Identity, biology and bionomics of the Common Mime Chilasa clytia Linnaeus (Lepidoptera: Papilionidae)

Acknowledgements: The study formed a part of the PhD work of the first author and the financial assistance received from the Kerala State Council for Science Technology and Environment is greatly acknowledged. The Genus Chilasa belonging to the tribe Papilionini was erected by Moore (1903) in his book entitled ‘Lepidoptera Indica’. Species belonging to this genus are mimics of the subfamily Danainae and hence, they are popularly known as mimes. The tribe Papilionini is classified into two genera Papilio and Chilasa based mainly on the pattern of oblique bands in the larva. The genus Chilasa comprises four groups, of which only two the agestor group and clytia group are found in the Indian region. Chilasa clytia, a tailless swallowtail butterfly, was first described by Linnaeus in Systema Naturae (1758). Talbot (1939) reported it from Kerala. Its form commixtus is a protected species under Schedule I of Indian Wildlife Protection Act (1972) (GOI). It occurs in two different forms clytia and dissimilis in Kerala. The form clytia mimics the Common Crow Euploea core Cramer, while the form dissimilis mimics the Blue Tiger Tirumala limniace Cramer. The larva develops mostly on Cinnamomum sp. and severe outbreaks have been reported on Cinnamon Cinnamomum zeylanicum and Chinese Cassia Cinnamomum cassia with the larvae voraciously feeding on the tender and partly mature leaves, leaving only the midrib and veins. Both seedlings and saplings are affected by the heavy incidence of this butterfly has been reported to adversely affect the plant growth (Anandaraj & Devasahayam 2004; Rajapakse et al. 2007). Identification of this species is based mainly on the descriptions given by Linnaeus (1758) and Talbot (1939). Considering its economic and ecological significance, a study was recently undertaken on the biology, ecology and taxonomy of this species and the results are presented here.

The Genus Chilasa belonging to the tribe Papilionini was erected by Moore (1903) in his book entitled 'Lepidoptera Indica'. Species belonging to this genus are mimics of the subfamily Danainae and hence, they are popularly known as mimes. The tribe Papilionini is classified into two genera Papilio and Chilasa based mainly on the pattern of oblique bands in the larva. The genus Chilasa comprises four groups, of which only two the agestor group and clytia group are found in the Indian region.
Chilasa clytia, a tailless swallowtail butterfly, was first described by Linnaeus in Systema Naturae (1758). Talbot (1939) reported it from Kerala. Its form commixtus is a protected species under Schedule I of Indian Wildlife Protection Act (1972) (GOI). It occurs in two different forms clytia and dissimilis in Kerala. The form clytia mimics the Common Crow Euploea core Cramer, while the form dissimilis mimics the Blue Tiger Tirumala limniace Cramer. The larva develops mostly on Cinnamomum sp. and severe outbreaks have been reported on Cinnamon Cinnamomum zeylanicum and Chinese Cassia Cinnamomum cassia with the larvae voraciously feeding on the tender and partly mature leaves, leaving only the midrib and veins. Both seedlings and saplings are affected by the heavy incidence of this butterfly has been reported to adversely affect the plant growth (Anandaraj & Devasahayam 2004;Rajapakse et al. 2007).
Identification of this species is based mainly on the descriptions given by Linnaeus (1758) and Talbot (1939). Considering its economic and ecological significance, a study was recently undertaken on the biology, ecology and taxonomy of this species and the results are presented here.

Materials and Methods
The sampling of butterflies was done by conducting a field survey in representative habitats in Kerala from 2010 to 2012. The areas covered included Nilambur

Chilasa clytia
Common Mime studies were made by making microscopic slide mounts of the genitalia. For preparing slide mounts of the external genitalia, the lower part of the abdomen (from the 7 th segment onwards) was removed using microneedles and treated with 10% KOH by gently boiling in a water bath. After appropriate maceration in KOH, the boiling was stopped and the material was thoroughly washed. The external genitalia were then extracted from the abdomen by gently tearing the inter-segmental membranes from and around the organ by using fine forceps and micro needles. After careful cleaning, the genitalia was stained with acid fuschin dissolved in acetic acid and transferred to carbol-xylol for clearing (Carbolic acid and xylol 2:3) and mounted in Canada balsam (Mathew & Menon 1985).
For studying its biology, eggs were collected from the field and reared in small glass jars, 16x10 cm in size, covered with a clean, dry cloth securely fastened with a rubber band. The containers were kept moist by placing a small piece of absorbent tissue holding as much water as will evaporate in 24 hours. All frass and excreta were removed daily and the larvae were provided with fresh leaves of the preferred host plant (Images 1,2). The duration of the larval instars was recorded based on observations of the moulted shells of the caterpillar's head that remains inside the container after moulting. The size of the caterpillar (length and breadth), mode of feeding, pupation and emergence were also recorded. On attaining the final instar, the container was provided with a dry twig placed diagonally within the container for giving anchorage to the developing pupa. Descriptions: Chilasa clytia Linnaeus is a blackbodied swallowtail butterfly with a wing span of 79.3 (±11.16) mm. It serves as an excellent example of a Batesian mimicry among the Indian butterflies. Adults of dissimilis form have slow and graceful flight resembling that of the distasteful Blue Tiger and the adults of clytia form resemble the Common Crow. They have the habit of puddling on wet grounds.

Results and Discussion
Adults: The form clytia (mimics the Common Crow Euploea core). It has a velvety black forewing and hindwings with white spots and patches present on both sides of both wings. On the underside of the hindwing a row of brownish-yellow conical or angular marginal spots are present.
Male genitalia: Uncus is short, narrow, tubular, ending bluntly. Socii absent. Gnathos relatively small, lobed. Tegumen elongate, with narrow arms. Vinculum elongate with narrow arms. Valvae symmetrical, conical, flap-shaped. Cucullus is pointed, costal margin almost straight, with short dense setae along the distal margin. Harpe flat with two lobes. Saccular margin is slightly wavy on sides and slightly curved in the middle into which fits the juxta. Saccus is low and U-shaped (Fig  1). Phallus medium sized, tubular, curved in the middle and moderately thickened and apically blunt.
Female genitalia: Ovipositor bean-shaped, sclerotised and fringed with thin hairs. Posterior apophysis is long and curved. Anterior apophysis is short and apically swollen. Ostium wide, W-'shaped, having lobular, leaflike lobes at the base. Ductus bursa is short. Corpus bursae large, swollen and basally narrowed. Signum is long and spindle-shaped (Fig. 3).
Adults: The form dissimilis (mimics the Blue Tiger Danaus limniace). It is velvety-black with extensive white streaks and spots on the upperside. Underside is similar to the upperside with slightly larger white markings, and on the hindwing there is a row of conspicuous yellow marginal spots. In both forms head, thorax and 1 2 abundant and common than the form dissimilis. Both forms were abundant during the monsoon and post monsoon seasons and they were least abundant during the summer season. The average sighting of the form clytia was 93 and that of the form dissimilis was 42 at Peechi during 2012, giving a ratio of 2:1. Therefore, it is presumed that the dissimilis form is relatively rarer compared to the form clytia. Both sexes feed on the flowers of a variety of plants including Lantana camara, Ixora sp. Clerodendrum capitatum, Cassia sp. Based on their sightings during surveys, their flight activity is maximum between 9:00-14:00 hr. During this study, it was observed that a sudden decline in number was attributed to parasitism of larval and pupal stages. The tachinid flies (Diptera: Tachinidae) showed a significant level of parasitism with the juvenile forms of C. clytia clytia.

Conclusions
On account of the occurrence of the different form which mimics Danainae butterflies, species identification of the Chilasa clytia L. is slightly confusing. An examination of the external genitalia revealed that both forms share close resemblance except for difference in the shape of valvae, harpe and phallus of male genitalia and the bursa copulatrix of the female genitalia. Direct or indirect effects of temperature have been observed in choice of oviposition sites, egglaying rates, larval development and survival rates, and range shifts and expansions (Davies et al. 2005). A thorough knowledge of the life history of each species is a prerequisite to frame a comprehensive conservation strategy. Information generated on the biology and ecology of the Chilasa clytia L. will be useful in order to develop appropriate conservation strategies.