Seed Treatment with Clothianidin Reduces Bagrada hilaris (Hemiptera: Pentatomidae) Damage to Crucifers

Abstract

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is an invasive pest native to countries in Africa, the Middle East, and Asia (Reed et al. 2013, J. Integr. Pest Manag. 4(3), doi: http://dx.doi.org/10.1603/IPM13007). The pest was found on cruciferous plants in the central coast of California in 2012 (Joseph 2014, J. Entomol. Sci. 49: 318–321), 4 yr after its initial detection in California in Los Angeles Co. (Palumbo and Natwick 2010, Plant Health Prog., http://www. plantmanagementnetwork.org/pub/php/brief/2010/bagrada/, doi: 10.1094/PHP2010-0621-01-BR). Bagrada hilaris prefers Brassica crops, including broccoli (Brassica oleracea var. italica Plenck), cauliflower (B. oleracea L. var. botrytis), and cabbage (B. oleracea L. var. capitata), which are the top vegetable crops grown in agricultural areas of California’s central coast. In 2016, Brassica crops were valued at more than US$778 million in Monterey Co. alone (Monterey Co. Crop Rep. 2017, http://www.co.monterey.ca.us/Home/ShowDocument?id1⁄465737). Bagrada hilaris feeding injury has been observed when the seeds germinate immediately following planting (Joseph et al. 2017, J. Entomol. Sci. 52: 468–471), as well as on the young plants up to the five-leaf stage (Reed et al. 2013). This feeding affects normal plant growth and sometimes plant survival. Widespread stand loss and stunting have been observed in B. hilaris–infested Brassica fields. Bagrada hilaris feeding often triggers production of multiple shoots, which produces a number of smaller, unmarketable broccoli, cauliflower, or cabbage heads. In California’s Salinas Valley, broccoli and cabbage are primarily direct-seeded; whereas, cauliflower is transplanted. Broccoli is usually planted at approximately 15.2-cm spacing between seeds. Management of B. hilaris in field-grown Brassica primarily relies on multiple applications of pyrethroid, neonicotinoid, or carbamate insecticides during the