Stored Product Mites Research Articles

Dry Dog Food Integrity and Mite Strain Influence the Density-Dependent Growth of the Stored-Product MiteTyrophagus putrescentiae(Acari: Acaridida)

The infestation of foodstuffs by mites is connected to health risks and economic losses. The cosmopolitan stored-product mite Tyrophagus putrescentiae (Schrank, 1781) is an emerging and predominant pest of dry dog food. In this study, the influences on mite population growth of 1) the different dry dog food kernels present in the package; 2) the integrity of the dry dog food kernel, whether intact or crushed; 3) the initial population density of 10 or 100 specimens; and 4) the four mite strains used were investigated under laboratory conditions. The population growth tests were performed for 28 d at 85% relative humidity and 25°C. The intrinsic growth rates of the mites were compared. The population growth was higher on the brown and green kernels than on the red and white kernels. The kernel integrity affected the population growth, and the integrity effect was highly influenced by the initial mite population density. The mites showed density-dependent growth in three of the four mite strains tested. The initial population density changed the population growth ranking among the mite strains, thereby indicating strain-specific density-dependent growth. The results of this study have important implications for predictive models of stored-product mite populations in dry dog food. One practical recommendation is that the growth of mites should be considered with regard to the mite strains and according to the strain-specific density dependent growth. Next, the integrity of the kernels should be maintained because disrupted or crushed kernels promote increases in mite populations.

Origin and higher-level diversification of acariform mites - evidence from nuclear ribosomal genes, extensive taxon sampling, and secondary structure alignment.

BackgroundAcariformes is the most species-rich and morphologically diverse radiation of chelicerate arthropods, known from the oldest terrestrial ecosystems. It is also a key lineage in understanding the evolution of this group, with the most vexing question whether mites, or Acari (Parasitiformes and Acariformes) is monophyletic. Previous molecular studies recovered Acari either as monophyletic or non-monophyletic, albeit with a limited taxon sampling. Similarly, relationships between basal acariform groups (include little-known, deep-soil 'endeostigmatan' mites) and major lineages of Acariformes (Sarcoptiformes, Prostigmata) are virtually unknown. We infer phylogeny of chelicerate arthropods, using a large and representative dataset, comprising all main in- and outgroups (228 taxa). Basal diversity of Acariformes is particularly well sampled. With this dataset, we conduct a series of phylogenetically explicit tests of chelicerate and acariform relationships and present a phylogenetic framework for internal relationships of acariform mites.ResultsOur molecular data strongly support a diphyletic Acari, with Acariformes as the sister group to Solifugae (PP =1.0; BP = 100), the so called Poecilophysidea. Among Acariformes, some representatives of the basal group Endeostigmata (mainly deep-soil mites) were recovered as sister-groups to the remaining Acariformes (i. e., Trombidiformes + and most of Sarcoptiformes). Desmonomatan oribatid mites (soil and litter mites) were recovered as the monophyletic sister group of Astigmata (e. g., stored product mites, house dust mites, mange mites, feather and fur mites). Trombidiformes (Sphaerolichida + Prostigmata) is strongly supported (PP =1.0; BP = 98–100). Labidostommatina was inferred as the basal lineage of Prostigmata. Eleutherengona (e. g., spider mites) and Parasitengona (e. g., chiggers, fresh water mites) were recovered as monophyletic. By contrast, Eupodina (e. g., snout mites and relatives) was not. Marine mites (Halacaridae) were traditionally regarded as the sister-group to Bdelloidea (Eupodina), but our analyses show their close relationships to Parasitengona.ConclusionsNon-trivial relationships recovered by our analyses with high support (i.e., basal arrangement of endeostigmatid lineages, the position of marine mites, polyphyly of Eupodina) had been proposed by previous underappreciated morphological studies. Thus, we update currently the accepted taxonomic classification to reflect these results: the superfamily Halacaroidea Murray, 1877 is moved from the infraorder Eupodina Krantz, 1978 to Anystina van der Hammen, 1972; and the subfamily Erythracarinae Oudemans, 1936 (formerly in Anystidae Oudemans, 1902) is elevated to family rank, Erythracaridae stat. ressur., leaving Anystidae only with the nominal subfamily. Our study also shows that a clade comprising early derivative Endeostigmata (Alycidae, Nanorchestidae, Nematalycidae, and maybe Alicorhagiidae) should be treated as a taxon with the same rank as Sarcoptiformes and Trombidiformes, and the scope of the superfamily Bdelloidea should be changed. Before turning those findings into nomenclatural changes, however, we consider that our study calls for (i) finding shared apomorphies of the early derivative Endeostigmata clade and the clade including the remaining Acariformes; (ii) a well-supported hypothesis for Alicorhagiidae placement; (iii) sampling the families Proterorhagiidae, Proteonematalycidae and Grandjeanicidae not yet included in molecular analyses; (iv) undertake a denser sampling of clades traditionally placed in Eupodina, Anystina (Trombidiformes) and Palaeosomata (Sarcoptiformes), since consensus networks and Internode certainty (IC) and IC All (ICA) indices indicate high levels of conflict in these tree regions. Our study shows that regions of ambiguous alignment may provide useful phylogenetic signal when secondary structure information is used to guide the alignment procedure and provides an R implementation to the Bayesian Relative Rates test.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0458-2) contains supplementary material, which is available to authorized users.

Carpoglyphus lactis (Acari: Astigmata) from various dried fruits differed in associated micro-organisms.

Carpoglyphus lactis is a stored product mite infesting saccharide-rich stored commodities including dried fruits, wine, beer, milk products, jams and honey. The association with micro-organisms can improve the survival of mites on dried fruits. The microbial communities associated with C. lactis were studied in specimens originating from the packages of dried apricot, plums and figs and compared to the laboratory strain reared on house dust mite diet (HDMd). Clone libraries of bacterial 16S rRNA gene and fungal internal transcribed spacer (ITS) region were constructed and analysed by operational taxonomic unit (OTU) approach. The 16S rRNA gene libraries differed among the compared diets. The sequences classified to the genera Leuconostoc, Elizabethkingia, Ewingella, Erwinia, Bacillus and Serratia were prevailing in mites sampled from the dried fruits. The ITS library showed smaller differences between the laboratory strain on HDMd and the isolates from dried fruits packages, with the exception of the mite strain from dried plums. The population growth was used as an indirect indicator of fitness and decreased in the order from yeast diet to HDMd and dried fruits. The treatment and pretreatment of mites by antibiotics did not reveal the presence of antagonistic bacteria which might slow down the C. lactis population growth. The shifts of the microbial community in the gut of C. lactis were induced by the diet changes. The identified yeasts and bacteria are suggested as the main food source of stored product mites on dried fruits. The study describes the adaptation of C. lactis to feeding on dried fruits including the interaction with micro-organisms. We also identified potentially pathogenic bacteria carried by the mites to dried fruits for human consumption.

The effect of antibiotics on associated bacterial community of stored product mites.

BackgroundBacteria are associated with the gut, fat bodies and reproductive organs of stored product mites (Acari: Astigmata). The mites are pests due to the production of allergens. Addition of antibiotics to diets can help to characterize the association between mites and bacteria.Methodology and Principal FindingsAmpicillin, neomycin and streptomycin were added to the diets of mites and the effects on mite population growth (Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae) and associated bacterial community structure were assessed. Mites were treated by antibiotic supplementation (1 mgg−1 of diet) for 21 days and numbers of mites and bacterial communities were analyzed and compared to the untreated control. Bacterial quantities, determined by real-time PCR, significantly decreased in antibiotic treated specimens from 5 to 30 times in A. siro and T. putrescentiae, while no decline was observed in L. destructor. Streptomycin treatment eliminated Bartonella-like bacteria in the both A. siro and T. putrescentiae and Cardinium in T. putrescentiae. Solitalea-like bacteria proportion increased in the communities of neomycin and streptomycin treated A. siro specimens. Kocuria proportion increased in the bacterial communities of ampicillin and streptomycin treated A. siro and neomycin and streptomycin treated L. destructor.Conclusions/SignificanceThe work demonstrated the changes of mite associated bacterial community under antibiotic pressure in pests of medical importance. Pre-treatment of mites by 1 mgg−1 antibiotic diets improved mite fitness as indicated accelerated population growth of A. siro pretreated streptomycin and neomycin and L. destructor pretreated by neomycin. All tested antibiotics supplemented to diets caused the decrease of mite growth rate in comparison to the control diet.

Effect of diatomaceous earth-treated wheat on population growth of stored product mites under laboratory test

The suppressive effect of Detia diatomaceous earth (DE) was tested on the mites Acarus siro L., Tyrophagus putrescentiae (Schrank) and Lepidoglyphus destructor (Schrank) in treated wheat grain. Fifty mites were reared on DE-treated wheat in concentrations ranging from 0 to 250 mg kg−1 in darkness at 25 ± 1°C, in 15 ± 0.5% moisture contents. After 21 days, mites were counted and their growth rates calculated using a polynomial regression model. The DE suppressed population growth of all mite species. The fitted doses of DE for 50% suppression of population growth ranged from 8 to 24 mg kg−1. The most sensitive was L. destructor, followed by A. siro and T. putrescentiae. The wheat treatment with the highest DE concentration (250 mg kg−1) did not eliminate mites completely, but their growth rate was negative. The applications of DE for the control of pest mites in the field condition are discussed in addition to other biological control agents.

Bartonella-like bacteria carried by domestic mite species

Bacteria of the genus Bartonella are carried by haematophagous mites, ticks, fleas and flies, and attack the erythrocytes of mammals. Here we describe a Bartonella-like clade, a distinct group related to Bartonellaceae, in stored-product mites (Acari: Astigmata) and a predatory mite Cheyletus eruditus (Acari: Prostigmata) based on the analysis of cloned 16S rRNA gene sequences. By using the clade-specific primers, closely related Bartonella-like 16S rRNA sequences were amplified from both laboratory colonies and field strains of three synanthropic mite species (Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae) and a predatory mite. Altogether, sequences of Bartonella-like bacteria were found in 11 strains, but were not detected in Dermatophagoides farinae and D. pteronyssinus and two strains of L. destructor. All obtained sequences formed a separate cluster branching as a sister group to Bartonellaceae and related to other separate clusters comprising uncultured bacterial clones from human skin and hemipteran insects (Nysius plebeius and Nysius sp.). The classification of sequences into operational taxonomic units (OTUs) showed a difference between A. siro and T. putrescentiae suggesting that the Bartonella-like bacteria are different in these two mite species. However, species specific sequences in separate OTUs were observed also for C. eruditus. Possible symbiotic interactions between Bartonella-like bacteria and their mite hosts are discussed.

Growth-suppressive effect of the α-amylase inhibitor of Triticum aestivum on stored-product mites varies by the species and type of diet

A naturally occurring α-amylase inhibitor (α-AI) of Triticum aestivum protects wheat grain from gramnivorous arthropod pests. The α-AI (Type-I) was incorporated into carbohydrate and protein diets to test its inhibitory activity on the stored-product mites Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae (Acari: Astigmata). Growth tests of mites fed the various diets were used to compare the suppressive effects. The final population size of mites attained from an initial population of 50 specimens maintained under controlled conditions (85 % relative humidity and 25 °C) was compared after 21 days of cultivation. The results showed that α-AI in the concentration in the range of 0.01-1 mg g(-1) did not suppress the growth of the tested stored-product mites. α-AI at a concentration of 10 mg g(-1) exerted a growth-suppressive effect that depended on the diet and species of the mites. The growth rate of A. siro was affected by the type of diet and was higher on carbohydrate diet than on the protein diet, the suppressive effect of α-AI was on the both diets. The growth-suppressive effect of α-AI on L. destructor and T. putrescentiae was significant when they were fed the protein diet but not when they were fed the carbohydrate diet. The higher resistance of tested mites to α-AI (proteinaceous) compared to non-proteinaceous acarbose corresponds to a powerful proteotolytic system in the mite gut. The results are discussed in terms of the adaptability of mites to utilize the starch from food sources.

PCR Detection of the 14.5 Antibacterial NlpC/P60-Like <I>Dermatophagoides pteronyssinus</I> Protein in <I>Dermatophagoides farinae</I> (Acari: Pyroglyphidae)

House dust mites produce antibacterial proteins suppressing bacterial growth. The 14.5-kDa bacteriolytic protein (UniProtKB Q8MWR6) has been known in Dermatophagoides pteronyssinus Trouessart. We have applied polymerase chain reaction and reverse transcription-PCR to detect a homologous gene sequence coding for a Q8MWR6-related protein in Dermatophagoides farinae (Hughes) using genomic DNA and total RNA, respectively. The resulting PCR product of expected size, 243 bp, was obtained from both Dermatophagoides spp., while no amplification was achieved from stored product mite samples. Sequence of the gene fragment from D. farinae showed 83% similarity to the previously described one in D. pteronyssinus. Successful amplification of the expected product from cDNA generated with oligo-dT primer implies that the NlpC/P60-like protein in Dermatophagoides mites is of eukaryotic or mite origin.

Efficacy of pea flour as an antifeedant against two stored-food mites (Acari: Acaridae) fed on dried medicinal Chinese herbs

Pea flour (Pisum sativum L.) is toxic to some stored-product pests. Botanical pesticides that contained efficient natural compounds have highlighted to be used for the control of storage mites. In the current investigation, we evaluated the effect of pea flour as an antifeedant on two stored-product mites, namely Tyrophagus putrescentiae (Schrank, 1781) and Aleuroglyphus ovatus (Troupeau, 1878) fed on two medicinal Chinese herbs: Crataegus pinnatifida Bge. var. major and Coix lachryma-jobi L. var. ma-yuen. The experiment was carried out from March to May 2012 under the optimal growth conditions of storage mites at constant temperature (25°C) and 85 ± 5% relative humidity (RH) in the dark. Pea flour was used at five concentrations (0, 0.01, 0.1, 1 and 10%). The values of LC50, LC90 and mortality of T. putrescentiae and A. ovatus were recorded at four periods (7, 14, 21 and 28 days), while their population dynamics were determined only after 21 days. The use of pea flour as an antifeedant was very efficient for the control of T. putrescentiae and A. ovatus adults. The controlling efficiency of pea flour improved due to the increase of its applied dose. The LC50 and LC90 estimates showed that pea flour was more toxic for T. putrescentiae than for A. ovatus. The concentration of 1% pea flour was responsible for more than 65% and 88% mortality of A. ovatus on C. pinnatifida and C. lachryma-jobi after 28 days, respectively. However, this concentration was sufficient to kill all individuals (100% mortality) of T. putrescentiae as the concentration of 10% pea flour. The addition of pea flour caused considerable decreases in the rate of the increase (r-value) of T. putrescentiae and A. ovatus. The highest r-values of T. putrescentiae and A. ovatus were recorded on the control treatment (0% pea flour), whereas the lowest values were observed at 1% and 10% concentrations of pea flour. The 1% concentration of pea flour is highly suggested to be used as a good and economical dose to control both of T. putrescentiae and A. ovatus on the studied Chinese herbs.

Reproduction of Caloglyphus redikorzevi Zach. (Acaridae) and Their Influence on Germination of Canola and Black Seeds

Laboratory studies on the stored product mite Caloglyphus redikorzevi Zach. proved that it affected the germination of the Canola seeds (Brassica napus) and the Black seeds (Nigella sativa). Also, results showed that the propagation of the C. redikorzevi increased when fed on seeds of either plant, under laboratory conditions, reaching its maximum at the 5th week of the study then sharply declined thereafter.

Effectiveness of Ultraviolet Radiation as a Physical Method in Controlling the Stored Product Mite, Tyrophagus putrescentiae (Acari: Acaridae)

Effectiveness of Ultraviolet Radiation as a Physical Method in Controlling the Stored Product Mite, Tyrophagus putrescentiae (Acari: Acaridae)

Effect of Stored Product Mite Extracts on Human Dermal Microvascular Endothelial Cells

Stored product mites commonly occur in agricultural work environments and sometimes in homes in significant numbers. They are a source of allergens that sensitize and induce allergic reactions. This may include atopic dermatitis. The purpose of this investigation was to determine if the common species of storage mites are the sources of molecules that influence the function of human dermal microvascular endothelial cells that regulate the trafficking of inflammatory and immune cells into the dermis during allergic reactions and other skin diseases. Human dermal microvascular endothelial cells were challenged with varying doses of extracts of the storage mites Acarus siro L., Chortoglyphus arcuatus (Troupeau), Lepidoglyphus destructor (Schrank), or Tyrophagus putrescentiae (Schrank) and the secretion of cytokines and expression of adhesion molecules were measured. The role of endotoxin and protein in inducing these responses was evaluated. These stored product mite extracts induced secretion of interleukin-6, interleukin-8, monocyte chemotactic protein-1, and granulocyte/monocyte colony stimulating factor. Some of these effects were induced by protein present in the extracts, some were induced by endotoxin, and some were induced by other substances. C. arcuatus and T. putrescentiae extracts also down-regulated tumor necrosis factor a-induced vascular cell adhesion molecule-1 expression. Stored product mite extracts contain an assortment of molecules, including endotoxins and proteins, which modulate the expression of cell adhesion molecules and the secretion of cytokines by microvascular endothelial cells. These modulating properties varied among mite species indicating that each mite species has a unique set of molecules that is responsible for its activity.

EFFECTIVENESS OF ESSENTIAL OILS OF MEDICINAL PLANTS AGAINST STORED PRODUCT MITE, SUIDASIA PONTIFICA OUDEMANS

Acaricidal activity of essential oils obtained from 28 selected medicinal plants against stored product mite, Suidasia pontifica Oudemans, was investigated using the dry film method. The bioassay was conducted in a glass tube, 0.4 cm in diameter, 3 cm long covered with fine nylon mesh on both ends. In preliminary tests, 1.0% (53 µg cm-2) of various essential oils and 95% ethanol used as control were evaluated. Each glass tube was treated internally with 20 µl essential oils. Observations were made at 24 h after treatment and the number of dead mites was recorded. At the dose of 1.0%, essential oils of clove (Syzygium aromaticum), cinnamon (Cinnamomum bejolghota), myrtle grass (Acorus calamus), betel vine (Piper betle), and turmeric (Curcuma longa) were highly toxic to S. pontifica with more than 70% mite mortality observed at 24 h. Dry film effect of essential oils at various concentrations (0, 0.05, 0.1, 0.5, 1.0 and 1.5% equaling to 0, 2.65, 5.3, 26.5, 53 and 79.5 µg cm-2, respectively) resulting in mite mortality observed at 24 h was used to establish LD50 values. Based upon 24 h LD50 values, the essential oil of cinnamon (fresh leaf) was the most toxic to the mite with high activity at 24.05 µg cm-2, followed by essential oils of clove (dried bud), myrtle grass, cinnamon (dried bark), clove (fresh leaf), turmeric and betel vine at 24.28, 28.34, 30.89, 33.67, 38.09 and 41.76 µg cm-2, respectively.

Damage effect of two storage mites (Acari: Acaridida) and their biology on the Shiitake mushroom (Lentinula edodes) at three constant temperatures

This study aims to estimate the influence of three constant temperatures (20, 25 and 30°C) on the damage effect, population growth, life cycle and longevity of two stored-product mites (Tyrophagus putrescentiae and Aleuroglyphus ovatus) reared on the dried Shiitake mushroom (Lentinula edodes) at 80% relative humidity (r.h.) and 14:10 (L:D) h (light: dark) photoperiod. The weight loss of the Shiitake mushroom caused by T. putrescentiae and A. ovatus increased with increasing temperature. The increase in the count of T. putrescentiae and A. ovatus in the rearing cells led to noticeable decrease in the weight of the Shiitake mushroom. The results indicated that T. putrescentiae was more harmful than A. ovatus on the Shiitake mushroom. The r-values of both mite species increased with increase in temperature up to 25°C, whereas the value of r decreased when the temperature increased to 30°C. At 20, 25 and 30°C, the values of r were 0.167, 0.182 and 0.159 for T. putrescentiae and 0.126, 0.140 and 0.115 for A. ovatus, respectively. The developmental time of immature stages, reproductive periods and female longevity of T. putrescentiae and A. ovatus were adversely affected by the increase in temperature. The life cycle of T. putrescentiae varied from 9.26 to 20.64 days and that of A. ovatus ranged from 11.65 to 25.21 days when the temperature increased from 20 to 30°C. The longest longevity of T. putrescentiae and A. ovatus (38.37 and 48.18 days) was recorded at 20°C, whereas the shortest (20.38 and 28.40 days) was found at 30°C. The results showed that T. putrescentiae had lower developmental time and reproductive periods than A. ovatus when reared on the Shiitake mushroom at all the studied temperatures.

Suitability of a range of Fusarium species to sustain populations of three stored product mite species (Acari: Astigmata)

Fusarium fungi continue to grow and produce mycotoxins in grain that has been poorly managed after harvesting. Such grain is also often infested by storage mites. Mites are able to feed on fungi and they also interact with both fungi and mycotoxins. Mite interactions with 10 species of Fusarium fungi, four of which are represented by two strains were studied. The fungi were isolated from different crops in the Czech Republic. Tyrophagus putrescentiae mites were able to feed and reproduce on all tested Fusarium strains. Microanatomical observations of T. putrescentiae specimens feeding on Fusarium poae, Fusarium culmorum, Fusarium verticillioides and Fusarium avenaceum showed intense consumption. Acarus siro, and Lepidoglyphus destructor mites showed negative growth rates on Fusarium. The growth rate of T. putrescentiae differed when grown on different Fusarium species. The following categories of Fusarium suitability to support mite growth were determined: (i) highly suitable (F. verticillioides and Fusarium oxysporum), (ii) suitable (e.g., F. culmorum, Fusarium solani and F. avenaceum) and (iii) lowly suitable (e.g., Fusarium subglutinans, Fusarium sporotrichioides, F. poae and Fusarium graminearum). The effect of grazing of mites on Fusarium species was tested on oatmeal agar plates. The grazing of T. putrescentiae destroyed mycelium of 11 Fusarium strains after three weeks. A. siro and L. destructor grazing damaged four and two strains, respectively. During grazing, T. putrescentiae, for example, could disseminate fungi throughout the stored grain. Consequently in improperly stored grain, the interactions between T. putrescentiae and Fusarium fungi can influence both pests and also the production of hazardous compounds.

The toxicity of selected acaricides against five stored product mites under laboratory assay

In laboratory tests, the toxicity of acaricides targeted against house dust mites was tested on five species of stored product mites (Acarus siro, Aleuroglyphus ovatus, Carpoglyphus lactis, Lepidoglyphus destructor, and Tyroborus lini). The formulations of benzyl-benzoate, benzyl-benzoate/permethrin/pyriproxyfen, and neem were diluted in water and applied to filter paper in an unventilated chamber. The mortality of mites was observed after 24 h of exposure to acaricide-impregnated filter paper. All of the tested acaricides were toxic to all of the mite species. There were significant differences in mortality among the species and the acaricides. Benzyl-benzoate/permethrin/pyriproxyfen was the most effective, followed by benzyl-benzoate and neem. L. destructor (LD50 0.01–0.11 μg) was the most sensitive mite species, followed by A. siro (LD50 0.04–0.12 μg), T. lini (LD50 2–21 μg), A. ovatus (LD50 3–18 μg), and C. lactis (LD50 4–64 μg). Based on the highly toxic effects of the tested acaricides against the stored product mites, the acaricides should be considered as a potential tool in the control of stored product mites, although next screening is necessary.

The effect of chitin metabolic effectors on the population increase of stored product mites

The study tested the effect of the chitin metabolic effectors, teflubenzuron, diflubenzuron, and calcofluor, and a combination of a chitinase and soybean trypsin inhibitor (STI) on the population growth of eight species of stored product mites under laboratory conditions. The compounds were incorporated into the diets of the mites in concentrations ranging from 0.01 to 50 mg g(-1). The final populations of mites were observed after 21 days of growth in controlled conditions. Diflubenzuron and calcofluor suppressed the growth of all the tested species more effectively than the other compounds. The doses required to suppress the mite populations to 50% (rc(50)) in comparison to the control ranged from 0.29 to 12.68 mg g(-1) for diflubenzuron and from 1.75 to 37.7 mg g(-1) for calcofluor, depending on the mite species. When tested at the highest concentration (10 mg g(-1)), teflubenzuron also suppressed all of the tested mite species in comparison to the control. The addition of chitinase/STI into the diet influenced population growth in several ways. When the highest concentration of chitinase in a cocktail of chitinase and STI (12.5 mg g(-1) of diet) was compared to the control, populations of Acarus siro, Aleuroglyphus ovatus and Aëroglyphus robustus decreased significantly, whereas populations of Tyroborus lini and Sancassania rodionovi increased significantly. The sensitivity of species to the tested compounds differed among species. The most tolerant species was S. rodionovi, the most sensitive was A. ovatus. The results confirmed that calcofluor and diflubenzuron have a toxic effect on stored product mites.

Acaricidal Effect of Different Diatomaceous Earth Formulations Against <I>Tyrophagus putrescentiae</I> (Astigmata: Acaridae) on Stored Wheat

Laboratory bioassays were conducted to evaluate the effect of different diatomaceous earth (DE) formulations against adults and immature stages of the stored-product mite species Tyrophagus putrescentiae (Schrank). Five DE formulations were used in the tests: SilicoSec, PyriSec, Insecto, Protect-It, and DEA-P. The tests were conducted at 25 degrees C and 75% RH, on wheat, Triticum aestivum L., treated with DEs at two dose rates, 0.2 and 0.5 g/kg. The mortality of mite individuals was measured after 5 d of exposure, and after 30 d the treated wheat was checked for T. putrescentiae offspring. Significant differences were noted among the DEs tested. Application of the lowest dose rate (0.2 g/kg) provided mortality of both adults and immatures that exceeded 78%, whereas the respective data for 0.5 g/kg were almost in all cases 100%. The adults of T. putrescentiae were more tolerant to DEs than the immature stages. Generally, PyriSec was the most effective against adults. Progeny production was dramatically reduced with the increase of dose. The results of the present work indicate that T. putrescentiae can be effectively controlled by DEs on wheat, at dose rates as low as 0.2 g/kg.

A Survey Of Stored Product Mites of Traditional Chinese Medicinal Materials

Eighteen hundred samples of Traditional Chinese medicinal materials from a traditional medical storehouse in Huainan City, Anhui Province, China were collected and examined for mites. The results indicated 87% (1566/1800) of samples were infested with 47 species of mites belonging to 25 genera and 7 families. It is concluded that Traditional Chinese medicinal materials are severely contaminated and much more importance should be given to the protection of stored products and to the prevention of human acariasis.

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.