S17: Yersinia entomophaga: a biopesticide active against a wide range of insect pests

The bacterium Yersinia entomophaga was isolated from larvae of the New Zealand grass grub, Costelytra zealandica (Coleoptera: Scarabaeidae), from New Zealand soils. Y. entomophaga has activity towards a number of Coleopteran and Lepidopteran pests with the main activity against members of the Scarabaeidae, where LD₅₀s of approximately 5 x 10⁴ bacteria/larva have been determined. Death typically occurs within 2-5 day post ingestion. The main virulence determinant of Y. entomophaga is an insect active toxin complex, termed the Yen-Tc, that is highly active against members of the Scarabaeidae and the diamondback moth (Plutella xylostella). The bacterium can be economically fermented in large volumes, producing >1 x 10¹⁰ cells/mL within 24 hours. Media and tools have been defined to alter the levels of Yen-Tc production and enable detection of the bacterium from environmental samples. Formulated Y. entomophaga has shown significant field control when applied as a foliar spray against chrysomelid beetles (Eucolaspis sp) or in bait formulation against ground dwelling Lepidoptera (Wiseana sp.). In pot trials Y. entomophaga has shown comparable efficacy to Spinosad or Dipel against P.  xylostella. Persistence studies have shown Y. entomophaga to have limited survival in the field post application but formulation technologies can be used to extend activity.