Monitoring of flea beetles (Coleoptera: Chrysomelidae) in radish in organic soil and evaluation of net covers and mass trapping as alternative control methods

The striped flea beetle Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidea) and the crucifer flea beetle P. cruciferae (Goeze) are significant insect pests of Brassica crops. We investigated the relationship between the presence of adult beetles and subsequent root damage caused by larvae. Additionally, we tested various alternative methods to control flea beetle damage, including net covers, fences, and mass trapping with plastic jugs. Our findings showed a correlation between the accumulation of adult striped flea beetles on foliage and the number of roots damaged. Approximately 96% of the larvae collected in 2023 were identified as striped flea beetles. Net covers helped increase marketable yield and reduce losses due to flea beetle damage to Chinese radish roots while insecticide treatments did not reduce root damage compared to untreated control. Mass trapping with jugs did not reduce root damage; instead, it attracted more adults to the plants, leading to increased foliage damage compared to control. A better understanding of the relative contribution to root damage by both flea beetle species would lead to an increase in monitoring efficiency and make its implementation easier. The use of net covers against flea beetle damage is recommended to increase yield and reduce damage to rooted crucifer crops.