STUDIES ON SYRPHID PREDATORS OF SUGARCANE WOOLLY APHID (Ceratovacuna lanigera Zehntner)
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Date
2007-09-01
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University of Agricultural Sciences GKVK, Banglore
Abstract
The role played by syrphids in the management of Sugarcane Woolly
Aphid were studied under both laboratory and field conditions during 2005-
06 at Department of Agricultural Entomology, College of Agriculture,
Dharwad and at farmer's fields. The syrphid species associated with SWA
comprised of two species viz., Eupeodes con/rater and Dideopsis aegrota and
E. coiifrater was the major species occurring in all the locations (62.58 to
100%). Two groups of natural enemies on syrphids were identified, one larvalpupal
parasitioid belonging to family Ichneumonidae [Diplazon laetatorius)
and three species of bacterial pathog'iiis viz., Citrobactor sp., Aeromonas sp.
and Bacillus sp. The breeding of E. con/rater was not possible in caged
condition. The predator completed three larval instars with a total larval
period of 12.12+0.31 (10-14) days. Pupal period ranged from 7 to 9 days v/ith
a mean of 8.30+0.26 days. The longevity of male and female was recorded at
13.27+0.89 (10-20) days and 17.6+1.52 (10-22) days, respectively.
A single larva of E. confrater consumed 442.74 sugarcane woolly
aphids in its total larval period at a rate of 36.53 aphids/individual/day. The
instarwise consumption was 45.83, 133.52 and 263.39 aphids during first,
second and third instar, respectively. In the absence of food, Eupeodes late
instar larvae fed on eggs, early and late instars of Micromus and early instars
of Diphcu Intum, the late instar Dipha larvae consumed early instar Eupeodes
larvae. In the field study, molasses and fruit fly diet attractants recorded
comparatively more syrphid larval population (1.13 and 0.92 larvae/leaf) and
registered lower mean aphid grades. All the tested chemical insecticides viz.,
thiamethoxam, chlorpyriphos and malathion were found highly toxic to
syrphids. However, the safest treatment was vitex + neem + lantana which
recorded least reduction of syrphid population in treated plots (3.72 and
6,13%) as well as under laboratory condition (23.01% mortality).
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