Insect Pests Associated with Flower Crops Under South Gujarat Region with Specail Reference to Bionomics and Chemical Control of Chrysanthemum Aphids
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Date
2007-01
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DEPARTMENT OF AGRICULTURAL ENTOMOLOGY N. M . COLLEGE OF AGRICULTURE NAVSARI AGRICULTURAL UNIVERSITY
Abstract
The investigation on insect pests associated with five major flower
crops viz., chrysanthemum, gaillardia, gerbera, rose and spiderlily under South
Gujarat region with special reference to bionomics and chemical control of
chrysanthemum aphid was conducted at N. M. College of Agriculture .
University, Navsari during 2005 - 2006. The results revealed that incidence of
aphids were predominant in all the five major flower crops followed by thrips.
Whitefly occurred on chrysanthemum and gerbera. Among leaf feeders. leaf
miner caused considerable damage to chrysanthemum and gerbera leaves.
Whereas. foliage caterpillar caused negligible damage only to rose and
spiderlily. Bud borer caused severe damage to rose flowers. The study on population dynamics of chrysanthemum aphids carried
out during October 2005 to September 2006 revealed higher activity during 46th
STW (12 - 18 November) to 9th STW (26 February to 4th March) with peak
incidence of M sanborni in 2'td STW (8 - 14 January) while the activity
drastically reduced during pre monsoon period (22"" STW) to early monsoon
period (26th STW). Correlation and regression studies of chrysanthemum aphid
population with weather factors indicated that minimum temperature. average
temperature, morning relative humidity, evening relative humidity. average relative humidity, rainfall, rainy days and wind velocity had negative impact
while sunshine hours directly (positively) innuenced the population build up of
chrysanthemum aphids. The coccinellid predator Menochilus sexmaculatus had
highly significant positive correlation with M sanborni population indicating
total reliance of the later on aphids. Spatial distribution of chrysanthemum
aphids on the top, middle and bottom portions of the leaf indicated contagious
distribution on the basis of various statistical parameters viz., variance mean
ratio, Uyod's index of patchiness, mean crowding, Morista's indices and Chi -
square (i). The laboratory studies on biology revealed that Msanborni passed
through four instars. The total nymphal period and longevity of apterous adult female was 6.23 ± 1.04 days and 6.33 ± 2.67 days, respectively with total life
cycle of 12.33 ± 2.39 days. The adults were dark brick red in colour and average
length and breadth measured 1.99 ± 0.16 mm and 1.43 ± 0.22 mm. The
fecundity was 13 .0 ± 7.79 nymphs per female. In laboratory trial on efficacy of
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insecticides against M sanborni treatment of methyl - 0 - demeton (0.025 %)
gave rapid mortality (85 % at 24 hours of post application) of M sanborni.
Whereas, at 48 hours of post treatment all the chemical insecticides included in
experiment exhibited more than 90 per cent mortality. The order of
effectiveness of insecticides against M sanborni in descending order was
methyl- 0 - demeton (0.025%) > acetamaprid (0.004%) > c10thianidin (0.015%)
> imidacloprid (0.005%) > fipronil (0.005) > thiomethoxam (0.005%) >
azadirechtin (0.0003%). In the field test of similar insecticides. imidacloprid(0.005 %) was found most effective and it was followed by methyl - 0 -
demeton (0.025 %) and firronil (0.005 %). The next order of effectiveness of
the treatments was clothianidin (0.015 %), thiomethoxam (0.005) and
acetamaprid (0.004 %). Treatment of azadirechtin (0.0003 %) failed to check
the aphid popUlation.
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