Phenotypic variation in adults of Chilo partellus (Swinhoe) from diverse ecological regions of India

Abstract

Geographic distance and ecological conditions are important factors for phenological differentiation, and the adult morphological characters play significant role in several biological functions in insects. Present study showed significant intraspecific and intersex variation in colour pattern, number of spots and stripes on the forewings of Chilo partellus adults of different ecological populations. Females were comparatively light in colour with less black spots and stripes than the males across populations. Length and width of head, thorax and abdomen, wingspan, and various parts of male and female genitalia varied significantly across C. partellus populations. Abdomen, corpus bursae and papillae anales were significantly longer in females of Hisar as compared to other populations. However, the length of aedeagus was significantly longer in males of Coimbatore and Delhi as compared to other populations. Range of wingspan: body size and body size: genitalia ratios across C. partellus populations were wider in females than males. Wingspan: body size ratio was significantly lower in males of Raichur and females of Hisar and Parbhani as compared to other populations. Body size: genitalia ratio was significantly lower in males of Coimbatore and Hyderabad, and females of Coimbatore, Raichur and Surat as compared to other ecological populations. These findings suggest phenotypic plasticity in C. partellus having implications for phenotypic expression and greater fitness in response to changing climatic conditions.