations (0, 3, and 6%) (v/v) in the liquid culture was investigated regarding the stability (at 4 and 27°C) of dried formulations. The virulence of SS was compared with aerial spores (AS) against Tetranychus urticae (Koch) (Acari: Tetranychidae). The results demonstrate the potential of using SS to control T. urticae. CBMAI 1306 and IBCB 868 isolates caused T. urticae mortality rates of 91.11% and 88.89% 5days after treatment, respectively, when applied at concentrations of 1 × 108 SS mL-1. The median Lethal Time (LT50) values for these strains were 2.64 and 2.61days, respectively. The dried formulations showed potential acaricidal activity. Higher glycerol concentrations in the liquid culture medium reduced formulation stability at 27°C.

Control of two-spotted spider mite, Tetranychus urticae, on strawberry by integrating with cyetpyrafen and Phytoseiulus persimilis

The two-spotted spider mite (TSSM, Tetranychus urticae Koch) is a significant agricultural pest, particularly in strawberries. Management of TSSM has traditionally relied on synthetic acaricides, but to mitigate dependency on these chemicals, the control of TSSM on strawberry is often combined with biological control measures and chemical control strategies. The predatory mite, Phytoseiulus persimilis, is a promising biological control agent, preying on all TSSM developmental stages. In this study, we examined the toxicity of six common acaricides on TSSM and P. persimilis, and cyetpyrafen was selected due to its highest relative toxicity value. Then, we examined the compatibility of cyetpyrafen with P. persimilis for TSSM management on strawberries. The results suggested that cyetpyrafen revealed no substantial differences in prey consumption or longevity when compared to the control, though minor effects on the development durations of protonymphs and deutonymphs were noted in the subsequent generation. Additionally, cyetpyrafen's toxicity on key pollinators, such as Apis mellifera and Bombus terrestris, was found to be low. Thus, an integrated strategy combining cyetpyrafen (0.83 mg/L) with P. persimilis (predator–prey ratio of 1:30) was examined under laboratory and field conditions. Laboratory trials demonstrated a reduction in mites per leaf from 32.72 to 14.50 within 3 days, correlating to a 70.23% control efficiency. This efficacy increased to 96.04% by day 9 and was sustained until the experiment concluded on day 27. Field trials similarly showed a reduction in TSSM from 53.93 to 9.63 mites/leaf by day 6, achieving an 83.64% control efficiency, and culminated in a 98.46% reduction by day 10. These findings suggested that an integrated approach utilizing cyetpyrafen in conjunction with P. persimilis can be an effective alternative for TSSM management on strawberry plants.

Beauveria bassiana (Balsamo) Vuillemin (Deuteromycota: Hyphomycetes) izolatlarının spor süspansiyonu ve kültür filtratının farklı koşullarda Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) üzerindeki etkinliği

Abstract In this study, the effectiveness of Beauveria bassiana (Balsamo) Vuillemin (Deuteromycota: Hyphomycetes) isolates on Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) was determined with Petri and pot experiments in laboratory and climate room conditions by applying spore suspension and culture filtrate in Isparta University of Applied Sciences of in 2022. In the Petri experiment, the spore suspensions (1x106, 1x107, and 1x108 spore/ml) and culture filtrates (1X, 5X, 10X) of BIM-001 and BY2 isolates of B. bassiana were sprayed in the form of mist for 10 seconds at a speed of 3 m/s onto leaf discs in Petri which included ten adult individuals. In the pot experiment, the same treatments were conducted with the same application method in the Petri experiment on single-leaf plants in pots. In the Petri and pot experiments, the difference between the mortality rates in the 108 spore/ml dose of BIM-001 and BY2 (64.00±4.52 and 42.00±2.49%, 58.00±2.91 and 41.00±2.77%, respectively) was significant on the 7th observation day. In the pure culture filtrate treatments, the mortality rates in the BIM-001 and BY2 were 73.00±2.13 - 68.00±3.59% and 60.00±3.65 -57.00±5.17% respectively in the Petri and pot experiments. BIM-001 and BY2 culture filtrate in both Petri and pot experiments (1X) applications were not statistically significant. The BIM-001 isolate of B. bassiana was more effective than the BY2 isolate treatment against adult females of T. urticae both in vivo and in vitro. In conclusion, it is thought that the culture filtrate of B. bassiana BIM-001 isolate is considered to have potential for the control of two-spotted spider mites.

The influence of Ahy1 strain of Acremonium hansfodii on functional response of Neoseiulus barkeri to Tetranychus urticae

The two spotted spider mite (TSSM) Tetranychus urticae is one of the most economically key mite pests of fields and greenhouse crops over the world. In order to clarify the control efficacy of Neoseiulus barkeri on Tetranychus urticae in the presence of entomopathogenic fungus (EPF) Acremonium hansfodii. This study was conducted to evaluate the control of combining N. barkeri with A. hansfodii against T. urticae. The results showed that the functional response of N. barkeri treated with Ahy1 strain to T. urticae was Holling type II equation. Among these, the highest predation number and the shortest attack time were obtained for the predator feeding on eggs, then followed by feeding on nymphs, female adults ranked as the lowest. That of N. barkeri to T. urticae treated with Ahy1 strain was also Holling type II equation. The predation capacity of N. barkeri on nymphs and female adults of T. urticae treated by Ahy1 strain increased with the increase of the concentration of Ahy1 strain, but that when feeding eggs had no significant difference. Therefore, the combination of EPF with N. barkeri on control of TSSM had synergistic effects, which will provide the guidance to carry out combined utilization of entomogenous fungi with predatory mites.

Efficacy of insecticides for control of two-spotted spider mites in strawberries, 2022

Efficacy of insecticides for control of two-spotted spider mites in strawberries, 2022

Evaluation of resistance in 16 eggplant genotypes to the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

With more than 200 host plant species, the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most common and destructive pests of agricultural crops including vegetables, fruits, field crops and ornamentals in both open-field and greenhouse cultivations in Turkey. Control of this pest generally depends on the use of synthetic pesticides. The use of resistant plant varieties in conjunction with other control tactics generates more effective and sustainable results in management of many pests. In the present study, a total of 16 eggplant genotypes, including eight wild sources and eight standard commercial cultivars, were evaluated for the first time using free-choice and bridge test methods for their resistance against this mite under controlled conditions. Resistance was evaluated by counting mites settled on plants of each genotype. Resistance data were calculated by taking mean number (no.) of mites that prefer the plants of susceptible or resistant genotypes at each time interval (1, 3, 5, 7 or 9 days after releasing mites in free-choice tests; 30 min, 1, 2 or 3 h in bridge tests). The results from free-choice tests showed that wild genotype, Solanum sisymbriifolium (from INRA, France) was the most resistant genotype to T. urticae with no settlement of mites per plant both at 7 and 9 days after releasing mites, and followed by two commercial S. melongena genotypes (Topan 374 and Kemer) that had 2.25 and 2.50, 4.25 and 3.50 mites per plant, respectively, on the 7th and 9th days of mite introduction. S. sisymbriifolium was also found to be the most resistant genotype in bridge tests with a mean no. of 13.0 mites per plant. These results can be used for breeding and management purposes for control of two-spotted spider mite.

Control of two-spotted spider mites with neem-based products on a leafy vegetable

Neem-based pesticides can be a valuable tool to control the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), in leafy minor crops that lack pest management options and often have pesticide level residues reported. We evaluated the efficacy of three commercially available neem-based products in controlling T. urticae populations on parsley plants. We calculated the concentration-response curves to evaluate the lethal effect of the products on T. urticae and the population level effects of the products by calculating the instantaneous rate of T. urticae population increase. A bioassay in a greenhouse using potted parsley plants was performed to evaluate product efficacy over time and the evolution of phytotoxicity symptoms. The lethal effects varied among products, indicating that formulation may play a role in product efficacy. All products presented sublethal effects on T. urticae populations, which reduced the mite population. However, product efficiency was below 80% and slight symptoms of phytotoxicity were observed, especially when products were applied at high concentrations. Our study revealed the importance in evaluating several components of botanical pesticide effects besides the lethal effects, and it can be used as a simple framework to select botanical pesticides to be used on minor crops such as parsley.

Lethal and sublethal effects of fluralaner on the two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae).

Two-spotted spider mite (TSSM), Tetranychus urticae Koch is a serious agricultural pest and has developed high levels of resistance to many acaricides. Hence, screening new acaricides is important in the control of TSSM. Fluralaner, a novel isoxazoline, has high activity against agricultural and ectoparasitic pests; however, little information is available about its effects on agricultural mites. Lethal and sublethal effects of fluralaner towards TSSM eggs and female adults were therefore evaluated in this study. Fluralaner exhibited higher activity towards TSSM female adults (LC50 , 0.49 mg L-1 ) compared with commercial acaricides including fenpyroximate, pyridaben and hexythiazox, and also excellent activity towards eggs (LC50 , 0.36 mg L-1 ). The results of a sublethal effect study showed a significant reduction in the duration and fecundity of female adults with increases in the tested concentrations. The net reproductive rate (R0 ) decreased to 67.34 ± 3.96 and 50.29 ± 3.40 offspring per individual in LC10 and LC30 treatments compared with control (108.31 ± 7.61 offspring per individual). The intrinsic rate of increase (r) and finite rate of increase (λ) in the controls (0.30 and 1.36 d-1 ) were significantly higher than in the LC30 treatment (0.25 and 1.29 d-1 ); whereas, they were almost identical to values for the LC10 treatment. No change in mean generation time (T) was observed at sublethal concentrations treatments. Our results demonstrated that fluralaner has high acaricidal activity and could be considered a potential acaricide for TSSM management. © 2019 Society of Chemical Industry.

Evaluation of the daily periodicity of acaricides and inhibition of hatching by spiracle-blocking insecticides for control of two-spotted spider mite (green form)

Evaluation of the daily periodicity of acaricides and inhibition of hatching by spiracle-blocking insecticides for control of two-spotted spider mite (green form)

Plant extracts with potential to control of two-spotted spider mite

ABSTRACT: Tetranychus urticae Koch (Acari: Tetranychidae) is a species of great economic importance to Brazil. In its control, the main option is the use of synthetic miticides, which, if used indiscriminately, can contaminate the environment, farmers and consumers. In the search for control alternatives, this study aimed to evaluate the effect of plant extracts and essential oils on females of this pest. For this, T. urticae females, reared in laboratory, were sprayed in Potter tower. Fourteen plants were tested in the form of aqueous extracts (AE), hydroethanolic extracts (HE) or essential oils (EO). The experimental plot consisted of a Petri dish with a Canavalia ensiformis L. leaf disk containing five T. urticae females, using ten plates per treatment. Mortality evaluations were performed 24, 48, 72, 96 and 120 hours after spraying, recording the number of dead females on the disc and the number of dead females on the moistened cotton. We considered that females found on cotton were repelled by treatments. Matricaria chamomilla L. HE and Pimpinella anisum L. AE have acaricidal effect for females, providing above 83% of mortality, after 120 hours. Origanum vulgare L. HE causes at least 75% mortality after 24 hours. Also 120 hours after spraying, P. anisum HE and O. vulgare AE cause repellency of females above 16%, and A. absinthium HE exceeds 22% for this parameter. The results stimulate further researches to determine the optimum dose and evaluation of additional effects on the fertility of surviving females.

Screening for suitable chemical acaricides against two-spotted spider mites, Tetranychus urticae, on greenhouse strawberries in China

Effective and safe acaricides based on scientific data are needed for that no chemical acaricides has been registered for the control of two-spotted spider mite in strawberry crops in China. To identify suitable acaricides, the efficacy, persistence, and toxicity of eight acaricides (hexythiazox, fenpyroximate, chlorfenapyr, propargite, etoxazole, bifenazate, spirodiclofen, and pyridaben) on greenhouse strawberries were tested. The eight acaricides were ranked, from highest average efficacy at the recommended dosage to lowest, as follows: etoxazole > bifenazate > fenpyroximate > propargite > spirodiclofen > pyridaben > hexythiazox> chlorfenapyr. The average recoveries of the eight acaricides at the spiking levels of 0.05 and 0.5 mg/L ranged from 72.4% to 108.1% (relative standard deviation, 1.3–8.8%). The concentrations of hexythiazox, fenpyroximate, etoxazole, bifenazate, spirodiclofen, and pyridaben at 5 days after application were lower than the maximum residue limits (MRLs) specified by China, the European Union (EU), the Codex Alimentarius Commission, and Japan, but those of chlorfenapyr and propargite residues were 8.8 and 1.9 times higher than the MRLs in the EU. Only propargite posed a high chronic dietary risk to humans. Pyridaben and chlorfenapyr showed unacceptable ecotoxicology risks for honeybees (hazard quotient values of > 50). The recommended acaricides to control spider mites in greenhouse-grown strawberry crops are etoxazole, bifenazate, fenpyroximate, spirodiclofen, and hexythiazox based on the efficacy, persistence and toxicity.

A population growth model of Tetranychus urticae Koch (Acari: Tetranychidae)

Two-spotted spider mite, Tetranychus urticae Koch is a serious pest of different crops over the world. Different strategies are used to regulate the population of this mite. To this end, as a first step, a population growth model has been developed for describing the dynamics of T. urticae population growth. In this regard, the population abundance of T. urticae was estimated weekly from 29 June to 29 September 2016 at two bean fields, each field was planted with Goli and Akhtar cultivars, separately. During each sampling period in each field, 30 plants were randomly chosen and a leaf was selected as a sample unit from the middle of a plant, then a simple population growth model was constructed for T. urticae on two bean cultivars. The result showed that T. urticae had a distinct seasonal pattern of abundance but differed between two cultivars. A logistic growth model was developed based on relationship between the cumulative density of T. urticae and time (day) and demonstrated high prediction capability for T. urticae population on Goli (R 2 = 0.99) and Akhtar (R 2 = 0.99) cultivars. According to the logistic equation, carrying capacity was recorded 463.9 ± 9.73 (mite/leaf) and 59.67 ± 8.72 (mite/leaf) on Goli and Akhtar cultivars, respectively. Furthermore, it has been shown that the logistic growth model can be used to make population predictions. The model parameters estimated for two different cultivars, providing a new mathematical tool for ecologists to predict two-spotted spider mite outbreaks, and ultimately to develop effective two-spotted spider mite control strategies.

Exploring virulence of new and less studied species of Metarhizium spp. from Brazil for two-spotted spider mite control.

The two-spotted spider mite Tetranychus urticae is an important pest of strawberry crops in Brazil and many other countries. Focus for biocontrol studies involving entomopathogenic fungi has been on three species from the genus Metarhizium: M. anisopliae sensu stricto (s.s.), M. brunneum and M. robertsii. Also, the species Beauveria bassiana has been studied for spider mite control and one isolate (ESALQPL63) is commercially available in Brazil. New and undescribed Metarhizium species have been found recently in Brazil and provide a pool of isolates with potential for biocontrol in Brazil and probably also elsewhere. The mortality of adult females of T. urticae when exposed to four new Brazilian species of Metarhizium was compared to the mortality when exposed to M. anisopliae s.s., M. brunneum, M. pingshaense, M. robertsii and Beauveria bassiana ESALQPL63. Fungal suspensions were sprayed onto mites at 107 conidia/mL with 0.05% Tween 80 in laboratory bio-assays. We measured total mortality and percentage sporulating cadavers 10days after exposure and calculated median lethal time (LT50). The lowest LT50 (4.0±0.17) was observed for mites treated with Metarhizium sp. Indet. 1 (ESALQ1638), which also performed well with respect to mortality after 10days and capacity to sporulate from cadavers. Among the other little studied species tested, M. pingshaense (ESALQ3069 and ESALQ3222) and Metarhizium Indet. 2 (ESALQ1476) performed well and were comparable to B. bassiana (ESALQPL63). The new Metarhizium isolates and species thus showed potential for biological control.

Optimization of spray deposition and Tetranychus urticae control with air assisted and electrostatic sprayer

Improved spray deposition can be attained by electrostatically charging spray droplets, which increases the attraction of droplets to plants and decreases operator exposure to pesticide and losses to the environment. However, this technique alone is not sufficient to achieve desirable penetration of the spray solution into the crop canopy; thus, air assistance can be added to the electrostatic spraying to further improve spray deposition. This study was conducted to compare different spraying technologies on spray deposition and two-spotted spider mite control in cut chrysanthemum. Treatments included in the study were: conventional TJ 8003 double flat fan nozzles, conventional TXVK-3 hollow cone nozzles, semi-stationary motorized jet launched spray with electrostatic spray system (ESS) and air assistance (AA), and semi-stationary motorized jet launched spray with AA only (no ESS). To evaluate the effect of these spraying technologies on the control of two-spotted spider mite, a control treatment was included that did not receive an acaricide application. The AA spraying technology, with or without ESS, optimized spray deposition and provided satisfactory two-spotted spider mite control up to 4 days after application.

Two-Spotted Spider Mite Control on Tart Cherry, 2016*

Two-Spotted Spider Mite Control on Tart Cherry, 2016*

Relative Toxicity of Fenazaquin Against Two-Spotted Spider Mite on Okra

Continuous use of previous generation acaricides in okra [Abelmoschus esculentus (L.) Moench] has increased resistance to pesticides and pest resurgence. The project was undertaken to evaluate a new acaricide, fenazaquin 10 EC, for effective control of two-spotted spider mites [Tetranychus urticae Koch (Acari: Tetranychidae)] in pot culture and under field conditions. Fenazaquin was used at 75, 100, 125, or 150 g·ha−1 a.i. and compared with the standard acaricide dicofol 18.5 EC at 250 g·ha−1 a.i. and an untreated control. The adulticide bioassay, ovicidal action to T. urticae and safety of Dwarf honey bees (Apis florea Fabricius), was performed under laboratory conditions. Pot culture and two field trials were conducted to evaluate efficacy. Impact on okra yield and phytotoxicity were determined. The LC50 was 1.440 mg·L−1 and LT50 at 1.50 mg·L−1 was ˜8 hours. Fenazaquin produced more than 70% egg mortality in all doses for T. urticae. Fenazaquin at 125 and 150 g·ha−1 a.i. caused the highest reduction in numbers of mites in pot culture and field experiments. Fruit yields (9.89 Mt·ha−1, 10.59 Mt·ha−1) and cost–benefit ratio (1:3.25, 1:3.48) were higher in fenazaquin-treated plants at 150 g·ha−1 a.i in field experiments. No test doses were phytotoxic and all doses were relatively safe to Dwarf honey bees.

Effects of soft soap and abamectin on the two spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) and predatory mite Phytoseiulus persimilis A-H (Acari: Phytoseiidae) under laboratory conditions

Soft soap at three dosages (3 ml/L, 5 ml/L and 7 ml/L) and abamectin (12.5 mg/100L) were applied to bean plants determine their residual effects on the predatory mite, Phytoseiulus persimilis A-H (Acari: Phytoseiidae) later released for the control of the two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions. The contact toxicity of soft soap and abamectin were evaluated and classified according to IOBC(International Organization for Biological Control) standards. The soap at 3 ml/L and 5 ml/L did not supress TSSM populations and could not provide satisfactory control when compared with soap at 7ml/L and abamectin. The efficacy of soap at 5 ml/L with P. persimilis gave sufficient control of TSSM when compared with soap at 3 ml/L with P. persimilis, and the predator alone. Both the soap at 7 ml/L and abamectin in combination with the predatory mite gave satisfactory control of TSSM ,but in the abamectin treatment, the predatory mite population was not observed due to harmful effects of abamectin. However, use of soft soap at suitable dosage, with or without predatory mite, gave encouraging results for controlling TSSM but was moderately toxic at 5 ml/L and 7 ml/L P. persimilis in contact toxicity testing by causing 50.0 % and 42.3 % mortality, respectively, to adulst of P. persimilis. In addition, abamectin at 12.5 and 25 mg/L (ppm) dosages was evaluated as harmful (T) to adults of P. persimilis. Separately, soft soap caused no phytotoxicity to host plants. However, its phytotoxicity needs to be further investigated under greenhouse and field conditions.

Life table parameters of Phytoseius plumifer (Phytoseiidae) fed on two-spotted spider mite at different constant temperatures

The life table parameters of Phytoseius plumifer Canestrini & Fanzago fed on corn pollen and nymphal stages of Tetranychus urticae Koch were determined at eight constant temperatures (10, 15, 20, 25, 27, 30, 35 and 40 ± 1°C), 50 ± 5% relative humidity and a photoperiod of 16:8 h (L:D). Fifty 1-day-old eggs of P. plumifer were kept individually in a growth chamber at each temperature and all events were recorded daily for all immature and adult stages. Adult female longevity decreased from 73.42 days at 15°C to 34.73 days at 35°C. The net reproductive rate (R 0) increased with increasing temperature from 15°C (8.70 females/female) to 27°C (29.6 females/female) and then decreased noticeably. The values of the intrinsic rate of increase (rm ) and finite rate of increase (λ) were recorded to be highest at 30°C (0.257 day–1 and 1.29 day–1, respectively), which decreased at 35°C (0.244 day–1 and 1.28 day–1, respectively). The mean generation time (T) decreased significantly with increasing temperature from 15°C (48.75 days) to 35°C (11.02 days). The shortest doubling time (DT) was observed at 30°C (2.69 days). The highest and lowest values of total fecundity were obtained at 25°C (49.10 eggs/female) and 35°C (19.71 eggs/female), respectively. Our findings revealed that the examined population of P. plumifer can develop and reproduce under a wide range of temperatures (15–35°C), but its potential for control of two-spotted spider mite in the field has yet to be determined.

Interaction Between Beneficial Organisms in Control of Spider Mite Tetranychus Urticae (Koch.)

Strict regulations limiting the availability of synthetic pesticides on vegetable crops in greenhouses have created a new challenge for plant protection. Many pests such as whiteflies, thrips aphids, spider mites, and other, still remain dangerous and difficult to control on vegetable crops in greenhouses. In the experience of many and in a review of world literature, it has been noted that effective methods of biological control of many pests are already available, or can be easily adapted for practice. According to the Polish Directives, biological methods should be used prior to any application of chemical products. Thus, biological control is a priority in plant protection, especially for vegetable crops in greenhouses. Tetranychus urticae is the most important pest in greenhouse crops. Successful control of this pest is very difficult. In laboratory studies the predator mites Amblyseius swirskii and Phytoseiulus persimilis showed a high efficacy when used together to control of two-spotted spider mites (86% mortality). When predators were used separately they were less effective against the pest (about 63% mortality). The studies showed that A. swirskii was competitive with P. persimilis populations for controlling the two-spotted spider mite. Other predators mites: Amblyseius degenerans and Amblyseius californicus used in the experiments demonstrated neutral interaction.