SEASONAL INCIDENCE, BIOLOGY AND MANAGEMENT OF MANGO LEAF WEBBER, Orthaga exvinacea HAMPSON (PYRALIDAE: LEPIDOPTERA)
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Date
2019-10
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University of Horticultural Sciences, Bagalkot
Abstract
The studies on seasonal incidence and biology of mango leaf webber under laboratory condition were conducted at the Department of Entomology, College of Horticulture, Bagalkot during 2018-19 and the field experiment to evaluate the efficacy of new insecticide molecules against mango leaf webber was conducted at Regional Horticultural Research and Extension Centre (RHREC), Kumbapur farm, Dharwad during 2018-19.
The most active period of flower webber complex was observed from flowering initiation to fruit set and the incidence of mango leaf webber was from 1st fortnight of July to 2nd fortnight of February with its peak incidence during 1st fortnight of November. The weather parameters played important role in the incidence of mango webber complex and results of correlation analysis revealed that, the weather factors had contributed in varying the infestation level of all nine species (4 major species and 5 minor species) of mango flower webbers and mango leaf webber (Orthaga exvinacea Hampson). In case of mango leaf webber negative significant correlation was observed with maximum and minimum temperature and wind speed, but showed the positive significant relation with minimum relative humidity.
The studies on biology of mango leaf webber revealed that the mean preoviposition, oviposition and postoviposition periods lasted for 2.60±0.52, 4.10±0.74 and 1.90±0.74 days, respectively. The larva moulted six times by passing through seven larval instars with mean total larval period of 42.54±2.53 days. The mean duration of male and female pupal stage were 11.80±0.63 days and 14.30±1.43 days respectively. The mean longevity of adult male and female were 4.10±0.74 days and 5.80±0.42 days, respectively, meanwhile the total life cycle of male and female completed in 58.44±3.90 and 62.64±4.59 days respectively.
All tested insecticides were found effective in controlling the mango leaf webber over control. However, considering cumulative pest incidence recorded fifteen days after second spray, the treatment chlorantraniliprole 18.5 % SC @ 0.2 ml/l recorded least mean active number of webs per tree (2.82) and least mean number of larvae per web (2.17) found effective in managing the pest over control. The treatment chlorantraniliprole 18.5 % SC @ 0.2 ml/l recorded significantly higher fruit yield and benefit cost ratio of 69.55 q/ha and 4.94 respectively.