INCIDENCE OF THRIPS ON MULBERRY AND THEIR MANAGEMENT
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Date
2019-09-05
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UNIVERSITY OF AGRICULTURAL SCIENCES GKVK, BENGALURU
Abstract
Thrips cause quantitative and qualitative loss to mulberry throughout the year. Seven species of thrips were noticed on mulberry during the roving survey in mulberry fields at GKVK, Ramanagara and Chikkaballapura. Among them Pseudodendrothrips bhattii Kudo and Bathrips melanicornis (Shumsher) were found common in all the places. The insecticide dinotefuran 20 per cent SG @ 0.25 g/l was found most effective in reducing the thrips population, followed by clothianidin 50 per cent WDG @ 0.08 g/l and azadirachtin 1 per cent @ 2 ml/l. However, during silkworm rearing the larval parameters viz., instar duration (3.02, 4.02 and 7.01 days for 3rd, 4th and 5th instars, respectively), moulting duration (24.02 and 24.01 hours for 3rd and 4th moult, respectively), larval weight of third (0.73 g/10 larvae) and fourth (4.61 g/10 larvae) instar and grown up larval weight (19.05 g/10 larvae), mortality (2.23 %), effective rate of rearing (97.77 %) and cocoon parameters viz., cocoon weight (9.46 g/10), pupal weight (7.92 g/10), shell weight (1.62 g/10), cocoon shell ratio (17.15 %), filament length (766.50 m) and denier (2.31) were found significantly superior in batches of silkworms fed on mulberry leaves sprayed with neem oil (1.5ml/l) at 30 days after spraying. However, the insecticide clothianidin is highly toxic to silkworms even at 30 days after spray (85.56 % mortality). The neem oil @ 1.5ml/l or azadirachtin 1% @ 2 ml/l was found to be effective in controlling thrips with better rearing performance of silkworms.