Bacterial entomopathogens improve cereal establishment in the presence of grass grub larvae

Abstract

Grass grub (Costelytra zealandica) larvae can damage or kill establishing cereal seedlings Two entomopathogenic bacteria applied as seed coatings were investigated as a means of protecting emerging wheat seedlings Seeds coated with Serratia entomophila or Yersinia sp nov were planted outdoors in pots containing grass grub larvae at rates equivalent to 70 and 140 larvae/m² Seedling establishment was significantly increased in both bacterial treatments compared to untreated controls with S entomophilacoated seed having the higher establishment rate 94 at both larval densities although this was not significantly different from the Yersinia sp nov treatment at the highest larval density When included in a comparison of chemical seed dressing treatments for grass grub a S entomophilacoated seed treatment was as efficacious as standard insecticide treatments indicating there is good potential to develop this bacterium as an alternative to chemical pesticides for use in cereal crops