Studies on the impact of temperature changes on the life-table parameters of Earias vittella Fabricius (Lepidoptera: Noctuidae) in Ranchi, Jharkhand.

Kanika Kumari^a & Anand Kumar Thakur^b*
^aDepartment of Zoology, J. J. College, Jhumri Telaiya, Koderma, Jharkhand, India
^bUniversity Department of Zoology, Ranchi University, Ranchi, Jharkhand, India
Received : 26^th December, 2022 ; Revised : 25^th January, 2023

Abstract– The spotted bollworm, Earias vitella (Fabricius, 1794) is one of the major agricultural pests with a wide range of hosts like sorghum, sunflower, cotton, okra, etc. The current study has been done on the okra host to observe the effect of different constant temperatures (15, 18, 20, 28 ± 1^oC with 70±5% RH) in laboratory conditions on the growth and reproduction of Earias vitella Fabricius using the age-stage, two-sex life table method. The results showed that Earias vitella could complete its entire life cycle on the okra hosts, in different constant temperatures with significantly different developmental and reproduction parameters. The result reveals that the durations of egg, larva, pupa, and adult development were significantly prolonged at lower temperatures whereas they became shorter at higher temperatures. The egg stage has the highest mortality in all temperatures. The incubation period at 15^oC is longer (14.08±0.07), while the shortest incubation observed at 28^oC (2.71± 0.06). The shortest larval period was calculated at 28^oC with 12.54± 0.4 whereas it becomes longest at 15^oC with 38.39± 0.41. The oviposition recorded more at 28^oC (310.21± 1.23) and lowest fecundity was observed at 20^oC (97.66± 0.75). No fecundity was observed at 15 and 18^oC. The intrinsic rate of increase and finite rate of increase were significantly different at both temperatures (20 and 28^oC). The Net reproductive rate and Gross reproductive rate are also significantly different. The mean generation time decreases as the temperature increases. The results indicate that Earias vitella can grow and reproduce normally at higher temperatures, but no reproduction is observed at lower temperatures. (15 and 18^oC). Nonetheless, the data show that this pest is harmful when the population density is high.

Key words: Earias vitella, Life table, Temperature, Okra, Spotted bollworm, Lepidoptera

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