Trichoptera: India
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Faunal Diversity in India: Trichoptera
This is an extract from FAUNAL DIVERSITY IN INDIA Edited by J. R. B. Alfred A. K. Das A. K. Sanyal. ENVIS Centre, Zoological Survey of India, Calcutta. 1998 ( J. R. B. Alfred was Director, Zoological Survey of India) |
Introduction
Trichoptera or hairy winged insects are popularly called as caddis flies and their larvae as the caddis worms because of the ability of the latter to construct and line with silk the cases in which they live. The trichopterans are moth-like insects. They are small to moderate in size with setaceous antennae and mandibles may be absent or vestigeal. Maxillae with single small lobe and elongated palpi and labium with large mentum and 3 segmented palps present. Wings are membranous, more or less densely hairy and held roof-like over the back in repose. Forewings are elongate but the hindwings are broader with folded anal area. Crossveins are very few in the wings. Legs are long, slender with long coxae and tibiae and provided with both apical and preapical spurs. Tarsi are with 5-segments. Larvae are more or less eruciform. Pupae are exarate and decticus.
Status Of The Taxon
Linnaeus (1758) while erecting the order Neuroptera included Trichoptera in it along with other groups of insects. So, Trichoptera was considered for a longtime in the heterogenous assemblage of order Neuroptera. Later, Trichoptera was considered as a separate order. Kolenati (1848) subdivided the order into two main subdivisions, namely, Inaequipalpia and Aequipalpia on the basis of relative number of joints in the maxillary palpi in male and female. Martynov (1924) divided Trichoptera into two suborders on the basis of the form and habits of the larvae and partly on structures in adult insects. The ultrascientific school, however, has divided these suborders into several superfamilies. Weaver (1983) classified Annulipalpia into two infraorders, Curvipalpia and 5picipalpia and included two superfamilies, namely, Hydropsychoidea and Phylopotamoidea in the former and Rhycophiloidea and Hydroptiloidea in the latter. He also divided Integrepalpia into two infraorders of which Plenitentoria contained superfamilies Limnephiloidea and Phryganoidea, whereas Brevitentoria included two superfamilies, Leptoceroidea and Phryganoidea.
Global Status
Numerically about 7000 species in 38 families are known from the whole world. Indian Status Amongst a tolal of 38 families from the whole world, 19 families have so far been recorded from India. Though family Arctopsychidae is not generally accepted as a distinct family and is considered as a subfamily of the family Hydropsychidae but in the following table the status hilS been restored. The approximate number of genera and species hitherto known from India are given as follows : Familia No. of genera No. of species
1. Molannidae 2 8
2. Hydropsychidae 16 60
3. Polycentropidae 5 24
4. Slenopsychidae 1 13
5. Calamoceratidae 2 5
6. Phryganeidae 3 4
7. Philopolamidae 3 47
8. Hydroptilidae 8 65
9. Leptoceridae 14 201
10. SeriCQsmatidae 13 36
11. Lirnnephilidae 20 52
12. Economidae 1 6
13. Psychomyidae 6 31
14. Xiphocentronidae 6 46
15. Rhyacophilidae 4 176
16. Glossosomatidae 4 19
17. Odontoceridae 1 1
18. Arctopsychidae 2 9
19. Hydrobiosidae 1 9
Total: 19 112 812
Distribution
There is a scope for rich species diversity in the diverse ecosystems of India. Trichoptera are generally aquatic in immature stages and occur in lakes, ponds, pools, rivers, streams etc. and the adults are entirely terrestrial. Our knowledge on Indian Trichoptera is far from complete. So, it is difficult to estimate the species diversity. From the available data, it may be mentioned that the trichopterans are very rich in species diversity in the Himalayan ecosystems and terrestrial ecosystem of Peninsular India. Our knowledge on this group in the desert ecosystem and insular ecosystem is fragmentary. The qualities of substrate, water temperature, types of vegetation and water current strongly influence the distribution of the species. Any change in the biotic environment may support different fauna.
Biological Diversity And Its Special Features
Majority of the caddis flies are weak fliers but some may fly great distance. In day time, the adults generally conceal themselves on vegetation, under bridges, etc. On the contrary, larvae are conspicuous in diverse aquatic habitats. When the adults live without sustenance or lapping up liquids, the larvae feed on algae, organic particles, invertebrates, etc. Larvae may be free living (Rhyacophilidae), net spinning (Hydropsychidae, Philopotamidae, Psychomyidae) and some inhabit in cases (majority of caddis flies larvae). Diversity is more in case bearing forms. Some are saddle case makers (Glossosomatidae) or purse case makers (Hydroptilidae). Larval cases of the species of some families are in the form of elongate tubes. Free living forms may take shelter beneath the submerged stones or debris or may spin nets, while the case bearing forms take shelter on sand, silt bottoms, stones, logs, etc.
Endemicity
The available data is not sufficient to estimate correctly the extent of endemism. But from the data hitherto available, it may be mentioned that more than 80% species are endemic in India. It is also difficult to provide any information on the threatened species as the faunistic surveys and taxonomic studies are not satisfactory.
Value
Because of the broad trophic habits of the larvae, they take an important part in the energy transfer at several levels in aquatic ecosystem and are therefore significant in the nutrition and management of fish and other aquatic vertebrates. Most larvae eat plant materials in one form or other, as for example, algae specially diatoms on rocks or decaying vascular plant tissue. So, they effectively control the growth of water weeds. Though this group is generally not recognised as insects of economic importance but they play the important role in fresh water ecology.
Threats, Conservation And Future Studies
Trichoptera has not been taxonomically well-worked out group in India and possibly there is no analytical data regarding the status of the species. Gaps still exsist on the distribution of species in India. As the status is not known it is not possible to indicate the names of the species threatened with extinction. The expertise available in the country is far less than required to deal with the number of species occurring in India. Efforts should be made to develop expertise in the group and also to explore fauna from diverse ecosystems in India. Particular emphasis should be given on identification, dUlification, status designation and biogegraphy. These information will provide the base-line data for a conservation strategy.
Selected References
Kolenati, F. S. 1848. Genera et species Trichopterorum. Pars. I.-Actis Regiae Bohemicae Societatis Scientanlm, Prague, 6 : 1-108. Linnaeus, C. V. 1758. Systema Natl/rae. I, Ed. 10,824 pp. Laur Salvii. Martynov, A. V. 1924. Trichoptera in "Practical Entomology" Leningrad, pp. IV + 338. Weaver, J. S. 1983. The evolution and classification of Trichoptera, with a revision of the Lepidostomatidae and a North American Synopsis of the family. Ph. D. Dissertation, Clemson University.
Trichoptera
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Introduction
Trichoptera was considered for a longtime by the entomologists within "the heterogeneous assemblage of the order Neurot>tera. It was Kirby who recognised Trichoptera as a separate Order. MacLachlan (1880) accepted this view to retain its status as an Order.
Trichopterans or Caddisflies, one of the large groups of aquatie insects, are generally aquatic in immature stages and occur in most types of aquatic habitats, but are abundant in freshwaters. Because of the broad trophic habits of larvae, they take an important part in the energy transfer at several levels in aquatic ecosystem and are therefore significant in the nutrition and management of fISh, waterfowl and other aquatic vertebrates. Most larvae eat plant materials in one form or other, as for example, algae specially diatoms on rocks or decaying vascular plant tissue. Some larvae are predacious. Some of the larvae of the family Hydropsychidae are resistant to pollution. Their involvement in many parts of food webs in diverse freshwater habitats also makes the trichopterans a sensitive indicator of change (Wiggins, 1979). Therefore, though this group is generally not recognised as insects of economic importance but they play the important role in freshwater ecology.
Classification
The recent classification of Trichoptera after Weaver and Morris (1986) may be tabulated, in order to highlight .the Phylogeny of the group (vide Table 2).
Historical Resume
i) Pre-1900
The study of Trichoptera started a little before the middle of the 19th century. Kolenati (1864-1873). Walker (1852), MacLachlan (1873, 1875, 1886) and Hagen (1864-1873) may be referred to as the earliest references to the study of Indian Trichoptera.
ii) 1900-1947
In early part of this century, Morton (1900-1902), Banks (1909-1939), Betten (1909) and MacLachlan (1916) contributed much to the study of Indian Trichoptera. Martynov (1935-1936) worked out the collections present in the. Indian" Museum (Zoological Survey of India). Mosely (1935-1949) worked out some Indian fonns.
iii) 1947-1989
Kimmins (1950-1956), Schmid (1949-1987), Wiggins (1968) and Malicky (1979-1981) contributed extensively to the study of Indian Trichoptera. Schmid (1949-1987) described more than 500 species, distributed over 9 families, namely, Limnephelidae, Arctopsychidae, Leptoceridae, Rhyacophilidae, Philopotamidae, Glossosomatidae, Xiphocentronidae, Stenopsychidae and Hydropsychidae, collected from Arunachal Pradesh, Sikkim, Assam, Manipur, West Bengal, Kerala, Tamil Nadu, Kamataka and Uttar Pradesh in India. Wiggins (1968) contributed to the study of Asian Trichoptera, particularly the family Molannidae, and described several new species from "India with particular reference to Assam, Manipur and Madhya Pradesh. Malicky (1979-1981) made some contributions from Andaman Islands. It may be ~entioned here that Fisher's (1960-70) "Trichopterorum Catalogus" is a very useful work and it included some Indian species also.
In Zoological Survey of India research work on Trichoptera has been initiated very recently. Ghosh and Majumder (1989) have published description of a new species of Phryganeidae and a paper on the fauna of Trichoptera from West Bengal is under publication. Studies on materials from Meghalaya and Garhwal Hills are in progress.
Studies from Different Environs
The National Zoological Collections of Trichoptera have been developed through extensive and intensive field explorations by the Zoological Survey of India parties for the last 75 years. The b'ichopterans are found in the neighbourhood of rivers, streams, ponds, lakes, etc. They are either crepuscular or nocturnal and generally concealed during the day. They may be collected from herbage and bushes bordering water bodies, the bushes and branches of trees overhanging water, isolated trees at a little distance away from water, crevices of the bark, underside of the bridges, under stones, or on the artificial light at night. The collections of Trichoptera have so far mainly been made from Himalayan ecosystem, specially from the Garhwal Himalayas, Sikkim, Darjeeling, Arunachal Pradesh, and from Meghalaya, peninsular part of West Bengal and Uttar Pradesh. It is obvious that extensive faunal surveys are required for the collections of Trichoptera not only from the remaining States and Union Territories, but also from the Insular regions, i. e. Andaman &Nicobar Islands and Laccadives.
Estimation of Taxa
Kolenati (1884) created two main subdivisions, namely, Inaequipalpia and Aequipalpia, on the basis of relative number of joints in the maxillary palpi in the two sexes. These subdivisions were retained both by MacLachlan (1880) and Ulmer (1907). Martynov (1924) divided Trichoptera into. two suborders, the Annulipalpia and the Integripalpia, partly on the basis of the form. and habits of the larvae and partly on structures in the adult insects.
The ultrascientific school, ho.wever, has divided Annulipalpia and Integripalpia into several superfamilies. Ross (1967) and Parker (1982) divided the order Trichoptera into three superfamilies, namely Rbyacophiloidea, Hydropsychoidea and Limnephiloidea. Schmid (1980) recognised four super families namely, Hydropsychoidea, Rhyacophiloidea, Limnephiloidea and Leptoceroidea. Weaver (1983) classified Annulipalpia into two infraorders Curvipalpia and Spicipalpia, and included two superfamilies namely, Hydropsychoidea and Phylopotamoidea in the former, anq Rhyacophiloidea and Hydroptiloidea in the latter. He also divided Integripalpia into two infraorders of which Plenitentoria contained two superfamilies namely, Limnephiloidea and Phryganoidea,. whereas Brevitentoria included two superfamilies, Leptoceroidea and Sericostoinatoidea. In these superfamilies a total of 38 families are known from the whole world (Weaver & Morse. 1986). Linnaeus (1758) recognised a single genus Phryganea, comprising 17 species. Since then the knowledge of Trichoptera has increased so substantially that by 1990 about 7000 species in 38 families from the whole world and about 812 spp. in 18 families from India are known.
Expertise India
In ZSI
S. K. Ghosh &M. Majumdar. Z.S.I .• M-Block, New Alipur. Calcutta 700 053.
Abroad
O. S. Flint. Smithsonian Institution, Washington D.' C. 20560, U.S.A.
H. Malicky. Biologische Station. Lunz 3293. [Hydroptilidae, Hydropsychidae, Psychomyiidae, Polycentropodidae. Glossosomatidae. Philopotamidae].
J. C. Morse, Clemson University, Department of Entomology. Clemson S. C. 29634• -0365, 1.[Leptoceridae, Uenoidae]. 2.Neboiss, Museum of Victoria, Department of Entomology, 71, Victoria Crescent, Abbotsford, 3067 Victoria, Australia. [Leptoceridae, Uenoidae, GlossosOinatidae]. 3.Schmid, Institute de la Recherche Biosystematique Ministere de I'Agriculture, Neatby Building, Ottawa, Ontario KIA OC6, Canada. [psychomyiidae, Leptoceridae. Rbyacophilidae, Xiphocentrinidae, Stenopsychidae]. 4.S. Weaver, University of New Hampshire. Department of Entomology. Durham NH 03824, 5.[Lepidostomatidae]. 6.B. Wiggins, Department of Entomology, Royal Ontario Museum, 100, Queens Park, Toronto, Ontario M 55 2C6, Canada. [Limnocentropodidae. Molannidae. Limnephilidae, Phrygaenidae].
Selected References
Martynov, A. V. 1935. On a collection of Trichoptera from the Indian Museum. Rec. Indian Mus.• 37 : 93-207.
Martynov, A. V. 1936. On a collection of Trichoptera from the Indian Museum. Rec. Indian Mus.• 38 : 238-306.
MacLachlan, R. 1874-1880. A monographic revision and synopsis of the Trichoptera of the European Fauna: i-iv + 523 pp. and pIs., E. W. Classey Ltd., Middlesex.
Mosely, M. E. 1939. The Brilish Caddisflies (Trichoptera): i-xii + 320 pp., George Routeledge & Sons Ltd., London. Neboiss, A. 1983. Check-list and Bibliography of the Australian Caddisflies (Trichoptera). Australian Society for Limnology, Special publication,S: 132 pp.
Schmid, F. 1955. Contribution u I'etuds des Limnephilidae (Trichoptera). Schweiz Ent. Gesell. Mitt., 28 : 1-245, 104 figs.
Schmid, F. 1970. Le Genere Rhyacophila et La famille Des Rhyacophilidae (Trichoptera). Mem. ent. soc. Can. no. 66 : 230 pp., pis I-II.
Walker, F. 1852. Catalogue of the specimens of Neuropterous Insects in the collection of the British Museum. Brit. Mus. Nat. Hist., 1 : 192 pp. Wiggins, G. B. 1984. An Introduction to the Aquatic Insects ofNorth America. Second edition, Chapter 16 (Trichoptem) : 271-347.
