Ecological studies on mango leaf webber (Orthaga exvinacea Hamp.) in Andhra Pradesh as a basis for IPM.
Kannan M., Venugopala Rao
Author Affiliation: Department of Entomology, S.V. Agricultural College, Tirupati (A.P.), India.
International Journal of Agricultural Sciences 2 : 308-311
Abstract : The influence of ecological factors viz. biotic (host plant) and abiotic factors (weather parameters) on the abundance and population fluctuation of the leaf webber, O. exvinacea infesting mango cultivars Neelum, Bangalore, Baneghan, Rumani, Mulgoa, Neeleshan, Swarnajahangir and Cherukurasam was determined in a field experiment conducted in Andhra Pradesh, India. The peak incidence of the pest was observed during the first fortnight of November (19.4 webs/tree). However, a gradual increase was observed from the first fortnight of July (2.6 webs/tree) and declined during the second fortnight of January (3.2 webs/tree). Correlation studies showed a positive relationship between the incidence of the pest and minimum temperature, relative humidity and rainfall, and a negative relationship with maximum temperature. None of the varieties was free from infestation. The infestation ranged from 7.80 to 29.47 webs/tree, 5.82 to 22.55 leaves/web and 1.92 to 29.47 larvae/tree. Cultivar Neelum showed less infestation, while Bangalore showed the most severe infestation. The rest of the cultivars showed moderate infestation by the pest. Older mango trees (15 and above years old) were more susceptible (18.26, 348.75, 121.61 webs/tree, webbed leaves/tree and larva/tree, respectively) to leaf webber damage than young trees (0-5 years old).