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Dennaptera

Introduction

Dennaptera, commonly known as earwigs, constitute a well-defined group of homogeneous insects. These are characterised by three segmented tarsi and a pair of unsegmented, chitinized cerci or forceps, present at the hind end of the body. Economically these insects are not of much importance, except that a few species act as pollinators when they inhabit flowers, or feed on pollen grains, and destroy tender parts of plants. Euborellia stali (Dohrn) causes damage to groundnut by boring through the pods and completing life cycle inside it (Cherian and Basheer, 1940). Dennaptera are spread all over .the world, but attain their maximum development in terms of numbers in tropical and subtropical parts of the world. The occur in variety of habitats, such as dead and decaying matter, bamboo scales, leafaxils, flowers, under loose bark of trees and occasionally in bird nests. A large number of species are found under dung of various animals. A few species are recorded from high altitudes up to ca 4500 m and even. on snow. They generally occur in humid places, in small to large groups, but it is not unusual to find solitary individuals. Parental care is exhibited by a few species.

Classification

Verhoeff (1902) gave entirely a new line of thought in the taxonomy of the group, by using male genitalia as the basis of classification. However, in the absence of detailed descriptions and illustrations it was not of much value. Later it was further elaborated by Zacher (1911). Bormans (1900) and Burr (1911) provided a detailed classification, which was based on morphological characters. Besides, Burr (1915-16) made hurried genitalic studies, utilizing Zacher's (I.e.) observations in support of his arrangement. His work was discontinued abruptly due to his involvement in 1st world war. Popham (1965) made made a comprehensive survey of male genitalia and presented a modified classification. Recently, Steinmann (1975) has provided an improved arrangement, which in essence is the extension of Popham's work. The outlines of this classification are presented as follows, with some modification :

I.Superfamily Pygidicranoidea (=Protodennaptera Zacher)

1.Family Pygidicranidae Verhoeff

Subfamilies Anataeliinae Burr, Challinae Steinmann, Pygidicraninae Verhoeff, Diplatyinae Verhoeff, Esphalmeninae Burr, Brindlensiinae Srivastava, Balndicinae Burr, Pyragrinae Burr, Karschiellinae Burr, Cylindrogastrinae Maccagno, Diplatymorphinae Boeseman and Prolabiscinae Bey-Bienko. Superfamily Anisolabioidea

2. Family Anisolabididae Sakai

Subfamilies Platylabininae Burr, Gonolabidinae Popham and Brindle, Titanolabidinae Srivastava, Anopthalmolabidinae Steinmann, Carcinophorinae Hincks, Brachylabidinae Burr, Isolabidinae Steinmann, Antisolabidinae Brindle, Parisolabidinae Verhoeff, Idolopsalidiilae Steinmann and Isolaboidinae Brindle.

III. Superfamily APACHYOIDEA (=Paradennaptera Verhoeft)

4. Family Apachyidae Verhoeff Subfamily ApachyinaeBWT

IV. Superfamily FORFICULOIDEA (=Eudennaptera Verhoeft)

5. Family Spongiphoridae Verhoeff (=Labiidae Burr)

Subfamilies Pericominae B orr, Nesogastrinae Verhoeff, Ramamurthinae Steinmann (~ Physogastrinae Ramamurthi), Vandicinae Burr, Strongylopsalidinae B~, Sparattinae Burr, Geracinae Brindle, Isopyginae Borelli, Cosmogeracinae Brindle, Irdexinae Srivastava, Spongiphorinae Burr, Homotaginae Srivastava and Labiinae Burr.

6. Family Chelisochidae Burr

Subfamilies Chelisochellinae Steinmann and Chelisochinae Burr.

7. Family Forficulidae Stephens

Subfamilies Ancistrogastrinae Burr, Sarcinattinae Steinmann, Cosmiellinae Steinmann, Opisthocosmiinae Verhoeff, Diperasticinae Burr, AlIQdahlinae Verhoeff, Anechurinae Burr, Eudohrniinae Bnrr, Rhycolabinae Steinmann, Neolobophorinae Burr and Forficullnae Burr.

Historical Resume

Linnaeus (1758) described two species and altogether 17 species of Dennaptera'were described by Fabricius (1775). Some of• these species are now worldwide in distribution and are also found in Indian subcontinent.

The earliest record of a species is by Guerin-Meneville (1838) from South India based on a female named as Pygidierana pieta. Subsequently, other authors namely Dohm (1863 and 1865), Bormans (1888 and 1894), Kirby (1891) and Bolivar (1897) dealt with and added several new species to the list of Indian Dermaptera. Bormans (1900) published a world monograph on Dermaptera, which brought at one place for the first time, the scattered informations on the group.

During the years 1900-1907, Burr published a number of papers partly based on the collections in the Indian Museum, Calcutta and described a large number of species from India and adjaceDt countries. In tlie year, 1910 Burr's monograph on Dermaptera under the Fauna ofBritish India series appeared. His other works (1911, 1913 and 1914) mainly dealt with Indian fauna on the material preserved in the Indian Museum, which was passed on in 1916 to the Zoological Survey of India. Borelli (1909, 1911, 1912 and 1931) published four papers dealing with Indian fauna. In his work in 1911 he described one interesting genus with a new species. Hebard (1917) described two new species from India and in 1923 published another paper exclusively on Indian fauna and established two new genera and 10 new species besides several known ones. In this work he also laid stress on the intraspecific variations.

Bey-Bjenko's (1936) monograph on the fauna of U.S.S.R. and adjacent countries, dealt with a few species occurring in Kashmir. In his another paper (1959), on fauna of South China, he dealt with species that also. occur in North-eastern India.

Hincks (1955 and 1959) revised Family Pygidicranidae at the world level, on the basis of male genitalia, recording several new species from India. He described some more new species from India and neighbouring countries in his subs~quent works (1954, 1957 and 1960). In recent years the work of Rinks (1955-1960), Brindle (1965-1980), Steinmann (1973-1990)..and Srivastava (1968-1990) have contributed much on the Indian Fauna. Besides, a number of known or new taxa from India were described in the works of Baijal and Singh (1954), Singh (1955), Gangola (1965), Ramamurthi (1960.. 1968), Kapoor (1966-1980) and Kapoor and Bharadwaj (1968). Srivastava's (1976) Catalogue on Oriental Dermaptera, Sakai's (1970-1991) Dermapterorum Catalogus Pmeliminaris, and Steinmann's (1989) World Catalogue of Dermaptera deserve mention.

Prior to 1960, studies on Indian Dermaptera were carried out mostly by foreign experts, who received collections for their study from Museums of Asiatic Society, Indian Museum and Zoological Survey of India. Ramamurthi (1960 .. 1968) was probably the first Indian to start systematic work on Indian Dermaptera. He worked on materials from South India at the Loyola College, Madras. Kapoor (1966-1980) made notable contributions while working at Agra College, Agra, Division of Entomology, Indian Agricultural Research Institute, New Delhi and Tribhuan University, IGrtipur Campus, Kathmandu (Nepal). Gangola worked at D.S.B. College, Nainital (U.P.) and has published (1965) two papers on Dermaptera of .Kumaon Hills. Srivastava is working in the Zoological Survey of India at Calcutta and contributing papers. since 1968 Qn the systematics of Indian Dennaptera extensively.

The Zoological Survey of India has infrastructure to collect material from the fie,ld and procure materials in exchange, as a result of which a large collection specimens of known .species and several new species are incorporated.

Estimation or Taxa

About 1800 species are known all over the world, out of which 320 species belonging to 74 genera and 7 families are recorded from India and adjacent countries. The accompanying table provides composition of Dermaptera from the area. (See table).

Although most of the States of India have been faunistically surveyed for Dermaptera, intensive surveys of Manipur, Tripura, Meghalaya, Mizoram, Madhya Pradesh and Western Ghats (Goa and Coorg) may yield interesting forms, since the fauna of these areas do not seem to be fully explored in view of the rich forest cover or remoteness of certain areas.

Expertise India

In ZSI

G. K. Srivastava, Zoological Survey of India, 13th floor, Nizam Palace, 234/4, AJ.C. Bose Road, Calcutta -700 020.

Elsewhere

V. C. Kapoor, Punjab Agricultural University, Ludhiana.

Abroad

Seiroku Sakai, Institute of Biology and Life Sciences, Daito BuDka University, No. 2-26-12, Sendagi, Bunkyo, Tokyo, (Japan 133). H. Steinmann, Zoology Department, Hungarian Natural History Museum, H -1088, Budapest Baross -U 13, (Hungary).

Selected References

Brindle, A. 1973. The Dermaptera of Africa, Pt.I. Ann. Mus. Roy. Afr. Centr., Tervuren in -8°, Zool., 20S : 1-335.

Brindle, A. 1978. The Dermaptera of Africa, Pte ll. Ann. Mus. Roy. Afr. Centro in -8° Zool., 225 : 1-204. Burr, M. 1910. Fauna ofBritish India, including Ceylon and Burma. Dermaptera. xviii, 127 pp., 10 pIs.

Hincks, W. D. 1955-1959. A Systematic Monograph of the Dermaptera of the World based upon the material in the British Museum (Natural History). Part I. Pygidicranidae, subfamily Diplatyinae, 132 pp., 167 figs.; Part II. Pygidicranidae excluding Diplatyinae, 218 pp., 214 figs., British Museum (Natural History), London. Kapoor, V. C. 1968. Catalogue on the Indian Dermaptera. Agra Univ. J. Res. (Scj.), 16 (1) : 1¬ 42. Sakai, S. 1970-1991. Dermapterorum Catalogus Praeliminaris, Pts. I-XXIII. Daito Bunka University, Tokyo.

Srivastava, G. K. 1976. Catalogue of Oriental Dermaptera, Rec. zooI. Surv. India, Dec. pap., 2 : 1-94.

Srivastava, G. K. 1988. Fauna ofIndia and Adjacent Countries. Dermaptera, Pt. I Superfamily Pygidicranoidea : xii + 268 pp and errata. Zoological Survey of India, Calcutta. Steinmann, H. 1986-1989. Dermaptera, Das Tierreich, 102, 105 and 106.

Steinmann, H. 1989. Worid Catalogue ofDermaptera, Series Entomologica, 43 : 1-934. Kluwer Academic Publishers, The Netherland and Kiado, Budapest, Hungary.