International Journal of Horticulture, 2017,Vol.7, No.2, 7-19
16
Host consumption rate (HCR) = CI+ER
Approximate digestibility (AD) (%) = 100 (R-T)/R
Efficiency of conversion of ingested food (ECI) (%) = 100P/R
Efficiency of conversion of digested food (ECD) (%) = 100P/(R-T)
Host utilization efficiency (HUE) (%) = 100 R/(R+T)
Hatchability (%) = 100A/B
Effective rate of rearing (ERR) (%) = 100C/D
Adult emergence (AE) (%) = 100E/C
Accumulated survivability (AS) (%) = N
b
% XN
a
% / 100
Growth index (GI) = AE%/H
Where, P: dry weight gain of insect; Q: duration of experimental period; R: dry weight of food eaten; S: mean dry
weight of insect during time Q; T: dry weight of faeces produced; A: number of eggs hatched; B: number of eggs
laid by per female; N
a
: number of larvae in beginning of instar; N
b
: number of larvae in succeeding instar; C:
number of cocoons harvested; D: number of last instar larvae reached pupation; E: number of beetles emerged; H:
Duration of immature period.
3.6 Life table parameters
The construction of life table includes several parameters which were calculated with the formulae of Carey
(1993), Krebs (1994) and Price (1998). These parameters include probability of survival from birth to age x
(lx),proportion dying each age (dx), mortality (qx), survival rate (sx) per day per age class from egg to adult stages.
Using these parameters, the following statistics like, average population alive in each stage (Lx), life expectancy
(ex), exponential mortality or killing power (kx), total generation mortality (K), generation survival (GS), gross
reproductive rate (GRR), net reproductive rate (R
0
), mean generation time (T
c
), doubling time (DT), intrinsic rate
of population increase (
r
m
) and finite rate of population increase (λ) were also computed, using Carey’s
formulae(Carey, 1993).
3.7 Statistical analysis
All the data on food utilization indices and life table parameters of
E. vigintioctopunctata
of the three host leaves
along with their phytochemical regime were analyzed u s i n g one way ANOVA (Zar, 1999). All the statistical
analysis was performed using the statistical program SPSS v. 13.0 (SPSS, 2004).
Author’s contributions
NR designed the whole study including sample collection, chemical analysis, index calculation, data analysis and drafts the
manuscript with the help of institutional support.
Acknowledgments
The financial assistance provided by the University Grants Commission [F. No. PSW-025/13-14], New Delhi, Government of India is
gratefully acknowledged.
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