Insect Fauna associated with the Tea Ecosystem of North Bengal, India

Present communication reports 167 species belonging to 139 genera of 42 families under 6 orders of insects from the tea gardens of North Bengal. Of them, Lepidoptera shares maximum number of species (77), followed by Hemiptera (29), Diptera (24), Coleoptera (19), Odonata (12) and Orthoptera (06). Among them, 20 species of Lepidoptera, 05 species of Hemiptera, 05 species of Coeloptera and 03 species of Orthoptera are found as tea pests. Besides this, 01 species of Diptera and Odonata are found as predators of tea pest. In addition to this, 14 species of Hemiptera, 11 species of Coleoptera and 09 species of Lepidoptera reported as pests/borers of other crops and timber plants. In addition to this, 03 species of Hemiptera and 03 species of Diptera as predator and 16 species of Diptera as flower visitors/pollinators in other ecosystem are also found.


Introduction
Insects are among the major animal visitors of any crop fields and act as pests, pollinators or some other biologically important organism to a particular plant including tea gardens.Therefore, accurate identification of insects at genus and species level is essential for understanding their biological role in a particular ecosystem.
Tea (Camellia sinensis (L.) O. Kuntze) is a popular beverage all over the world.Globally, 1031 arthropod species are associated with tea; a small number of pests (about 3%) are common throughout the world (Hazarika et al., 2009).All parts of the plant, leaf, stem, root, flower, and seed, are fed upon by at least one pest species, resulting in 11%-55% loss in yield if left unchecked (Hazarika et al., 2009).Tea with perennial foliage is infested by about 167 insect species in the North-Eastern tea growing regions of India (Das et al., 2010) including the Dooars and Terai.Besides the role of insects in tea ecosystem as pest, they are serving other functional role as predator, parasites and pollinator.Bezbaruah, (1975) stated that, insect pollinators contribute to pollination success in tea.
Majority of the works in North Bengal tea gardens are restricted with insect pest, predator, and parasites and their control.Khewa and Mukhopadhyay (2010) worked on biopesticides of Arctonis submarginata.Roy et al. (2010) evaluated the ef ectiveness of acaricides/insecticides in killing the eggs of Helopeltis theivora Waterhouse and Oligonychus coffeae Nietner in North Bengal.Roy et al. (2010) studied the bio efficacy of coccinellid predators on major tea pests.Das et al. (2010) studied the seasonal occurrence of the three lepidopteron species from Terai tea plantations.Das et al. (2010) reported 94 species of predators and 33 of parasitoids as natural enemies of arthropods in sub-Himalayan tea plantations of North Bengal, India.After that, Mitra et al. (2014a and2014b) published a list of 07 species of Orthoptera and 28 species of Hemiptera from tea plantations of Dooars.Biswas et al. (2015) reported 14 species of moths (Lepidoptera: Erebidae) associated with the tea plantations of northern West Bengal.Shah and Mitra (2015) also published a list of 39 species as tea associated moths, of which, 15 species were recognized as serious pests of tea.Documentation of butterflies has also been done by Mitra et al. (2015), Bulganin Mitra, Suresh Kumar Shah and Purnendu Mishra where 37 species were observed to visit in tea plantations.Apart from this, the interactions of 12 species of Odonata (Shah et al., 2015) and 13 species of Coleoptera (Mitra et al., 2016) have also been recorded from this ecosystem.Recently, Mitra et al. (2017) documented 24 species belonging to 08 families of dipteran flies and their association with the tea plants.
Apart from these, there are many more insect species unknown to us in tea gardens.They may be beneficial or harmful to the tea plants.Without regular surveys and proper identification of these species, it is not possible to undertake any action on them.
Field surveys were conducted in 74 tea gardens and its adjoining areas from 04 districts i.e., Jalpaiguri, Alipurduar, Kochbihar and Darjeeling of northern West Bengal from 2012-2016.
167 species belonging to 139 genera of 42 families under 6 orders of insects are reported from the tea gardens of North Bengal.Of them, Lepidoptera (77 species), followed by Hemiptera (29 species), Diptera (24 species), Coleoptera (19 species), Odonata (12 species) and Orthoptera (06 species) were collected and identified

Study area
Survey was conducted in Dooars and the hilly area of Darjeeling of West Bengal from 2012 to 2016 in three districts of North Bengal and visited 74 tea gardens (Map.1-4).The serial number (1-74) has been maintained as per Table 1.Insect Fauna associated with the Tea Ecosystem of North Bengal, India

Methodology
The insects were randomly collected from various types of habitats observed in tea ecosystem.At day time, collections were operated by sweeping insect net, beating vegetation and handpicking method.The nocturnal insects were collected between 5.30 p.m. to 10.00 p.m. by using light trap (a white screen and a 27 Watt CFL lamp operated by portable rechargeable UPS machines).Collection permission was not granted after 10 PM., due to elephants and leopards movement.Butterflies and other macro insects were mostly photographed and identified in the field itself.The doubtful specimens were collected, killed by putting them in killing bottle containing ethyl acetate and brought to the laboratory in insect envelops.Soft bodied insects like Hymenopterans and some dipterans etc. were collected and preserved in glass vials containing 90 percent ethyl alcohol.The collected specimens, after bringing in Z.S.I. laboratory, were further processed using standard methods (Arora, 1986).The collected specimens were identified after setting and pinning by Scientists of Z.S.I., Kolkata.

Brief Description of the Plant
C. sinensis (Linnaeus) belonging to the family Theaceae is an evergreen tree or shrub that attains a height of 10-15 m in the wild and 0.6-1.5 m when cultivated.These are characterized by the presence of light green leaves, short stalked, coriaceous, alternate, lanceolate, serrate margin, glabrous or pubescent beneath, varying in length from 5-30 cm and about 4 cm width.Mature leaves are bright green colored, smooth and leathery while young leaves are pubescent.Flowers are white fragrant, 2.5-4 cm in diameter, found in solitary or in clusters of two or four.Flowers bear numerous stamens with yellow anther and produce brownish red capsules (Ross, 2005).Fruit is a flattened, smooth, rounded trigonous three celled capsule, seed solitary in each, size of a small nut (Biswas, 2006).1).In all, 167 species belonging to 139 genera of 41 families under 6 order of insects were reported and identified from the tea gardens (74) of North Bengal.

Order LEPIDOPTERA
Butterflies, moths and skippers are one of the most important groups of insect in the animal world under the order Lepidoptera.They are beautiful in colours, diverse in their numbers, and play a pivotal role in the faunal analysis and environmental monitoring and planning of any region.The role of butterflies and some moths in any habitat is best known by even common people nowadays, as good and potential natural pollinators, ecological indicators etc., which enable to assess or monitor habitat changes.Among insects, butterflies are well studied groups in terms of their taxonomy, geographic distribution etc., and therefore, they are the suitable group for ecological studies, Butterflies show distinct pattern of habitat utilization.The presence of butterflies denotes the availability of larval food plants in great abundance.
Butterfly host plants are those plants, on which specific butterfly species lay eggs, and caterpillars will then hatch and use plant as their sole food source.Butterflies are generally diurnal and visit flowers that open in the morning and also during the hours of bright sunshine.Presently 37 species belonging to 06 families of butterflies from North Bengal tea gardens were collected and identified.Of them, Nymphalidae shares 20 species followed by Pieridae (10 species), Hesperiidae (03 species), Papilionidae (02 species), Lycaenidae (01 species) and Riodinidae (01 species) (Table 2).Order HEMIPTERA Hemiptera (True Bugs), is a very large and diverse order and also important in agriculture, known to cause direct damage to plants by herbivory and indirectly by transporting diseases.Predatory Hemiptera have also been used in agricultural systems to control pests 29 species belonging to 28 genera of hemipteran bugs from the tea gardens of North Bengal were reported.Of them, the family Pentatomidae shares the highest number of species (07), followed by Coreidae (04), Lygaeidae (03), Fulgoridae (03), Reduviidae (03), Cicadidae (02), Cercopidae (01), Membracidae (01), Largidae (01), Pyrrhocoridae (01), Scutelleridae (01), Miridae (01).05 hemipteran species (*) were reported as pest of tea from North Bengal (Table 4).

Order DIPTERA
The Diptera are commonly known as "True flies" and include many familiar insects such as mosquitoes, flies (black flies, fruit flies, blow flies, house flies etc.), midges (biting, non-biting), gnats (fungus, root), keds, bots etc.This diversity of names denotes the importance of the group and reflects the range of organisms in the order.Diptera exploit most of the available ecological niches in most of the biological roles, e.g., saprophages (many), commensals (some Scatopsidae, Chironomidae and Phoridae), predators (many), parasites (many), symbionts (some Chironomidae and algae) and scavengers.24 species under 23 genera of (08) families of Diptera were reported from the tea gardens of North Bengal (Table 5).Of them, the family Syrphidae shares maximum number of species (09), followed by Asilidae (04), Bombyllidae (02), Calliphoridae (02), Rhiniidae (02), Insect Fauna associated with the Tea Ecosystem of North Bengal, India Muscidae (02) and Sarcophagidae (02) and Tipulidae (01).Shah and Mitra (2015) reports Microstyllum pseudoanantakrishnanii Joseph and Parui as the predator of the moths from the tea gardens of North Bengal (**).Das et al. (2010) confirmed 54 species of predators of insect pests from tea gardens of northern West Bengal, of which a single dipteran species Ischiodon scutellaris (**) as a predator (maggot stage) of tea pest (Table 5).

Order COLEOPTERA
Coleoptera (beetles and weevils) is the largest order in the class Insecta.They feed on a wide variety of diets, inhabit all terrestrial and fresh-water environments, and exhibit a number of diferent life styles.Many species are herbivores, adapted to feed on the roots, stems, leaves, or reproductive structures of their host plants.Some species live on fungi, others burrow into plant tissues and some excavate tunnels in wood or under bark.Many beetles are predators.Some beetles are scavengers, feeding primarily on carrion, decaying wood or other dead organic matter.19 species under 16 genera belonging to 05 families of the order Coleoptera were reported from the tea gardens of North Bengal (Table 6).Of them, Scarabaeidae represent 09 Species followed by Cerambycidae (06 Species), Coccinellidae (02 Species), Lucanidae (01 species) and Curculionidae (01 species).Among the family Scarabaeidae, three species namely, Holotrichia sp., Anomala dimidiata and Xylotrupes gideon are reported as pests of tea (Roy et al., 2014).
Only two species of the family Cocinellidae, Micraspis discolor and Coccinella septempunctata are recorded during present study (Table 6).Micraspis discolor is the most abundant species of coccinellid in all the ecosystems.Roy et al., (2010) were observed twenty species of coccinellid predators in Sub-Himalayan tea plantation of North Bengal during 2004 to 2006.Of these, Micraspis discolor (**) was dominant (42.5%) in the conventionally managed tea plantations.The life cycle studies also suggested that the tea aphid was the preferred prey for Micraspis discolor, but the predator can survive on red spider mite also Roy et al., (2010).The abundance of adult M. discolor in rice at flowering phase does not correspond to prey abundance in the field but rather reflects an inclination to pollen feeding more than entomophagy (Shanker et al. 2013).C. septempunctata (**) has a broad ecological range.Both the adults and the larvae are voracious predators of aphids.The diversity of lady bird beetles in tea ecosystem may be due to the complex and stable ecosystem of tea plantations.
05 species (*) as pest and 02 species as predators (**) of the order Coleoptera were reported from the tea gardens of North Bengal (Table 6).

Order ODONATA
The Odonata is an important insect order which comprises of fascinating and harmless insects popularly known as dragonflies (Anisoptera) and damsel flies (Zygoptera).
Odonates are amphibiotic and diverse in nature.Many of these species inhabit wide variety of natural fresh water habitats, though there are some species which have adapted themselves to man-made water bodies.Being habitat specific and sensitive to habitat change their presence or absence indicates the quality of an ecosystem.They are considered as beneficial insects because their larvae (aquatic) and adults (terrestrial) are predators.Thus, assist in control of insect pest populations.12 species under 08 genera belonging to 02 families of the order Odonata were reported from diferent tea gardens of North Bengal.The family Libellulidae shared 09 species and the family Coenagrionidae shared 03 species.Das et al. (2010) observed that in sub Himalayan tea plantations of North Bengal, 4% of the predatory insects comprised of odonates.Present study documented Orthetrum sabina (Drury) (**) predates on the Hyposidra talaca (Walker) in the tea gardens of North Bengal (Table 7).

Order ORTHOPTERA
The insects under order Orthoptera are popularly known as grasshoppers, crickets etc.These insects inhabit many variety of habitats, like open grasslands, gardens, pastures, agro-fields, swamps and rain forests etc. Present communication reports 06 species under 06 genera belonging to 03 families of Orthoptera from the tea gardens of North Bengal (Table 8).Of them, Tettigonidae shares highest number of species (04) followed by Gryllidae and Pyrgomorphidae one species each.Nath et al., (2009) has been detected Atractomorpha crenulata (Fabricius, 1793) as possible pest of tea plant and other crops.Present communication reports only four orthopteran species (*) as pest of tea plant from North Bengal (Table 8).

Discussion
Tea is grown as a perennial monoculture crop over large contiguous areas in diferent parts of India.These tea gardens itself occupy a wide variety of functional niches and microhabitats.Insects, the most diverse component of tea gardens play a major role in the sustainable and healthy functioning of tea ecosystem.The tea estates of Assam and North Bengal are well known for the pest infestation since time immemorial.The tea garden owners/ researcher/ managers are only interested to high yields and control of the major pests.Therefore, there conventional tea cultivation has often accomplished high yields and stable crop production which need more use of chemical pesticides.These ultimately lead resistance, resurgence of pests and destruction of natural enemies.
In addition to this, there is very limited taxonomic knowledge on other group of insects who are also part and parcel of this tea ecosystem.In fact, there number is more and playing vital role in maintaining ecosystem healthy and sustainable.Keeping this in view, the present study was conducted in 74 tea gardens to identify the tea plant associated insects and their functional role in tea garden ecosystem.(1979) reported that such characteristics are typical floral syndromes among insect pollinated plant species.In their study, Bezbaruah (1975), Wickramaratne and Vitarana (1985) showed that, general pollinators, mainly dipterans contribute to pollination success in tea.A study on Camelia sinensis from Sri Lanka by Wickramaratne and Vitarana (1985) reveals that dipteran flies were numerous (60-90 % of total insects) and the efficient pollinators of tea whereas bees only visit seasonally and in very few numbers.Mitra et al., (2017) are also discussed about their pollination ability on tea plants in North Bengal.Present study recorded 24 species of 8 families from the tea gardens of North Bengal (Table 5).Of them, the syrphids, bombyllids, calliphorids and muscids are potetial pollinators of many crop plants (Table 9).Beside their role as pollination, dipterans are also act as biological control agents.Robber flies (Diptera: Asilidae) are the natural predators to several insect pest for diferent agricultural crops or plants.Various work reveals robber fly as the predators of spider (Dennis et al., 2012) and insects like Hymenoptera (Dennis and Lavigne, 2007), Lepidoptera, (Dennis et al., 2012), Coleoptera, (Shelly and Pearson, 1978), Orthoptera, (Joern and Rudd, 1982) and Hemiptera (Dennis et al., 2010) Apart from this, few coprophagous species (Catharsius molossus, Catharsius sagax and Onitis subopacus) are also recorded during this survey (Table 9).These beetles are dung feeders which feed on the dungs and excreta of the animals.Thus it helps in breaking down of plant and animal remains that contribute to the recycling of nutrients and the cleaning of the environment.The next dominant group of beetles in the tea ecosystems of North Bengal are Longhorn beetles or round-headed borers (Family Cerambycidae).Wood boring is carried out by various groups of insects either to obtain food or as means of protection of their eggs, larvae and pupae.Among the wood boring insects, the members of the family Cerambycidae are the most notorious pests of the freshly felled logs or dying standing trees.They mostly damage the shade trees of tea gardens and may also attack the tea plants.Majority of the cerambycid species are the borers of shade trees of tea gardens or other timber plants (Table 9).The members of the family Coccinellidae are mostly phytophagous but few species are also flower visitors and some are key predators that are conserved and augmented in agricultural ecosystems, to achieve biological control of pests.The other two families, Lucanidae are mostly rotten wood feeder and Curculionidae phytophagous (Table 9).Odonata are key organisms of the food web as predators both as larvae and as imagoes.They are among the dominant invertebrates predators in an ecosystem (Manwar NA et al., 2012).Present communication reports 12 species under 08 genera belonging to 02 families of the order Odonata from diferent tea gardens of North Bengal (Table 1).Worldwide orthopterans are considered of immense economic and ecological importance, because many species are accepted as pests of crops.Both nymphs and adults devour diferent kinds of vegetation, particularly succulent types.In ecology these insects provide food for the predators at all stages of life and some prey upon smaller invertebrates (Table 9).Eventually it can be concluded that long term monitoring of insects and their taxonomic study in tea ecosystem is very much essential to understand their biological role (Pest, predator, pollinator and parasite) in the tea gardens of North Bengal.During this study, it has been observed that, apart from regular pests of tea Insect Fauna associated with the Tea Ecosystem of North Bengal, India plants there are many insects visited tea gardens those are recognised pests of other plants/crops.In future they may play a major role on the economy of tea gardens.Therefore, this study will definitely help to the tea gardens owner for making a full proof plan to control the pest and parasite attack in one side and in the other side conservation of the beneficial insects (Predator and pollinator) of the tea gardens.
Bulganin Mitra, Suresh Kumar Shah and Purnendu Mishra Table1).Of them, 29 tea gardens are in the Jalapiguri, 26 tea gardens in Alipurduar, 18 in Darjeeling and single in Kochbihar district.Most of the tea gardens were visited once in a year but few gardens visited for more than one time (Table

Table 1 .
Details of visited Tea gardens of North Bengal

Table 2 .
List of Butterflies associated with tea plants of

Table 3 .
List of moths associated with tea plants of North

Table 4 .
List of hemipteran species associated with tea plants of North Bengal

Table 5 .
List of dipteran species associated with tea plants of North Bengal Bulganin Mitra, SureshKumar Shah and Purnendu Mishra

Table 6 .
List of coleopteran species associated with tea plants of North Bengal

Table 7 .
List of odonate species associated with tea plants of North Bengal

Table 8 .
List of orthopteran species associated with tea plants of North Bengal

Table 9 .
Ariyarathna et al., (2007) pollinators species of other plants reported from the tea ecosystem of North Bengal Amaranthus viridis L. Portula caoleracea L. Suresh Kumar Shah and Purnendu Mishra from the tea gardens of North Bengal.Of them, 14 species of hemipteran bugs are found as pests and 3 species as carnivore/predators of other crops (Table9).Ariyarathna et al., (2007)stated that, insufficient knowledge on breeding systems and floral biology is a major barrier in strategic planning of practical tea crop breeding programmes as well as in research on tea crop improvement.As observed, tea flowers being bisexual, bowl shaped, actinormorphic, with large number of stamens, are unspecialised and arranged solitarily or loosely clustered.Faegri and Pijl . In this communication, 3 species of robber flies, viz.Microstyllum brunnipenneMacquart, 1849, Cophinopoda chinensis (Fabricius, 1794)and Promachus duvaucelii (Macquart, 1838) are reported which are carnivores and predators (Table9).Among five families of the order Coleoptera from the tea gardens of North Bengal scarabs are the dominant group found during this study.Adults of this beetle generally feed on dung, carrion, fungi, vegetation, pollen, fruits, compost or roots.Unfortunately knowledge on the Indian scarab beetles is still poor.Only need of the hour is to utilize this potential boioresource in the interest of human society.The scarabs reported during this study are mainly phytophagous species (Brahmina sp., Holotrichia sp., Xylotrupes gideon, Anomala dimidiata, Anomala grandis).