LIFE TABLE STUDIES OF Spodoptera litura (FABRICIUS) (LEPIDOPTERA: NOCTUIDAE) ON GROUNDNUT
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Date
2018-07-30
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UNIVERSITY OF AGRICULTURAL SCIENCES, RAICHUR
Abstract
Life table studies of Spodoptera litura (Fabricius) on groundnut cv. TMV-2 was
conducted under laboratory conditions at 26±1°C to study the different population growth
statistics from two generations and also field life tables were conducted to know the different
mortality factors. In the first generation, survival of different life stages was 3, 17 and 10 days,
respectively. Females contributed highest birth (mx=346.12) on 39th day. The mean length of
generation (Tc) was 38.86 days. The innate capacity (rm) and finite rate for increase in number
(λ) was 0.1738 and 1.19 females/female/day, respectively. Stable age distribution of various
stages viz., eggs, larvae, pupae and adult was 52.46, 45.71, 1.60 and 0.20 per cent, respectively.
In the second generation, survival of different life stages was 3, 19 and 10 days, respectively.
Females contributed highest birth (mx=338.13) on 41st day. The mean length of generation (Tc)
was 40.86 days. The innate capacity (rm) and finite rate for increase in number (λ) was 0.1615
and 1.17 females/female/day, respectively. Stable age distribution of various stages viz., eggs,
larvae, pupae and adult was 50.25, 48.14, 1.19 and 0.20 per cent, respectively. In field life-table
studies total of 83.02 per cent mortality of S. litura was recorded. The highest mortality was in
the larval stage (64.95%), followed by pupa (26.33%), egg (17.54%) and adult (10.30%). The
survivorship curve indicated type III curve. The major mortality factor in the larva was tachinids,
Sl NPV and braconids, but large proportion of the mortality was categorized as unknown factor.
Total of 15 mortality factors were identified in S. litura. Larval parasitoids (Cotesia sp.,
Chelonus sp. and tachinids), virus (NPV), malformed pupa, adult malformation and unknown
causes contributed to mortality factors.
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