Seasonal Incidence of Insect Pests and Predatory Fauna on Toria (Brassica rapa) in West Central Tableland of Odisha, India

The present field investigation was conducted for two consecutive Rabi seasons of years 2021/22 and 2022/23 at the College of Horticulture, Odisha University of Agriculture and Technology, Chiplima, Odisha to record the seasonal incidence of major insect pests with the predatory fauna on toria (Brassica rapa) in relation to meteorological parameters. The occurring pest complex in both seasons constituted a total nine number of insects and three consistent predatory fauna.

The highest peak population of pests recorded for 2021/22 were: mustard aphid (3.7 A.I plant-1 at 50th SMW), whitefly (25.9 whiteflies plant-1 at 50th SMW), painted bug (13.37 nymphs+adults plant-1 at 50th SMW), mustard sawfly (12 larvae plant-1 at 48th SMW), flea beetle (12.45 grubs+adults plant-1 at 50th SMW), diamondback moth (1.3 larvae plant-1 at 52nd SMW), leaf Webber (6.45 larvae plant-1 at 51st SMW), Bihar hairy caterpillar (29.3 larvae plant-1 at 50th SMW) and tobacco caterpillar (8.9 larvae plant-1 at 49th SMW. Similarly, the highest peak population of pests recorded for 2022/23 were: mustard aphid (3.82 A.I plant-1 at 51st SMW), whitefly (23.8 whiteflies plant-1 at 50th SMW), painted bug (13.7 nymphs+adults plant-1 at 51st SMW), mustard sawfly (15 larvae plant-1 at 48th SMW), flea beetle (13.45 grubs+adults plant-1 at 50th SMW), diamondback moth (1.2 larvae plant-1 at 47th SMW), leaf Webber (5.45 larvae plant-1 at 51st SMW) which coincided the abundance of natural enemies namely, coccinellid predators, syrphid fly and spider between 50th to 52nd SMW of the experimental year for both seasons.

The correlation of insect pest density with weather parameters (Rabi, 2021/22) showed negative correlations with Tmax (mustard aphid, painted bug, flea beetle, leaf Webber, diamondback moth, Bihar hairy caterpillar), Tmin (all pests), rainfall (mustard aphid, whitefly, mustard sawfly, flea beetle, tobacco caterpillar), RH% at 7 hours (all pests), and RH% at 14 hours (mustard aphid, whitefly, painted bug, leaf Webber, diamondback moth, Bihar hairy caterpillar).For natural enemies, Tmax, Tmin, RH% at 7 hours, RH% at 14 hours, and wind velocity had negative effects on their population, while rainfall had a positive influence. However, in Rabi 2022/23, Tmax, Tmin, and RH% at 14 hours negatively influenced the pest population mostly except for wind velocity and RH% at 7 hours. For predators, wind velocity showed positive correlation with its’ population.