The status of Elateridae (Coleoptera) in India

Beetles are a group of insects that form the order Coleoptera, in the superorder Endopterygota. It is estimated that a quarter of all described species in the world belongs to this order. The family Elateridae or click beetles is the ninth - largest family under this order. Wireworms are the larval stage of this family and they play a role in the ecosystem as they are omnivorous and act as pests. There are over 800 species of elaterids recorded from the Indian Subcontinent under eight subfamilies. India is rich in floral and faunal diversity and insect diversity in particular constitute about 6% of all identified insects in the world with a large number being endemic species. But in contrast to its extreme species richness, there is comparatively very little knowledge about this family of beetles when compared to other families. And as such, there is still a lot of potential to study its ecology and diversity. It is also because of this same reason that review of the status of the elaterid family is being done as a prequel to the actual field study


Introduction
Beetles belong to the order Coleoptera, the largest order of insects and has an estimated 3,50,000 species that are classified into 4 sub orders and 177 families. 1 The distinguishing feature of beetles is the modified forewings into hardened protective cover called 'elytra' while the hindwings are entirely membranous and folded and hidden beneath the elytra and they have adapted to almost all types of habitats, from aquatic to soil, trees, foliage, and are present in almost all types of ecosystems with the exclusion of the Polar Regions. They can range in size from 1 mm to approximately 75 mm in length. 2 In India alone, more than 15,500 species of beetles have been recorded. 3 Under the order Coleoptera, there are around 176 extant families and 32 fossil families. 4 altitude of more than 3000m. 6,7 The adult stage of this family comprises of both nocturnal and diurnal species. During the day, they can be found hidden under the bark and in rotting wood, stones and crevices, etc. and can also be occasionally found resting on foliage and flowers. At night they are attracted to yellow, black and white light. In terms of feeding habits, adult beetles may be nectarivorous, pollen feeders or phytophagous. The larvae of these beetles are commonly known as "wire worms" and are mostly mycetophagous, phytophagous, saproxylic, rhizophagous and even predatory in some species. 8-12 The larvae are found in soil, moss, leaf litter and in rotting wood. Rhizophagous species are major pests of economically important crops like sugarcane, groundnut, potato, maize, and tobacco. 13

Early Taxonomic Studies
The first record of Elateridae was given by Linnaeus 14 in 1758 and all the then known elaterids were put under one genus Elater Linnaeus. The first elaterid species described from India is Calais speciosus Linnaeus, 1767 and was reported as Elater speciosus Linn. 15 Lanelater fuscipes Fabricius was described by Fabricius in 1775 16 from South India, and the same author also gave description for Elater luridus 17 and Elater tomentosus 18 (now both under Lanelater) in 1798 and 1891 respectively.
In 1806, Herbst 19 provided a description for the species Elater muticus. In 1840, Lacon mustellinus Fabricius was described by Germer 20 , and Kollar 21 , in 1844, described a new species Lacon brachychaetus from Kashmir. Candeze, 22-31 a Belgian entomologist, also contributed a lot towards the study of this family in India and in between 1857 to 1900, recorded over 50 species from different parts of India. Westwood 32 described two click beetles from North-East India. In 1858, Russian enotomologist Motschulsky 33 described a new species Trachylacon lobicollis (now under Adelocera) from India. Schwarz in 1902 34 and 1905 35 described Lacon oberndorferi and Pericus oberndorferi, and Lacon niger and Allotypus duchoni from South India with specimens collected from Madras and catalogued and described few species from North-East India. [36][37][38] Fowler 39 in "Fauna of British India" provided brief reports of elaterids without providing keys to the family. Fleutiaux 40 provided a revised description on a number of elaterid species from Indo-Burma region. One of the series of works by Stibick, 41 dedicated to Indian species provided a revision of 12 species under 2 genera from different parts of India.

Recent Taxonomic Studies
The more recent works on Elateridae in India include the works by  and his co-workers, who carried out surveys in the North Indian states including Haryana, Himachal Pradesh, Punjab, Rajasthan, Uttarakhand and some parts of Jammu & Kashmir. They reported and described around 168 species of elaterids under 37 genera, and among these, 139 species were reported as new species and among these 57 species belonging to Agrypninae. Garg et al. [49][50][51][52][53] reported several new species of elaterids and has also added to the elaterid fauna of North India and also worked on revised keys for a number of genus of this family.
Schimmel 54 73 There has not been any other survey work for Elateridae from the other North-East states, nor is there any IUCN status on any elaterid beetles for India.

Conclusion
Although being one of the largest families of beetles, the elaterids are not studied as extensively as other families and because of this, very little is known about their ecology and life cycle when compared with other families like Scarabaeidae and Cerambycidae. This may be due to its elusive nature or extreme morphological homogeneity. The complete and detailed life cycle is also known only for some economically important species like Cryptalaus spp. or Athous spp. whose status as pests gives them higher focus for research. The present knowledge about the faunal composition of elaterids within the Indian Subcontinent is represented by 835 species and 113 genera coming under 8 subfamilies. 74 There is still a lot to be learned about this family of elusive beetles, and especially in the northeast states of the Himalayan biodiversity hotspot region, there is believed to be more species which are yet to be discovered upon further investigations and adding to the present knowledge.