Vol. 12, Issue 6 (2023)

Author(s):
Jharna Chaturvedani and Jayalaxmi Ganguli

Abstract:
Studies on the biology and biometrics of Earias vittella Fabr. were conducted in the Biocontrol laboratory, department of Entomology, IGKV, Raipur, Chhattisgarh, during September to November, 2022. Results depicted that the females of E. vittella laid spherical, bluish green coloured eggs usually singly and in small groups of 4 to 5. The mean incubation period and hatching percentage was 3.2 ± 0.46 days and 76.82 ± 2.35% respectively. The larvae passed through five instars. Boat shaped cocoons were formed for pupation and pupae were light brown to dark in colour and later turned to grey to greenish grey. Newly emerged adults were soft bodied, pale white with green longitudinal wedged shaped band in the middle of forewing whereas hind wings were pale white. Males were smaller in size than females. The last abdominal segment of male was roundish, while in female it was pointed with a tuft of hair. Duration of 1^st, 2^nd, 3^rd, 4^th and 5^th instars were completed in (2.4 ± 0.22, 2.4 ± 0.22, 2.4 ± 0.22, 2.4 ± 0.22 and 3.40 ± 0.22 days), respectively and the mean total larval period was 13 ± 1.02 days. The average duration of pre-pupal and pupal periods were of 3.2 ± 0.45 and7.2 ± 0.53 days. The mean sex ratio (male: female), pre-oviposition period, oviposition period, post-oviposition period and fecundity recorded were 1:1.12 ± 0.24, 1.4 ± 0.22 days, 6.4 ± 0.51 days, 3.8 ± 0.77 days and 375.4 ± 33.79 eggs, respectively while average male and female longevity was 6.6 ± 0.46 and 8.2 ± 0.47 days, respectively. The average life span for male and female were completed in 32.6 ± 2.34 and 32.0 ± 3.06 days, respectively. Biometrics studies of E. vittella revealed that the mean width of eggs were 0.63 ± 0.22 mm. The mean length and width of 1^st, 2^nd, 3^rd, 4^th and 5^th instar larvae were (1.65 ± 0.59 and 0.27 ± 0.1) mm, (2.30 ± 0.81 and 0.34 ± 0.14 mm), (6.13 ± 2.13 and 1.10 ± 0.37 mm), (12.36 ± 4.28 and 2.07 ± 0.72 mm) and (4.99 ± 5.26 and 3.11 ± 1.09 mm), respectively. The mean width of head capsule of 1^st, 2^nd, 3^rd, 4^th and 5^th instar were 0.27 ± 0.06, 0.49 ± 0.17, 0.79 ± 0.26, 1.25 ± 0.42 and 2.10 ± 0.70 mm, respectively. The mean length and width of pupa were 9.95 ± 3.53 and 2.98 ± 1.03 mm. The mean length and width of adult male were 9.17 ± 3.18 and 20.93 ± 7.36 mm and adult female were 11.47 ± 4.06, and 17.92 ± 5.40 mm.