Population dynamics, damage potential of Tetranychus urticae Koch and its management in strawberry (Fragaria × ananassa Duch.)

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dc.contributor.advisorGulati, Rachna
dc.contributor.authorSumti Rani
dc.date.accessioned2021-07-28T04:13:30Z
dc.date.available2021-07-28T04:13:30Z
dc.date.issued2020-02
dc.description.abstractFor population dynamics studies on Tetranychus urticae on strawberry, maximum population was recorded in the last week of March (31.03.2018) with 7.50, 11.50 and 10.00 mites/leaf and fourth week of February with 11.00, 11.00, 8.80 mites/ leaf on ventral surface of tender, grown up and older leaves, respectively during first (January to May, 2018) and second (October, 2018 to May, 2019) season. Initially the population was more on margins; feeding caused small white patches on the margins which spread to near mid rib along with webbing. During first season crop, older leaves harboured 39 per cent mites followed by 31 and 30 per cent on the tender and grown up leaves of strawberry crop, respectively. However, during second season crop, occurrence of T. urticae was more on tender leaves (45 %) than on grown up (30 %) and older leaves (25 %). During second season of strawberry crop, significantly more number of T. urticae was recorded on tender leaves (21.68 mites/leaf) than on grown up (14.52 mites/leaf) and older leaves of the plants (11.85 mites/leaf). Under field conditions, T. urticae population increased to 4.10, 5.83 and 7.10 mites/leaf on 7th, 9th and 11th April, when the peak was attained, although the latter two values are statistically comparable. In present study, number of mites was statistically higher on ventral surface (1.90 mites/leaf) as compared to dorsal surface (0.67 mites/leaf) of strawberry leaves. During 2019, maximum temperature (r= -0.690), minimum temperature (r= -0.643) and sunshine hours (r= -0.580) showed significant negative correlation with T. urticae population whereas, morning relative humidity recorded significant positive correlation (r= 0.761) on strawberry crop. Rainfall and wind velocity did not play significant role in affecting the T. urticae population during the present investigation. Mite population showed a significant negative correlation with total chlorophyll (r= -0.98), chlorophyll ‘a’(r= -0.78), chlorophyll ‘b’ (r= -0.63), carotenoid (r = -0.62), total sugar (r= -0.42), reducing sugar (r= -0.87), protein (r= -0.81), nitrogen (-0.83), phosphorus (r=-0.62), potassium (r=-0.87) content, fruit length(r= -0.88), fruit width(r= -0.89), fruit weight (r= -0.92) and fruit number (r= -0.69). The fruits on uninfested crop was bigger, brighter and uniform in size, whereas fruits obtained from infested strawberry crop were deformed, showed stunted growth, discoloured and unmarketable. Statistically higher phenol (4.33 % dry weight) and proline (1.09 μg/ 100 mg fresh weight) content was recorded in T. urticae infested leaves than in uninfested leaves (3.01 % dry weight, 0.65 μg/ 100 mg fresh weight, respectively) showing significant positive correlation with mite number. In vitro bioassay by leaf disc method indicated significantly lower number of mites (4.21, 3.29 mites/leaf) on leaf disc sprayed with higher concentration (10%) than on leaf disc sprayed with lower concentration (0.50 %) (5.96, 4.83 mites/leaf) of aqueous and methanolic extracts of A. sativum straws, respectively. The LC50 value in methanol extract was 0.26 per cent while it was 1.03 per cent in aqueous extract against T. urticae. The extracts caused 39.64 to 100 and 50.63 to 97.32 per cent reduction in T. urticae population on dorsal and ventral surface, respectively under in vivo conditions on strawberry crop. In T. urticae adults, increase in esterase and GST level after 24h and 48h exposure of aqueous extract A. sativum was recorded.en_US
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810170943
dc.keywordsAllium sativum extracts, Population dynamics, Phytochemicals, Strawberry, Tetranychus urticaeen_US
dc.language.isoEnglishen_US
dc.pages65+xiien_US
dc.publisherCCSHAU, Hisaren_US
dc.subZoologyen_US
dc.themePopulation dynamics, Damage Potential of Tetranychus urticae Koch and its management in strawberry (Fragaria × ananassa Duch.)en_US
dc.these.typePh.Den_US
dc.titlePopulation dynamics, damage potential of Tetranychus urticae Koch and its management in strawberry (Fragaria × ananassa Duch.)en_US
dc.typeThesisen_US
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