Tetranychus urticae

Beauveria bassiana colonizes insect hosts initially through a yeast phase, which is common in some artificial liquid cultures, but not reported on artificial solid media. We describe a yeast-like phase for B. bassiana isolate 447 (ATCC 20872) on MacConkey agar and its virulence toward Diatraea saccharalis and Tetranychus urticae. The yeast-like cells of B. bassiana developed by budding from germinating conidia after 24-h incubation. Cells were typically and fungal colonies were initially circular and mucoid, but later were covered with mycelia and conidia. Ability to produce yeast-like cells on MacConkey medium was relatively common among different B. bassiana isolates, but growth rate and timing of yeast-like cell production also varied. Metarhizium anisopliae and Paecilomyces spp. isolates did not grow as yeast-like cells on MacConkey medium. Yeast-like cells of B. bassiana 447 were more virulent against D. saccharalis than conidia when 107 cells/ml were used. At 108 cells/ml, the estimated mean survival time was 5.4 days for the yeast suspension and 7.7 days for the conidial suspension, perhaps due to faster germination. The LC50 was also lower for yeast than conidial suspensions. Yeast-like cells and conidia had similar virulence against T. urticae; the average mortalities with yeast-like cells and conidia were, respectively, 42.8 and 45.0%, with 107 cells/ml, and 77.8 and 74.4%, with 108 cells/ml. The estimated mean survival times were 3.6 and 3.9 for yeast and conidial suspensions, respectively. The bioassay results demonstrate the yeast-like structures produced on MacConkey agar are effective as inoculum for B. bassiana applications against arthropod pests, and possibly superior to conidia against some species. Obtaining well-defined yeast phase cultures of entomopathogenic hyphomycetes may be an important step in studies of the biology and nutrition, pathogenesis, and the genetic manipulation of these fungi.

From 1995 to 1999, four experiments were conducted on greenhouse roses to assess the effectiveness of the nC24 petroleum spray oil (PSO), D-C-Tron Plus, against two-spotted mite, Tetranychus urticae Koch (Acarina: Tetranychidae), and to determine how the oil could be most efficiently and effectively used in combination with the predatory mite Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae) in an integrated pest management program. The results showed that 0.5% PSO applied fortnightly to roses gave excellent protection from T urticae infestation when the mite population was not already established. However, PSO applied after roses were infested with T. urticae above the economic threshold only stabilised populations without reducing them below that threshold. Populations of P. persimilis in the upper and lower canopies were unchanged after two sprays of PSO at 7-day intervals, and application of PSO to the upper canopy was as effective in controlling T. urticae in the p...

The spider mites Tetranychus urticae Koch and Tetranychus evansi Baker and Pritchard are important pests of horticultural crops. They are infected by entomopathogenic fungi naturally or experimentally. Fungal pathogens known to cause high infection in spider mite populations belong to the order Entomophthorales and include Neozygites spp. Studies are being carried out to develop some of these fungi as mycoacaricides, as stand-alone control measures in an inundative strategy to replace the synthetic acaricides currently in use or as a component of integrated mite management. Although emphasis has been put on inundative releases, entomopathogenic fungi can also be used in classical, conservation and augmentative biological control. Permanent establishment of an exotic agent in a new area of introduction may be possible in the case of spider mites. Conservation biological control can be achieved by identifying strategies to promote any natural enemies already present within crop ecosystems, based on a thorough understanding of their biology, ecology and behaviour. Further research should focus on development of efficient mass production systems, formulation, and delivery systems of fungal pathogens.

Ethanolic extract of Mentha pulegium was evaluated against the adults of important arthropod pest species, the two-spotted spider mite, Tetranychus urticae. Potential acaricidal impact of plant was determined by contact application. Phytotoxicity was recorded after 24 h. The value of LC50 was 59,149 mg L−1. Also, LT50 values were 27.42, 25.56 and 19.79 h for 35,000, 50,000 and 100,000 mg L−1, respectively. Also, results showed that this ethanolic extract had impact on repellency of T. urticae. All of the tested concentrations were similar in the repellency test. On the other hand, the used concentrations (1000, 4000, 6000 and 8000 mg L−1) affected on the oviposition of mite females. These extract doses significantly decreased the egg laying on the treated surface. The current study indicated that this ethanolic extract can be used as a safe acaricide on T. urticae.

Dispersal behaviors of phytoseiid and tetranychid mites are key factors in understanding predator-prey dynamics and biological control of pest mites at different spatial levels in agricultural and natural ecosystems. In this review, ambulatory and aerial dispersal of both mite groups are discussed at spatial levels of leaf, plant, crop and region. Emphasis is on dispersal of phytoseiids, and specifically, the specialist-predator, Neoseiulusfallacis (Garman), and two-spotted spider mite prey, Tetranychus urticae (Koch). Dispersal aspects that are discussed are ambulation on a leaf; plant or in a prey patch; aerial dispersal between plants; behavior and aerodynamics of aerial take-off; modeling vs. monitoring of dispersal distance; fates of dispersing mites that land on soil substrates; plants as take-off platforms and landing targets for dispersers; and regional dispersal patterns and integrated mite management.

Internet of things (IoT) technology declared its effects in agriculture generally and for pests’ control specifically. IoT is able to do many tasks in greenhouses which were infested with the two-spotted spider mite, Tetranychus urticae. The full automated system depended on the wireless protocol that used sensors, Arduino, geographic information system (GIS), global system for mobile communication (GSM), etc., for data collection, processing, and others. It could be effective for pest monitoring, then data transference and finally decisions related to the activation of the distinctive procedure automatically. Such technology can direct even light or sound or both to let particular predator come and victual its prey with little efforts than occurred in control. Drone with light emitting diodes (LEDs) caused more than 90% reduction of infestation with most used colors by attracting specific predators to both exposed types, green and red, of T.urticae. Also but with little difference, recorded voices of adult females of T.urticae in the case of high infestations, showed their effectiveness to attract predators to cause reduction with about 80%. In other words, the precision agricultural system is so close for being applied to control mites through IoT as an advanced technology in both open fields and greenhouses successfully.

Background and Objectives: Tetranychus urticae is a pest but also a resource of bio-nanoparticles which could be used as an effective biocide. The aim of this study was to biosynthesize silver nanoparticles (AgNPs) by Tetranychus urticae against Spodoptera littoralis. Materials and Methods: Biosynthesized silver nanoparticles (AgNPs) which coated by biogenic amines resulted from exploded mite’s bodies were able to control the cotton leafworm, Spodoptera littoralis under laboratory conditions. Results: Bio AgNPs caused mortality with 91.24 and 83.77% in case of treated 2nd and 4th larval instars in comparison with control 10.39 and 7.02%, for the same previous arrangement. While, malformation was appeared clearly in the metamorphosis stage to pupal stage after alive treated larvae. Subsequently, oxidative stress was increased and indicating that reactive oxygen scavengers were reduced drastically in interaction effectively with induced treatments. Conclusion: Current research is a novel trend to control pest by another pest which could present bio AgNPs as a biocide and also cause malformation.

Spider mites are serious pests on many economically important plant species, because they may reduce plant productivity and, at high mite densities, overexploit and even kill the host plants. We have conducted a series of greenhouse experiments to quantify the effects of two-spotted spider mites (Tetranychus urticae) on host plants (Phaseolusvulgaris). The average amount of chlorophyll per cm2 leaf area was used as a measure of plant condition. It was shown that chlorophyll concentration decreases with plant age and intensity of spider mite feeding. Damage caused by spider mites was assessed visually, using the Leaf Damage Index (LDI) defined by, and a mathematical relationship between the visual measurements and the amount of chlorophyll/cm2 was fitted to data. The relationship may serve as a short-cut to estimate overall plant injury, expressed as the relative loss of chlorophyll/cm2 leaf area caused by spider mites (D). D takes values between 0 (no injury) and 1 (all leaves dead). A highly significant positive relationship between the instantaneous spider mite density and D was found, even though D is expected to reflect the cumulated density of mites (mite-days). A model of plant growth incorporating information about plant age and D predicts that plant area has a maximum when plant age is about 60 days, and that plant area decreases exponentially with an increase in D.

The novel method to produce green silver nanoparticles by Tetranychus urticae was depicted to provide new biocides. It was started by the exposure of adult females of T. urticae to little amounts of silver nitrate AgNO3.Then, table-salt, sodium chloride, was used as an intermediate compound to produce biological spherical silver nanoparticles (AgNPs) by mites. Coating with biogenic amines released from exploded T.urticae was detected by monoamine oxidase interaction. Then, such a structure played an important role to penetrate the integument of exposed T.urticae easily. Bio-nanoparticles of silver produced from the green form of T.urticae, which caused certain mortality percentages over 97% against the same species, while they were more than 90% against the red form of T.urticae. In the same trend, the bio product from the red form of T.urticae, caused mortality over 88% and 94% in the case of treatments against green and red T.urticae forms, respectively. Consequently, determined LC50s of bio AgNPs from green against both forms were 20.58 and 31.81 μLL¯¹ while they were 29.24 and 58.35 μLL¯¹ of bio AgNPs from red T.urticae and against the same arrangement of morphs. Therefore, AgNPs resulted from the green form of T.urticae, caused sterility with 91.21% and 86.07 % in case of treatments against T.urticae green and red forms, respectively. Also, AgNPs from the red form of T.urticae, caused sterility with 88.68% and 94.21 % in case of treatments against the same arrangement of morphs, in comparison with control. Revealed data showed that oxidative stress interacted effectively by increase with induced treatments. Reactive oxygen scavengers (ROS) were significantly lower than control (P < 0.05). To conclude, the new trend to produce bio AgNPs by mite against the same pest presented a cheap, simple and ecofriendly method to expand the use of nanoparticles in the plant protection field.

Tetranychus urticae is the main pest rapidly developing resistance to chemical acaricides used to treat tomato
(Lycopersicon esculentum) in the Far North Region of Cameroon. In an effort to develop an alternative tomato
production strategy, a survey was undertaken on 100 producers to collect information on this crop and field
experimentation to determine the effectiveness of the powder of neem seeds was performed. The results show that 63.2% of producers recognize tomato pests. Mites are the most important followed by whiteflies. Producers protect their culture with chemical pesticides (70%) or with available products: soap (26%); cow urine (30%). 82% use the neem seed to treat tomato crops. Treatment with neem seed powder shows that it improves the development of tomato (P > 0.05) and fruit yield (977 fruit) compared to the control (514 fruit), although it remains below the treatment with chemical acaricide Acarius (1464 fruits). Neem seed powder effectively protects tomato against T. urticae. Get more articles at: http://www.innspub.net/volume-7-number-2-august-2015-ijaar/

The study was carried out to assess the efficacy of Oberon 22.9% (spiromesifen) SC against okra red spider mite at surrounding area of PAU Regional Research Station Gurdaspur. The efficacy of Oberon 22.9% @ 250, 375 & 500 ml was compared along with earlier recommended insecticide Rogor 30 EC @ 675 ml per hectare. The results revealed that all the insecticidal treatment significantly decreased the mite population (1.41 to 2.04 mites/2 cm2 leaf area) as compared to control (21.01mites/2 cm2 leaf area) fourteen days after spray. But Oberon 22.9% @ 500 ml/ha showed high performance with least mite population (1.41) and it was par with its median and lowest doses with mite population (1.71 & 1.93) and Rogor 30 EC (2.04). The maximum fruit yield (100.42 q/ha) was recorded with highest dose of Oberon. All the acaricidal treatments under present study had no any significant impact on population of natural enemies of red spider mite.

Recent studies have reported an increased prevalence of respiratory symptoms among farm workers. The aim of this study was to identify risk factors associated with spider mite allergy among table grape farm workers. A cross-sectional study of 207 workers in table grape farms was conducted. Skin prick tests used extracts of 8 common aeroallergens, grape mould (Botrytis cinerea) and Tetranychus urticae. Specific IgE to T. urticae was quantified using ImmunoCAP (Phadia). Erythrocyte cholinesterase levels were determined using the Test-mate ChE Cholinesterase Test System (model 460). The average duration of employment of workers was 10 years and 12% were pesticide crop sprayers. Work-related wheeze (26%), ocular-nasal (24%) and urticaria/skin symptoms (14%) were more prevalent in the orchards. The prevalence of sensitization (skin prick test) was highest to T. urticae (22%) followed by house dust mite (16%), with 25% being atopic. The prevalence of allergy to T. urticae (skin reactivity...