Biology and Productivity-linked Parameters of Lac Insect on Pigeonpea and its Natural Enemies
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Date
2017
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MPUAT, Udaipur
Abstract
The investigations on biology and productivity-linked parameters of lac insect
on pigeonpea and its natural enemies were carried out in the lac insect gene bank cum
garden situated at Department of Entomology, Rajasthan College of Agriculture,
MPUAT, Udaipur during 2016 with an aim to study the biological parameters viz.,
duration of pre-sexual stages (days), duration of male emergence (days), sex ratio (per
cent male insect) and life period of female lac insect (days) on pigeonpea, to evaluate
the productivity-linked parameters viz., initial and final density of settlement (crawlers
per sq.cm), initial mortality (%), density at crop maturity (number of female cells per
sq.cm), fecundity (larvae per female cell), weight of female cell and resin (mg) and
yield (g) of lac insect and to record the natural enemies (parasitoids and predators) of
lac insect.
The mean duration of pre-sexual stages lasts 48.36 days from the inoculation
of broodlac with 11.50 days mean duration of male emergence and 11.33, 7.33, 4.02;
17.75, 10.63, 6.23 and 17.75, 11.73, 11.56 per cent male in lower, middle and upper
portion of plant in three set of experiment respectively. The total life period of
Rangeeni strain of lac insect in Katki crop season on pigeonpea recorded 117 days.
The initial density of settlement of first instar crawlers on a plant varied in
different parts of plant which ranged from 20-121 crawlers per sq.cm and with a mean
initial density of settlement of 92.60, 84.10, 60.00; 86.70, 91.60, 71.00 and 67.40,
64.70, 61.00 crawlers per sq.cm at lower, middle and upper parts of plants in three set
of experiment respectively and the per cent mortality ranged from 6.46-12.58 per
cent. The mean final density of settlement first instar crawlers ranged from 17-114
crawlers per sq.cm with mean of 85.50, 78.20, 53.10; 80.20, 85.90, 65.00 and 61.90,
57.30, 54.60 crawlers sq.cm on lower, middle and upper portion of plant in three set
of experiment respectively. The density of female cells during maturity ranged from
01-11 cells per sq.cm and the fecundity recorded for single female cell was 95-430
larvae per cell. The cell and resin weight ranged from 6-24 mg per cell, 4-19 mg per
cell, respectively while mean sticklac and scrappedlac yield recorded were 235g per
plant, 15.63 g per plant respectively.
The three species of hymenopteran parasitoids viz., Erencyrtus dewitzi Mahd,
Tachardiaephagus tachardiae Howard and Aprostocetus (Tetrastichus) purpureus
Cameron contributed 97.77 per cent to the total natural enemies population whereas
two species of lepidopteran and one species of coleopteran predators viz., Eublemma
amabilis, Pseudohypatopa (Holcocera) pulverea Meyr and Oryzaephilus spp
contributed 0.70, 0.28 and 1.26 per cent to the total natural enemies population
respectively.
Description
Biology and Productivity-linked Parameters of Lac Insect on Pigeonpea and its Natural Enemies
Keywords
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Citation
Kalal and Swami, 2017