Physicomorphic Response of Polyphagous Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) Towards Different Host Plants

How fitness of herbivore insects alters with different host plants in terms of their physicomorphic attributes has been the subject of great interest with point of their integrated pest management. Helicoverpa armigera (Noctuidae; Lepidoptera) -being highly polyphagous- is the pest of many crops and exhibits high fecundity and migrating efficiency. The present study aimed to evaluate its physicomorphic responses towards different host plants. The highest larval and pupal weights were observed when fed on gram, Cicer arietinum (L.). The maximum (97.23%) larval survivorship was recorded on gram while, the lowest (56.25%) on okra, Abelmoschus esculentus (L.). The consumption index (CI) was also observed to be the highest (1.49 %) in gram and the lowest (0.95 %) in tomato, Lycopersicon esculentum (L.) The sizes of fore and hind wings, head, femur and tibia were the maximum in the individuals fed on gram. Furthermore, physiological parameters of the adults were also significantly better when larvae were fed on gram. The relative growth rate (RGR) and relative consumption rate (RCR) values were the maximum (2.09 mg/mg/day and 10.14 mg/mg/day, respectively) in individuals fed on gram. Therefore, the efficiency of conversion of ingested food (ECI) was the highest (70.65%) in gram feeding as compared to other host plants. The areas of fore and hind wings (0.98 cm(2) and 0.79 cm(2)) and hind tibia length (0.82 cm) were also greater in the adults fed on gram. Among natural host plants, gram was proved to be the highly nutritious food plant facilitating both the development and the survival effectiveness of this pest. Therefore, it is recommended to carefully include gram in a cropping scheme especially where H. armigera is a regular pest whilst future studies should focus on demographic and nutritional parameters of this pest as affected by different host plants.