Moths (Insecta: Lepidoptera) of Delhi, India: An illustrated checklist based on museum specimens and surveys

Abstract Background There have been several recent checklists, books and publications about Indian moths; however, much of this work has focused on biodiversity hotspots such as North-east India, Western Ghats and Western Himalayas. There is a lack of published literature on urban centres in India, despite the increased need to monitor insects at sites with high levels of human disturbance. In this study, we examine the moths of Delhi, the national capital region of India, one of the fastest growing mega-metropolitan cities. We present a comprehensive checklist of 338 moths species using 8 years of light trapping data (2012-2020) and examining about 2000 specimens from historical collections at the National Pusa Collection of ICAR-Indian Agricultural Research Institute, New Delhi (NPC-IARI) spanning over 100 years (1907-2020). The checklist comprises moths from 32 families spanning 14 superfamilies with Noctuoidea (48.5%) and Pyraloidea (20.4%) being the the two most dominant superfamilies. We provide links to images of live individuals and pinned specimens for all moths and provide detailed distribution records and an updated taxonomic treatment. New information This is the first comprehensive annotated checklist of the moths of Delhi. The present study adds 234 species to the biodiversity of moths from Delhi that were not reported previously, along with illustrations for 195 species.


Introduction
Lepidoptera Linnaeus, 1758 which includes butterflies and moths, is one of the largest insect orders consisting of 45 super families and having 157,424 species described (Van Nieukerken et al. 2011). It constitutes 10% of the total described species of living organisms (Mallet 2007). Of these, moths form roughly 85% of all known Lepidoptera, with over 12000 known species of moths from the Indian subcontinent (Chandra 2007). Moths are ecologically and economically significant as a primary food source for vertebrate insectivores, as pests of crop plants (Common 1990), pollinators (MacGregor et al. 2015), food for humans (Zagrobelny et al. 2009) and model organisms in scientific research (Roe and Just 2009). Nevertheless, the recent reports on insect decline are alarming and it is also evident in decline in moth diversity and abundance around the world (Hallmann et al. 2020). Numerous factors contribute to the decline of moths, such as rapid urbanisation, habitat loss, artificial light, intensive agriculture, pesticide pollution and lack of conservation policies (Dennis et al. 2019). These reports on global insect declines highlight the need for better conservation and management; however, they need to occur in tandem with ongoing monitoring and cataloguing of insects. Much of the work on Indian moth fauna was done pre-independence, including Hampson (1891), Hampson (1892), Hampson (1894), Hampson (1895), Hampson (1896), Fletcher (1920), Fletcher (1932), Fletcher (1933), Moore (1880), Moore (1882), Moore (1884), Bell and Scott (1937) and while they are extensive contributions to Indian moth fauna, these works are in need of a systematic update with additional modern surveys and current taxonomy. The more recent studies on moth fauna by Indian authors have been growing in number and include surveys, based checklists on the moth fauna of specific regions, viz. Mathew and Rahmathulla (1995)  There has been a tendencey to focus on studying regions of higher biodiversity, including the Western and Eastern Himalayas and the Western Ghats; however, there has been much less work done from regions with higher levels of human disturbance or metropolitian cities in India.
In this study, we focus on the moth fauna of Delhi, the National capital territory of India, one of the largest growing metropolitan centres in the world with an estimated population of 23 million (MPD 2021). Delhi, with a geographical coverage of 783 km , extends on the western bank of River Yamuna between 28º12' and 28º53' N latitude and 76º50' and 77º23' E longitude and is bound on the northeast by the Indo-Gangetic plain and on the southeast by the Thar Desert (Dakshini 1968). The prominent component of the natural vegetation is the Delhi Ridge forest which is an outcrop of the Aravali Hills, one of the oldest chains of hills in the world. Open scrub forest, classified under the Tropical Dry Thorn Forest type (Champion and Seth 1968), covers a large extent of the ridge. Such vegetation type is widely distributed in the arid and semi-arid zones of the Earth where the total annual rainfall ranges from 50-100 mm. Tree species commonly found in Delhi, in such vegetation include, Acacia leucoplachia, Prosopis cineraria, Ziziphus nummularia, Anogeissus pendula etc. ( Maheshwari 1953, Maheshwari 1963. Additionally, Prosopis juliflora, an exotic species introduced, as part of the afforestation drive, also dominates this thorny vegetation (Sinha 2014). Another prominent feature of the natural vegetation in Delhi is the Dichanthium-Cenchrus-Lasiurus grasslands (Dabadghao et al. 1973). The fertile alluvial plains of the State support agricultural crops which also influence the moth diversity of the region by favouring many heteroceran agricultural pests. Donahue (1966), in his study of Butterflies of Delhi, identified two distinct habitats in Delhi: the arid xerophytic Aravalli Ridge (Delhi Ridge) and mesophytic urban nursery area. Though the city is a highly urbanised landscape with a human population of about 16.75 million (as per 2011 census), it holds a forest cover of about 13.18% (Forest Survey of India 2019), one of the largest percentages of forest cover when compared to other Indian cities. This, along with factors like the presence of the Yamuna River and its nearness to the Himalayas, adds to factors that augment biodiversity of the area. Much of the rainfall in Delhi is received during the months of July to August during which the otherwise dry vegetation shows luxuriant growth and supports the insect diversity.
In general, the insect fauna of Delhi has received less attention with only very few groups like butterflies (Lepidoptera) (Biswas et al. 2017) and Odonata (Nazneen 2019) being well documented. The studies on moth fauna of Delhi were always insufficient, the State fauna series of Delhi, published by the Zoological Survey of India in the year 1997, included only 11 species of moths (Ghosh and Varshney 1997). Later, after two decades, Paul et al. (2016) added 36 species of moths to the biodiversity of Delhi which included mostly agricultural pests. The recent checklist of moths of Delhi consists of only 74 species (Paul et al. 2017, Paul 2021. There are limited studies in India that have utilised moth collections preserved in museums and none that have integrated this with primary survey data and secondary data from literature and citizen science projects. In the present work, we have studied the moth collections at National Pusa Collection, Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi (NPC-IARI) which is one of the four important Lepidoptera collections in India (Smetacek 2011). NPC houses over 0.4 million specimens, comprising 56000 specimens of Lepidoptera representing 3300 species. NPC has an illustrious history in agriculturally important insect pest collection. Famous lepidopterists such as T.B. Fletcher and Edward Meyrick, worked on these collections prior to India's independence. However, after independence, there are only a few experts on moths who could visit and work on these collections. In the current study, we studied all the moths that are collected from Delhi housed in NPC-IARI, including our own observations from 2012-2020 and data from different citizen science portals. An illustrated checklist of the 338 moths found in Delhi, along with up-to-date taxonomic treatment, are presented.

Museum specimens
In the present study, the biodiversity of moths of the region was studied by an exhaustive exploration of the museum holdings of the National Pusa Collection, Department of Entomology at ICAR-Indian Agricultural Research Institute, Delhi (NPC-IARI) which is one of the largest insect repositories in Asia for agricultural pests since the 1900s. The specimens of moths belonging to Delhi were sorted separately for the present study. A database has been created from individual specimens, based on label data including the name of the collector, date of collection, method of collection, associated host plants and sex. This includes more than 1500 specimens since 1907 up to 2020 which can be accessed at Moths of Delhi, India dataset. Furthermore, identification and reconfirmation of all the specimens was done and were updated to their current taxonomic positions. All the representative species were photographed with a Cannon 70D with a 100 mm macro lens. The micromoths were photographed with a digitalised camera Leica DFC 425C on the Leica 19205FA Stereozoom Automountage microscope.

Field surveys
Field surveys were conducted from 2012 to 2020 by setting up light traps at different locations, viz. the Indian Agricultural Research Institute (ICAR-IARI), Pusa (28.04°N, 77.12°E), Rashtrapathi Bhawan (28. 61°N, 77.19°E) and Asola Bhatti Wildlife Sanctuary (28.4762°N, 77.23°E). This accounted for a total of 73 survey nights. The light traps were set after sunset during the evening hours generally for 5 hours from 6 to 11 PM using a Mercury vapour bulb of 160 W. Most of the time, electrical mains were available for surveys, but a portable diesel-based generator was used to set the light traps at the locations without a source of electricity. All the moths were photographed in the field using a Cannon 70D with a 100 mm macro lens.
Along with the above museum collection data and surveys, additionally, data from citizen science internet portals, such as the Moths of India (http://www.mothsofindia.org/; Sondhi et al. 2021), iNaturalist (https://www.inaturalist.org) and India Biodiversity (http://indiabiodiversity.org/), were also used to prepare the checklist. For a few morphospecies, we could not identify up to species and we have mentioned only genera name and numbers.
Finally, a comprehensive checklist has been prepared by including all the data from museum specimens, field surveys, available literature and citizen science portals. The classification system used by Van Nieukerken et al. (2011) was followed. Systematic arrangement was made alphabetically, the checklist being presented below with notes mentioning previous reports. Additional data related to materials studied can be accessed here: http://ipt.pensoft.net/resource?r=moths_of_delhi&amp;v=1.8. Representative species photographs of museum specimens and also those captured in the field are arranged into plates alphabetically.
Notes: Present study; Fig. 4b a b c d e f  Notes: Present study; Fig. 5f a b c d e f   Fig. 6c a b c d e f    more moth species associated with agricultural and horticultural habitat (e.g. Helicoverpa armigera, Spodoptera litura etc.) likely due to extensive human-led landscaping in Delhi and also due to the greater survey effort in the IARI campus, which contains many agricultrual and horticultural research farms.
The paucity of baseline data, both in terms of abundance and diversity of moths, poses a significant hurdle in assessing the impact of various threats like land-use changes, rapid urbanisation, pollution, insecticides and global warming (Dennis et al. 2019) to insect diversity. According to a recent analysis (Sharma et al. 2020), unplanned urbanisation in Delhi that occurred between 1998 and 2018 led to Delhi's forest cover shrinking by half between 1998 and 2018, suggesting the need for development of conservation zones inside and adjacent to the capital, as well as increased interaction with urban citizens to create a better understanding of urban biodiversity. There are examples of the forested land converted into conserved sites, such as the Sanjay Van, Aravalli Biodiversity Parks and Asola Wildlife Sanctuary has assisted in sustaining the biodiversity to an appreciable extent. However, there have been no systematic studies on moth diversity till now in these locations and, given the rapid urban growth, more such sites are needed to prioritise the conservation efforts documenting available biodiversity and continuous monitoring is very important. We strongly recommend the setting up of a study site/sites for long term monitoring of insect populations and their diversity in the State of Delhi. The monitoring programme could be undertaken by public participation in biodiversity documentation involving citizens and it has been proven successful in certain nations (Miller-Rushing et al. 2012.
In conclusion, we believe that there will still be many more species that can be added to the present list as moths are sampled more extensively and studied more intensively using modern techniques, such as DNA barcoding. However, our study helps to establish the first comprehensive preliminary dataset on moths of the region, which can be a spring-board for future well-planned moth recording in Delhi. The areas for future investigation include concentrating on developing comprehensive species inventory, studying larval host associations and evaluation and prioritising moth species for conservation.
Wildlife Institute of India, Dehradun, Uttarakhand, India for helping us in GBIF data submission.

Author contributions
JK, SPR, SS, SM: Conducted fieldwork, compiled data, inspected specimens, manuscript writing. SPR: Conceived the project. NMM, YS and AS: Compiled data, verified records, assisted in writing the manuscript. SPR: Supervision. SPR and NMM: Funding acquisition.