Management of Citrus Root Weevils (Coleoptera: Curculionidae) on Florida Citrus with Soil-Applied Entomopathogenic Nematodes (Nematoda: Rhabditida)

Abstract

The entomopathogenic nematodes Steinernema carpocapsae Weiser and S. riobravis Cabanillas, Poiner and Raulston were compared as twice a year soil treatments for control of the west indian sugarcane root stalk borer weevil, Diaprepes abbreviatus (L.), and citrus root weevil, Pachnaeus litus (Germar). Additionally, four single rate demonstrations evaluated S. riobravis and a 2- year test compared single versus double annual treatments of S. riobravis. The 6 experiments were conducted in the Indian River Area of Florida, U.S.A. Two applications per year of S. carpocapsae were as effective as S. riobravis for P. litus control but failed to control D. abbreviatus. A single application of S. riobravis delivering 2 million nematodes per tree through low volume irrigation systems or a tractor-mounted herbicide boom in demonstration tests provided 64% and 89% reduction of P. litus and D. abbreviatus, respectively. Single annual applications of 2 million S. riobravis per tree delivered with sprinkling cans reduced P. litus populations by 65% and D. abbreviatus populations by 85% over a 2 year period and was statistically equal to a 2-a-year treatment of S. riobravis that provided 80% and 95% reductions, respectively.