Laboratory virulence of entomopathogenic nematodes to the sweetpotato whitefly, Bemisia tabaci

The sweetpotato whitefly, Bemisia tabaci Middle East-Asia Minor 1 (MEAM1), is a major insect pest on vegetable crops worldwide. Enormous economic losses result from direct and indirect plant damage caused by MEAM1. Biological control using entomopathogenic nematodes (EPN) may be an effective alternative strategy against MEAM1 because this pest has developed resistance to most insecticides. First, nine EPNspecies (Heterorhabditis bacteriophora, H. indica, H. georgiana, H. floridensis, Steinernema feltiae, S. carpocapsae, S. riobrave, S. glaseri, and S. rarum) were investigated for virulence against MEAM1 third instar nymphs on the snap bean. The percentage mortality of MEAM1 nymphs was evaluated at 3 days post-inoculation (dpi). The mortality of MEAM1 nymphs resulted from the application of H. bacteriophora (66.31%), H. floridensis (56.38%), S. carpocapsae (54.54%), and S. rarum (57.80%) were significantly higher than the water control. Subsequently, the four most virulent EPN species, H. bacteriophora, H. floridensis, S. carpocapsae, and S. rarum were evaluated further for virulence against MEAM1 nymphs on snap bean and tomato. The percentage mortality of MEAM1 nymphs was assessed at 3 and 7 dpi. There were no significant differences in MEAM1 nymphal mortality between tomato and snap bean at  3 or 7 dpi. Compared with other EPN species and water control, the mortality of MEAM1 nymphs (99.25%) caused by the application of H. floridensis was significantly higher at 7dpi. The results indicate that H. floridensis is a very promising biocontrol agent for B. tabaci management.