Monitoring and trapping effects of yellow and blue sticky traps on the population dynamics of thrips on an alfalfa community

To understand the population dynamics of thrips on alfalfa, blue and yellow sticky traps were used in a clover field from late April to late September, 2019. We also utilized different directions (east, south, west, and north) and different hanging heights (mid of alfalfa, top of alfalfa, and 20 cm above the top of alfalfa). Most of the thrips on the alfalfa were collected by both colored sticky traps in early August. The population of Odontothrips loti reached its highest peak in mid-July to early-August. The largest amount of thrips on the alfalfa and O. loti were collected during the third harvest, which showed a significant difference to the other three harvests (P < 0.05). The results showed that the thrips on the alfalfa preferred the blue sticky traps, whereas O. loti had a strong tendency for the yellow sticky traps. The hanging height at the top of the alfalfa was suggested for the sticky cards. In addition, the number of thrips trapped in the east and south was greater than the other two directions. Multi-way analysis of variance showed that the trapped number of thrips was significantly influenced by color, direction, and height (P < 0.01).