Assessment of Yersinia entomophaga as a control agent of the diamondback moth Plutella xylostella

The application of the biocontrol bacterium Yersinia entomophaga as a foliar spray was assessed for its efficacy against larvae of the diamondback moth, Plutella xylostella. The bacterium was applied as either a broth suspension, or as a biopolymer-based gel foliar spray and compared with commercial insecticides Dipel (Bacillus thuringiensis) and Spinosad. The performance of Y. entomophaga was comparable with that of Dipel. The gel based formulation extended leaf persistence over that of the basic broth culture spray, while also providing higher initial foliar deposition rates. The bacterium was found to multiply within the P. xylostella larvae to 5.8 x 10(5) cells per larva, while the median lethal dose (LD50) was determined to be 2.69 x 10(3) cells per larva. Importantly, B. thuringiensis Cry1A-resistant, Cry1C-resistant, indoxacarb/pyrethroid-resistant, and Spinosadresistant P. xylostella larvae were susceptible to Y. entomophaga.