Open Access E-Repository @ Indian Institute of Horticultural Research >
Theses and Dissertations >
DIVISION OF ENTOMOLOGY & NEMATOLOGY >
Please use this identifier to cite or link to this item:
|Title: ||Species complex, biology and management of thrips on grapes, cv. Bangalore Blue|
|Authors: ||R, Harish|
|Guide/Chairperson: ||Abraham Verghese|
|Keywords: ||Species complex|
|Issue Date: ||2002|
|Year of Submission: ||2002|
|Abstract: ||The investigations on the thrips species complex, biology & seasonal incidence of S.
dorsalis in relation to weather climate parameters; extent of damage and management
chemical control of S. dorsalis were made from 2001-2002 for two seasons one being
carried out(winter and summer) in the field and laboratory during 2000-01. During survey
in South India five species of thrips belonging to three different families were recorded.
Of these, four are new records for India. This study has revealed two families viz.,
Aeolothripidae and Phlaeothripidae as having new records of species that are associated
with S. dorsalis. This is a significant addition to the known species complex of thrips in
Karnataka and India. No inter vine variation was observed in the thrips distribution.
However, the density of thrips differed between the different crop stages. The larvae and
adults of S. dorsalis caused damage to all stages of the crop. The insect pierced the
leaves, petioles and berries and sucked the sap resulting in silvery white scorch patches
on the leaves and scars on berries, Under severe infestations, the leaves withered and
ultimately fell down. Further, scarring and cracks on fruit surface was exhibited. The
affected mature berries turn ugly and severely affected bunches are unfit for marketing.
Phenology of the crop played a significant role in determining the level of thrips
infestation. The density of S. dorsalis and other species of thrips reached the peak level
(12.92 and 0.74 during winter) at 30-40 days after pruning, when the crop was in tender
leaf stage and flowering initiated. Similarly, in summer, peak populations of S. dorsalis
(16/49) and other species of thrips(0.80) coincided with tender leaf and flowering stage.
As far as the effect of crop phenology on thrips density, tender leaves were found to have
positive effect. Fully matured leaves, small, medium and large size fruits were found to
have negative effect. The female laid eggs singly in the tissues mostly on the tender pods,
occasionally in older pods. The egg was kidney or oval shaped and glossy white in
colour. On an average it took 14.35 + 3.18 days to complete the life cycle. On an average
each stage viz., egg, first, second instar larva, prepupa and pupa lasted for 3.97 + 1.58 +
0.42 days, 2.92 + 0.55 days, 1.03 + 0.28 days and 3.88 + 0.46 days, respectively. The
oviposition started after a period of 1.5 + 0.48 days and lasted for 1.89 + 0.65 days.
Female laid on an average 2.1 + 0.94 eggs per day and lived for 4.48 + 1.03 days. The incidence of S. dorsalis prevailed throughout the cropping period, except during the late
fruiting stage. The pest number attai9ned a peak during the first week of November(12.92
S. dorsalis/shoot) and third week of May(16.48 S. dorsalis/shoot) in winter and summer
season, respectively. Regarding the effect of weather parameters on S. dorsalis
infestation, temperature (both maximum and minimum) was found to have positive effect.
Relative humidity, rainfall and wind speed were found to have negative effect. The per
cent damage due to attack of S. dorsalis on Bangalore Blue grapes was 5.67 and 33.18
during winter and summer, respectively. The efficacy of synthetic, contact and botanical
insecticides viz., acephate 75% SP @ 0.075% verticel 100 SP 0.2% endosulfan 35 EC @
0.07%. chlorphriphos 20EC @ 0.05% carbaryl 50% WDP, cartap hydrochloride 5% SP,
fipronil 5% SC, fish oil rosin soap, azadirachtin 0.03 EC, endosulafan + azadirachtin and
soil raking were evaluated against S. dorsalis on grapes in the form of two folia
applications at 10 days interval. Of these endosulfan followed by cartap hydrochloride
and carbaryl proved effective in the control of S. dorsalis during both the seasons.
Whereas, fipronil, endosulfan+ azadirachtin and acephate had moderate effect, verticel
and soil raking were less effective in controlling S. dorsalis.|
|University in which they received their degree: ||University of Agricultural Sciences, Bangalore|
|Degree Level: ||M.Sc|
|Appears in Collections:||DIVISION OF ENTOMOLOGY & NEMATOLOGY|
Items in E-Repository@IIHR are protected by copyright, with all rights reserved, unless otherwise indicated.