Virulence of entomopathogenic nematodes to Diaprepes abbreviatus (Coleoptera : Curculionidae) in the laboratory

The Diaprepes root weevil, Diaprepes abbreviatus (L.) is the most severe we evil pest in Florida citrus. Entomopathogenic nematodes have effectively su ppressed larval populations of D. abbreviatus. Our objective was to conduct a broad laboratory comparison of entomopathogenic nematodes for virulence toward larvae of D. abbreviatus. The study was conducted at three temperatu res (20, 24, and 29 degrees C) and included nine entomopathogenic species a nd 17 strains: Heterorhabditis bacteriophora Poinar (Baine, NJ1, Hb, Hb1, H P88, and Lewiston strains), II indica Poinar, Karunakar & David (original a nd Hom1 strains), inarelatus Liu & Berry (IN and Point Reyes strains), Il. megidis Poinar, Jackson & Klein (UK211 strain), Ii. zealandica Poinar (NZH3 strain), Steinernema riobrave Cabanillas, Poinar & Raulston (355 strain), S. carpocapsae (Weiser) (All strain), S. feltiae (Filipjev) (SN and UK76 st rains), and S. glaseri (Steiner) (NJ43 strain). At 20 degrees C, the greate st mortality was caused Lp S, riobrave although it was not significantly gr eater than II. bacteriophora (Baine), ii. bacteriophora (I-IL), Ii. bacteri ophora (Hb1), and ii indica (original). At 24 and 29 degrees C, S. riobrave caused greater larval mortality than other nematodes tested. Two strains o f H. indica, H. bacteriophora (Baine), and S, glaseri were next in terms of virulence at 29 degrees C. Our results suggest that S. riobrave has the gr eatest potential for control of D, abbreviatus.