“The tale of ‘pandavas’- Distribution of the seasonal forms of Chilades pandava and its relation with the life cycle parameters”
Mode of Presentation: Poster
Conference Name: Student Conference on Conservation Science(SCCS 2019)
Year: 2019
Area: Entomofauna
Authors: Archan Paul, Sarika Baidya, Souparno Roy, Namrata Das and Arjan Basu Roy
Abstract
Introduction: Chilades pandava, a lycaenid butterfly, uses Cycas revoluta as its primary host plant which supports the huge polyphenic population of this species. Being a garden variety, C. revoluta experiences extensive application of pesticide and insecticide, which ultimately hamper the population dynamics and thus may question the existence of polyphenic forms in wild. In this pilot study, the urban wild population of C. pandava was assessed and proportion of the Wet Season Form and Dry Season Form was determined in Eco-Tourism Park, Kolkata, India. Furthermore, using the wild population, sex-bias trait was checked against the seasonal forms. The occurrence of the polyphenic forms were related with life cycle parameters and analysed for any significant findings in different rearing conditions.
Methodology: Pollard Walk was conducted once a week through the pre-defined path in Eco-Tourism Park for 30 minutes prior to conducting the weekly Mark-Release-Recapture (MRR) technique in order to estimate the approximate population size. The date, time and weather conditions were noted during MRR, duration of which was fixed to 1 hour. Individuals of C. pandava were caught using Insect Sweeping Net and marked on the hind wings with a marker. The marked individuals were again released into the wild after recording their sex and form. Eggs of C. pandava were collected from Eco-Tourism Park and kept in polypropylene jar. The hatched larvae were transferred to insect rearing cages either inside a weather-controlled insectarium or in wild conditions. The cages were cleaned and provided with fresh leaves of C. revoluta after every 24 hours until pupation. The hatching date as well as the pupation date was noted for determining the larval and pupal durations.
Results: Proportion of WSF was highest in October, 2018 (0.9692) and then gradual decrease was seen in subsequent months, i.e. 0.7142 in November and 0.133 in December. After the break in the population of C. pandava due to extreme winter conditions in January, the second surge in population, which started late in February, recorded 3/4th of the population as WSF. The proportion of WSF further increased in March to 0.9247. Apart from the February to April wild population, all other distributions were normally distributed and no significant difference was found between the ratios of male and female for different forms. The DSFs emerging during Oct.-Dec. 2018 exhibited increased pupal duration (10 ± 0.977 days) than their WSF counterparts (6.93 ± 0.261 days) and difference was found to be significant (p<0.005). Interestingly, this trend was not observed during Feb.-Apr. 2019, where the difference between pupal duration of WSF (6.84 ± 0.016 days) and DSF (6.79 ± 0.144 days) was negligible.
