Comparative Biology of Bihar Hairy Caterpillar, Spilosoma obliqua on Wild and Cultivated Species of Jute

Sources of resistance in cultivated as well as wild jute species against Bihar hairy caterpillar, Spilosoma obliqua Walker was determined on the basis of antibiosis effect through ‘no-choice test’. Larval growth rate in terms of weekly weight gain was significantly impaired on the wild species particularly Corchorus tridens and C. aestuans but later it was reversed. The growth of 5-day old larvae on different jute species indicated maximum antibiosis effect of C. aestuans on S. obliqua. After feeding for 4 days, the larval weight of S. obliqua in C. olitorius (JRO-204) was 9.92 mg whereasin case of wild species, it was ranged from 0.9–8.8 mg. The antibiosis effect was more prominent in 13-day old larvae during which, the larval weight in the wild species was ranged from 18.1–40.8 mg and it was very less as compared to the C. olitorius (58.8 mg). There was no pupation on C. tridens and C. aestuans because of high larval mortality. The pupation on C. pseudo-olitorius, C. tricularis and C. fascicularis was to the extent of 37.5%, 22.5% and 15.0%, respectively as compared to 62.5% on the cultivated species i.e. C. olitorius. The pupal weight of larvae fed on C. olitorius was ranged from 378 mg (mean of 6.25 pupa), which was more than the wild hosts (198–283 mg). Among the wild species, C. pseudo-olitorius only supported for adult emergence (27%). The present study revealed that the effect of wild jute species as host plant, manifested adversely on larval development, growth, survival, pupation and adult emergence of S. obliqua.