Effect of Exposure and Assessment of Diversity, Abundance of Insects in Cabbage Crop Using Yellow Sticky Traps

Cabbage is a leafy vegetable cultivated worldwide for its dense heads. Many insects affecting cabbage and posing challenges to cultivation. Yellow sticky traps are adhesive sheets used to attract and capture flying insects and help to monitor and manage infestations in gardens and greenhouses. The study aims at providing insights on effectiveness of use of yellow sticky traps in cabbage ecosystem. An experiment was conducted in a cabbage field using sticky traps (22 cm X 11 cm) over a 12-days period at Avathi village, Devanahalli Taluk, Karnataka, India. A set of 60 traps were installed randomly in the field when the crop was at 60 days old. Five traps were sampled daily and examined microscopically and the number of insects trapped were recorded over the 12-day study period. The number of insects caught showed an increasing trend from day 1 to day 7 and almost reached saturation by day 10. Similarly, the number of insects added to the trap decreased from 8 to 12 days after installation. These trends suggest that the 22 cm X 11 cm size sticky traps get saturated by the 10th day resulting in steadily reducing catches with further sampling. On the 10th day of exposure, the cumulative number of Operational Taxonomic Units (OTUs) was maximum. The diversity indices were also found to be maximum on the 10th day. Marginal additions of insects by numbers and OTUs after a 10-days period suggest that sticky traps of the given size are ideal for sampling insects only up to 10 days after installation in the cabbage system. Further, on the same logic, from the point of view of pest reduction, continuous exposure of sticky traps for the whole cropping period, as is currently being practiced by the farmers, is not a wise practice.