Tyroglyphid Mites Research Articles

A survey of the mite fauna of Scottish farms

The mite fauna of 31 Scottish farms was studied during 1971–1972 to determine the species found in grain storage and handling areas, and associated stock rearing facilities. Methods of sampling and preparing mites for identification are described. Tables listing habitats, frequency of occurrence and intensity of infestation are included, with an appendix listing the 70 species, 39 genera, and 22 families found during the survey. The commonest mite species in grain stores were also those most frequently found in the stock rearing areas. Comparisons are made with recent similar surveys on farms and in poultry houses in England and Wales, and on stored grain and grain products in Ireland. The pest potential of Acarus, Tyrophagus and Glycyphagus spp is considered and it is concluded that Acarus farris is a true stored products pest found throughout the storage period. Tyrophagus longior and Glycyphagus destructor , two of the commonest species on farms, showed no adverse effect on the germinative capacity of grain tested. The possibility of biological control of Tyroglyphid mites by two predacious species, Cheyletus eruditus and Androlaelaps casalis is examined and some evidence of successful control is presented.

An Automatic Collecting Device for Tyroglyphid (Acaridae) Mites

Tyroglyphid mites are excellent experimental animals for studies of mite ecology and physiology, because identification to species is easy, and they are among the easiest mites to culture. Their importance as stored-product pests may one day be overshadowed by the significance of their relationships, as yet not clear, with insects and fungi. Many species have extensive geographical distributions and occur in many niches outside those associated with stored products. Various methods of basic culturing or rearing individual mites are discussed by Woodring (1963) and Solomon and Cunningham (1964).

Entomophthora floridana n. sp. (Phycomycetes: Entomophthoraceae), a Parasite of the Texas Citrus Mite, Eutetranychus banksi

Recently, Selhime and Muma (1966) studied the biology of an entomophthoraceous fungus attacking the Texas citrus mite, Eutetranychus banksi (McGregor). This study and a series of earlier publications including Fisher (1954), Muma (1955 and 1958) and Muma et al. (1961) have indicated the unusual frequency of the fungus in the field and its potential importance in the biological control of the Texas Citrus mite. This fungus, described in the present paper, is not the only Entomophthora known to infect Acarina. Petch (1940) described Entomophthorct acaricida from Halotydems destructor Tucker and later, Petch (1944) described E. acaridis from other infected Acarina. Recently, Batko (1965) recorded Conidiobolus brefeldianus Couch from Tyrophagus perniciosus Zachvatkin and other tyroglyphid mites. METHODS

Rearing Tyroglyphid Mites on Neurospora1

In the course of preliminary investigations for a population dynamics study, we have successfully reared four species of tyroglyphid mites on Neurospora . Several authors (Solomon 1943, Hughes 1948, and Krantz 1955) have reported that a number of species of mites commonly found in stored grain and stored grain products probably feed on fungi and vegetable debris rather than on the grain itself. Rivard (1958a, 1958b) reported rearing Tyrophagus castellanii (Hirst.) on Aspergillus sp.

A Technique for Rearing Tyroglyphid Mites on Mould Cultures

This technique was developed to discover whether a tyroglyphid mite, Tyrophagus castellanii Hirst, was feeding on moulds growing on a food medium rather than on the food medium itself. Later on the technique was also found satisfactory for obtaining, under controlled temperature and humidity conditions, individual development records for all stages of the life-cycle of the mite.

Silk Production in the Cheyletidae (Acarina: Arachnida)

WHILE examining some grain infected with tyroglyphid mites, I found a specimen of Cheletomorpha lepidoptorum Shaw (=venustissima Berlese), which had just finished laying eggs. About six eggs were scattered on the ground, and the Cheletomorpha was moving backwards and forwards, covering them with a sparse network of silk. In this mite, the mouth is at the end of a gnathosoma, which is shaped like a cone and completely encircles the cheliceral stylets. The silk was coming from the mouth in the form of a very fine thread, which was stretched from side to side over the eggs, the pedipalpal claw being used for manipulating it at times. Unlike Cheyletus eruditus Schrank, which remains crouched over its eggs until the larvae emerge, the Cheletomorpha took no further interest in the welfare of its young, but wandered away to lay a few more eggs in another place.

コナダニ類の医学的意義特に人体内ダニ症について(第 3 回大会講演要旨 II)

コナダニ類の医学的意義特に人体内ダニ症について(第 3 回大会講演要旨 II)

Oribatid Mites and Their Economic Importance

REVIEWING some of the literature on Tyrogly-phid mites, Lapage1 directed attention to their role in pulmonary acariasis of man, in addition to destruction of stored food-products. The Oribatids are allied to these cheese- and flour-mites and to the well-known harvest- and chigger-mites, and have been, until a few years ago, of comparatively little economic significance. Otherwise known as moss-mites and beetle-mites, they have been studied for many years and from all over the world. They are mostly microscopic in size, free-living and terrestrial, although a few are aquatic and crawl on weeds. Their activity is greater in darkness, when they swarm out in search of food, and progression is normally slow. They havda shiny chitinous body-wall, a wing-like extension (the pteromorpha) at the antero-lateral corner of the abdomen on each side, a pair of peculiarly shaped sense-organs (the pseudo-sbigmatic organs), and no eyes.

Tyroglyphid mites in stored products. Nature and amount of damage to wheat

The paper describes experiments and observations on the damage done by mites to stored grain, and methods of assessing the damage. It is confirmed that mites cannot penetrate grains if the grain‐coat is intact; but usually less than 10% of the grains are so intact.In laboratory experiments, mites consumed up to 3% by weight of the grain before dying out; they were able to destroy the germ completely, but consumed very little of the remainder; the maximum rate of consumption observed over a 5‐week period was 0‐29% of grain weight per week; when added to grain at 75% relative humidity in the proportion of 1% by weight, mites consumed 1% of the grain in 27 days at 21d̀ C, or in 37 days at 10‐15d̀ C. Although mites consumed the grain more rapidly at higher temperatures or humidities, they survived longer at lower temperatures or humidities, and finally did more damage. Mites consumed wheat germ flakes more rapidly than grain, and finally reduced its weight by 74‐85%.A system of symbols to represent degrees of damage to grain by mites, assessed visually, is presented, and approximate values for the equivalent weight losses are given. The relationship between the product, no. of mites per 100 ex. grain × time in weeks, and the degree of damage to grain, was calculated from experimental data; the damage done per unit of this density × time product was 2‐2‐5 times higher at 25 than at 5‐9d̀ C, and about 1‐4 times higher at 70 than at 90% relative humidity. The mean density × time value corresponding to 1% loss of grain weight was 526,000 at 250 C, and 1,765,000 at 5‐9d̀ C.Data from granary investigations show the degree of damage associated with various levels of population density and grain moisture. In infested storages, the amount of embryo material destroyed ranged from less than 1% of the total (bulk grain) to about 15% (grain in bags).Mites may cause a rise in the temperature or moisture‐content of grain, or an increase in the growth of microorganisms; but there is no evidence to suggest that serious damage from these causes is likely except that dense infestations can cause heating.

Tyroglyphid mites in stored products. Ecological studies

The ecology of Tyroglyphids in stored products, particularly wheat grain, was studied by examining samples taken from the material. The moisture content and the numbers of mites in each sample were determined and in many cases extensive temperature data were available.Manitoba grain stored in bulk in one granary was repeatedly examined over a period of 15 months. Examinations of infested grain in other granaries provided corroborative data.The chief mite pest of grain is Tyroglyphus farinae (L.). In imported grain it usually attacks only those parts of a bulk which have taken up extra moisture, e.g. from damp walls or from the atmosphere. Glycyphagus destructor (Schr.) is commonly found throughout the surface layer of a bulk of grain; it does not damage the grains. Differences were found in the distribution and population density of Tyroglyphus, Glycyphagus, and the predatory mite Cheyletus eruditus Schr., in relation to the moisture content of the grain. Tyroglyphus was abundant in winter and spring, but was often reduced to very small numbers during summer and autumn. This was due to the attacks of Cheyletus, which was nearly always associated with Tyroglyphus, and maintained a moderate population density throughout the year. Tyroglyphus is known to multiply less rapidly as the moisture decreases; the drier conditions in the grain during summer and autumn enabled Cheyletus to control it. A subsidiary factor was the migration of Tyroglyphus into somewhat drier grain after dense populations had exhausted the available food (wheat germ). Extremely high moisture occasionally appeared to cause similar migrations. The seasonal temperature difference may also have been a factor affecting the predator/prey cycle, but if so its effect was masked by variations due to other factors. Cheyletus was able to survive in grain too dry for Tyroglyphus. The predator was also associated with Glycyphagus, but was unable to reduce its numbers to a comparable extent. Hence Glycyphagus assisted the distribution and maintenance of Clieyletus populations. The predator is also known to attack various insects.Grain stored in bags has a much larger area exposed to atmospheric moisture, so that infestations tend to be more widespread than in bulk grain. Concrete floors at ground level tend to transmit extra moisture to the bottom of a stack of grain, and to any loose grain on the floor, thereby providing conditions favourable to the growth of dense populations of Tyroglyphus. Hence it is important to keep the bags away from the floor by the use of dunnage. Cheyletus is less common in bagged grain and in flour.Infestations of flour in bags were also studied. The conclusions drawn were similar to those relating to bagged grain. Mites tended to concentrate in the more superficial flour in a bag, very few penetrating more than a few cm. into the flour. This would facilitate control by fumigation. It seems possible that Tyroglyphids, or at least their eggs, may survive the processes of milling.Dried fruits seemed to have become infested by Carpoglyphus lactis (L.) as a result of an increase in moisture.The most effective means of preventing the infestation of stored products by mites is to keep them moderately dry, so that Tyroglyphids cannot live in them. Failing this, steps should be taken to prevent local increases in moisture, which increase the potential rate of multiplication of Tyroglyphids. It might be useful in certain circumstances to introduce Cheyletus, perhaps together with Glycyphagus as a source of food, into stored products, to prevent the possibility of Tyroglyphus being introduced without its predators, e.g. after a fumigation.

Tyroglyphid Mites and Human Disease

STUDENTS of applied zoology are familiar with the damage caused by Tyroglyphid mites to stored products valuable to man. The part they may play in the causation of disease is less well known.

Tyroglyphid Mites in Stored Products. I. A Survey of Published Information. Supplement

Tyroglyphid Mites in Stored Products. I. A Survey of Published Information. Supplement

Reports and Other Publications

(not included in the monthly Books Supplement) Great Britain and Ireland Department of Scientific and Industrial Research. Tyroglyphid Mites in Stored Products, 1: A Survey of Published Information, Supplement 1944. By M. E. Solomon. Pp. 8. (London: H.M. Stationery Office, 1944.) 2d. net. [12

Tyroglyphid mites in stored products Methods for the study of population density

The known methods for detecting the presence of tyroglyphids are described. For coarse materials, such as seeds, sieving is recommended. For flour, it is better to examine exposed surfaces, or to keep samples in glass vessels and examine for the runnels made by mites against the glass. Methods of sampling to provide information about the density and extent of infestations are described. Samples must usually be treated in the laboratory. While methods which do not involve the separation of the mites from the material are referred to, such separation is usually necessary. Mites may be separated from most materials by the modified Berlese funnel method of Chernuishev and Petrova; means of overcoming certain disadvantages are suggested. However, vigorous sieving is recommended for coarse materials, and a flotation method, using dichlorethylene, for fine materials such as flour. It is usually more satisfactory to examine and count the mites than to estimate the numbers volumetrically or gravimetrically. They are counted in a dish containing oil, placed on squared paper under a low‐power microscope. A modification of this method, for dealing with large numbers, is described. Methods of expressing population density are briefly discussed.

Tyroglyphid Mites In Stored Products. I. A Survey Of Published Information

Tyroglyphid Mites In Stored Products. I. A Survey Of Published Information

Department of Scientific and Industrial Research. Tyroglyphid mites in stored products

Department of Scientific and Industrial Research. Tyroglyphid mites in stored products