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An Introduction to Medical Entomology

For educational purposes. 

 

PARASITOIDEA

(Bird, Reptile & Mammal parasites)

(Contact)

 

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       There are at least three families in the Parasitoidea, and their morphology is similar to that of the ticks.  Tracheae open through a pair of spiracles situated on plates that are located above and between the 3rd and 4th coxae.  The mouthparts are well developed and made up of piercing chelicerae, a hypostome and a pair of palpi.  There are no furrows on the ventral surface, but sclerotized plates are usually present.  One family, the Dermanyssidae, is of main interest.  All members of this family are parasitic on mammals, reptiles and birds.  The chelicerae resemble needles without teeth.  Ventral and anal plates occur most of the time; a dorsal plate exists but covers only a part of the body.  Humans are attacked by only two genera (Liponyssus & Dermanyssus), which also can transmit disease.  The dermatitis and scratching resulting from the presence of these mites can be followed by severe infections, especially in young children.

 

       A chicken mite, Dermanyssus gallinae (L.) is a bloodsucker that usually feeds at night when the birds are roosting.  The mites engorge rapidly and depart from their hosts in daytime when they hide in surrounding crevices of a structure.  Eggs are laid in the trash and they hatch in 3-4 days.  The larvae and nymphs require 10 days to two weeks for development.  Humans working in the vicinity are attacked, which may result in a severe dermatitis.  This species also serves as a reservoir for the Saint Louis Encephalitis virus in chickens.  If a house mosquito (Culex pipiens) feeds on chickens and then on humans the encephalitis can be transmitted.  The mosquito may also serve as a reservoir for Eastern Equine Encephalomyelitis.

 

       An invaded mite from Egypt, Dermanyssus sanguineus Hirst is parasitic on mice and rats.  It became established in eastern North america and was found to transmit Rickettsial pox in New York State.  There are two dorsal shields on the thorax, which distinguish it from D. gallinae.

 

       Another invaded mite species from Egypt, Liponyssus bacoti, is primarily a parasite of rats, but it also attacks humans.  The mite feeds only on blood.  Nymphs and adults drop from their hosts after a blood meal and will invade other animals nearby.  The life cycle is short, eggs hatching in about 4 days and adults developed 12 days later.  Experiments have shown that this species is capable of transmitting Rickettsial pox (Rickettsia akari).

 

CONTROL

 

       Elimination of the rats and mites that may harbor the diseases is the preferred control method.  Available acaricides applied to the interior of heavily-infested structures is also advisable.

 

 

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  Key References:     <medvet.ref.htm>     [Additional references may be found at:  MELVYL Library]

 

Banks, Nathan.  1915.  The Acarina or Mites: A Review of the Group for the Use of Economic Entomologists.  Report No. 108, Washington D.C.

Hallan, Joel.  2010.  Parasitidae Species Listing.   Biology Catalog, Texas A. & M. Univ.

Matheson, R. 1950.  Medical Entomology.  Comstock Publ. Co, Inc.  610 p.

O'Conner, B.,  B. Pavel &  B. Klmiov.  2004.  Bee Mites: Acari: Parasitiformes.  Division of Insects, Univ. of Michigan Museum of Zool.

Service, M.  2008.  Medical Entomology For Students.  Cambridge Univ. Press.  289 p.

 Zhi-Quiang, Zhang.  2003.  Other Beneficial Mites:  Mites of greenhouses.  Wallingford, Oxon, Cambridge, MA.