Bionomics, Population Dynamics and Management of Mite (Tetranychus urticae Koch.) on Marigold (Tagetes spp.)
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Date
2015-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
AGRICULTURAL ENTOMOLOGY DEPT., N.M. COLLEGE OF AGRICULTURE, NAVSARI AGRICULTURAL UNIVERSITY, NAVSARI
Abstract
An
investigation
was
carried
out
on
bionomics,
population
dynamics, and management of mite ( Tetranychus urticae Koch.) on
marigold (Tagetes
spp.) at Navsari Agricultural Universit y, Navsari,
Gujarat during 2014 -2015.
Studies on biology of T. urticae revealed that both the sexes passed
through five different stages. The average duration of incubation period
was
04.76
±
1.48
days.
Larva,
nymphochrysalis,
protonymph,
deutochrysalis, deutonymph, teleochrysalis and adult was 02.84 ± 0.80,
00.85 ± 0.36, 03.56 ± 1.19, 0.93 ± 0.31, 03.04 ± 0.84, 0.86 ± 0.16 and
09.88 ± 1.45 days, respectivel y for male , whereas it was 05.36 ± 1.11,
02.84 ± 1.50, 04.52 ± 1.11, 2.94 ± 0.81, 04.04 ± 0.93, 2.42 ± 0.87 and
18.44 ± 1.92 days, respectivel y for female. The total life period occupied
b y T. urticae varied from 18.00 to 27.60 days with an average of
21.96 ± 2.26 days in male and 29.50 to 44.50 days w ith an average of
37.59 ± 3.80 days for unmated female and 35.00 to 46.50 days with an
average of 40.55 ± 3.12 days for mated female . A short resting period was
known as quiescent. The newl y hatched larva was hexapodous while other
nymphal instars were oct opodous. Male as to female ratio was 1: 2.43.
Males were produced parthenogenitically while female were produced
bisexuall y. Morphology of all the stages, longevit y of adults and
reproductive potential of T. urticae were also studied.
The length of eggs, larva, protonymph, and deutonymph were
0.12 ± 0.01, 0.14 ± 0.01, 0.20 ± 0.02 and 0.29 ± 0.03 mm, respectivel y. The breadth
of eggs, larva, protonymph, and deutonymph was 0.12 ± 0.01, 0.09 ± 0.01, 0.12
± 0.01 and 0.14 ± 0.02 mm, respectivel y. The length and breadth was 0.42 ± 0.03
and 0.18 ± 0.01 for male and 0.47 ± 0.02 and 0.22 ± 0.02 for female, respectively.
Studies
on
population
dynamics
of
T.
urticae
revealed that
incidence of T. urticae was started from the first week of April and
increased graduall y to reach its peak during fourth week of Jul y
(17.8 mites/cm 2 leaf area). The lowest population recorded in 5 t h standard
week i.e. fifth week of January (0.4 mite/ cm 2 leaf area). There was a
highl y significant positive correlation bet ween population of T. urticae
with minimum temperature, morning relative humidit y, evening relative
humidit y and wind speed. The decreasing trends of bright sunshine hours
had shown increasing trends of mite population in marigold and showed
highl y significant negative association with T. urticae population. The
correlation study between mite population and maximum temperature
indicated non significant effect on mite population.
Description
Keywords
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