Introduction

Recording data on the larval host plants of Lepidoptera is very crucial in order to understand their ecology, as well as significant for the formulation of conservation strategies. The diversity and distribution of Lepidoptera chiefly governed by the diversity and distribution of their larval host plants. Some of the major contributions to the documentation of larval host plants of Indian Lepidoptera are of Bell (1909, 1910, 1927), Wynter-Blyth (1957), Kunte (2000), Kalesh & Prakash (2007), Naik & Mustak (2015), Nitin et al. (2018) and Karmakar et al. (2018). In recent five years several authors have reported new larval host plants of Lepidoptera from different parts of the West Bengal (Dey, 2021; Payra, 2021; Mukherjee 2021, 2022; Banerjee et al. 2023). In the present communication, we report for the first time Vigna stipulacea (Lam). Kuntze as a larval host plant of Euchrysops cnejus (Fabricius, 1798) and Caesalpinia bonduc (L.) Roxb. as host plant of Rapala manea schistacea (Moore, 1879) from the coastal areas of Purba Medinipur district, West Bengal, India.

Results and discussions

E. cnejus is widely distributed from Indian Subcontinent to Myanmar, China, Thailand, Lao PDR, Cambodia, Vietnam, Taiwan, Japan, West Malaysia, Singapore to New Guinea, Northeastern Australia, Fiji and Samoa (Inayoshi, 2023). In India, it occurs throughout the country except in some parts of north Indian states (western Rajasthan, western Haryana and southern Punjab) and in some states of Northeast India (Arunachal Pradesh and Mizoram) (Varshney & Smetacek, 2015; Kehimkar, 2016; van Gasse, 2021). In the adjoining coastal areas of Purba Medinipur district, West Bengal the status of the Lycaenidae is “Common” (Payra et al. 2017).The larval stages of this Lycaenidae are known to feed mainly on the members of Fabaceae family (Robinson et al. 2010) and the previously recorded larval host plants of this species are Acacia caesia (L.) Willd., Butea monosperma (Lam.) Taub., Cajanus cajan (L.) Millsp., Canavalia ensiformis (L.) DC, Lablab purpureus (L.) Sweet, Ougeinia oojeinensis (Roxb.) Hochr., Paracalyx scariosus (Roxb.) Ali, Phaseolus, Pisum satvum L., Pueraria phaseoloides (Roxb.) Benth., Vigna cylindrica (L.) Skeels, Vigna radiata (L.) R. Wilczek, Vigna trilobata (L.) Verdc., and Vigna unguiculata (L.) Walp. (Wynter-Blyth, 1957; Kunte, 2000; Robinson et al. 2010; Nitin et al. 2018). On 09-VII-2020 a female of Euchrysops cnejus was observed laying eggs underneath the leaves of a Vigna plant near Kuliyata village (21º39’47.93”N, 87º34’11.44!E), Purba Medinipur, West Bengal (Figure 1. A-H). On the same day several caterpillars were also observed underneath the leaves, on stem, stipule, flowers and pods of the plant. Later on, during July-August 2020 several caterpillars were observed at the same place. A final instar caterpillar was collected from the field during August and reared. The Vigna plant was identified as V. stipulacea by the characteristics of angular stem, large stipule, raceme above foliage, compact inflorescence, purple keel, oblong shaped hilum, and which can easily be separated from its closely allied species V. trilobata. Aforementioned records show V. stipulacea was unreported as larval host plant of this Lycaenidae. Moreover, previous distribution records of this plant indicate, it has never been reported from West Bengal (Yadav et al. 2014, Bhattacharjee et al. 2019; Gore et al. 2019). Hence the present record from Purba Medinipur district represents new locality of this plant and resulting in 11^thVigna spp. of the state West Bengal. This study also reports V. stipulacea as the first larval host plant of an Indian Lepidoptera.

Figure 1.
A. Flowers of Vigna stipulacea (09-VII-2020). B. Egg of Euchrysops cnejus underneath the leaf (09- VII-2020). C. Caterpillar of E. cnejus underneath the leaf (09-VII-2020). D. Caterpillar of E. cnejus associated with Polyrhachis ants (16-VIII-2020). E. Caterpillar of E. cnejus associated with Tetramorium ants (16-VIII2020). F. Caterpillar of E. cnejus inside the pod (16-VIII-2020). G. Final instar caterpillar of E. cnejus on stipule (09-VII-2020). H.Euchrysops cnejus (09-VII-2020) (Photos: A Payra).

R. manea schistacea widely occurs in Oriental region, distributed from Indian subcontinent to Myanmar, southern China, Thailand, Lao PDR and Vietnam (Inayoshi, 2023). It occurs throughout India, except northern Arid region and Northeastern state Mizoram (Varshney & Smetacek, 2015; Kehimkar, 2016; van Gasse, 2021). This Lycaenidae stated as “Not Rare” in the adjoining coastal areas of Purba Medinipur district, West Bengal (Payra et al. 2017). Until now, the recorded larval host plants of R. manea schistacea are Mangifera indica L. and Spondias pinnata (L.f.) Kurz (Anacardiaceae); Combretum indicum (L.) DeFilipps (Combretaceae); Mallotus repandus (Willd.) Müll.Arg. (Euphorbiaceae); Acacia caesia (L.) Willd., Acacia megaladena Desv., Acacia pennata (L.) Willd. Calliandra heamatocephala Hassk. Mimosa diplotricha C. Wright ex Sauvalle, Saraca asoca (Roxb.) Willd., Senegalia torta (Roxb.) Maslin, Seigler & Ebinger and Senna tora (L.) Roxb. (Fabaceae); Clerodendrum infortunatum L. (Lamiaceae); Syzygium sp. (Myrtaceae); Urena lobata L. (Malvaceae); Averrhoa bilimbi L. (Oxalidaceae); Antidesma acidum Retz. and Antidesma ghaesembilla Gaertn. (Phyllanthaceae); Ziziphus spp. (Rhamnaceae); Ixora sp. (Rubiaceae); Lepisanthes tetraphylla Radlk. and Litchi chinensis Sonn. (Sapindaceae); Camellia sinensis (L.) Kuntze (Theaceae); Lantana camara (Verbenaceae) (Wynter-Blyth, 1957; Kunte, 2000; Robinson et al. 2010; Bhakare & Ogale, 2018; Nitin et al. 2018; Naik & Mustak, 2020; Mukherjee 2021, 2022; Banerjee et al. 2023). On 22-VIII-2020, two females of R. manea schistacea were observed laying eggs on the inflorescence and leaves of C. bonduc near Shankarpur (21º38’47.17”N, 87º34’18.09”E), Purba Medinipur, West Bengal (Figure 2 AF). On the same day a caterpillar was also observed inside the inflorescence. Later on 26-X-2020, an individual was observed laying eggs on the inflorescence of C. bonduc, near Nilpur Village (21º39’1.50”N, 87º33’52.29”E). Although, the caterpillar was not reared, findings of caterpillar and egg laying observations suggest C. bonduc as a putative larval host plant of Rapla manea schistacea. C. bonduc already been reported as larval host plant of Nacaduba beroe gythion Fruhstorfer, 1916, Nacaduba kurava canaraica Toxopeus, 1927 (Lycaenidae). Charaxes bharata C. Felder & R. Felder, [1867] (Nymphalidae); Eurema blanda (Boisduval, 1836) (Pieridae) (Nitin et al. 2019, Payra, 2020).

Figure 2.
A.Rapala manea schistacea laying eggs on the inflorescence of C. bonduc (22-VIII-2020). B.R. manea schistacea laying eggs on the leaf (22-VIII-2020). C. Egg of R. manea schistacea (22-VIII-2020). D-E. Caterpillar of R. manea schistacea (22-VIII-2020). F. R.manea. schistacea laying eggs on the inflorescence (26-X-2020) (Photos: A Payra).

Acknowledgments

Authors would like to thank Dr. Pankaj Koparde and Dr. Anup Kale (Dr. Vishwanath Karad MIT World Peace University, Pune, Maharashtra, India) for their encouragement and support.

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Author notes

* Autor para la correspondencia / Corresponding author: arapayra@gmail.com