The microbiota in spider mite feces potentially reflects intestinal bacterial communities in the host

Microorganisms provide many physiological functions to herbivorous hosts. Spider mites (genus Tetranychus) are important agricultural pests throughout the world; however, the composition of the spider mite microbial community, especially gut microbiome, remains unclear. Here, we investigated the bacterial community in five spider mite species and their associated feces by deep sequencing of the 16S rRNA gene. The composition of the bacterial community was significantly different among the five prevalent spider mite species, and some bacterial symbionts showed host‐species specificity. Moreover, the abundance of the bacterial community in spider mite feces was significantly higher than that in the corresponding spider mite samples. However, Flavobacterium was detected in all samples, and represent a “core microbiome”. Remarkably, the maternally inherited endosymbiont Wolbachia was detected in both spider mite and feces. Overall, these results offer insight into the complex community of symbionts in spider mites, and give a new direction for future studies.     

Impact of transgenic Bacillus thuringiensis cotton on a non-target pest Tetranychus spp. in northern China

Field studies were carried out to evaluate the effect of two transgenic cotton varieties (SGK321 carrying Cry1A+CpTI and DP99B carrying Cry1Ac) and the conventional variety (shiyuan321‐parental line of SGK321) on spider mites, Tetranychus spp. from 2002 to 2004. In 2002, this experiment included three treatments: Bt cotton field (SGK321) treated with acaricides against spider mites, untreated non‐Bt cotton field (Shiyuan321), and untreated Bt cotton field (SGK321). In 2003–2004, there are four types of treatments after a new transgenic Bt cotton variety, DP99B (non‐chemical control), was added into the experiments. The results showed that there were no significant difference in densities of spider mites among Bt without acaricides and non‐Bt without acaricides cotton fields, nor was there a significant difference in damage of spider mites to cotton among these treatments (P > 0.1). However, there are significant differences (P < 0.05) in densities of spider mites and damage caused by spider mites between cotton fields with and without acaricides. Acaricide significantly reduced the densities of spider mites in Bt cotton (P < 0.05). These results suggest that Bt cotton has no effect on spider mites populations. However, spider mites have the potential for severe damage in Bt cotton fields. Acaricides are essential tools in controlling cotton spider mites in northern China.     

Species composition of thrips (Thysanoptera: Thripidae) and spider mites (Acari: Tetranychidae) on cultivated chrysanthemum (Asteraceae) in Okinawa,southwestern Japan

We investigated the species composition of phytophagous thrips and spider mites on cultivated chrysanthemum in Okinawa, southwestern Japan. Eight thrips species belonging to the genera Frankliniella, Microcephalothrips, Scirtothrips and Thrips were found on chrysanthemum leaves. Among them, Thrips nigropilosus was the predominant species irrespective of season, island or cultivation environment (meshed greenhouse or open field), with its infestation frequency being 89% of the fields in which thrips occurred. This high frequency of occurrence suggests that T. nigropilosus is a major pest of chrysanthemum in Okinawa, even though this species has rarely been regarded as an important pest of chrysanthemum or other crops in any other areas. Thrips palmi was the second most dominant (infestation frequency 36%) and other species were scarce (<14%). Tetranychus urticae (green form) was the only tetranychid species on chrysanthemum in our survey. This lack of diversity among spider mites on chrysanthemum is peculiar considering that eight Tetranychus species have been found on vegetables in the same area. Since T. urticae (green form) has been shown to be resistant to a number of pesticides, severe pesticide applications might have simplified the spider mite fauna on chrysanthemum in Okinawa.     

Response of predatory mites with different rearing histories to volatiles of uninfested plants

The behavioural response of the predatory mite Phytoseiulus persimilis to volatiles from several host plants of its prey, spider mites in the genus Tetranychus, was investigated in a Y-tube olfactometer. A positive response to volatiles from tomato leaves and Lima bean leaves was recorded, whereas no response was observed to volatiles from cucumber leaves, or leaves of Solanum luteum and Solanum dulcamara.Different results were obtained for predators that differed in rearing history. Predators that were reared on spider mites (Tetranychus urticae) on Lima bean leaves did respond to volatiles from Lima bean leaves, while predators that had been reared on the same spider mite species but with cucumber as host plant did not respond to Lima bean leaf volatiles. This effect is compared with the effect of rearing history on the response of P. persimilis to volatile allelochemicals of prey-infested plant leaves.     

Reproductive success ofAmblyseius idaeus andA. anonymus on a diet of two-spotted spider mites

Amblyseius idaeus is a drought-resistant predatory mite of tetranychid spider mites. In this paper, life-history parameters ofA. idaeus and a morphologically similar species,A. anonymus, are measured and compared on a diet ofTetranychus urticae. Intrinsic rates of increase of both phytoseiids are similar, and are comparable to rates of phytoseiids that successfully controlTetranychus species. This makes both species promising candidates as biological control agents,A. idaeus especially under dry conditions.     

Lima bean�Clady beetle interactions: spider mite mediates sublethal effects of its host plant on growth and development of its predator

Cultivated plants can have negative effects on natural enemies that attack spider mites. In this study, we tested the hypothesis that spider mites mediate effects of a lima bean, Phaseolus lunatus L., cultivar on the life history of a lady beetle Stethorus punctillum Weise. We provisioned laboratory arenas with two-spotted spider mites, Tetranychus urticae Koch, from planters containing Henderson Bush Bean or Fordhook 242 lima bean plants and monitored the growth, development, larval survival, fecundity, and adult life span of predators. We determined the protein content and the linamarin (a cyanogenic glycoside) content in foliage, spider mites, and predators. Predators took longer to develop and were smaller sized when consuming mites from the Henderson foliage. There was no significant mite-mediated effect of cultivar on predator fecundity or life span. Although soluble protein was greater in foliage of the Henderson than the Fordhook cultivar, mites contained less protein when reared on the Henderson, and predators contained less protein when fed with mites from the Henderson. Linamarin content was greater in Henderson than Fordhook foliage, and greater in spider mites and predators in the Henderson treatment. Linamarin in Henderson foliage may reduce the ability of spider mites to utilize plant protein. As a result, prey quality is reduced and predators that feed on these prey (from the Henderson treatment) grow at a slower rate and are smaller sized than their cohorts (from the Fordhook treatment). In conclusion, T. urticae mediates the effects of the Henderson cultivar on S. punctillum development but not fecundity or life span.     

Potential lethal and non-lethal effects of predators on dispersal of spider mites

Predators can affect prey dispersal lethally by direct consumption or non-lethally by making prey hesitate to disperse. These lethal and non-lethal effects are detectable only in systems where prey can disperse between multiple patches. However, most studies have drawn their conclusions concerning the ability of predatory mites to suppress spider mites based on observations of their interactions on a single patch or on heavily infested host plants where spider mites could hardly disperse toward intact patches. In these systems, specialist predatory mites that penetrate protective webs produced by spider mites quickly suppress the spider mites, whereas generalist predators that cannot penetrate the webs were ineffective. By using a connected patch system, we revealed that a generalist ant, Pristomyrmex punctatus Mayr (Hymenoptera: Formicidae), effectively prevented dispersal of spider mites, Tetranychus kanzawai Kishida (Acari: Tetranychidae), by directly consuming dispersing individuals. We also revealed that a generalist predatory mite, Euseius sojaensis Ehara (Acari: Phytoseiidae), prevented between-patch dispersal of T. kanzawai by making them hesitate to disperse. In contrast, a specialist phytoseiid predatory mite, Neoseiulus womersleyi Schicha, allowed spider mites to escape an initial patch, increasing the number of colonized patches within the system. Our results suggest that ants and generalist predatory mites can effectively suppress Tetranychus species under some conditions, and should receive more attention as agents for conservation biological control in agroecosystems.     

Functionally different predators break down antipredator defenses of spider mites

Prey that lives with functionally different predators may experience enhanced mortality risk, because of conflicts between the specific defenses against their predators. Because natural communities usually contain combinations of prey and functionally different predators, examining risk enhancement with multiple predators may help to understand prey population dynamics. It is also important in an applied context: risk enhancement with multiple biological control agents could lead to successful suppression of pests. We examined whether risk enhancement occurs in the spider mite Tetranychus kanzawai Kishida (Acari: Tetranychidae) when exposed to two predator species: a generalist ant, Pristomyrmex punctatus Mayr (Hymenoptera: Formicidae), and a specialist predatory mite, Neoseiulus womersleyi Schicha (Acari: Phytoseiidae). We replicated microcosms that consisted of spider mites, ants, and predatory mites. Spider mites avoided generalist ants by staying inside their webs on leaf surfaces. In contrast, spider mites avoided specialist predatory mites that intruded into their webs by exiting the web, which obviously conflicts with the defense against ants. In the presence of both predators, enhanced mortality of spider mites was observed. A conflict occurred between the spider mites’ defenses: they seemed to move out of their webs and be preyed upon by ants. This is the first study to suggest that risk enhancement occurs in web‐spinning spider mites that are exposed to both generalist and specialist predator species, and to provide evidence that ants can have remarkable synergistic effects on the biological control of spider mites using specialist predatory mites.     

Pest species diversity enhances control of spider mites and whiteflies by a generalist phytoseiid predator

To test the hypothesis that pest species diversity enhances biological pest control with generalist predators, we studied the dynamics of three major pest species on greenhouse cucumber: Western flower thrips, Frankliniella occidentalis (Pergande), greenhouse whitefly, Trialeurodes vaporariorum (Westwood), and two-spotted spider mites, Tetranychus urticae Koch in combination with the predator species Amblyseius swirskii Athias-Henriot. When spider mites infested plants prior to predator release, predatory mites were not capable of controlling spider mite populations in the absence of other pest species. A laboratory experiment showed that predators were hindered by the webbing of spider mites. In a greenhouse experiment, spider mite leaf damage was lower in the presence of thrips and predators than in the presence of whiteflies and predators, but damage was lowest in the presence of thrips, whiteflies and predators. Whitefly control was also improved in the presence of thrips. The lower levels of spider mite leaf damage probably resulted from (1) a strong numerical response of the predator (up to 50 times higher densities) when a second and third pest species were present in addition to spider mites, and (2) from A. swirskii attacking mobile spider mite stages outside or near the edges of the spider mite webbing. Interactions of spider mites with thrips and whiteflies might also result in suppression of spider mites. However, when predators were released prior to spider mite infestations in the absence of other pest species, but with pollen as food for the predators, we found increased suppression of spider mites with increased numbers of predators released, confirming the role of predators in spider mite control. Thus, our study provides evidence that diversity of pest species can enhance biological control through increased predator densities.     

Aerodynamic advantages of upside down take-off for aerial dispersal in <Emphasis Type="Italic">Tetranychus</Emphasis> spider mites

Aerial dispersal may be important for redistribution of spider mites into new habitats. Evidence for behavioral control of aerial take-off has been well documented for Tetranychus urticae Koch. Before aerial dispersal they exhibit the aerial take-off posture that involves lifting the forelegs upright and raising the forebody. However, whether the aerial take-off posture functions to increase drag has remained unclear. The objectives of this study were to clarify: (i) aerodynamic effects of the aerial take-off posture; and (ii) actual aerial take-off behavior in T. urticae. To evaluate the aerodynamic forces experienced by grounded spider mites in different postures, we constructed three-dimensional models of T. urticae, exhibiting the aerial take-off posture and the normal posture, using computer graphics. We found that the aerial take-off posture was effective in receiving greater rearward forces from wind rather than upward forces. As a result, aerial take-off from a horizontal platform is unlikely. Instead, inverted departure surfaces, e.g., lower leaf surfaces, with inclines are likely to be effective sites for take-off. Laboratory experiments and field observations indicated that the mites preferentially adopted such a position for orientation and take-off. Our findings provided a rationale for the take-off behavior of Tetranychus spider mites.     

Inter‐ and intraspecific variation of spider mite susceptibility to fungal infections: Implications for the long‐term success of biological control

Spider mites are severe pests of several annual and perennial crops worldwide, often causing important economic damages. As rapid evolution of pesticide resistance in this group hampers the efficiency of chemical control, alternative control strategies, such as the use of entomopathogenic fungi, are being developed. However, while several studies have focused on the evaluation of the control potential of different fungal species and/or isolates as well as their compatibility with other control methods (e.g., predators or chemical pesticides), knowledge on the extent of inter‐ and intraspecific variation in spider mite susceptibility to fungal infection is as yet incipient. Here, we measured the mortality induced by two generalist fungi, Beauveria bassiana and Metarhizium brunneum, in 12 spider mite populations belonging to different Tetranychus species: T. evansi, T. ludeni, and T. urticae (green and red form), within a full factorial experiment. We found that spider mite species differed in their susceptibility to infection by both fungal species. Moreover, we also found important intraspecific variation for this trait. These results draw caution on the development of single strains as biocontrol agents. Indeed, the high level of intraspecific variation suggests that (a) the one‐size‐fits‐all strategy may fail to control spider mite populations and (b) hosts resistance to infection may evolve at a rapid pace. Finally, we propose future directions to better understand this system and improve the long‐term success of spider mite control strategies based on entomopathogenic fungi.     

Die Feinde der Raubmilben als Reduzierender Faktor der Spinnmilben

Summary The relations betweenMetatetranychus ulmi living on apple trees and its different predators are complex. The most important natural enemy of this spider mite is the predacious miteTyphlodromus pyri (= T. tiliae). It destroys more spider mites than the beneficial insects do. In the district of Stuttgart-Hohenheim about 38 species of insects and spiders feed onTyphlodromus mites. For instanceT. pyri is reduced considerably byOrius minutus. This bug is a natural enemy of aphids and spider mites, however it prefers the predatory mites. It attacks the spider mites and aphids only ifTyphlodromus mites are not available.Chrysopa vulgaris andAnthocoris nemorum are similar in their feeding habits. These two destroyTyphlodromus pyri also but they are less important thanO. minutus. The other beneficial insects in our orchards have little effect on spider mites or predacious mites. If we have enough pests on our apple trees to make spraying necessary, we should look forTyphlodromus mites and be careful no to destroy them. We should always examine the composition of the biocoenosis applying chemical agents because the populations of insects and predacious mites may vary from one area to the other.      

A critical review on some closely related species of <Emphasis Type="Italic">Tetranychus</Emphasis> sensu stricto (Acari: Tetranychidae) in the public DNA sequences databases

Taxonomic misidentification of the specimens used to obtain DNA sequences is a growing problem reported for different groups of organisms, which threatens the utility of the deposited sequences in public DNA databases. This paper provides new evidence of misidentifications in molecular DNA public databases in phytophagous mites of the Tetranychidae family belonging to the group Tetranychus (Tetranychus). Several species in this group are of economic and quarantine importance in agriculture and among them Tetranychus urticae, a highly polyphagous mite causing outbreaks in many crops worldwide, is certainly the most studied. We analyzed and evaluated the identity of 105 GenBank accessions of ITS2 rDNA and 138 COI mtDNA sequences which were deposited as T. urticae and those of 14 other taxa morphologically closely related to Tetranychus sensu stricto. In addition, ITS2 and COI sequences of 18 T. urticae samples collected for this study and identified by morphological criteria, were generated and included in the analyzed dataset. Among the deposited sequences in the GenBank database, numerous cases of apparently mistaken identities were identified in the group Tetranychus s. str., especially between T. urticae, T. cinnabarinus, T. kanzawai and T. truncatus. Unreliable sequences (misidentified or dubious) were estimated at nearly 30%. In particular the analysis supports the invalidity of the controversial species status of T. cinnabarinus. More generally, it highlights the need of using combined morphological and molecular approaches to guarantee solid species diagnostics for reliable sequence accessions in public databases.     

Intraguild predation of Orius tristicolor by Geocoris spp. and the paradox of irruptive spider mite dynamics in California cotton

It is paradoxical when a community of several natural enemies fails to control a pest population when it can be shown experimentally that single members of the natural enemy community are effective control agents when tested individually. This is the case for spider mites, Tetranychus spp., in California cotton. Spider mites exhibit irruptive population dynamics despite that fact that experiments have shown that there are at least four predators (Galendromus occidentalis, Frankliniella occidentalis, Orius tristicolor, and Geocoris spp.) that, when tested singly, can suppress mite populations. One possible explanation for the paradox is intraguild predation, wherein one predator consumes another. Here, I evaluate the hypothesis that intraguild predation is a strong interaction among spider mite predators. I report manipulative field experiments, focal observations of freely foraging predators in the field, and population survey data that suggest that the minute pirate bug O. tristicolor, is subject to strong predation by other members of the predator community, and in particular by Geocoris spp. These results, combined with the results of prior work, suggest that pervasive intraguild predation among spider mite predators may explain the pest status of Tetranychus spp. in cotton.     

Spider mite infestations reduce Bacillus thuringiensis toxin concentration in corn leaves and predators avoid spider mites that have fed on Bacillus thuringiensis corn

Perceived benefits of insecticidal transgenic crops include reduced usage of broad‐based insecticides, and therefore lower risk to non‐target organisms. Numerous studies have documented low or no direct toxicity of Bacillus thuringiensis (Bt)‐derived toxins against non‐target organisms, but there has been less research on (a) effects of secondary pest infestations on Bt expressing in crops and (b) behavioural responses by predators feeding on host arthropods from Bt crops – both topics are investigated in this study. We quantified predation by the obligate spider mite predator Phytoseiulus persimilis of carmine spider mites (Tetranychus cinnabarinus), reared on Bt or non‐Bt corn (Zea mays). Both no‐choice and two‐choice studies were conducted. In addition, we quantified toxin levels in corn leaves with/without spider mite infestation. Under no‐choice conditions, P. persimilis consumed non‐Bt spider mites at a faster rate than Bt spider mites. Under two‐choice conditions, P. persimilis spent more time in the vicinity of non‐Bt spider mites than near Bt spider mites. Corn infested with spider mites exhibited lower toxin levels than non‐infested plants. These results suggest potentially complex interactions among non‐target herbivores, their natural enemies and Bt crops.     

The invasive spider mite Tetranychus evansi (Acari: Tetranychidae) alters community composition and host-plant use of native relatives

The tomato spider mite Tetranychus evansi Baker and Pritchard (Acari: Tetranychidae), is a worldwide pest of solanaceous crops that has recently invaded many parts of the world. In the present study we examined the ecological impact of its arrival in the Mediterranean region. The spider mite and phytoseiid mite assemblages in various crop and non-crop plants in three areas of Valencia (Spain) were studied a few months before and 10 years after the invasion of T. evansi. According to rarefaction analyses, the invasion of T. evansi did not affect neither the total number of species in the mite community examined (spider mite and phytoseiid species) nor the number of species when the two communities were examined separately. However, after the invasion, the absolute and relative abundance of the native Tetranychus species was significantly reduced. Before the invasion, T. urticae and T. turkestani were the most abundant spider mites, accounting for 62.9 and 22.8 % of the specimens. After the invasion, T. evansi became the most abundant species, representing 60 % of the total spider mites recorded, whereas the abundance of T. urticae was significantly reduced (23 %). This reduction took place principally on non-crop plants, where native species were replaced by the invader. Null model analyses provided evidence for competition structuring the spider mite community on non-crop plants after the invasion of T. evansi. Resistance to acaricides, the absence of efficient native natural enemies, manipulation of the plant defenses and the web type produced by T. evansi are discussed as possible causes for the competitive displacement.     

Spider-Mite Problems and Control in Taiwan

Problems with spider mites first appeared in Taiwan in 1958, eight years after the importation of synthetic pesticides, and the mites evolved into major pests on many crops during the 1980s. Of the 74 spider mite species recorded from Taiwan 10 are major pests, with Tetranychus kanzawai most important, followed by T. urticae, Panonychus citri, T. cinnabarinus, T. truncatus and Oligonychus litchii. Most crops suffer from more than one species. Spider mites reproduce year-round in Taiwan. Diapause occurs only in high-elevation areas. Precipitation is the most important abiotic factor restricting spider-mite populations. Control is usually accomplished by applying chemicals. Fifty acaricides are currently registered for the control of spider mites. Acaricide resistance is a serious problem, with regional variation in resistance levels. Several phytoseiid mites and a chrysopid predator have been studied for control of spider mites with good effect. Efforts to market these predators should be intensified so that biological control can be a real choice for farmers.     

Influence of prey on developmental performance, reproduction and prey consumption of Neoseiulus californicus (Acari: Phytoseiidae)

The Spical strain of the predatory mite Neoseiulus californicus (McGregor) is used as a biological control agent, but little is known about its preferred prey and host plants in Japan. Here we studied the development, reproduction and prey consumption of the Spical strain when fed on eggs of five different spider mite species deposited on both their laboratory-rearing plant and cherry, on which all five spider mite species developed well. The developmental periods of immature N. californicus females and males were significantly affected by the prey species they fed on, but not by the plants. No difference was found between males and females. The developmental period was shorter on eggs of two Tetranychus species than on eggs of Panonychus ulmi. Immature females had a higher predation rate than immature males. Preoviposition period, oviposition period and the number of eggs laid per female were not significantly affected by either the plants or the type of prey eggs. The postoviposition period and total adult longevity were shorter on eggs of P. ulmi than of the other four prey species, but there was no effect of plant substrate. The postoviposition period of the Spical strain was much longer than that of other N. californicus strains or other predatory mite species: the postoviposition period of the Spical strain was more than three times longer than the oviposition period, accounting for more than 75% of the total adult longevity. This suggests that the females need multiple mating to reach full egg load, but this remains to be tested. Total consumption by N. californicus adults was lower for eggs of P. ulmi than for eggs of the other four species, apparently because of the shorter postoviposition period when fed on eggs of P. ulmi. The intrinsic rates of natural increase (r _m) on the rearing plant did not differ among prey species, whereas those on cherry were significantly different: the value was higher on Tetranychus urticae eggs than on eggs of other species. Only when N. californicus fed on T. urticae eggs, the r _m-values were significantly different between the rearing plant and cherry (higher on cherry). Thus, the Spical strain of N. californicus could feed on eggs of all five spider mite species, deposited on a variety of plants with similar r _m-values, suggesting that it could be successfully used to control spider mites in orchards and various crop fields of Japan.     

Interactions between white mealybugs and red spider mites sequentially colonizing coffee plants

Plants under herbivore attack often respond defensively by mounting chemical and physical defences. However, some herbivores can manipulate plant defences to their own benefit by suppressing the expression of induced defences. These herbivore‐induced changes specific to the attacking herbivore can either facilitate or impede the colonization and establishment of a second herbivore. Although recent studies have focused on the effect of multiple herbivory on plant induced response and the third trophic level, few have examined the ecological relevance of multiple herbivores sharing the host. Here, we investigated whether herbivory by the white mealybug Planococcus minor (Maskell) (Hemiptera: Pseudococcidae) or the red spider mite Olygonychus ilicis (McGregor) (Acari: Tetranychidae), two herbivores that peak in coffee plantations during the dry season, may facilitate the colonization and establishment of the other species in coffee plants. Dual‐choice arena tests showed that white mealybugs preferred mite‐infested over uninfested coffee plants as hosts. Fifteen days after the release of 50 first‐instar P. minor nymphs, greater numbers of nymphs and adults were found on mite‐infested than uninfested plants, indicating superior performance on mite‐infested plants. On the other hand, female red spider mites did not show clear preference between uninfested and mealybug‐infested plants and deposited similar numbers of eggs on both treatments. In a no‐choice test, red spider mites performed poorly on mealybug‐infested plants with a smaller number of eggs, nymphs, females and males found in mealybug‐infested plants relative to uninfested plants. Thus, our results indicate that coffee plants are more likely to be infested by the red spider mite before white mealybug, rather than the inverse sequence (i.e. mealybug infestation followed by red spider mites). Our findings are discussed in the context of plant manipulation reported for pseudococcid mealybugs and spider mites.     

Diseases of Mites

An overview is given of studies on diseases of mites. Knowledge of diseases of mites is still fragmentary but in recent years more attention has been paid to acaropathogens, often because of the economic importance of many mite species. Most research on mite pathogens concerns studies on fungal pathogens of eriophyoids and spider mites especially. These fungi often play an important role in the regulation of natural mite populations and are sometimes able to decimate populations of phytophagous mites. Studies are being conducted to develop some of these fungi as commercial acaricides.Virus diseases are known in only a few mites, namely, the citrus red mite and the European red mite. In both cases, non-occluded viruses play an important role in the regulation of mite populations in citrus and peach orchards, respectively, but application of these viruses as biological control agents does not seem feasible. A putative iridovirus has been observed in association with Varroa mites in moribund honeybee colonies. The virus is probably also pathogenic for honeybees and may be transmitted to them through this parasitic mite.Few bacteria have been reported as pathogens of the Acari but in recent years research has been concentrated on intracellular organisms such as Wolbachia that may cause distorted sex ratios in offspring and incompatibility between populations. The role of these organisms in natural populations of spider mites is in particular discussed. The effect of Bacillus thuringiensis on mites is also treated in this review, although its mode of action in arthropods is mainly due to the presence of toxins and it is, therefore, not considered to be a pathogen in the true sense of the word.Microsporidia have been observed in several mite species especially in oribatid mites, although other groups of mites may also be affected. In recent years, Microsporidia infections in Phytoseiidae have received considerable attention, as they are often found in mass rearings of beneficial arthropods. They affect the efficacy of these predators as biological control agent of insect and mite pests. Microsporidia do not seem to have potential for biological control of mites.