Monitoring predation of bagrada bug eggs using field cameras

The invasive stinkbug bagrada bug, Bagrada hilaris, a native of southern Asia, rapidly became a major pest of cole crops (i.e., broccoli, cabbage, cauliflower, kale) in California after its discovery near Los Angeles in 2008. Conventional pesticides are the most effective means of controlling this pest, leaving organic growers with few options. In California bagrada bug persists on brassicaceous weeds such as mustards for most of the year, and then disperses into crops in late summer or fall after the weeds senesce. Bagrada bug is the only known stinkbug that oviposits in the soil, a habit that may provide protection from natural enemies. We used field cameras to monitor ground predators of sentinel bagrada eggs at five sites in northcentral California. Sentinel bagrada bug eggs were glued to waterproof index cards, which were placed under field cameras in patches of weedy bagrada bug hosts. Up to 100% of bagrada bug eggs were consumed by predators at some sites. Ants accounted for the majority of egg predators and were equally efficient in removing buried and exposed eggs. Collembola were also observed attacking eggs at some sites.