Biology and Morphometry of Gram Pod Borer Helicoverpa armigera Hubner Infesting Gram Cicer arietinum L.

Abstract

Aims: To investigate the biology and morphometry of gram pod borer Helicoverpa armigera Hubner infesting gram Cicer arietinum L. Place and Duration of Study: The investigation was conducted in the PG Research Laboratory, Department of Entomology, Navsari Agricultural University, Navsari, Gujarat, India under laboratory conditions at 26.7±1.66°C temperature and 51.11±6.35 per cent relative humidity during 2021-22. Methodology: The Helicoverpa armigera was reared from eggs to the adult stage under laboratory conditions. Twenty-five samples of eggs, larval instars, pre-pupa, pupa, and adults were used for morphometrics measurement and fifty samples of each stage were used for determining the biological parameters. Results: The Helicoverpa armigera female laid eggs singly or in batches of 2 to 3 during nighttime. The incubation period was 2.84±0.58 days with 58.39±4.22 per cent hatching. The larvae passed through six different instars having durations, 2.54±0.50, 4.04±0.88, 4.04±0.88, 4.24±0.77, 4.50±0.51, and 4.92±0.80 days of first, second, third, fourth, fifth, and sixth instars, respectively. The mean larval, pre-pupal, pupal, pre-oviposition, oviposition, and post-oviposition periods were 23.12±1.83, 1.64±0.69, 13.40±1.25, 2.60±0.49, 6.94±0.82, and 1.62±0.49 days, respectively. The lengths of egg, first, second, third, fourth, fifth, and sixth instar larvae, prepupa, pupa, and male and female adults, were 0.49±0.05, 1.56±0.12, 4.27±0.38, 8.47±0.70, 13.50±0.95, 21.84±0.97, 32.58±0.99, 25.03±0.97, 19.95±0.96, 17.25±0.56, and 20.32±0.95mm, respectively. Whereas, the breadths were 0.50±0.04, 0.46±0.03, 0.72±0.04, 2.45±0.03, 2.72±0.07, 3.22±0.11, 4.12±0.16, 3.88±0.39, 5.26±0.31, 34.44±1.09, and 39.86±1.03mm, respectively. The lengths of head capsules of first, second, third, fourth, fifth, and sixth instar larvae were 0.23±0.01, 0.45±0.01, 0.63±0.02, 1.12±0.01, 2.19±0.02, and 2.61±0.04, respectively which was not studied before. Whereas, the breadths were 0.26±0.01, 0.50±0.01, 0.73±0.01, 1.28±0.01, 2.22±0.01, and 2.70±0.05, respectively. The sex ratio of male to female was 1:0.76±0.05. The fecundity of gravid females was 544.85±63.89 eggs/female. The adult longevity was 9.04±0.78 and 10.54±0.99 days in males and females, respectively. The total life span was recorded as 47.20±2.57 and 48.70±2.79 days in males and females, respectively Conclusion: The Helicoverpa armigera adults completed their life cycle in 43 to 56 days. The adult longevity was higher in females than males. The males were smaller than the females. The sex ratio was male-biased. The various biological parameters would be useful in the planning of integrated management strategy under field conditions.