Spider Mite Injury Research Articles

Impact of Twospotted Spider Mite (Acari: Tetranychidae) Duration of Infestation on Cotton Seedlings

The yield response of cotton, Gossypium hirsutum L., to twospotted spider mite, Tetranychus urticae Koch, duration of infestation during the seedling stage was measured at Starkville and Stoneville, MS, during 2010 and 2011. The treatments included a noninfested control, infestations lasting for 7, 14, 21, or 28 d, and a season long infested control. Twospotted spider mites from a greenhouse colony were inoculated on all of the infested cotton plots during the three-leaf stage. Applications of miticides were made to terminate infestations at the desired timings for each treatment. Twospotted spider mite densities and injury ratings were determined for each treatment at the end of the infestation period and yield was measured at the end of the season. Twospotted spider mite densities and injury rating significantly increased as duration of infestation increased. Significant differences in yield were observed between treatments. These data suggest infestations initiated at the three-leaf cotton growth stage with population densities at a minimum of 0.39 mites/cm2 existing > 14 d could result in reduction of cotton yields.

Photosynthetic response of soybean to twospotted spider mite (Acari: Tetranychydae) injury

The twospotted spider mite Tetranychus urticae Koch is a common pest on soybean plants. To clarify plant-arthropod interaction on mite-soybean system, leaf fluorescence, photosynthetic responses to variable carbon dioxide levels, and chlorophyll content were evaluated. Significant photosynthetic rate reduction was observed due to stomatal limitation. Stomatal closure was the major plant physiological response. As a consequence, there was reduction in photosynthetic rates. Surprisingly, plants did not show chlorophyll content reduction associated with photosynthetic impairment. No differences in fluorescence data indicate that T. urticae injury did not impair the function of light harvesting and photoelectron transport. These results showed that T. urticae could be a serious pest of soybean even on lower infestation, at least when photosynthesis was determinant to yield.

Changes in Soybean Gas-Exchange After Moisture Stress and Spider Mite Injury

Field experiments were conducted in 1997 and 1998 to understand the physiological responses of soybean, Glycine max (L.) Merrill, to injury from two-spotted spider mite, Tetranychus urticae Koch, and to examine the contribution of soil moisture toward soybean tolerance to spider mite injury. A split-plot treatment design was used consisting of moisture stress as the main plot and spider mite injury as the sub-plot treatments in a randomized complete block design with eight replications. Soybeans were moisture-stressed beginning approximately at V10 growth stage, and spider mites were maintained on soybeans for 10 d, and then physiological responses of soybean were determined. Moisture-stressed soybeans had lower leaf water potentials, photosynthetic rates, stomatal conductances, and transpiration rates. Spider mite injury also caused a significant reduction in photosynthesis, stomatal conductance, transpiration, and chlorophyll content. The lack of a significant impact of spider mite injury on chlorophyll fluorescence and similar light curves, at low light intensities, of soybean leaves with and without spider mite injury, suggest that spider mite injury does not interfere with the light reaction center at the initial stage of photosynthesis. Despite measurable reductions in total chlorophyll content from mite injury, fluorescence data and light curves strongly indicate photosynthetic rate reductions from mite injury were not immediately associated with chlorophyll loss or effects on photosynthetic electron transport. There were significant interactions between moisture stress and spider mite injury for some gas-exchange parameters. Photosynthetic rate reductions by spider mites were greater in moisture-unstressed than stressed soybeans. Superimposing spider mite injury did not reduce photosynthetic rates greatly in moisture-stressed soybeans because of an initially low photosynthetic rate from moisture stress. However, comparison of absolute photosynthetic rates of spider mite-injured soybean leaves with and without moisture stress suggested that soil moisture improved soybean tolerance to spider mite injury.

Tillage and Chlorpyrifos Treatment Effects on Peanut Arthropods—An Incidence of Severe Burrower Bug Injury

Abstract A 2-yr study was conducted on the effects of tillage and soil insecticide (chlorpyrifos) treatment on peanut arthropod pests. A 3 by 2 split-plot experiment with five replications was subjected to factorial ANOVA. Main plot treatments consisted of three tillage systems: conventional moldboard plow, strip tillage into a killed wheat cover crop, and strip tillage into corn stubble residue. Subplot insecticide treatments were granular chlorpyrifos applied at early pegging (growth stage R2) and untreated. Populations of corn earworn, Helicoverpa zea (Boddie), and velevetbean caterpillar, Anticarsia gemmatalis Hübner, were lower in strip tillage systems. Chlorpyrifos applications caused corn earworm outbreaks in all tillage systems, but these applications were more disruptive in strip tillage. Chlorpyrifos treatment also increased populations of fall armyworm, Spodoptera frugiperda (J.E. Smith), but had no measurable effect on velvetbean caterpillar populations. Pod damage from lesser cornstalk borer, Elasmopalpus lignosellus (Zeller), and wire-worms, Conoderus spp., was lower in strip tillage systems, and chlorpyrifos suppressed pod damage in all systems. Threecornered alfalfa hopper, Spissistilus festinus (Say), damage to peanut was greater in the wheat residue strip tillage system. Chlorpyrifos treatment reduced threecornered alfalfa hopper damage in all systems. Spider mite injury was not affected by tillage, but chlorpyrifos treatments resulted in mite outbreaks in all tillage systems. Burrower bug, Pangaeus bilineatus Say, injury to peanut kernels was greater in the strip tillage systems in 1999; and burrower bug injury was suppressed in the strip tillage systems by chlorpyrifos treatment. There was a significant interaction effect for burrower bug injury between tillage and insecticide treatment. Incidence of tomato spotted wilt virus also was reduced by strip tillage. Use of an effective fungicide program and a 3-yr crop rotation out of peanut production probably obscured any potential tillage effects on fungal diseases (southern stem rot, Rhizoctonia limb rot, and leaf spot). However, chlorpyrifos treatment increased Rhizoctonia limb rot incidence. Weed populations were generally greater in strip tillage systems, but postemergence herbicides effectively eliminated any potential confounding effect on yield and grade. Yield was not affected by tillage in either year, and chlorpyrifos had no effect on yield in 1998. In 1999, however, chlorpyrifos increased yield in both strip tillage systems. Neither tillage nor insecticide treatment affected grade (percentage total mature kernels) in 1998, but in 1999 grade was highest in conventional tillage and grade was improved by chlorpyrifos treatment in strip tillage systems. Crop value losses of $249 and $388/ha were attributed to burrower bug injury in untreated corn and wheat residue strip tillage systems, respectively. This injury may have been an anomaly of drought conditions but, given the potential economic impact, burrower bug merits further study in conservation tillage peanut production.

Observations of Population Increases and Injury by Spider Mites (Acari: Tetranychidae) on Ornamental Plants Treated with Imidacloprid

A series of experiments were conducted to investigate previous observations that soil applications of imidacloprid resulted in increased spider mite populations and spider mite injury on ornamental plants. Marigolds, Tagetes erecta L., treated with either a soil drench or soil granular formulation of imidacloprid were observed to sustain significantly greater damage from twospotted spider mite, Tetranychus urticae Koch, than untreated plants. Populations of the honeylocust spider mite, Platytetranychus multidigituli (Ewing), were as much as 3-4 times higher on honeylocust, Gleditsia triacanthos L., which had received an imidacloprid soil drench, compared with control plants. Effects on spider mite populations or injury were not observed in greenhouse trials involving marigolds, suggesting that this effect was not caused by either hormoligosis or phytotoxicity. However, mortality of Orius tristicolor (White), a hemipteran predator of spider mites, was observed to increase significantly when confined with leaves collected from plants that had received soil treatments of imiclacloprid. The adverse effects to predators may be an important reason for the increase in spider mite injury and abundance resulting from soil treatments of imidacloprid in Colorado.

Control of Mites and Thrips in Turfgrass, Golden, Co, 1989

Abstract Trials were conducted on a turfgrass growing along the south facing slope of a roadway median that had a previous history of spider mite injury. Individual plots were 10-ft × 15-ft, arranged in a RCB design with 4 replications. A fall application was applied 28 Nov; spring treatments were applied 7 Apr. Treatments were applied using a hand-operated compressed air sprayer delivering 3 gal/1000 ft2. Evaluations were made by use of a D-Vac suction sampler, of 15-inch diameter, with six “put-downs” per plot. Samples were evaluated for brown wheat mites and grass thrips.

A rapid and non-destructive method to assess leaf injury caused by the cassava green mite, Mononychellus tanajoa (Bondar) (Acarina: Tetranychidae)

A relative scale of Leaf Damage Indices (LDI) from 0 to 5 describes the visible injury to leaves of cassava, Manihot esculenta Crantz caused by the cassava green mite, Mononychellus tanajoa (Bondar). As the scale is ordinal and thus not quantitative, the observed LDIs are converted individually to relative loss of chlorophyll on a ratio scale before an average injury is determined. This calibration is required because the ordinal and the ratio scales are not linearly related. A calibration curve was established on the basis of laboratory experiments to determine the chlorophyll content, c, of leaves representing various leaf damage indices. Several monotonously decreasing functions were fitted to the experimental data yielding the following relation \(c = c_0 \left( {1 - \frac{{LDI}}{5}} \right)^a \), where c o is the chlorophyll content of unijured leaf tissue and a is a constant describing the steepness of the curvilinear relation. This means that LDIs could be converted to relative loss of chlorophyll, d, where \(d = \left( {\frac{{LDI}}{5}} \right)^a \). The photosynthetically active leaf area of plants can be estimated by combining the relative loss of chlorophyll with leaf area assessments and adds the effects of defoliation and suspended growth to the chlorophyll depletion. The difference in photosynthetically active area that arises between uninjured and injured plants over a period of time provides a measure of spider mite injury that can be related to growth and yield. The method integrates the injury inflicted over a period of time, allows successive observations of the same plants, and is rapid and reasonably precise considering the time savings.

Physiological Responses of Avocado Leaves to Avocado Brown Mite 1 Feeding Injury

Effects of various levels of feeding injury caused by the avocado brown mite, Oligonychus punicae (Hirst) (Acari: Tetranychidae), on avocado leaves were examined. Mite feeding from the upper leaf surface reduced chlorophyll content of the upper mesophyll layer of avocado leaves, whereas chlorophyll content remained unchanged in the lower spongy parenchyma layer. Stomatal and mesophyll conductance values, photosynthesis, and transpiration were found to be negatively correlated with increasing levels of spider mite injury. Avocado photosynthesis rates were reduced 56% when 100% feeding injury was sustained on the upper leaf surface.

The Effect of Spider Mite Populations on Yield and Quality of Cotton

Results from field experiments conducted during 1961 and 1962 revealed that infestations of the carmine spider mite, Tetranychus cinnabarinus (Boisduval), artificially established at different times of the growing season, reduced yield of seed cotton 14 to 44%. In general, yield depression was directly related to population density and duration of infestation. Spider mite injury also reduced boll size and appeared to adversely affect several characters of the seed and lint. Infestation counts and climatic data from each experiment revealed that mite populations and subsequent damage were greatest during periods of hot, dry weather. Hard and heavy rainfall reduced population density. Heavy mite infestations caused typical foliage discoloration and desiccation, but rarely caused extensive defoliation.

Genetic Variability of Sugar beets in Relation to Spider Mite Injury

Genetic Variability of Sugar beets in Relation to Spider Mite Injury