Adult Female Mites Research Articles

Laboratory Activity of Spinosad on Non-Target Beneficial Arthropods, 1994

Abstract This report details the results of a number of laboratory tests on spinosad as spray-dried broth (NAF-144) and an extracted 480 gms/liter SC (NAF-85) against a variety of beneficial organisms. All beneficial insects were obtained from a commercial supplier, Nature’s Control, P.O. Box 35, Medford, OR 97501. For topical, honey bee tests, the bees were confined to a petri dish and then sprayed with a hand syringe. For contact exposure, the exposure units consisted of glass tubes, 7.5 cm. long × 4 cm. in diameter. The tubes were treated by applying a uniform film to the inside of the glass tube using a fine DeVilbis sprayer. Materials were field applied to ‘Courtland’ Apples during bloom. Branches were harvested at 0, 16, 24, and 40 hours post spray. Bees were caged in the laboratory with the treated blossoms. The experiment was held at 40-50% RH and 23°C. The exposure units for Encarsia were treated by applying a uniform film to the inside of the glass tube using a fine DeVilbis sprayer. Ten newly emerged adult Encarsia formosa were aspired from the emergence chamber into each of the treated vials which were then capped with fine muslin. For Orius and Hippodamia and Lacewing exposure units were created by first treating the glass sheet by applying an even film of pesticide using a DeVilbis nozzle. After the sheet was dry, the Plexiglas sheet was placed on top of the glass sheet. 5 cm. tall rings were coated with Fluon and placed in holes drilled in the Plexiglas sheet and seated firmly against the glass creating separate exposure units. Each exposure unit was capped with muslin held in place with rubber bands. For the treated prey ingestion studies in the ladybird beetle test, squash leaves heavily infested with aphids were sprayed to run off and the treated aphids were driven off into the cage to be consumed by the beetles. Second instar, green lacewing larvae were fed tobacco budworm eggs which had been killed by freezing and treated by swirling them in formulated pesticides. For predatory mites, an even film of pesticide was applied to each leaf using a hand held syringe. After the leaves were dry, they were trimmed to an approximate diameter of 4 cm. and placed abaxial side up on agar in a petri dish. Five adult female predator mites were transferred by hand to each leaf. Tests were held under ambient laboratory conditions of approximately 23°C and 50% RH for 72 hours at which time, they were graded for mortality. LC50’s were generated using the Trimmed Spearman Karber method.

Resistance to carmine spider mite in watermelon

Resistance of 37Citrullus lanatus L. lines to the carmine spider mite,Tetranychus cinnabarinus (Boisduval), was evaluated in three laboratory experiments, each including seven plants per line. Infestation with ten adult female mites per leaf, of each plant, was done at the three-leaf stage. In experiment A, average counts 10 days after infestation of three leaves ranged from 42 to 144 mites per leaf. In experiment B, average counts 8 days after infestation of two leaves ranged from 40 to 286 mites per leaf. In experiment C, average counts 8 days after infestation of two leaves ranged from 15 to 196 mites per leaf. The results suggest that a definite variation in resistance against mite infestation exists among watermelon lines.

Effects of mite age, mite density, and host quality on aerial dispersal behavior in the twospotted spider mite

AbstractMite age, population density, and host leaf quality affect various life history traits in spider mites. We investigated the effects of these factors on the aerial dispersal behavior of adult female twospotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae). The proportion of adult females exhibiting the dispersal behavior dropped significantly with age following adult emergence, particularly in the first 3 days. Sixty to eighty percent of female mites 2‐days old or younger displayed the behavior under test conditions, whereas less than 20% of female mites older than 3‐days‐old showed the behavior. Younger adult females also exhibited shorter latency for the behavior, although this trend was not as clear. Leaf quality experienced during deutonymph development had no effect on the behavior adults subsequently displayed. On the other hand, adult females that fed on poor quality leaves after emergence were twice as likely to display the behavior (90% vs. 45%), and with shorter latency (37 vs. 77 min), than those that fed on high quality leaves. When newly emerged adult females encountered high mite density and dry leaves, the incidence of the behavior increased (69% vs. 47%) and latency decreased (69 vs. 93 min) compared to mites that encountered low density on well watered leaves. Our results suggest that both starvation and desiccation of adult females may enhance their dispersal behavior.

Factors Affecting Toxicity of Propargite to the European Red Mite (Acari: Tetranychidae)

Laboratory tests with adult female European red mites, Panonychus ulmi (Koch), showed that toxicity of propargite was correlated with temperature; toxicity was 4.75-fold higher at 24°C than at 15°C. Mortality of female European red mites was higher on foliage treated with an emulsifiable (6 EC) formulation of propargite than with a wettable powder (30 WP) formulation both in the laboratory and in the field. In laboratory tests, higher mortalities were observed on peach compared with apple foliage. Investigations using the scanning electron microscope, fluorescent dyes, and analysis of field-treated foliar residues did not explain the increased toxicity of the emulsifiable formulation. Scanning electron microscope studies showed discrete deposits formed from dried spray droplets of propargite 30 WP suspension on leaf surfaces, but there were no visible deposits on leaf surfaces treated with propargite 6 EC. Deposits of both formulations mixed with fluorescent dye appeared similar under short-wave ultraviolet light. Amounts of residue recovered from 6 EC and 30 WP applications to field-treated apple foliage were dependent on initial application rates of both formulations and were not associated with a particular formulation. Rate of residue loss for the EC formulation was not significantly different than that for the WP formulation.

Laboratory transmission of eastern equine encephalomyelitis virus to chickens by chicken mites (Acari: Dermanyssidae).

Pools of adult female chicken mites, Dermanyssus gallinae (De Geer), were allowed to feed on chicks that had been inoculated with eastern equine encephalomyelitis (EEE) virus and that had a viremia level of 10(6.2)-10(6.6) plaque-forming units per milliliter of blood. Virus remained detectable by plaque assay in samples of these mites for 30 d after the infectious blood meal. Virus was not recovered from any of 151 progeny of virus-exposed female mites. Mites that had fed on viremic chicks were allowed to feed on naive chicks 3, 7, 11, 15, or 30 d later. EEE virus was transmitted to chicks by these mites on days 3 (one transmission in four trials) and 7 (one transmission in four trials). Both transmissions were confirmed by the presence of virus in chick blood 24-72 h after mites had fed, and by plaque-reduction neutralization assays of 21-d convalescent chick sera against the original viral strain.

Lack of allozyme variability amongVarroa mite populations

A gene-enzyme analysis was carried out on the honeybee miteVarroa jacobsoni. By means of gel electrophoresis, 17 presumptive gene loci, belonging to 14 enzyme systems, were scored. Adult female mites were collected in 12 apiaries from European countries and in one apiary from Beijing (China). The populations analysed were monomorphic for all the loci considered, almost all the individuals being homozygous for the same alleles. The breeding system and stochastic mechanisms during the spread ofV. jacobsoni over the world may account for the uncommonly low level of genetic variability observed. The genetic identity found among the analysed samples suggests that taxonomic differentiation is absent even among mite populations living in the different honeybee races considered.

Economic Effect of the Citrus Red Mite (Acari: Tetranychidae) on Southern California Coastal Lemons

In a 2-yr study, we found no significant relationship between the variation in density and duration of citrus red mite, Panonychus citri (McGregor), populations peaking at > 19 adult females per leaf and variation in total yield, size, or grade of lemon fruit. No effects of high mite populations in the first year were evident upon crop yield, grade, or size in the second year. The conventional treatment threshold for P. citri on lemon has been two adult female mites per leaf. These data do not support the premise that growers who observe that threshold are achieving an economic return.

Influence of monoterpene vapors on spruce spider mite,Oligonychus ununguis, adult females

Adult female spruce spider mite,Oligonychus ununguis (Jacobi), were exposed to various concentrations of four host conifer monoterpene vapors (limonene,β-pinene,α-pinene, and Δ(3)-carene) for 24 hr to determine the lethal and sublethal effects. All four compounds were toxic to the mites. Further, at concentrations below the calculated LC50s, all four compounds decreased oviposition by the mites and three of the compounds (limonene,β-pinene, andα-pinene) influenced movement. WhereasO. ununguis populations may not normally be exposed to high concentrations of host monoterpenes, trees continuously emit some monoterpene vapors, and when trees are damaged or under stress, oleoresin may accumulate at points on the external surface of tree tissues thereby exposing mites to the influence of monoterpene vapors.

Susceptibility ofEuseius addoensis addoensis (Acari: Phytoseiidae) to field-weathered residues of insecticides used on citrus

Comparisons of the toxicities of field-weathered residues of insecticides to adult femaleEuseius addoensis addoensis (McMurtry) were conducted by bioassay using leaf disks. The products tested are registered for the control of certain insect pests on citrus in South Africa. The treatments which caused the highest mortality, in order of decreasing toxicity, were: methiocarb plus sugar, cypermethrin plus profenofos, fenpropathrin plus phenthoate, methomyl, methidathion, phenthoate, prothiofos plus oil, and profenofos. Most of these treatments also had prolonged residual effects. Endosulfan, which caused only intermediate mortality to adult female mites, had a very persistent residue. Sublethal effects of insecticide residues on mite fecundity were negligible in most cases.

Host preference of the honey bee tracheal mite (Acarapis woodi (Rennie))

Field and laboratory bioassays were used to test the preference of the honey bee tracheal mite,Acarapis woodi (Rennie), for drones versus workers. Groups of newly-emerged drones and workers were marked and introduced into either heavily infested colonies (field bioassays) or into the cages of infested bees obtained from the field colonies (laboratory bioassays). Seven days later all of the marked bees in each bioassay were removed. The numbers of mites of each life stage in each drone or worker target bee of each experiment were quantified. Mite prevalence values for the two castes were not found to differ significantly for either experiment. However, the caste of the target bee was shown to influence the migration of the adult female mites. Drones contained a greater number of migratory female mites and greater total numbers of all mite stages as compared to workers. These results indicate that migrating female mites preferentially infest drones and suggest that the role of drones in the dissemination and population dynamics of the tracheal mite needs to be examined further.

Simple in-vitro feeding system for northern fowl mites (Acari: Macronyssidae).

The use of Parafilm membranes for in-vitro feeding of northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago), is described. A membrane stretched in two perpendicular directions, folded, heat-sealed, inflated, and twisted at the ends to form a sphere allowed a high percentage (greater than 80%) of surviving adult female mites to feed on whole chicken blood. A high percentage (7 of 10) of protonymphs also fed through the membrane. Mites were able to feed from the same sac for 3 d and oviposited on the sac. This technology has potential applications for use in rearing O. sylviarum and other hematophagous arthropods, and for physiological experimentation.

Responses of Susceptible and Resistant Eusieus Tularensis Congdon to Ac 801,757 and Ac 303630, 1991

Abstract An organophosphate and carbamate resistant strain (R) and a susceptible strain (S) of the predatory mite E. tularensis were collected from citrus and reared for 6 months without pesticide selection. Both strains of the predatory mite were maintained in mass culture on citrus leaves with iceplant pollen (Malephora crocea (Jacq.)), under conditions of semi-darkness and 25 ° 3°C. Neither strain had been previously exposed to AC 801,757 or AC 303630. Initial laboratory screening categorized strain R with a 9.2 fold resistance to dimethoate (Cygon 4 E), a 6.8 fold resistance to chlorpyrifos (Lorsban 4 E), a 287.1 fold resistance to carbaryl (Sevin 50 W), and a 3.7 fold resistance to formetanate hydrochloride (Carzol 92 SP) compared with strain S. Predatory mites were tested using a leaf dip bioassay procedure. Lima bean leaf discs (3.5 cm in diam) were dipped into insecticide concentrations for 5 s, placed lower side up on water-soaked cellucotton, and dried under a fume hood. Ten adult female mites were added to each leaf disc. Six to seven concentrations of AC 801,757 (20 EC) and AC 303630 (24 SC) and a water control were tested with each mite strain. Each leaf disc concentration was replicated 10 times. A 5 mm circle of paper was placed on each disc for oviposition and iceplant pollen was added for food. Exposed mites were kept in a growth chamber in complete darkness at 27 ° 1°C for 48 h after which mortality was recorded. Females that drowned in the water-leaf edge interface were scored as dead. Data were analyzed with the probit option of the POLO-PC program (LeOra Software, Berkeley, Calif.).

The influence of temperature and resource level on the fecundity of a predatory planktonic mite, Piona exigua Viets.

Piona exigua Viets is a predaceous freshwater mite that can potentially affect the population densities of its cladoceran prey. As part of a study of the effect of Piona exigua on its prey populations we measured the effects of water temperature and prey density on the lifespan, age at first reproduction and per capita egg production of adult female mites. Mites were raised in the laboratory at five prey (Ceriodaphnia, Daphnia) densities (5, 15, 30, 60, 120/l) at 15° C and at four temperatures (10, 15, 18, 22° C) at c. 60 prey/l. In response to increased food level, mites increased the number of eggs laid to reach a maximum at 60 prey/l, the rate at which they were laid increased and the pre-reproductive period was shorter. Low temperatures prolonged the pre-reproductive period. At temperatures above 10° C, food level and temperature had more influence on the timing of reproductive events (growth rate, oviposition rate, age at first reproduction) than on the size of females at first reproduction. When temperatures exceed 10° C and food levels exceed 5 prey/l the major scope for reproductive plasticity in Piona lies in the timing and duration of egg production.

Miticide Efficacy Trial, 1990

Abstract This experiment was conducted in a furrow-irrigated corn field at the Southwest Research-Extension Center. Treatments were arranged in a randomized complete block design with 4 replications. Plots were 4 rows wide (10 ft), 50 ft long with a 10 ft border of untreated corn on each side and a 10 ft alley between plots. Prior to treatment, 2 plants in each of the 2 center rows of each plot were flagged. The natural field population of spider mites was very high and reasonably well distributed so no artificial infestation was necessary. Pretreatment counts were made on 26 Jul by visually searching one-half of every other leaf (one-quarter plant) on the flagged plants for large (adult female) mites. All treatments were applied on 27 Jul, except for the experimental pesticidal soap which was applied on 31 Jul. Most of the treatments were applied with a high clearance sprayer using a 10 ft boom with 3 nozzles directed at each row (1 nozzle directly over the row and 1 on each side of the row on 18-in drop hoses). The sprayer was calibrated to deliver 20 gal/acre using a ground speed of 2.4 mph and 30 psi. Thio-Sul was applied with a high clearance sprayer calibrated to deliver the equivalent of a 0.2 inch irrigation on the 2 center rows (5227 gal/acre) using 3 Delavan 100/140, .75-inch rain drop nozzles. The experimental pesticidal soap used in this test was produced at Kansas State University. Counts were made on 2 and 15 Aug (6 and 19 DAT) by searching one-half of every other leaf on the flagged plants. Mite counts were converted to mites per plant for analyses and presentation. Efficacy was evaluated by comparing the mean number of mites per plant among treatments using SAS Proc ANOVA and by comparing pretreatment means with posttreatment means using the Henderson and Tilton formula. The spider mite species composition which was present during the test was evaluated by collecting several mites from the flagged plants in each plot with a vacuum sampler and mounting them on glass slides for microscopic examination.

Miticide Efficacy Trial, 1989

Abstract This experiment was conducted in a furrow-irrigated corn field at the Southwest Research-Extension Center. Treatments were arranged in a randomized complete block design with 4 replications. Plots were 4 rows wide (10 ft), 50 ft long with a 10 ft border of untreated corn on each side and a 10 ft alley between plots. Prior to treatment, 2 plants in each of the 2 center rows of each plot were flagged. The natural field population of spider mites was augmented by attaching small sections of corn leaves infested with BGM from a nearby corn field to these 4 flagged plants on 27 Jul. Pretreatment counts in the untreated check and Avid plots were made on 4 Aug. All other pre-treatment counts were made on 8 Aug by visually searching all leaves (whole plant) on the flagged plants for large (adult female) mites. Treatments were applied on 10 Aug (except Avid which was applied on 7 Aug) with a high clearance sprayer using a 10 ft boom with 3 nozzles directed at each row (one nozzle directly over the row and one on each side of the row on 18 inch drop hoses). The sprayer was calibrated to deliver 20 gal/acre using a ground speed of 2.3 mph and 30 psi. Posttreatment counts were made on 15 and 28 Aug by searching one half of every other leaf (one quarter plant) on the flagged plants. Mite counts were converted to mites/plant for analyses and presentation. Efficacy was evaluated by comparing the mean number of mites/plant among treatments using SAS Proc ANOVA and by comparing pretreatment means with post-treatment means using the Henderson and Tilton formula. The spider mite species composition which was present during the test was evaluated by collecting several mites from the flagged plants in each plot with a vacuum sampler on 18 Aug and mounting them on glass slides for microscopic determination of species.

Twospotted Spider Mite Control on Marigolds, 1989

Abstract Four trials carried out at the University of Nebraska, Lincoln, NE to evaluate the efficacy of selected insecticides/miticides, an insecticidal soap (Safer Insecticide Concentrate), a horticultural spray oil (SunSpray Ultra-Fine Spray Oil) and various combinations of these products for control of twospotted spider mites on marigolds. Treatments included Safer Concentrate and SunSpray Oil combined with 0.5 and 0.125 the labeled rates of Dursban 4 E or Orthene 75 SP. Plot design for all trials was a RCB with 4 replicates. Each trial consisted of four, 10-ft rows (replications) of a single marigold cultivar planted on 36-inch centers. Individual plots, which consisted of 2-3 marigold plants, were delineated by placing 2 × 2 ft sheets of waxed cardboard within rows at approximately 2-ft intervals. Marigold cultivars were Queens Mix, Scarlet Sophia, Crackerjack and Jamie Gold for trials 1-4, respectively. Treatments were applied on 8 Aug. Conditions at the time of application were as follows: air temperature, 76°F; relative humidity, 46%; soil moisture was well below field capacity. Treatments were applied with a COz sprayer using a LF-4 nozzle at 24 psi to the point of runoff (ca. 0.5 pts finished spray per plot). No rain fell during the post-treatment period. Product efficacy was evaluated 3 and 7 DAT by randomly selecting and excising 4 leaves each from the lower, middle and upper portion of plants in each plot (12 leaves total). Leaves were returned to the laboratory where numbers of adult female mites were recorded. Trial 1 (Queens Mix): All insecticides/miticides provided statistically significant reductions in mite numbers at both 3 and 7 DAT. Overall, mite reductions were relatively low with only Tempo 2 at 3 DAT (81.3%) and Morestan 4 F at 7 DAT (90.8%), providing percent mite reductions of greater than 80%. Trial 2 (Scarlet Sophia): Safer Insecticide Concentrate, Dursban 4 E and all combinations of Safer Insecticide Concentrate plus Dursban 4 E provided significant reductions in spider mite numbers at 3 DAT. By 7 DAT, however, only Safer Insecticide Concentrate and Safer Insecticide Concentrate plus Dursban 4 E at 1.0 fl oz continued to provide significant mite reductions. Overall, percent reductions were less than 50% except for Safer Insecticide Concentrate plus Dursban 4 E at 4.0 fl oz, which provided 52.2% at 3 DAT. Trial 3 (Crackerjack): At 3 DAT, only 2% SunSpray Ultra-Fine Spray Oil plus Dursban 4 E at 4.0 fl oz had provided a significant reduction in spider mite numbers. By 7 DAT, however, there were no significant differences among treatments. Spider mite control was poor for all treatments with only the 2% SunSpray oil plus Dursban 4 E at 4.0 fl oz providing greater than 70% reduction. Trial 4 (Jamie Gold): Two percent SunSpray Ultra-Fine Spray Oil plus Orthene 75 SP at 5.25 fl oz and 2% SunSpray were the only treatments to provide significant reductions in spider mite numbers at 3 and 7 DAT, respectively. Percent mite reductions were relatively low for all treatments, with only the 2% SunSpray oil plus Orthene 75 SP at 5.25 fl oz at 7 DAT exceeding 70%. No phytotoxicity was observed in any of the trials.

Scanning electron microscopy of sarcoptic mange lesions in swine

Scanning electron microscopy revealed that lesions of sarcoptic mange in swine, pass through 3 different stages. During the first 3 weeks of infestation, adult female mites tunnel into the epidermis. During the following 3 or 4 weeks, the surface openings of these tunnels become covered with keratinized epidermal crust which increases in thickness. After 7 weeks of infestation, the crust falls off, the tunnel openings become apparent again and most of the mites vacate these tunnels.

Demographic Analysis of Induced Resistance Against Spider Mites (Acari: Tetranychidae) in Cotton

Demographic analyses were conducted of twospotted spider mites, Tetranychus utica Koch, raised on excised leaves of cotton, Gossypium hirsutum L., plants that had been previously damaged by mites, Tetranychus Turkestani Ugarov and Nikolski, or on leaves of undamaged controls. There were no differences in survival or development of individuals reared on leaves of the two treatments. Fecundity of mites was reduced by approximately 50% on excised leaves from plants that had been damaged as cotyledons relative to mites grown on leaves from undamaged control plants. Other workers who have examined the effects of plant conditioning on spider mites also have found this striking effect on fecundity and no effect on survivorship and development. This demographic pattern is consistent with patterns noted when the nutritional quality of the host plant is diminished but inconsistent with patterns caused by changes in the “secondary chemistry” of the host. Adult female mites behaviorally preferred excised leaves of control plants compared with excised leaves of damaged plants. Further work is required before a reliable behavioral assay is available that can be used to determine the chemical nature of induced resistance in cotton.

Development of the filaria Litomosoides galizai in the acarian vector

L. galizai develops in the gamasid B. bacoti in 11 days at 28 degrees C. Molts I and II take place respectively 5 and 7 days after feeding. The development is studied in the adult female mites; as for the laboratory filaria L. sigmodontis, the interstitial tissue is the main parasitized organ; microfilariae penetrate in the two cell types which constitute it: adipose cells and secretory cells (these secretory cells are described here for the first time). The filariae develop also in the salivary glands, the digestive wall, the genital envelopes and exceptionally in the coxal and vaginal glands. The filariae produce the formation of syncytia. Larvae which stay in the haemocele do not develop.

Pesticide Efficacy Against CRM in the San Joaquin Valley, 1988

Abstract Acaricides were tested for control of CRM populations near Exeter, Calif. A completely randomized design was used with 5 single-tree replicates/treatment. Trees were assigned to treatments based on pretreatment mite counts to minimize within-treatment variation. Applications were made on 31 Mar to an established population. Materials were applied with a handgun at 450 psi (7 gal/tree; 700 gal/acre) using a John Bean sprayer. Counts of live, adult female mites from one 5-leaf terminal/tree quadrant (20 leaves/tree) were made at 5 DAT and at 7- to 14-d intervals thereafter until mite populations naturally declined due to the onset of high mid-summer temperatures.