*4.1.3* Dermatophagoides microceras *Griffiths and Cunnington (House dust mite, dust mite)*

House dust mite *Dermatophagoides microceras* Griffiths and Cunnington (**Figure 4**) is a species first described in 1971 and part of the Pyroglyphidae family of mites. This mite has been identified in house dust in various geographic regions, including Great Britain, Scandinavia, the Netherlands, Spain and United States; however its distribution in the rest of the world has not been explored well. Morphologically, males tarsus I is without small apical protuberance (process S), but with curved spine and tarsus II without process S or spine. Females tarsus I with short, straight, blunted spine, tarsus II lacking spine and bursa copulatrix narrow as well as weakly sclerotized in region adjacent to external opening. In females, propodonotal shield is about 1.4 times as lengthy as wide; idiosoma 395–435 μm in length; vestibule of bursa absent, bursa unfastens at the bottom of a non-sclerotized depression of tegmen; first portion of bursa proper is a little dilated and clearly sclerotized; and apical progression of tarsus I mostly very minor or absent. In males, idiosoma is 285–345 μm in length; males either heteromorphic with epimera I joined to form a V or Y shape (and first legs enlarged) or homeomorphic with epimera I free (and first legs normal) [33].

*D. microceras* is more closely related to *D. farinae*, and the biological and immunochemical identification of these two species are argued. Using an enzymelinked immunosorbent assay (ELISA) technique, the response of mite material from different stock cultures demonstrated that *D. farinae* and *D. microceras* are discrete entities, and also at the major allergen level, with no apparent subspecies or strain variation. Females of *D. farinae* and *D. microceras* receptaculum seminis not U-shaped in cross section, while males with hysteronotal shield as long as broad and extending anteriorly to point between setae d1 and e or slightly anterior of d1 [34].

**281**

**Figure 5.**

Dermatophagoides evansi.

*House Dust Mites: Ecology, Biology, Prevalence, Epidemiology and Elimination*

Specifically, *Dermatophagoides evansi* Fain (**Figure 5**) Hughes and Johnston mites are found in the poultry dust samples and also in bird's nests. Hen poultry farmers and their families, but also other professionals working in the poultry industry, such as veterinarians, may be exposed to house dust mites. In females, bursa copulatrix is strongly enlarged in its distal third and very narrow in proximal two thirds (internal); and spermatheca sclerotized and tulip-like. In males, hysteronotal shield markedly spread frontward away from bases of setae d1; adanal suckers 12 μm in span; coxae II shut; legs III 1.8 times denser (at level of femur) and 1.6 times lengthier (length of 4 distal segments) than legs IV; tarsus I with 2 uneven apical progressions (ongles); tarsus II with a slight apical progression; setae cp 110 μm in length; setae d2 located at 55–65 μm from opening of fat gland; setae h2 and h3 with bases intensely sclerotized; epimera I free; and males are homeomorphic. The males differ from males of *D. pteronyssinus* primarily through dorsal hysterosomal shield that is longer and narrower; ratio width (at level of setae d1):length = 1:2.5 [whereas in *D. pteronyssinus* this ratio is 1.8–1.9]; while legs III and IV are much more unequal

The life cycle of *D. evansi* has been studied and reared at a relative humidity of 75–80% and temperature 25–27°C in a medium consisted of human skin or chicken skin scales plus baker's yeast powder. The average period of mite life cycle for each stage in days is the following: egg 8.3; larva and protonymph 5.4; tritonymph 6.6; female 52.9; and male 28.9. The mean time necessary for accomplishment of one generation is 28.7 days. The female is oviparous, parthenogenesis not detected, and lays 35.5 mean eggs during its life span. The adults copulate repeatedly and the

Female with the distal part of the bursa copulatrix in the form of a small, oval and strongly sclerotized pocket, while male is with anal suckers (*Euroglyphus* Fain), but male and female are without this combination of characters in *Pyroglyphus*. In *Euroglyphus maynei* (Cooreman), male trochanters I–III without hairs and is with a large oval anal plate spreading near to posterior edge of body, while female hairs ga, ae and those of trochanters I–III missing, and have a small posterior vulval lip that does not shelter to anterior of vulva. In case of *Euroglyphus longior* (Trouessart), male trochanters I–III with one hair and is with a minute hexagonal anal plate distant from posterior edge of the body. Female hairs ga, ae and those on trochanters I–III present, and posterior vulval lip is long nearly completely casing to vulva.

*4.1.4* Dermatophagoides evansi *Fain, Hughes and Johnston*

*DOI: http://dx.doi.org/10.5772/intechopen.91891*

than in *D. pteronyssinus* [35].

female-male ratio is 1:1.2 [36].

**4.2 Subfamily Pyroglyphinae Cunliffe, 1958**

**Figure 4.** Dermatophagoides microceras.
