About Bagrada hilaris (Burmeister, 1835)
Bagrada hilaris is a species of shield bug with common names bagrada bug and painted bug, and it may be mistaken for or incorrectly called harlequin bug. This species is native to southeastern Africa, and it is an introduced species in many other regions, including California and Arizona, where it was first reported in 2008. Bagrada hilaris is a major pest of Brassica oleracea crops such as cabbage, kale, cauliflower, Brussels sprouts, and broccoli, as well as related crucifers including turnips, rape, and mustard. Both adult and nymph Bagrada hilaris suck sap from plant leaves, causing wilting, yellowing, and stunted plant growth. Beyond crucifers, this bug has been recorded on papaya, sorghum, maize, potato, cotton, caper, pearl millet, and some legumes. Large groups of the bug gather on host plants and cause extensive damage. Adult Bagrada hilaris are 5 to 7 millimeters long, with a shield-shaped, black body marked with white and orange. Females, which are larger than males, lay up to 100 oval or barrel-shaped eggs on leaves or in soil beneath plants. Freshly deposited eggs are white, and turn orange over time. The first-instar nymph emerges within 8 days; it is bright orange-red, darkens as it develops, and becomes black by the last instar. Bagrada hilaris was first sighted in the Western Hemisphere when it appeared suddenly in Los Angeles in June 2008. It then spread to cropland in the agricultural Coachella and Imperial Valleys of California, damaging cole crops there, particularly organically grown cole crops. By September 2014, it had reached as far north as San Mateo, Santa Cruz, Merced and Inyo counties, and all California counties south of these areas except Tulare County. As of 2020, it had been found as far north as Yolo County. Past infestations of this bug have been reported in India. It was first recorded in Chile in 2016, where it rapidly became established, caused economic losses, and invaded homes in several localities. A 2019 study found that eggs of invasive B. hilaris in Mexico are parasitized by a new species of parasitoid wasp, Idris elba, which is named after the actor of the same name. Idris elba has been identified as a potential biological control agent for Bagrada hilaris, which may benefit broccoli crops infested by this pest.
