Abstract: 【Aim】 The present study was designed to find out whether eco-climatic factors affect the morphometric parameters and basic biology of the progeny of the parthenium beetle, Zygogramma bicolorata adults inhabiting the Parthenium hysterophorus abundant regions of Nepal. 【Methods】 Z. bicolorata adults were collected from Kathmandu (24℃, 1 400 m above sea level, warm-temperate climate), Chitwan (25℃, 415 m above sea level, upper-tropical/sub-tropical climate) and Mahendranagar (34℃, 229 m above sea level, humid-subtropical climate) regions of Nepal, and the 4th instar larvae and adult females of the first generation (F₁) per eco-climatic zone were assessed for their feeding attributes under optimal laboratory conditions. We hypothesized that rearing the progeny under ad libitum food and optimal abiotic conditions would nullify the indirect effect of food and temperature; and regardless of the eco-climatic regions to which parents belong, the progeny would utilize the food uniformly. 【Results】 We found that despite being reared under optimal conditions, the progeny of Z. bicolorata displayed body size pattern and feeding attributes similar to their parents. Offspring obtained from larger parents (Kathmandu) were large, but had lower food utilization efficiency than the progeny from smaller parents (Chitwan and Mahendranagar). Irrespective of the three eco-climatic regions, developing female adults were heavier and had reduced food utilization efficiency than the larvae. 【Conclusion】 Present findings suggest that immediate effect of food and optimal abiotic conditions may not affect the phenotypic plasticity of Z. bicolorata progeny, and the progeny display body size pattern and feeding attributes similar to the parents. Possibly the heritable changes might be owing to genetic diversity within the species. We anticipate that such findings may be utilized to understand phenotypic plasticity, distribution pattern and feeding behaviour of Z. bicolorata adults under changing climate scenario.

Key words: Zygogramma bicolorata, Parthenium hysterophorus, phenotypic plasticity; biological control, feeding attributes, climate