Strepsiptera: India
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Faunal Diversity in India: Strepsiptera
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
The strepsiptera commonly called as "twisted winged insects"or "stylops" are entomophagous parasitoids of cosmopolitan distribution. Because of many Wlusaul features of biology and striking structural modifications, they have been a favourite subject for philosophical speculation to entomologists since the early part of nineteenth centrury. They exhibit extreme sexual dimorphism in the form of an adult male which is free-living and a neotenic female being permanently endoparasitic in the host except in the family Mengenillidae where the female is also free-living. Strepsiptera are reported to parasitize 35 families of 7 orders but their principal hosts are proved to be Hymenoptera and Auchenorrhynchim Hemiptera. Other hosts belong to the orders Thysanura, Dictyoptera, Diptera, Lepidoptera and Orthoptera. Recently, a first stage strepsipteron larva or triungulin belonging to genus Xenos Rossi or Pselldoxenos SaWlders has been noticed in the adbdominal cavity of a caddis fly, OXlJetlzia janella (Manuel & Bohart).
Status Of The Taxon
The first record of male strepsipteron insect motilal Xenos vesparllm Rossi parasitic in Polistes gallicus Lat. was made by Peter Rossi (1793). Later, Stylops melittae Kirby, a parasite of Andrena nigroaenea was described by Kirby (1802) but he could not associate it with Xenos vesparum until 1813.
So far more than 554 species of strepsiptera have been described from different parts of the world (Kathiarithamby, 1993). Approximately 73 species have been made known from the Neotropics, 169 from Australian, 111 from the Oriental, 94 from Afrotropical, 73 from the Palaearctic and 64 species from the Nearctic regions. Uptil now, 41 genera of strepsiptera have been made known worldwide, out of which 20 genera were reported from the Orient.
Indian Status
There is very little information on record about Indian representatives of the extremely interesting group of insects. As far as the author is aware, only two species are described definitely from the Indian region. One is Pyrilloxenos compactlls Pierce from Bihar as a parasite on species of Hemiptera belonging to the families Fulgoridae and Jassidae. The other Tachytixellos ;m!iclIs Pierce parasitizing a wasp, Techytes from South India. Leproy in his book, "Indian Insect Life" (1909) made a mention of a Xenos without mentioning what species it was. He simply quoted Home that the wasp, Polistes hebraells was the host of a Xenos. Nurse (1909) also obtained a number of stylopized wasps of the genus Techytes from Deesa (India). Subramanian (1922) erroneously identified Pyrilloxenos compactus as a new species which later became synonym with Halictophagus indicus, a new species described by Bohart (1943) parasitizing mango jassids in Mysore. Subramanian (1927) reported another strepsipteron, Halictphagus (Indoxenos) membraciphaga from a membracid bug, Otinotus pallescens Dist. from Sasalu (Kamataka) followed by one more species, Tridactylophaglls mysorensis in 1932 parasitizing Tridactylus sp. Bohart (1943) revised the generic status of Pyrilloxenos compactlls Pierce to Halictophagus and described one species, Halictophagus indicus. Since then there was not much progress until Baliga (1967) described Corioxenos raoi parasitizing Antestiopsis cruciata (Pentatomidae).Chaudhuri et al. (1978) recorded Parastylops plantipes from Pasighat (Arunachal). In subsequent years, Chaudhuri et al. (1978-1983) added 6 more species of genera, Triozcera Pierce, Halictoplurgus Dale, Tridactylophaglls Subramanian, Myrmecolax Westwood and Lychnolax Bohart to the directory of Indian strepsiptera. During the recent years 8 more species belonging to genera, Dundoxenos carvalho, Elenchus Curtis, Halictopltagus, Tridactylophagus and Myrmecolax have been made known from India (Mazumdar & Chaudhuri 1997, 1998) raising the number of species to 18 under 8 genera from this subcontinent.
Distribution
These insects have been recorded from all the major zoogeographical regions viz., Afrotropical, Australasian, Nearctic, Neotropical, Palaearctic and Oriental. Owing to the endoparasitic life, strepsipteron is not easily noticed and remains an enigma to the entomologists. The families that are widespread in distribution are Corioxenidae, Elenchidae, Halictophagidae and Stylopidae. However, the remaining families are characterised by a discontinuous distribution or extremely limited distribution (Kathirithamby, 1989). The distribution of various genera is restricted to the distribution of the hosts although in most cases, the hosts are more widely distributed than the parasites in all the zoogeographical regions. The maximum number of strepsiptera was recorded from Australia followed by the Oriental. Although only 18 species have so far been recorded from the Indian region, it may be emphasized that this region may be rich in strepsipteran species which remains very ill explored.
The following outline distribution and host relationship of the Indian genera have been made on the basis of previous reports and investigation made by the author during the past years: Table -1 Distribution of host and parasitic genera Host genus Distribution Parasitic genus Antestiopsis sp. (Hemiptera) Aethlls sp. (Cydnidae) Cydnidae (Hemiptera) Javesella sp. Nephotettix sp. Nilaparvata sp. (Hemiptera) Pyrilla sp. (Lepidoptera) Otinotlls sp. Halictlls sp. Tettigonia sp. (Orthoptera) Cicadella sp. Idiocerclls sp. (Hemiptera) Tridactyills sp. Grylllls sp. (OrthopteraJ India (Mysore) Africa and India (Maithon, Burdwan) India (Raniganj & Burdwan) Japan, Malaysia, Philippines, Thailand & India (Burdwan & Maida) Australia & India (Burdwan) Sri Lanka, China, Philippines & India (Asansol, Burdwan, Calcutta, Chinsurah, Maithon, Maida, Muzaffarpur, Mysore, Raniganj & Taki) Corioxenolls Blair Dundoxenous Carvalho Triozocera Pierce Elene/illS Curtis Halictophaglls Dale Tridactylophaglls Subramanian
Biological Diversity And Its Special Features
The knowledge of biology of these curious insects is meagre. There are 1¬7 larval instars in strepsiptera. The distinction of larval instars is determined by the increment of larval size. In most cases (e.g, HaIictophagidae), development comprises of six instars and pupa before eclosion to imagines. The first instar larvae (triungulin) parasitizes second to fourth instar nymphs of the host. On entering the nymphal host, it moults to an apodous second larva and remain endoparasitic until fourth instar. In all the families (except Mangenillidae) at the end of fourth instar, the male extrudes its head out of prothorax and pupates while the female extrudes the head, pro-and mesothorax and becomes a neotenic female. In Mangenillidae the male and female larvae emerge at the end of last instar from the host to pupate externally. The freeIiving adult male emerges at the end of pupation while the female remains endoparasitic in the host. The duration of each of the life stages as revealed in experiment with H. australiensis happens to be 1 day for the first instar and 5 days for the second instar. Male requires 2-14 days for the third, 5-13 days for the fourth, 5-13 for the fifth and 5-22 for the sixth instar. Whereas the female takes 7-15 days for the third, 5-14 days for the fourth, 3-12 days for the fifth and 1-18 days for the sixth instar larvae. The pupal stage lasts for 10-12 days. Average time from infection to protrusion requires 23-41 days in male parasitoid while in the female it takes 23-36 days. The life cycle requires 20-23 days in Elencllus and 46-59 days in Sticltotrema (Young 1987, Gu Xiu-Hui, 1990) and 23-41 days in Halictopltaglls australiensis. The larval development of both the sexes appears to be dependent on several biotic factors which need investigation. The insects generally emerge in the morning and fly rapidly for an hour.
Life span is extremely short but in humid condition, they survive little longer. Habitat diversity The adult male (particularly of the families Corioxenidae and Myrmecolacidae) and female of Mengenillidae are free-living and are attracted to light. Alternavely, they may be had through rearing from the host or by chance caught in sweep nets, malaise or truck traps. In all known families except Mengenillae, the sexually mature female is "larviform" and lacks diagnostic characters. The externally visible feature like cephalothorax extrudes through 4-6th abdominal segments from the adult hosts. The more interesting side of the phenomenon of extrusion concerns the male. In Delphacids which are mainly brachypterous,the male strepsipteran pupa always extrudes and the free-living male emerges from the fifth instar nymphs in delphacids. In most macropterous the male extrudes and emerges from both fifth instar and adult hosts.The extrusion of male takes place through 4-5th abdominal segments of the host. Nilaparvata Iugens with Elellclllls male pupae often appears in the light traps. A good number of insects serve as hosts of strepsipteran parasites, some of them are said to be Lepismatidae (Thysanura); Blattadidae and Mantidae (Dictyoptera); Gryllidae, Gryllotalpidae, Tettigonidae, Tridactylidae (Orthoptera); Cercopidae, Cicadellidae, Membracidae, Delphacidae, Dictyophasidae, Eurobrachyidae, Ricaniidae, Flatidae, Fulgoridae, Jassidae, Tettigometridae, Coreidae, Cydnidae and Lygaeidae (Hemiptera), Andrenidae and formicidae (Hymenoptera). Usually one strepsipteran parasitoid parasitizes one host but more than one with any combination of sexes become involved. If there are two males or a male and a female strepsiptera, the male emerges first bearing an empty puparium which gets fungal infected and kills the host along with the remaining male or females in it (Kathirithamby, 1989). Strepsiptera have also been reported to be parasitized by Hymenoptera and Nematoda (Kinzel¬ bachi, 1971.). There are reports of the Eurybrachyids (PIatybrachus) to be parasitized by two strepsipteran members of HalictoplUlgus and Deinelenclllls. It is acaseof multiparasitism of two strepsipteran parasitoids which may be considered as a deviation from the general rule of one parasitoid and one host relationship. Multiparasitism involves parasitoids belonging to different orders. The species of strepsiptera are not absolutely host specific. Specificity may therefore extend over a genus or even a family. As for examples, members of HaIictoplUlgus attack the hosts of Fulgoridae, Cicadellidae, Membracidae and Cercopidae ( Hemiptera) while the closely related Tridactylophagus parasitizes only Gryllidae (Orthoptera). The specificity appears to be high in Hymenoptera while it is not so in Hemiptera (Rick, 1970). Myrmecolacids parasitize hosts of two different orders, the male parasitizes Hymenoptera and the female, Orthoptera. Infection of mixed species occur in low frequencies in strepsiptera as in other parasitoids and parasitic castrators of Crustacea.
Endemicity
Of the eighteen species described from India 15 species may at this moment be considered as endemic in India. These are: Corioxenos raoi, Halictophagus acerbus, H. compactlts, H. indicus, H. membracipllaga, H. tenebrosus; Tridactylopllagus adllnCllS, T. carinatus, T kiftmei, T. maculatus, T mysorensis; Lychnocolax similis; Myrmecolax pierci, M. plantipes and Trizocera pugipenis. The remaining three were previously reported from other countries enjoy distribution in India. These are (i) Dundoxenox kinzelbachi described by Luna de Carvalho (1985) from Republic of Cape Verde; (ii) Elenchus japanicus described by Esaki and Hashimoto (1931) from Japan and (iii) Halictophagus australiensis described first by Perkins (1905) from Australia.
Value
The insects harbouring the strepsipteran parasites undergo "castration" which is attributed to as "stylopization" Species are known to attack members of the various insect orders. Some of them are economic pests. For example, Nilaparvata Illgells Stal and Sagatella fllreifera Horvath (Homoptera : Delphacidae), which spread virus diseases and cause "hopper bum" in rice in South and Southeast Asia, are parasitized by Elendlus sp.; Javesella pellucida (F.) (Homoptera : Delphacidae), a vector of a virus disease in oats in the Palaearctic region, is parasitized by Elenehus tenuicamis (Kirby); Nephotettix sp. (Homoptera : Cicadellidae), a vector of a virus disease in rice in South and East Asia, is parasitized by Halietophagus sp.; fruit flies (Diptera : Tephritidae) that damage fruits in Australia and Southeast Asia are parasitized by Dipteroplzagus daci Drew and Allwood; Segestes deeoratus Redtenbacher. Sexava nubila (Stal) and Segestidae novaeguineae (Brancsik) (Orthoptera : Tettigoniidae), causing severe defoliation of coconuts, oil palm and Pandanus spp. in Papua New Guinea, are parasitized by Stiellotrema dallatarreanum Hofeneder; and Antestia (Heteroptera; Pentatomidae), a pest of coffee in Africa, is parasitized by Corioxenos antestiae Blair. The effect of stylopization on beneficial pollinators and predators is difficult to evaluate. The degree of parasitization is usually low rarely exceeding 50%. The situation is more definite in case of leafhoppers. Halictophagids are definite factor in the control of sugarcane leafhoppers of genus Pyrilla and planthoppers, Nilaparvata and Cicadella in this country.
Stylopization causes reduction of reproductive potentiality of the host. Sex conversion is found to occur in Hymenoptera due to stylopization which may also cause considerable reduction of external genitalia of the host.
Future Studies
Strepsiptera exerts some control of the population level of the host. The rate of parasitism by strepsipteran insect varies according to the season of the year. There is ample scope for studying the bio-control aspects of the crop pest by Strepsiptera. Therefore exploration of the fields and the various types of insect host must be made to find out the species of strepsiptera infecting them. There are certain biotic factors which are assumed to play major role in the parasite population. The stability of the host population, migration, presence of other parasites and cropping pattern might determine the percentage parasitization in the rice field ecosystem. However, the method may not be free from errors but on the other hand is advantageous while considering observations of the large number of hosts. The protrusion provides a much reliable and quicker method than dissecting the host indiVidually for parasitism. However, it is too premature to conclude the effectiveness of H. australiensis in controlling the population of C. spectra. Several factors require to be taken into consideration before drawing a meaningful conclusion.
Selected References
Bohart, R. M. 1941. A revision of the Strepsiptera with special reference to the species of North America. Univ. Calif Publ. Ent., 7 (6) : 91-159. Chattopadhyay, A. K. & Chaudhuri, P. K. 1980. Record of genus Caenoclwlax Pierce (Myrmecolacidae, Strepsiptera) from India. J. Bomb. Nat. Hist. Soc., 76(3) : 490-492. Chaudhuri, P. K., Das Gupta, S. K. & Chatterjee, A. K. 1978. Description of a new species of Parastylops (Strepsiptera: Stylopidae) from Arunachal Pradesh. Orient. Ins., 12 (3) : 387-389. Chaudhuri, P. K. & Das Gupta, S. K. 1979. New species of Halictophaglls and Triozocera (Strepsiptera) from West Bengal, India. Orient. Ins., 13 (1-2) : 133-137. Chaudhuri, P. K., Ghosh, M. & Das Gupta, S. K. 1983. Notes on Indian Strepsiptera with description of three new species. Dt. Ent. Z., 30(1-3) : 23-29. Kathirithamby, J. 1978. The effect of stylopization on the sexual development of Javesella dubia (Kirchbaum) (Homoptera : Delphacidae). BioI. J. Linn. Soc., 10 (2) : 163-180 Kathirithamby, J. 1979. The effects of stylopization in two species of planthoppers in the Krian District, West Malaysia (Homoptera : Delphacidae). J. Zool. Lond., 187 : 393-401. Kathirithamby, J. 1983. The mode of emergence of the adult male Elenchlls tenllicomis 9Strepsiptera, Elenchidae) from its puparium, Zool. J. Soc., 77(1) : 97-102. CHAUDHURI : Strepsiptera Kathirithamby, J. 1989. Review of the order Strepsiptera. 5yst. Ent., 14(1) : 41-92. Kathirithamby , J. 1993. Description and biological notes of Halictophagidae (Strepsiptera) from Australia with a checklist of the world genera and species. Invert. Taxon., 6 (1) : 159-196. ~azumdar, Alpana & Chaudhuri, P. K. 1997. Report of three genera of Strepsiptera from India with description of a new species of Halictophaglls Curtis. The Entomologist, 116 : 119-123. Raatikainen, M. 1967. Bionomics, enemies and population dynamics of laveselIa pelillcida (P.) (Homoptera : Delphacidae). Ann. Agric. Fenn., 6 : 1-147. Subramanium, T.V. 1927. A new genus and species of Strepsiptera fI:om South India, Indoxenos membraciphaga gen. and spec. nov. Trans. R. Ent. Soc. Lond., 7S : 131-134. Subramanium T.V. 1932. On a new genus and species of Slrepsiptera. Rec. Indian MilS., 34 : 43-46.
Strepsiptera
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Introduction
Strepsiptera, popularly called as the Stylops or twisted-winged insects, was considered by some authorities as closely related to the order Coleoptera. These strange insects have also had few changes in nomenclature until they were placed in the order Sttepsiptera by Kirby (1913). They were regarded as Rhipidoptera in the order Diptera Lamarck 1816; Rhipiptera Latreille 1817; Strepsata Billberg 1820; Rhipidoptera BUrmeister 1829; Stylopites Newman 1834 and Stylopida Haeckel 1896. In view of the similarities in the larvae and metamorphosis, the stylopids were included with Coleoptera, but the peculiar characters of the stylopids justified their separation as an independent order, Suepsiptem.
The strepsipterans are small insects, and the males are about 1.5-4 mm in length. They are distinguished by the marked sexual dimorphism. They are parasites of Hymenoptera (bees and wasps), Homoptera and also Orthoptera. The development of both the sexes are different. All the stages of development of females take place within the body of the host where the adult female remains. whereas the adult male flies off leaving the host.
They are of little or of no economic importance to man, as their role in biological control of pest species is very much limited. However, Tillyard (1926) indicated that the species which parasitize Homoptera are to be regarded as highly beneficial, the effects of their parasitism being severe to destroy the host or to render it i~fertile.
Classification
Bohart (1941) classified Strepsiptera into six families, namely, Mengeidae (parasites of Lepismatidae), Myrmecolacidae (parasites of Formicidae Male or of Orthopteroids Female, Callipharixenidae (parasites of Heteroptera), Stylopidae (parasites of Aculeate Hymenoptera), Elenchidae (parasites ofDelphacidae) and Halictophagi~ (parasites of Homoptera:Auchenonnynca and ofOrthoptera :Tridactylidae).
The family Mengeidae is the most primitive family .of the order. The oldest known species of the order is Menges tertiaria (Menga), which is a Tertiary insect taken from the Eocene in German Baltic Amber. The order is composed of some 35 genera and subgenera and approximately 300 species from the whole world, of which 8 species are hitherto known from India.
According to Bohart, three genera of Orthoptera, 45 genera of Homoptera, three genera of Heteroptera and 41 genera ofHymenoptera are recorded as the hosts of stylops.
Historial Resume
The frrst male of Strepsiptera namely, Xenos vesparum was recorded from Europe by Rossius in 1793 and it was taken from a wasp, Polistes gallicus Linnaeus. Information on the Indian species of this interesting group is restricted to the contribution of Pierce (1909, 1911 &1918) and Subramanian (1922, 1927 &1932). Through their works, only three species belonging to three genera are known. After these works on Indian Strepsiptera, no study was undertaken until Chaudhuri, Dasgupm &Chatterjee, Sinha .Roy (1977, 1978) published "the account of four new species. The majority of 300 species known from all over the world are from the Holarctic region though the order is represented in remaining Zoogeographical regions also.
Studies from Different Environs
It may be pointed out that since very few works have bee.n published from India, so there is sufficient scope for exploration and detennination of Strepsiptera from different environs ofIndia.
Estimation of Taxa
Only a total of eight species distributed over seven genera and three families are known from India.
Expertise India
P. Chaudhury, Zoology Department, University of Burdwan, Burdw8D. S. K. Dasgupta, Zoology Department, Presidency College, Calcutta.
Abroad
T. Kifune, H. Brailovsky &Y. Hirashima, all of Escuela de Med., Dep. de Parasitol. Univ. de Fukuoka, (Japan). A. T. Banion &J. A. Litsinger, Entomol. Dep.t lnt. Rice Res. lnst., Post Box 933, Manila, (Philippines). J. Kathirithamby, Dep. Zool., South Parks Road, Oxford"Oxl3PS (U.K.).
Selected References
Bohart, R. M. 1941. A revision of the Strepsiptera with special reference to the species of North America. Univ. Calif. Publ. Ent., 7 : 91-160, Ipl., 8 figs.
Kathirithamby, J. 1989. Review of the order Strepsiptera. Syst. Entomol., 14 (1) : 41-92.
Pierce, W. D. 1909. A monographic revision of the twisted-winged insects comprising the order Strepsiptera
Kirby. Bull. U.S. nat. Mus.. : xii + 232 pp., 3 figs., 1 map, 15 pis.
Pierce, W. D. 1911. Strepsiptera. Gen. Insectorum, 121 : 1 ..54, 1 fig., 5 pIs.
Pierce, W. D., 1918. The comparative morphology of the Order Strepsiptera together with records and descriptions of insects. Proc.• U.S. Nat. Mus .• S4 : 381-501.
Ulrich, W. 1927. Strepsiptera. Bioi. Tiere Deutsealands. 41 : 1-103.
See also
Lepidoptera Amatidae, Arctiidae &Noctuidae: India
Strepsiptera: India
