Mite Eggs Research Articles

Characterization of vitellin protein in the twospotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

In mites, vitellogenin synthesis, regulation and uptake by the oocytes as vitellin remain practically unknown. Although a partial sequence of the gene is now available, no previous studies have been conducted that describe the native vitellin protein in mites. The objective of this study was to characterize vitellin in the twospotted spider mite, Tetranychus urticae. The native twospotted spider mite vitellin migrated as a single major band with a molecular weight of 476 ± 14.5 kDa as compared to 590 ± 25.5 kDa for vitellin from the American dog tick, Dermacentor variabilis. However, isoelectric focusing analysis of native spider mite vitellin showed five bands with p I values slightly acidic to neutral (pH 5.8, 6.2, 6.7, 7.0 and 7.2), as is the case for insect and tick vitellins. Reducing conditions (SDS-PAGE) also revealed multiple subunits ranging from 290.9 to 3.6 kDa and was similar to that found in D. variabilis. Spider mite vitellin weakly bound lipids and carbohydrates compared to the tick. Unlike D. variabilis, the spider mite egg yolk protein does not bind heme. The significance of non-heme binding in mites is discussed.

Interactions between Orius albidipennis (Heteroptera: Anthocoridae) and Neoseiulus cucumeris (Acari: Phytoseiidae): Effects of host plants under microcosm condition

In three-dimensional microcosm set-ups we explored the influence of host plant traits of cucumber, eggplant and sweet pepper on the interactions between minute pirate bugs, Orius albidipennis (Reuter) and predatory mites, Neoseiulus cucumeris (Oudemans) in the presence of extraguild prey, Thrips tabaci Lindeman. The host plant influenced the population development of thrips with sweet pepper being most inferior and cucumber being the best for egg laying and/or juvenile development and survival. No host plant effect was found on the survival of adult thrips. The host plant also influenced the biocontrol efficiency of O. albidipennis which, on its own, significantly reduced thrips populations on sweet pepper and eggplant, but not on cucumber. A similar host plant effect was not seen for N. cucumeris which, on its own, was unable to reduce thrips populations on either of the host plants. No additive or synergistic effect between the two predators was observed. Finally, the host plant influenced the interactions between the two predators—when both predators were present, a significant reduction in the density of adult mites was observed on cucumber and sweet pepper, presumably a result of intraguild predation from O. albidipennis. No influence of O. albidipennis on the predatory mites was found on eggplant and on none of the host plants was a negative influence observed on mite eggs or nymphs. The results point to the importance of including host plant aspects in studies aimed at evaluations of possible interactions between beneficials intended for simultaneous applications for biocontrol.

Morphological diagnosis of the eggs of stored-products mites

Eggs of 13 species of common, economically important stored-product pest mites (Acarus siro, A. gracilis, Tyrophagus putrescentiae, T. brevicrinatus, Tyroborus lini, Aleuroglyphus ovatus, Caloglyphus redikorzevi, C. oudemansi, Lepidoglyphus destructor, Glycyphagus domesticus, Aeroglyphus robustus, Chortoglyphus arcuatus and Carpoglyphus lactis) from four families (Acaridae, Glycyphagidae, Chortoglyphidae, Carpoglyphidae) were studied in order to build a diagnostic key. The morphological study dealt with shape, size and surface sculpturing of eggs. Morphological details were visualised using scanning electron microscopy. A key for distinguishing eggs at genus and species level was developed for the major stored-product mites.

ミツユビナミハダニＴｅｔｒａｎｙｃｈｕｓ ｔａｋａｆｕｊｉｉ Ｅｈａｒａ ＆ Ｏｈａｓｈｉの殺ダニ剤および殺虫剤感受性

The spider mite, Tetranychus takafujii Ehara and Ohashi,2002, is known to occur mainly on weeds and black nightshade in Tokyo, Osaka, Kyoto and Hyogo prefectures on Honshu island. In 2007, T. takafujii was found to cause heavy damage to cherry tomatoes in Kagoshima on Kyushu island. To test the possibility of chemically controling this spider mite, we tested its susceptibility to 18 acaricides/pesticides available for tomato and other vegetables in the Solanaceae using a leaf dip method. Spider mite females were highly susceptible to most acaricides/pesticides, except Etoxazole SC and Spirodiclofen SC which are categorized as slow-acting. Spider mite eggs were also highly susceptible to many of treatments, except Malathion EC, Bifentrin 2.0% WP, Emamectin benzoate EC, Chlorfenapyr SC and Bifenazate SC. Egg hatchability at day 4 were ranged from 24.7% to 89.4% among the treatments, and most neonate larvae died after 1 day of Emamectin benzoate EC, Chlorfenapyr SC and Bifenazate SC treatments. Results suggest that many of the treatments tested will be effective in controlling of T. takafujii either at the egg, larval or adult stage.

Evaluation of Metarhizium anisopliae (Deuteromycota: Hyphomycetes) for control of broad mite Polyphagotarsonemus latus (Acari: Tarsonemidae) in mulberry

A study on 12 entomopathogenic fungi for controlling broad mite (Polyphagotarsonemus latus (Banks)) in mulberry found that Metarhizium anisopliae CKM-048 was the most virulent strain in controlling both larvae and adult broad mites at the concentration of 2 x 10(8) conidia/ml. There was no ovicidal effect when tested with broad mite eggs. Median lethal concentrations (LC(50)) of M. anisopliae in killing larvae and adults were 8.7 x 10(6) and 1.3 x 10(7 )conidia/ml, respectively. Median lethal times (LT(50)) of larvae and adults were 2.4 and 3.8 days, respectively, at the concentration of 2 x 10(8) conidia/ml. The fungus was found to produce protease and chitinase. Scanning electron microscope (SEM) studies were done to monitor the infection steps of the fungus on broad mites. A greenhouse test on mulberry trees revealed that M. anisopliae could reduce the broad mite population within 4 days after treatment. However, after 7 days, its efficacy was decreased significantly.

<i>Orius albidipennis</i> (Heteroptera: Anthocoridae): Intraguild predation of and prey preference for <i>Neoseiulus cucumeris</i> (Acari: Phytoseiidae) on different host plants

A widespread interaction in natural enemy populations is intraguild predation (IGP), the intensity and outcome of which may be influenced by several factors. This study examined the influence of host plant characteristics on IGP between Orius albidipennis (Reuter) and Neoseiulus cucumeris (Oudemans) in laboratory experiments. The intraguild predation between the two predators was bi-directional, but predation by N. cucumeris on O. albidipennis is presumably of negligible importance. Orius albidipennis preyed uponmite eggs and adults in the absence of Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), but in its presence predation on mite eggs was abandoned and predation on adult mites unchanged (sweet pepper) or reduced (eggplant, cucumber). The IGP-level of O. albidipennis on N. cucumeris was highest on sweet pepper and lowest on cucumber. Inclusion of host plant aspects in evaluations of the IGPpotential between predators intended for simultaneous applications for biocontrol is thus of importance.

EVALUATION OF NEW MITICIDES FOR SPIDER MITE CONTROL IN COTTON, 2007

This test was conducted in a commercial cotton field grown near Idalou, TX. The field was planted on 40-inch rows, and was irrigated using a subsurface drip irrigation system. The test was a RCB design with four replications. Plots were 4-rows wide × 60 ft in length. Miticides were applied with a CO2 pressurized hand-boom sprayer calibrated to deliver 10 gpa through TX-6 hollow cone nozzles (2 per row) at 40 psi. Insecticides were applied to all four rows of each plot on 4 Aug. A pre-treatment count was made on 3 Aug. Post treatment evaluations were made at 6, 12 and 19 days after treatment (DAT). Treatments were evaluated by collecting 5, mid-canopy leaves per plot and returning these to the laboratory where the mites were removed onto a liquid detergent coated glass plate with a mite brush. Mite eggs, larvae and adults were counted from the middle 1-inch diameter area of the glass plate. Mite population data discussed is the number per 1-inch diameter mite brush sample per leaf. Data were analyzed using ANOVA and means were separated using an F-protected LSD (P ≤ 0.05).

Observations on oribatid mites (Acari: Oribatida) serving as intermediate hosts of Moniezia expansa (Cestoda: Anoplocephalidae) in Iran

Preliminary observations on oribatid mites, intermediate hosts of tapeworms of the family Anoplocephalidae, based on mites collected from soil and grass samples from Mazandaran province in the north of Iran, showed that Galumna iranensis Mahunka and Akrami, 2001, Galumna karajica Mahunka and Akrami, 2001 and Scheloribates fimbriatus Thor, 1930 harbored cysticercoids. Therefore, it is likely that they may act as natural vectors of anoplocephalids. Subsequently these mite species were used for artificial infection with Moniezia expansa eggs. Fully developed cysticercoids were recovered only in S. fimbriatus, 35 days after incubation at 28 ± 1°C and 90 ± 5% RH. The percentage of infection was 70.8, and average and maximum number of cysticercoids per mite was 1.9 and 6.0, respectively. No mite eggs were found in infected mites.

Toxicity of bifenazate and its principal active metabolite, diazene, to Tetranychus urticae and Panonychus citri and their relative toxicity to the predaceous mites, Phytoseiulus persimilis and Neoseiulus californicus

Bifenazate is a novel carbazate acaricide discovered by Uniroyal Chemical (now Chemtura Corporation) for the control of phytophagous mites infesting agricultural and ornamental crops. Its acaricidal activity and that of its principal active metabolite, diazene, were characterized. Bifenazate and diazene had high toxicity and specificity both orally and topically to all life stages of Tetranychus urticae and Panonychus citri. Acute poisoning was observed with no temperature dependency. No cross-resistance was found to mites resistant to several other classes of acaricides, such as tebufenpyrad, etoxazole, fenbutatin oxide and dicofol. Bifenazate remained effective for a long time with only about a 10% loss of efficacy on T. urticae after 1 month of application in the field. All stages of development of the predatory mites, Phytoseiulus persimilis and Neoseiulus californicus, survived treatment by both bifenazate and diazene. When adult females of the two predatory mite species were treated with either bifenazate or diazene, they showed a normal level of fecundity and predatory activity in the laboratory, effectively suppressing spider mite population growth. Even when the predators were fed spider mite eggs that had been treated previously with bifenazate, they survived. These findings indicate that bifenazate is a very useful acaricide giving high efficacy, long-lasting activity and excellent selectivity for spider mites. It is, therefore, concluded that bifenazate is an ideal compound for controlling these pest mites.

Mites in clinical stool specimens: potential misidentification as helminth eggs

We report the finding of unexpected microscopic oval structures in clinical stool samples processed by AFIP/Medicina Laboratorial, a laboratory performing routine clinical analysis in São Paulo, Brazil. Surprisingly, these objects were identified as mite eggs, sometimes accompanied by adult mites. Because misidentification of mite eggs as helminth ova may lead to erroneous treatment with far-reaching consequences, we sought to verify the frequency of adult mites and mite eggs among a number of processed stool specimens. Given their similarity to some helminth eggs, it is important that clinical laboratories recognize these structures, especially in geographic regions where intestinal parasitosis is prevalent.

Field efficacy of phoxim 50% (ByeMite®) against the poultry red mite Dermanyssus gallinae in battery cages stocked with laying hens

Infestations with the poultry red mite Dermanyssus gallinae represent a major ectoparasite problem in poultry and can affect egg layers worldwide. There is presently a lack of an ectoparasiticide in Europe for poultry which can assure a 0-day withholding period for eggs. In this study, ByeMite® (phoxim 50%, Bayer HealthCare, Animal Health Division) was administered to treat a D. gallinae infestation in a poultry house stocked with egg-laying hens kept in a cage system. A layer house was sprayed twice within a 7-day interval using a solution containing 2000ppm phoxim and a similar layer house was used as an untreated control unit. Specially developed D. gallinae traps made of cardboard were used to assess the mite density in both layer houses during a 49-day period after the treatment. In order to collect mites, the traps were placed on days −1, 2, 6, 9, 13, 20, 34 and 48 and always removed after 24h. The collected mites were counted and differentiated according to their developmental stage (mite eggs, larvae, nymphs, adults). Three days after the first spray treatment, the efficacy against all mite stages (larvae, nymphs, adults) was 96.1%, and from day 7 post-treatment until the end of the trial (day 49) the efficacy exceeded 99%. In contrast, in the untreated layer house (negative control group) the mite population showed a 400% increase. No treatment-related side effects in chickens were detectable. It is concluded that two administrations of ByeMite® within a 7-day interval are highly effective against D. gallinae infestations in a stocked poultry house.

Predation and Life Table of Feltiella acarisuga (Diptera: Cecidomyiidae) Preying on Eggs of Tetranychus urticae (Acari: Tetranychidae)

Feltiella acarisuga (Vallot) is a common gall midge that feeds on many species of spider mites. Predation and all major biological and life table parameters of F. acarisuga were determined using eggs of the twospotted spider mite, Tetranychus urticae (Koch), as prey under laboratory conditions (26.7°C, 85% RH, and 14:10 [L:D] h). First-, second-, and third-instar F. acarisuga larvae consumed an average of 37.8, 60.4, and 87.2 T. urticae eggs per day, respectively. Larvae consumed a total of 185.4 eggs each from first to third instars, and female larvae consumed 201.2 spider mite eggs, 18.6% more than male larvae. Developmental time of F. acarisuga was 2.6, 7.8, and 7.0 d for eggs, larvae, and pupae, respectively, with an average of 17.4 d from oviposition to adult emergence. Female immatures developed slightly slower (≈1 d) than males. Adult longevities of F. acarisuga averaged 13.0 d. After an average of 1.1-d preoviposition period, each female laid an average of 33.3 eggs during her lifespan. The intrinsic rate of natural population increase (r), net reproductive rates (Ro), gross reproductive rate (Σmx), generation time (T), doubling time (DT), and the finite rate of increase (&lgr;) of F. acarisuga were estimated by life table analysis at 0.1155/d, 15.25 eggs per female, 21.69 eggs per female, 23.6 d, 6.0 d, and 1.1225/d, respectively. Because the r value of F. acarisuga is relatively lower than that of T. urticae, frequent release of F. acarisuga may be necessary to suppress populations of T. urticae.

Predation and Life Table of <I>Feltiella acarisuga</I> (Diptera: Cecidomyiidae) Preying on Eggs of <I>Tetranychus urticae</I> (Acari: Tetranychidae)

Feltiella acarisuga (Vallot) is a common gall midge that feeds on many species of spider mites. Predation and all major biological and life table parameters of F. acarisuga were determined using eggs of the twospotted spider mite, Tetranychus urticae (Koch), as prey under laboratory conditions (26.7 degrees C, 85% RH, and 14:10 [L:D] h). First-, second-, and third-instar F. acarisuga larvae consumed an average of 37.8, 60.4, and 87.2 T. urticae eggs per day, respectively. Larvae consumed a total of 185.4 eggs each from first to third instars, and female larvae consumed 201.2 spider mite eggs, 18.6% more than male larvae. Developmental time of F. acarisuga was 2.6, 7.8, and 7.0 d for eggs, larvae, and pupae, respectively, with an average of 17.4 d from oviposition to adult emergence. Female immatures developed slightly slower ( approximately 1 d) than males. Adult longevities of F. acarisuga averaged 13.0 d. After an average of 1.1-d preoviposition period, each female laid an average of 33.3 eggs during her lifespan. The intrinsic rate of natural population increase (r), net reproductive rates (R(o)), gross reproductive rate (Sigmam(x)), generation time (T), doubling time (DT), and the finite rate of increase (lambda) of F. acarisuga were estimated by life table analysis at 0.1155/d, 15.25 eggs per female, 21.69 eggs per female, 23.6 d, 6.0 d, and 1.1225/d, respectively. Because the r value of F. acarisuga is relatively lower than that of T. urticae, frequent release of F. acarisuga may be necessary to suppress populations of T. urticae.

屋内塵性ダニの卵に対する脱酸素剤の致死効果

The lethal effects of two types of oxygen absorbers on the eggs of the house dust mites, Dermatophagoides farinae, D. pteronyssinus, and Tyrophagus putrescentiae were studied. For D. farinae, and D. pteronyssinus, the mortality obtained after 2 days in an air-tight container with iron (Fe)-type oxygen absorbers was 100%, while an ascorbic-acid-type oxygen absorber needed 5 days to obtain 100% mortality. On the other hand, the two types of oxygen absorbers showed no significant lethal difference on T. putrescentiae.

ATP assay for determining the viability of the two-spotted spider mite (Tetranychus urticae Koch) and the European red mite (Panonychus ulmi (Koch)) (Acari: Tetranychidae) during diapause

A bioluminescent adenosine triphosphate (ATP) assay for determining viability in adult females of the two-spotted spider mite, Tetranychus urticae, and eggs of the European red mite, Panonychus ulmi, (both diapause and non-diapause state), was investigated. ATP contents in living and dead individual mites (adult females or eggs) were measured. The mites of the lethal treatment group were killed by freezing at −35°C. Mean (±SD) ATP contents for non-diapause and diapause T. urticae female adults were 34.39±5.14 pmol and 26.40±2.67 pmol, respectively. Corresponding values for non-diapause and diapause P. ulmi eggs were 1.12±0.19 pmol and 0.87±0.16 pmol, respectively. ATP contents in living mites in diapause were therefore approximately 77% of those in non-diapause mites. A wide variance in the ATP contents (0.00–0.94 pmol) was found in individual P. ulmi diapause eggs at 2 and 4 h after treatment; therefore, their mean ATP contents did not show a rapid decrease. We speculated that some P. ulmi diapause eggs survived for several hours after treatment by cold hardiness, maintaining metabolic activities until death. However, with the exception of P. ulmi diapause eggs, ATP contents in both mite species rapidly decreased at 2 h after treatment. At 24 h after treatment, ATP contents in both mite species had decreased significantly to 0.4–2.7% of the pre-treatment values, regardless of whether they were in a non-diapause or diapause state. Thus, based on our findings with T. urticae adult females and P. ulmi eggs, the ATP bioluminescence assay could be applicable to the determination of pest viability, regardless of their diapause state.

Biology, life table and predation of Feltiella acarisuga (Diptera: Cecidomyiidae) feeding on Tetranychus cinnabarinus eggs (Acari: Tetranychidae)

Abstract Feltiella acarisuga (Vallot) is a common predatory gall midge, which feeds on many species of spider mites. All major life history and life table parameters of F. acarisuga were determined using the carmine spider mite, Tetranychus cinnabarinus (Boisduval) eggs as prey under laboratory conditions [26.7 ± 2 °C, 75 ± 5% RH, and a photoperiod of l4:10 (L:D) h]. Developmental times of F. acarisuga were 2.6, 7.1, and 6.7 d for eggs, larvae, and pupae, respectively, with an average of 16.4 d from egg to adult emergence. Female immatures development took ≈1 d longer than male immatures did. Adult F. acarisuga lived an average of 12.8 d, and the female adults (13.3 d) lived significantly longer than male adults did (11.9 d). After an average of 1.5 d preoviposition period, each female laid an average of 27.3 eggs in its life span with an average of 2.1 eggs per day and an average of 2.8 eggs on each of its oviposition day. The raw data were analyzed using an age-stage, two-sex life table method that takes into consideration of the variable developmental rates among individuals and between sexes. The intrinsic rate of natural population increase (r), net reproductive rates (Ro), gross reproductive rate ( ∑ m x ) , generation time (T), and doubling time (DT), and the finite rate of increase (λ) of F. acarisuga were estimated using the age-stage, two-sex (male and female) life table analysis as 0.122 d−1, 16.19 eggs per female, 20.81 eggs per female, 22.81 d, 1.1298 d, and 5.7 d−1, respectively. Each of the first, second, and third instar larvae of F. acarisuga consumed an average of 35.5, 54.0 and 86.9 T. cinnabarinus eggs per day, respectively. Larvae of F. acarisuga could consume an average of 175.4, T. cinnabarinus eggs, and female larvae consumed 14% more spider mite eggs (187.6 eggs) than male larvae (165.1 eggs). The significance of other life table parameters related to the population and the potential of using F. acarisuga as a biological control agent are discussed.

TWO SPECIES OF CECIDOMYIIDAE PREDACIOUS ON CITRUS RUST MITE, PHYLLOCOPTRUTA OLEIVORA, ON FLORIDA CITRUS

Larvae of two undescribed species of Cecidomyiidae (Diptera) were found preying upon Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) on Florida citrus. Identifications to genus were made from adults reared in the laboratory. The two species had distinctive larval coloration. One larval type was completely yellow and was identified as Feltiella n. sp., while the second larval type had an orange color with a transverse white band close to the mouthparts. The latter cecidomyiid was identified as belonging to a genus near Lestodiplosis in the broad sense. Feltiella n. sp. (n = 17) and the species near the genus Lestodiplosis (n = 12) consumed 33.8 ± 4.6 (mean ± SEM) and 43.0 ± 6.4 citrus rust mite eggs; 14.2 ± 1.4 and 15.0 ± 2.0 citrus rust mite nymphs, and 3.0 ± 0.4 and 5.6 ± 0.9 citrus rust mite adults/10 min., respectively. There were no significant differences (P > 0.05) in the consumption rates of either predator on any rust mite life stage. These data indicate that Feltiella n. sp. and the species near the genus Lestodiplosis are both efficient predators of P. oleivora eggs, larvae, and nymphs.

Effect of high-pressure hot water washing treatment on fruit quality, insects, and disease in apples and pears: Part IV: Use of silicone-based materials and mechanical methods to eliminate surface arthropod eggs

The presence of surface arthropods on commercially processed apples and pears poses a problem when these fruits are exported to countries where there are either limits on the numbers of eggs or a total quarantine restriction against these pests. Removal of mite and other arthropod eggs, such as European red mite (ERM) and codling moth (CM) eggs, may be enhanced by the use of a surface cleaning system, such as a hot water, high-pressure spray. Even if organosilicones, like Silwet L-77, have been used to kill spider mites, it was unclear if these chemicals could also facilitate the removal of arthropod eggs from the surface of fruit. In the present study, high-pressure washing process was highly effective in removing CM and ERM eggs at pressures as low as 400 kPa, resulting in greater than 60% removal of ERM eggs and 90% of CM eggs. High-pressure washing was the most important factor in removal of codling moth and European red mite eggs than organosilicone dips or hot water sprays.

Host plant preference of aphids, thrips and spider mites on GNA-expressing and control potatoes

The effect of snowdrop lectin (Galanthus nivalis agglutinin: GNA) expression on host-plant preference was examined with a two-choice disc test. Discrimination between a transgenic potato [Solanum tuberosum (Solanaceae)] capable of synthesizing GNA, and an isogenic cultivar, was studied under laboratory conditions using the glasshouse potato aphidAulacorthum solani (Hemiptera: Aphididae), the onion thripThrips tabaci (Thysanoptera: Thripidae), and the two-spotted spider miteTetranychus urticae (Acari: Tetranychidae). Adults of these species were placed individually on leaf discs (one half transgenic and one half control) and observed 1, 24, 48, 72 and 96 h after release, at which times also the distributions ofA. solani nymphs andT. urticae eggs on the discs were recorded. Aphids were found more frequently on control leaves at all observation periods, with the highest bias observed at 72 h (only 35.9% of all aphids were found on the GNA halves). Similarly, more aphid nymphs (57.6% of the total) were found on isogenic half-discs. The percentage of thrips found on GNA halves ranged from 36.8% to 48.4%, with significant control-potato bias at the first three observations. Contrary to this, the proportion ofT. urticae females found on GNA halves was significantly lower than the expected proportion (0.5) at 72 and 96 h, with a minimum of 34.0% on GNA. The distribution of spider mite eggs reflected the observed biased distribution of females (only 34.1% of all eggs were laid on GNA half-discs). These results indicate that potatoes expressing GNA for resistance against aphids are less preferred than an isogenic cultivar by all three tested species under a choice test condition using excised leaves.

Laboratory Studies on the use of Two New Arenas to Evaluate the Impact of the Predatory Mites Blattisocius tarsalis and Cheyletus eruditus on Residual Populations of the Stored Product Mite Acarus siro

Residual populations of storage mites sheltering in crevices and cracks escape conventional control treatments and are implicated in the infestation of newly harvested grain. In a series of 24 h laboratory tests, the performance of solitary adults of two predatory mite species, Cheyletus eruditus (Schrank) and Blattisocius tarsalis (Berlese), were assessed for controlling small numbers of the flour mite Acarus siro (L.). Tests were carried out in the presence or absence of prey refuges or grain debris to afford shelter to the flour mites. While C. eruditus had a significant effect on the motile stages of A. siro, in contrast B. tarsalis had a significant effect on the eggs. The maximum percentage of motile stages of A. siro eaten by C. eruditus was 82%, whereas the minimum percentage of A. siro eggs eaten by B. tarsalis was 99%. While the performance of C. eruditus in predating on motile stages of the flour mite was hindered by the presence of the prey refuge (38% eaten) and grain debris (25% eaten), the performance of B. tarsalis in predating on flour mite eggs was unaffected (100% eaten in presence of prey refuge or grain debris). In prolonged exposures (36 days) the performance of 2, 4 or 8 adult predators, either a single species or a combination of both, was assessed for their ability to control a population of the flour mite developing up to F(2) from an initial inoculum of 80 females and 20 males, allowed to oviposit for 72 h in the absence of predatory mites. The maximum reduction in prey population of 80% was achieved with eight B. tarsalis. Combining the two predatory species did not enhance the reduction of A. siro population.