Abundance Of Spider Mites Research Articles

Determination of spider mite abundance in soil of field-grown cucumbers and in plants under predatory mite pressure in invasive infestations using HRM real-time PCR assay

The two spotted spider mite, Tetranychus urticae Koch L. (Acari: Tetranychidae), is a plant pest that can lead to severe economic losses in open field cucumber cultivation. Between 2017 and 2019 we studied the abundance of spider mites in the soil to estimate the potential infestation pressure of soil colonizing spider mites. The spider mites were heterogeneously distributed in small concentrations in the soil. Soil colonizing spider mites did not affect spider mite abundance on plants and reversed. We observed that spider mite migration occurred primarily from the edge of the field adjacent to the weed strip. In 2020 and 2021, we investigated the efficacy of the predatory mite Neoseiulus californicus (McGregor) for suppressing spider mite hotspots in the cropland. We compared untreated spider mite hotspots with N. californicus treated hotspots and showed that a single release of predatory mites could result in a high level of control when spider mite infestation density was initially high. With this study, soil can be ruled out as a habitat for spider mites, and attention to spider mite pest control can be directed to plant infestations. The highly sensitive HRM real-time PCR assay was used for the quantification of the spider mites.

Intercropping With Fruit Trees Increases Population Abundance and Alters Species Composition of Spider Mites on Cotton.

With the recent increase in planting of fruit trees in southern Xinjiang, the intercropping of fruit trees and cotton has been widely adopted. From 2014 to 2016, a large-scale study was conducted in Aksu, an important agricultural area in southern Xinjiang, to compare the abundance and species composition of spider mites in cotton fields under jujube-cotton, apple-cotton, and cotton monocrop systems. The abundance of spider mites in cotton fields under both intercropping systems was generally higher than in the cotton monocrop. The species composition of spider mites also differed greatly between cotton intercropped with apple or jujube compared to the cotton monocrop. The relative proportion of Tetranychus truncates Ehara (Acari: Tetranychidae) in the species complex generally increased while that of another spider mite, Tetranychus dunhuangensis Wang (Acari: Tetranychidae), decreased under fruit tree-cotton systems. More attention should be paid to the monitoring and management of spider mites, especially T. truncates in this important region of China.

Effect of Drive Row Ground Covers on Hop (Rosales: Cannabaceae) Yard Arthropod Pests in Vermont, USA.

Alternatives to pesticides are necessary for the management of hop (Humulus lupulus L.) arthropod pests. The three major arthropod pests in northeastern US hop production include two-spotted spider mite, Tetranychus urticae Koch, hop aphid Phorodon humuli (Schrank), and potato leafhopper, Empoasca fabae Harris. This 3-yr study (2012-2014) in Vermont investigated the effect of flowering ground covers on arthropod pest abundance. Hop cultivars 'Nugget' and 'Cascade' were evaluated under a strip-split plot experimental design. Ground cover treatments included 1) Control: mowed red clover (Trifolium pratense) and resident weeds, 2) Clover: red clover, and 3) Diverse: common yarrow (Achillea millefolium), beebalm (Monarda fistulosa), red clover, and annual sunflower (Helianthus annuus). Natural enemies were grouped by associated pest and indicated by our mixed model to be strong predictors of the number of hop aphid and potato leafhopper on hop plants. In year two, ground cover treatment had a significant effect on two-spotted spider mite abundance where fewer two-spotted spider mite were observed on hop plants in Diverse plots. The established, un-mowed Clover treatment was preferred by potato leafhopper over Diverse ground cover and hop plants. This revealed the potential for clover ground cover to serve as a trap crop for potato leafhopper management in northeastern hop yards. Our findings are evidence that ground covers implemented for conservation biological control may serve more specific pest management functions instead of or in addition to boosting top-down pest pressure.

Effect Of Agrotechnical Measures And Varieties On Seasonal Dynamics Of Tetranychus Urticae Koch (Acari, Trombidiformes, Tetranychidae) On High Tunnel-Cultivated Garden Strawberries

Abstract The aim of the present study was to determine the seasonal pattern of two-spotted spider mite Tetranychus urticae on strawberries cultivated in polythene-covered high tunnels in temperate climatic conditions. Various cultivars were used and the effect of modification of plant covering indices on abundance and incidence of these mites was also tested. The number of two-spotted spider mites was relatively low at the beginning of the vegetation season and started to increase when average air temperature rose above 20 to 25 °C. In the experiment two types of tunnels differing in additional plant cover were used. The maximum mite abundance did not significantly vary between varieties in tunnel 1 conditions, but it was significantly lower for variety 'Sonata' in tunnel 2 conditions. Mite numbers significantly declined after strawberry foliage mowing and removal of polythene cover. Mite development was prolonged in tunnel 1, where additional cover of plants was used and higher early season air temperature was recorded in comparison to tunnel 2. It was concluded that increase in early season temperature can increase two-spotted spider mite abundance and have a more negative effect on strawberry plants in respect of foliage damage by mites.

Bahasa Indonesia

Red spider mite Tetranychus sp. is one of the most important pests attacking leaves of Jatropha curcas. The objective of this study was to elucidate life history parameters and abundance of spider mite on two J. curcas cultivars. Field studies were carried out in BALITTRI Pakuwon Sukabumi, and laboratory experiments were conducted at the Department of Plant Protection, Bogor Agricultural University, from June to November 2008. Cultivars significantly affected several life history parameters of the spider mite. Spider mite reared on IP1-P cultivar have longer oviposition period and higher fecundity than those on IP2-P (7.00 days and 25.56 eggs against 5.00 days and 10.00 eggs). The sex ratio of spider mite was 3.2 : 1 on IP1-P and 2.5 : 1 on IP2-P. Intrinsic rate of increase was also higher on IP1-P. However, field studies indicated that the spider mite were less abundant on this cultivar. These might be due to the presence of other arthropods which were higher on IP1-P. In general, the highest population of spider mite occurred in August and the lowest in October–November. Predatory mite Family Phytoseiidae was found associated with spider mite, however its role as natural control agent was not significant.

Population Density and Phenology ofTetranychus urticae(Acari: Tetranychidae) in Hop is Linked to the Timing of Sulfur Applications

The twospotted spider mite, Tetranychus urticae Koch, is a worldwide pest of numerous agronomic and horticultural plants. Sulfur fungicides are known to induce outbreaks of this pest on several crops, although mechanisms associated with sulfur-induced mite outbreaks are largely unknown. Studies were conducted during 2007-2009 in Oregon and Washington hop yards to evaluate the effect of timing of sulfur applications on T. urticae and key predators. In both regions, applications of sulfur made relatively late in the growing season (mid-June to mid-July) were associated with the greatest exacerbation of spider mite outbreaks, particularly in the upper canopy of the crop. The severity of mite outbreaks was closely associated with sulfur applications made during a relatively narrow time period coincident with the early exponential phase of spider mite increase and rapid host growth. A nonlinear model relating mean cumulative mite days during the time of sulfur sprays to the percent increase in total cumulative mite days (standardized to a nontreated plot) explained 58% of the variability observed in increased spider mite severity related to sulfur spray timing. Spatial patterns of spider mites in the Oregon plots indicated similar dispersal of motile stages of spider mites among leaves treated with sulfur versus nontreated leaves; however, in two of three years, eggs were less aggregated on leaves of sulfur-treated plants, pointing to enhanced dispersal. Apart from one experiment in Washington, relatively few predatory mites were observed during the course of these studies, and sulfur-induced mite outbreaks generally occurred irrespective of predatory mite abundance. Collectively, these studies indicate sulfur induces mite outbreaks through direct or indirect effects on T. urticae, mostly independent of predatory mite abundance or toxicity to these predators. Avoidance of exacerbation of spider mite outbreaks by sulfur sprays was achieved by carefully timing applications to periods of low spider mite abundance and slower host development, which is generally early to mid-spring for hop.

Seasonal abundance of spider mite <i>Tetranychus urticae</i> Koch on vegetable and ornamental plants in Rajshahi

The seasonal abundance of spider mite T. urticae on twenty vegetable and twenty four ornamental plants in Rajshahi was conducted during August 2010 to January 2011. The mite was present on joscpks coat, kathua, lady’s finger, cucumber, brinjal, tomato, bottle gourd, bean, loofah, spinach, bitter melon, pointed gourd, radish, and cowpea but no mite was recorded on other six plants. But all the ornamental plants bagan-bilash, bottlebrush, nayantara, morog-jhuti, hasnahena, chandramallika, dalia, krisno-chura, togor, joba, madhobilata, rongon, beli, daisy, sondhamaloti, kamini, musanda, rakto-karobi, shewli, kath-golap, rajanigandha, golap, ganda, zinia contained mites. The pick population was prevailed during August. The increase of mite number is directly related with the increase of temperature. DOI: http://dx.doi.org/10.3329/ujzru.v30i0.10745Univ. j. zool. Rajshahi Univ. Vol. 30, 2011 pp. 37-40

Effects of Imidacloprid on Spider Mite (Acari: Tetranychidae) Abundance and Associated Injury to Boxwood (Buxus spp.)

Boxwoods are one of the most widely used woody shrubs in managed landscapes, but they suffer frequent attack by the boxwood leafminer (Monarthropalpus flavus). The neonicotinoid insecticide imidacloprid is highly efficacious in reducing the abundance of M. flavus when applied as a foliar spray or a soil drench. Recent reports of elevated populations of spider mites following applications of imidacloprid to other species of woody plants prompted an investigation to determine the effects of imidacloprid on abundance of a specialist spider mite, Eurytetranychus buxi, and the resultant damage it causes. Boxwoods treated with imidacloprid housed significantly more E. buxi and sustained more discoloration than untreated boxwoods. Moreover, there was a direct relationship between the abundance of E. buxi and the amount of associated injury. Arborists and landscape managers should be aware of the potential for elevated abundance of spider mites on boxwoods and greater levels of discoloration following applications of imidacloprid.

Reducing Fertilization for Cut Roses: Effect on Crop Productivity and Twospotted Spider Mite Abundance, Distribution, and Management

Fertilization reduction could be a useful pest management tactic for floriculture crops if it reduced pest populations with little loss in crop yield and quality. We evaluated the response of the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), to different fertilization levels for cut roses, Rosa hybrida L. 'Tropicana' and quantified fertilization effects on (1) management of T. urticae on roses, (2) abundance and distribution of T. urticae on roses, and (3) yield and quality of the cut rose crop. We tested two fertilization levels, 10% (15 ppm N) and 100% (150 ppm N) of the recommended level for commercial production, and three control methods: no control measure; a predatory mite, Phytoseiulus persimilis Athias-Henriot; and a miticide, bifenazate. Combinations of both bottom up (fertilization) and top down (biological or chemical control) tactics provided a greater degree of T. urticae control than either tactic alone. Rose productivity was reduced with fertilization at 10% of the recommended level; therefore, we conducted studies with T. urticae on roses fertilized with 33% (50 ppm N), 50% (75 ppm N), and 100% (150 ppm N) of the recommended level. Mean numbers of T. urticae and T. urticae eggs per flower shoot were twice as high on roses fertilized with 100 versus 33% or 50% of the recommended level. Number of rose leaves and total leaf area infested by T. urticae were similar at all fertilization levels. Cut rose yield and marketability were not compromised on plants fertilized with 50% of the recommended level.

Seasonal activity of the spider mite predators Stethorus punctillum (Coleoptera: Coccinellidae) and Neoseiulus fallacis (Acarina: Phytoseiidae) in raspberry, two predators of Tetranychus mcdanieli (Acarina: Tetranychidae)

Colonization of raspberry Rubus idaeus L. fields by the Mcdaniel spider mite Tetranychus mcdanieli McGregor and two of its predators Stethorus punctillum Weise and Neoseiulus fallacis (Garman) was studied in Québec in 1995 and 1996 in three sites, to determine predator seasonal synchrony with prey, and compare their impact in pesticide-managed and pesticide-free fields. The potential role of weeds as reservoirs of spider mites and predators was also examined by sampling the ground cover. In both types of fields and in both years, N. fallacis established very early on raspberry and was closely synchronized with T. mcdanieli. In contrast, S. punctillum was absent in pyrethroid and organophosphate insecticide-managed raspberry, and its arrival was delayed by ≈1 month in pesticide-free systems, suggesting that only the summer generations colonize raspberry by immigrating from overwintering habitats. At all sites and in both years, there was a relationship between the estimated impact of N. fallacis and S. punctillum and spider mite abundance, greater impact of the predators being associated with lower tetranychid abundance. The effects of insecticides in spring were not as dramatic as for S. punctillum , but greatly reduced N. fallacis populations and lowered their impact compared to the pesticide-free systems. Despite some species including Potentilla norvegica clearly being suitable for spider mites, weeds in the ground cover did not appear to influence the colonization or abundance of spider mites, nor synchrony or impact of N. fallacis and S. punctillum . We suggest that N. fallacis and S. punctillum are complementary predators of mites in the raspberry fields in Québec. Because of its sustained activity throughout the season and its early synchrony with the predominant T. mcdanieli , N. fallacis is a critical factor to spider mite population regulation in this system, while S. punctillum appears later as a mobile and voracious predator capable of substantial impact during summer when Tetranychus urticae joins T. mcdanieli in this system.

Evaluation of large-scale releases of western predatory mite for spider mite control in cotton

Abstract We evaluated economically feasible release rates of the western predatory mite, Galendromus occidentalis , for spider mite control in organically and conventionally managed commercial cotton fields. An important feature of the experimental design was the evaluation of predatory mite releases at a large spatial scale; the majority of plots were near 2 ha. Predatory mite releases did not enhance the density of the western predatory mite, and populations of western predatory mites remained very low throughout the growing season. However, predatory mite releases did appear to reduce the seasonal abundance of spider mites. Nevertheless, spider mite densities exceeded economic thresholds in many of the release plots, and neither early releases (3–6 nodes per plant) or late releases (>7 nodes per plant) enhanced seed cotton yields. We discuss some potential factors that could have limited the impact of the released predatory mites.

Grape downy mildew spread and mite seasonal abundance in vineyards: evidence for the predatory mites Amblyseius andersoni and Typhlodromus pyri

Abstract Mite populations, in particular those belonging to the Phytoseiidae family were monitored in a commercial vineyard comprising two varieties (Prosecco and Pinot gris). On Prosecco, densities of Amblyseius andersoni , and to a lesser extent of Typhlodromus pyri increased when downy mildew symptoms occurred on a high number of leaves. On Pinot, A. andersoni was the dominant species and its densities markedly increased when downy mildew spread. A. andersoni populations were significantly larger on leaves with downy mildew symptoms than on leaves without symptoms and their densities were positively correlated to the extent of leaf surface showing symptoms. The effect of downy mildew on T. pyri populations was less marked. There were no relationships between downy mildew spread and spider mite abundance ( Panonychus ulmi ). Untreated plots or plots treated with folpet to control downy mildew were monitored in an experimental vineyard colonized by A. andersoni . A. andersoni populations increased when downy mildew symptoms spread and their densities were significantly higher in the control than on folpet plots. In another experimental vineyard, T. pyri densities were significantly higher in the control (severely infected by downy mildew) than on copper hydroxide plots. Isoelectric focusing electrophoresis (IEF) was employed to detect downy mildew in mites and glucose phosphate isomerase (GPI) was selected from among different enzymes. A stain corresponding to downy mildew in addition to the phytoseiid intrinsic stains was detected in a high proportion of A. andersoni and T. pyri collected from infected leaves. Downy mildew stains were not detected in P. ulmi females collected from infected leaves. Most A. andersoni and T. pyri females confined on symptomatic leaves became positive to IEF a few hours later.

Predatory Role of <I>Neoseiulus fallacis</I> (Acari: Phytoseiidae): Spatial and Temporal Dynamics in Washington Red Raspberry Fields

The seasonal abundance of spider mites and their predator Neoseiulus fallacis (Garman) (Acari: Phytoseiidae) was determined during three consecutive years in Washington State red raspberry fields. Tetranychus urticae Koch (Acari: Tetranychidae), Eotetranychus carpini borealis (Ewing) (Acari: Tetranychidae), and N. fallacis were commonly found in Skagit and Whatcom Counties. E. carpini borealis colonized the fruiting canes earlier in the season than T. urticae. The two phytophages overlapped in midseason, but T. urticae entered diapause earlier than E. carpini borealis and N. fallacis. Densities of N. fallacis increased with increase in spider mite densities. However, the numerical response of the predator was more evident for T. urticae than for E. carpini borealis. Nevertheless, the predator was spatially associated with the two prey species. The spatial and seasonal distribution of N. fallacis in relationship to host plant phenology and prey distribution may influence the effectiveness of this predator as a biological control agent against spider mites in red raspberry. Densities of the predator increased too late to prevent spider mite damage. The predatory role of N. fallacis could be enhanced by introducing or conserving predators that are more tolerant to climatic factors that prevail in and around the cane canopy in the beginning of the season.

Seasonal Abundance of Spider Mites and Their Predators on Red Raspberry in Quebec, Canada

Seasonal abundance of spider mites and their predators on red raspberry was studied in 1993 and 1994 at 2 agricultural locations near Quebec City, Canada. Three raspberry systems, wild raspberry, pesticide-free cultivated raspberry, and commercial raspberry treated with a variety of pesticides, were sampled at frequent intervals. Tetranychus mcdanieli McGregor accounted for 87.5, 80.6, and 95.0% of the identified spider mites collected in the commercial, untreated, and wild systems, respectively. Tetranychus urticae Koch was observed in low numbers in both years. Spider mites were more abundant in the commercial and untreated systems than in the wild system, and there was generally no difference between commercial and untreated systems in 1993, whereas in 1994 there was more spider mites in the commercial system than in the untreated one. Predatory mites were present in all systems. Amblyseius fallacis (Garman) was the most abundant predator in the commercial system, whereas a complex of other predatory mites species dominated the wild system. The coccinellid Stethorus punctillum Weise was abundant in the untreated system and rare in the commercial and the wild systems. Variations of predator abundance among treatments did not correlate with variations of spider mite abundance, and could be explained by seasonal predator-prey asynchrony.

Natural Enemies of Spider Mites (Acari: Tetranychidae) on Cotton: Density Regulation or Casual Association?

Environ. Entomol. 20(3): 849-856 (1991) ABSTRACT This study addresses the potential impact of natural enemies on the abundance of spider mites, Tetranychus spy., on cotton in the San Joaquin Valley of California. These natural enemies are omnivorous predators, and include the big-eyed bug, Geocoris pallens StAl and G. punctipes (Say), the minute pirate bug, Orius trfsticolor (White), and the western flower thrips, Frankliniella occidentalis (Pergande). Simple linear regression suggested that omnivorous predators were potentially effective in delaying the buildup of spider mites, with the highest rz (0.65) recorded for adult F. occidentalis. Geocoris showed the potential to suppress the rate of spider mite population increase (rl = 0.73). All three tested predator species exhibited the capacity to suppress early season spider mite abundance, with the highest r2 (0.62) recorded for Ceocoris and Orius. Predators were also potentially able to suppress mid- to late-season spider mite populations. Multiple regression analysis indicated a significant negative correlation between mid- to late-season spider mite abundance and early season predators. Results from a second year were less conclusive, suggesting that the reduced range of spider mite abundance limited our ability to discern potentially significant interactions during that year.

Control of Spider Mites on Celery, 1989

Abstract Plots were established in the portion of a celery field near Mission, Tex. which had not been harvested because of high spider mite densities and associated damage. Each plot consisted of 2 beds (4 rows) on 40 inch centers by 15 ft. Plots were arranged in a randomized complete block design with 3 replications. All acaricides were applied on 12 Dec and 20 Dec, 1988, using a CO2-pressurized backpack sprayer calibrated to deliver 69.5 gal/acre (2 flat-fan nozzles/bed; 40 psi). Acaricide treatments were evaluated by counting the number of motile adult mites on the underside of 5 randomly selected trifoliates/plot. A visual rating technique was also used with a 1 (lowest) to 5 (highest) rating, based on the relative abundance of spider mites, assigned to each of 15 randomly selected trifoliates/plot.

Sampling strategies for assessing the intra-plant density of the cassava green mite (Mononychellus tanajoa): A case-study

Sampling data from a single cassava plant were used for testing various sampling methods. It was found that the degree of leaf damage was poorly correlated with the number of cassava green mites (CGM) present on a leaf. Sampling of specific mite stages should take into consideration the effect of leaf damage on the age distribution of the mites. Simple random sampling resulted in a high between-leaf variation caused by a vertical gradient in spider-mite abundance. The between-leaf variation could be reduced by stratified sampling. The optimum number of strata was three. Subsampling of leaflets combined with stratification provided the most precise estimates for a given sampling effort. Various regression methods for estimating the area of a cassava leaf from some simple measurements were compared. Combining the length of the longest leaflet with the number of leaflets gave the best prediction, explaining 95.8% of the total variation in observed leaf areas.

Nonlinear responses of spider mites to drought‐stressed host plants

Abstract. 1. This study examines the shape of the population response curve of the two‐spotted spider mite, Tetranychus urticae Koch, feeding on bean plants, Phaseolus vulgaris L., which have been subjected to one of a range of drought stresses.2. Abundance of spider mites declined at slight drought stress, increased at intermediate intensities of stress, and declined again at severe stress.3. Fecundity showed the same pattern found for total abundance. Developmental rates of immatures, on the other hand, generally increased with stress intensity. Survivorship of immatures and adult females appeared unrelated to stress intensity.4. These results indicate that responses of mites to drought‐stressed beans are nonlinear. Such a pattern helps explain contradictory results obtained for spider mites and other arthropod herbivores.

Population Densities of Tetranychus spp. (Acari: Tetranychidae) After Treatment with Insecticides for Amyelois transitella (Lepidoptera: Pyralidae)

In field studies in four California almond orchards, effects of azinphosmethyl, carbaryl, diazinon, permethrin, flucythrinate, and cyfluthrin on abundance of web-spinning spider mites, Tetranychus spp., and their predators were compared. Except for trees treated with azinphosmethyl, those sprayed with each of the insecticides had a significantly greater abundance of spider mites than untreated control trees in the year of treatment. Only the trees treated in May with azinphosmethyl at one test site gave this result. During the year after treatment, population abundance of web-spinning spider mites on trees treated with only pyrethroids was significantly greater than on trees treated with the other insecticides or on untreated controls. Although numbers were low at each site, pyrethroid treatments tended to have greatest impact on predators during the year of application. In the year after treatment, predator populations were significantly greater on permethrin-treated trees in all but one location. Predator abundance was also greatest on trees treated with the two highest flucythrinaterates during the year following treatment. Results of this study suggest that use of pyrethroid foliar sprays on almonds may compromise California’s current spider mite management program.