Behavioural strategies of some lycaenid butterflies in relation to nutrition of host and nectar plants

Abstract

Behaviours are resulted from the functional activities of butterflies in every stages of life cycle. They exhibit different behavioural activities for nutrition, reproduction, and defense. The behavioural activities of butterflies are associated with enormous numbers of plants. An attempt has been undertaken to study on “Behavioural strategies of some lycaenid butterflies in relation to nutrition of host and nectar plants” from January 2015 to December 2017. The field investigation has been carried out in Butterfly Research Park of Bhawal National Park, Gazipur; Madhupur National Park, Tangail; Satchori National Park and Rema-kalenga Wildlife Sanctuary of Habigonj. Several field studies also conducted in Botanical Garden, Bangladesh Agricultural University, Mymansingh; Krishibari Butterfly Park at Savar, Dhaka; and also in Botanical garden and Zoological garden of Curzon Hall, University of Dhaka. The behavioural activities of 25 lycaenid butterfly species were observed on related plants in experimental sites. 53 plant species was identified as the supporting factors for lycaenid activities. This study provided basic information of lycaenid butterflies and their activityrelated plants. A total of 6724 lycaenids have been recorded from four experimental forests to assess their relative abundance and population dynamics. The dominant species was Arhopala pseudocentaurus with 21.85% relative frequency and the least abundant species was Rathinda amor with 0.75% relative frequency. Butterfly Research Park showed the maximum number of butterfly individuals with a covariance of 40% followed by Madhupur National Park (37%), Rema-Kalenga Wildlife Sanctuary (13%), and Satchori National Park (10%). Lycaenid butterflies displayed highest abundance (13.19%) in December and lowest (5.38%) in October, though this phenomenon is altered in years among habitats. Temperature and relative humidity influences the presence of butterflies. Lycaenid butterflies demonstrated highest abundance (887) in 26.9°C temperature along with 64% relative humidity whereas least abundance (362) has been recorded at 31.7°C temperature with 77% relative humidity. Adult lycaenid butterflies display a surprising range of behaviours including mating, egglaying, basking, resting, puddling, and most common foraging behaviour. A total of 473 individuals under 20 lycaenid species were observed in foraging to exploit 20 plant species belong to 11 families. They visit 2,585 times on different examined flowers and engaged 85,052 seconds in foraging. Flowers of Chromolaena odorata and Ziziphus mauritiana has been foraged by highest (9) number of species whereas Catharanthus roseus and Mussaenda frondosa visited by only one species. The flowers of the family Asteraceae have been found most attractive to lycaenid butterflies. A total of 245 individuals belong to 16 lycaenid species spent 31,152 seconds in foraging for 1,373 times visit to flowers of familyvi Asteraceae. A significant relationship was also found (F = 74.03, R2 = 0.81; p-value = 0.23) between the flowering plants and the flower visit frequency of butterflies. Seven lycaenid butterflies (67 individuals) were considered to record nectar feeding activities from five selected plants (viz. Catharanthus roseus, Ixora coccinea, Pentas lanceolata, Mussaenda frondosa and Lantana camara). Lampides boeticus spent more time in nectar searching (16.86±11.08 seconds) and nectar feeding (33.71±16.68 seconds) whereas Tajuria cippus spent less time in nectar searching (8.50±4.79 seconds) and nectar feeding (17.25±10.64 seconds). The collected nectar volume per flower was measured as 1.85±0.35 µL, 0.92±0.88 µL, 2.24±0.91 µL, 2.92±0.59 µL, and 0.13±0.04 µL from the flowers of Catharanthus roseus, Pentas lanceolata, Ixora coccinea, Mussaenda frondosa, and Lanatana camara, respectively. Lycaenids usually visited nectaring flowers with corolla tube between 2.5 and 10 mm long because of their short probosces. The pollen grains of lycaenid related plants were collected, and their structural variations were studied. The mobility of the butterflies has been examined assessing the gene-flow activities to the related plants. In an experiment, butterflies visited 55 plants out of 60 plant species. The number of visits made by butterflies was 1-42 times/individuals per hours. They visited 15 to 46 plant species at a time with foraging time ranges 1-62 seconds. Because of the diverse and distance covering mobility butterflies are considered as diverse pollinators. A total of 172 individuals belonging to 16 lycaenid species have been observed 2748 times for 69,113 seconds in basking with different baking postures. Butterflies spent 20,429 (29.56%) seconds in basking with horizontal wing posture, and the frequencies were 819 (29.8%). The lycaenids used 22,110 (31.99%) seconds for basking in angled wing posture with 943 (34.32%) frequencies. Butterflies engaged 26,574 (38.45%) seconds for basking in closed sun posture with 986 (35.88%) basking frequencies. The basking time has been accelerating from 1-10 seconds time frame, and a prominent peak was made within 31-40 seconds time frame. After that basking time was decreasing along with frequencies. The highest frequencies of basking was recorded from 10-11 am and made a highly evident peak. Lycaenid basking is negatively correlated with temperature (r = 0.41) and relative humidity (r = 0.13). The basking is increased with decreasing temperature and relative humidity. 12 lycaenid species (107 individuals) were observed to puddle 138 times for the duration of 656 minutes on different substratum. The lycaenid spent maximum time (194 min) on moist ground while minimum (33 min) on mud. The highest number (31) of butterflies puddles on moist ground whereas lowest (7) on dung. Eight lycaenid species was observed in mating condition. Among them, maximum (26) number of Chilades lajus were found in mating while minimum (2 individuals) in Tarucusvii callinara. The highest (20) number of butterflies was found in mating during the month of March and lowest (4 individuals) in August and December. Maximum (34) lycaenid butterflies were recorded in mating condition from 11.00 am to 12.00 pm whereas minimum (6 individuals) were spotted in between 15.00 and 16.00 pm. The egg laying behaviour of lycaynid butterflies was also examined. 17 females of three lycaenid speices were considered to record data on egg laying activities. The egg laying duration of lycaenid females was noted from 0.5 to 2 seconds time range. The duration of egg laying or egg deposition done by Chilades lajus was between the time range of 0.01-0.50 seconds in maximum (13) eggs and that of the 1.01-1.50 seconds in minimum (4) eggs while Catochrysops strabo and Remelana jangala laid maximum (17 and 14) eggs within 0.51-1.00 seconds and minimum (5 and 4) eggs between 1.51 to 2 seconds, respectively. No Chilades lajus was spotted to lay eggs within 1.51-2.00 seconds. In a short duration of 1-2 seconds Chilades lajus and Catochrysops strabo laid maximum four eggs at one bout while Remelana jangala laid maximum five eggs at one bout. Females completed 2-3 egg laying bouts in short period. The butterflies were also spotted to deposit eggs on different part(s) of host plants. Biology of five lycaenid butterflies has been studied under laboratory condition and their interacting plants‟ phenology also observed in the study sites. Metamorphosis from egg to adult, or life cycle duration of examined species Chilades lajus, Chilades pandava, Catochrysops strabo, Remelana jangala and Rathinda amor required 21.43, 19.54, 23.09, 30.05 and 22.45 days, respectively. Larvae of Remelana jangala exclusively feed on flowers with unopened petals. Chilades lajus feed young tender leaves only while Chilades pandava feed on tender leaves and the undersurface of young/mature leaves leaving the upper epidermis intact. The larvae of Catochrysops strabo feed on young tender leaves, young buds, flowers, young pods and young seeds inside pods. And larvae of Rathinda amor feed on young tender leaves, young buds, and flowers. Larval food consumption, growth, and food utilization efficiencies were also calculated. Larval food materials of host plants have been analyzed. Proximate composition of macronutrients (viz. carbohydrates, protein, fat etc.) was sequestered from feeding parts of host plants (viz. Citrus aurantifolia, Cycas pectinata, Cajanus cajan and Ixora coccinea). Fourteen amino acids were also extracted from consumed materials of host plants. The plant nutritional elements played vital role in the development of immature stages. Lycaenid butterflies are strongly adapted to their respective host plants from the adult morphological behaviour to the larval nutrition, and completely depend upon them. Lycaenid butterfly displays a diverse array of life history strategies. An intricate relationship has been found between lycaenid activities and activity-related plants. This behavioural study offers a vibrant idea to test biotic-biotic interaction in an ecosystem.