Insect Diversity and Abundance in Yellow Sticky Traps across Various Growth Stages of the Cabbage Ecosystem

Abstract

The study was conducted in a cabbage field located in Avathi village, Devanahalli Taluk, Bangalore rural district, Karnataka, India. Forty yellow sticky traps (22cm × 11cm) were strategically positioned in the field with a spacing of 10 meters between each pair of traps. Over the course of the experiment, ten traps were collected at 10-day intervals, with observations conducted at five different growth stages of the crop. A total of 19,292 insects were captured in the yellow sticky traps throughout the varying growth stages ranging from 35 to 75 Days After Planting (DAP). Notably, the peak insect count occurred at 55 DAP (4,536), followed by 45 DAP (4,446), while the lowest count was observed at 75 DAP (2,460). Similarly, the Operational Taxonomic Units (OTUs) exhibited their highest count at 35 DAP (41), closely followed by 45 DAP and 75 DAP, with the lowest OTU count occurring at 65 DAP. In terms of taxonomic categorization, the majority of insects belonged to the order Hemiptera, comprising 70% of the total catch (13,471), followed by Diptera at 17% (3,302). On the other hand, OTUs were predominantly represented by Diptera at 32%, followed by Hemiptera at 27%, Hymenoptera at 20%, Coleoptera at 12%, Lepidoptera at 5%, and Isoptera and Thysanoptera at 2% each. Diversity analysis conducted on the insects captured during different cabbage crop growth stages revealed that the Shannon and Simpson diversity indices reached their highest values at 75 DAP, with the lowest recorded at 65 DAP. Similarly, evenness and equitability were maximized at 75 DAP, contrasting with their lowest values observed at 55 DAP. Additionally, Margalef’s index reached its peak at 35 DAP (4.84) and hit its lowest point at 65 DAP (3.61).