ABSTRACT
ABSTRACT Studies on seasonal dynamics of white fly (Bemesia tabaci) on tomato (Solanum esculentum var. Pusa Ruby) revealed that it appeared first during the 13th and reached maximum during 21st standard meteorological week. A positive correlation between adult population and abiotic factors viz. temperature (maximum and minimum) and sunshine hours was observed, whereas humidity (maximum and minimum) and rainfall showed a negative correlation with it. Taken together, the key weather parameters studied, caused 89.00 per cent variation in whitefly population (R2 value). Combination of carbofuran (soil application) + imidacloprid (seed treatment ) + imidacloprid (foliar application) proved significantly superior and caused maximum reduction in whitefly population followed by imidacloprid (seed treatment) + thiomethoxam (spray), imidacloprid (seed treatment) + imidacloprid (spray), imidacloprid (seed treatment) + dimetheoate (spray), carbofuran (soil application) + malathion (spray), and imidacloprid (seed treatment) + yellow sticky traps. The highest cost benefit ratio of 1:25.04 was recorded in case of carbofuran (soil application) + imidacloprid (seed treatment ) + imidacloprid (foliar application) followed by 1:22.38 for imidacloprid (seed treatment) + thiomethoxam (spray) ; 1:21.81 for imidacloprid (seed treatment) + imidacloprid (spray); 1:19.27 imidacloprid (seed treatment) + dimetheoate (spray); 1:19.48 carbofuran (soil application) + malathion (spray), and 1:8.33 for imidacloprid (seed treatment) + yellow sticky traps. The soil application of carbofuran + seed treatment with imidacloprid and three foliar sprays of imidacloprid at fortnight interval starting 40 days after transplanting is found effective and is advised for whitefly management in susceptible tomato cultivars.
ABSTRACT
ABSTRACT The 28-spotted hadda beetle Henosepilachna vigintioctopunctata Fab. (Coleoptera: Coccinellidae) is a poly-phagous pest, commonly infesting solanacious crops including brinjal, Solanum melongena L. Upon its severe infestation on brinjal, it causes considerable damage to the foliage and also to the calyx of fruits. The studies were made to record the seasonal abundance of hadda beetle and identification of its natural enemies present in the region for two consecutive years. The pooled data for two years showed that the maximum number of H. vigintioctopunctata egg clusters on brinjal were recorded in the 27th (0.40 egg cluster/ plant), followed by grub population in 35th (3.78 grubs/ plant), pupae in 33rd and 39th (0.83 pupae/ plant) and adult beetles in 36th (5.48 adults/ plant) standard meteorological weeks, respectively. It was observed that the key meteorological factors had 35.9%, 87.3%, 66.8% and 81.9% effect on the abundance of egg clusters, grubs, pupae and adults respectively in summer planted brinjal crop. Two natural enemies of hadda beetle viz. Tetrastichus sp. (egg parasitoid) and Pediobius foveolatus (pupal parasitoid) were recorded. The maximum parasitisation by Tetrastichus sp. and P. foveolatus on the egg clusters and pupae was recorded 22.64% and 6.62% respectively, during the month of August (34th and 35th standard meteorological week respectively). Further, the morphometric parameters of these two adult parasitoids were recorded and greater morphometric variability was observed in P. foveolatus in comparison to Tetrastichus sp.