Butterfly species diversity and their floral preferences in the Rupa wetland of Nepal

The diversity of butterflies is known to some extent in Nepal, but the study of their interactions with nectar plant sources and floral attributes is limited. This study was conducted along the periphery of Rupa Wetland, a Ramsar site, from February to November 2019 to assess butterfly species diversity and to identify the factors influencing their foraging choices at nectar plants. We assessed the number of butterfly species, their abundance, and their floral foraging behavior, from 28 linear transects (500 m long each) placed in a stratified and random manner throughout the study area. Five factors, i.e., category of plant, flower colour, corolla shape, corolla depth, and the proboscis length of butterfly species were taken into account to assess the nectar plant choices of butterfly families. Moreover, species diversity at the family level, and overall, were determined through several indices. When examining overall butterfly diversity and abundance, we recorded a total of 1,535 butterflies belonging to 138 species within six families. For our examination of butterfly-nectar plant observations, we recorded a total of 298 individuals belonging to 31 species of butterfly visiting a total of 28 nectar plant species. Among the recorded butterflies, Zemeros flegyas was found to be the most abundant (92 individuals), while only a single individual each of the species Troides helena, Gandaca herina and Belonois aurota were recorded. Of the 28 nectar host plant species, Biden pilosa was the most popular and was visited by 13 species of butterflies. Overall, total butterfly visitation was found to be significantly influenced by plant category (herbaceous preferred over woody), floral colour (yellow, white, and purple preferred over pink), and corolla shape (tubular preferred over non-tubular).  Moreover, there was a significant positive correlation (r = 0.466) between the proboscis length of butterflies and the corolla tube length of flowers (p<0.001).  

Methods
See section 2.2 and 2.3 in the manuscript

尼泊尔地区蝴蝶多样性的研究已取得一定进展，但有关蝴蝶与蜜源植物及其花部性状间互作关系的探究仍相对匮乏。本研究于2019年2月至11月期间，在拉姆萨尔（Ramsar）湿地名录站点鲁帕湿地（Rupa Wetland）周边开展，旨在评估蝴蝶物种多样性，并解析影响其在蜜源植物上取食选择的相关因子。研究人员采用分层随机布设的方式，在研究区域内设置28条长度为500米的直线样带，对蝴蝶物种数、种群丰度及其访花取食行为开展调查。本次研究纳入5类因子以解析蝴蝶类群的蜜源植物选择偏好，分别为植物类别、花色、花冠形状、花冠深度以及蝴蝶物种的喙长。同时，通过多项多样性指数对科级水平及整体的物种多样性进行测算。在整体蝴蝶多样性与种群丰度调查中，共记录到隶属于6科138种的1535只蝴蝶个体。针对蝴蝶-蜜源植物互作的观测显示，共记录到31种蝴蝶的298个个体，造访了总计28种蜜源植物。其中，展斑灰蝶（Zemeros flegyas）为优势类群，共计记录92只个体；而裳凤蝶（Troides helena）、大斑粉蝶（Gandaca herina）以及尖襟粉蝶（Belonois aurota）仅各记录到1只个体。在28种蜜源寄主植物中，狼把草（Biden pilosa）最受蝴蝶青睐，共有13种蝴蝶造访该植物。整体而言，蝴蝶总访花频次显著受以下因子影响：植物类别（草本植物相较于木本植物更受偏好）、花色（黄色、白色与紫色相较于粉色更受偏好）以及花冠形状（管状花冠相较于非管状花冠更受偏好）。此外，蝴蝶喙长与花的花冠管长度之间存在显著正相关关系（r=0.466，p<0.001）。方法详见论文第2.2与2.3节。