Diamondback moth, Plutella xylostella (Linnaeus) responses on Chinese kale (Brassica oleracea Var. alboglabra) Treated by plant growth promoting rhizobacteria

Background and Objective: Plant Growth Promoting Rhizobacteria (PGPR) is a new and potential tool of the biocontrol for pests on crops. Pseudomonas fluorescens (P. fluorescens) and Bacillus subtilis (B. subtilis) are two species of PGPR that proved in biocontrol of crop pests and diseases. This research aimed to investigate the diamondback moth (DBM) responses on the Chinese kale that treated by P. fluorescens, B. subtilis and combination between both species. Materials and Methods: Research was conducted in the Pest Laboratory, Department of Plant Pests and Diseases, University of Brawijaya from January-April, 2015. Completely randomized design was adopted with four treatments (immersed seeds into P. fluorescens, B. subtilis, P. fluorescens and B. subtilis combination and control) and four replications to investigate the feeding activities, period of larval instars and oviposition of diamondback moth. In addition, phenolic and wax content tests were performed to get additional data related to the diamondback moth responses. Results: Result showed that feeding activities of Plutella xylostella (P. xylostella) was inhibited by application of PGPR. Concentration of phenolic compound contained in the plant tissue which treated by PGPR was higher than control. Period of larva become shorter after application of B. subtilis, P. fluorescens and combination of P. fluorescens and B. subtilis. Oviposition of P. xylostella was affected by PGPR and application of single species of PGPR reduced oviposition better than combination application. Pseudomonas fluorescens produced the lowest oviposition. Phenolic and wax compounds were produced higher than control for all PGPR treatments and it may be related to plant defense mechanisms against the diamondback moth. Conclusion: Application of PGPR cause the changes of DBM responses such as feeding and oviposition activities and it reduce period of larva. The high concentration of phenolic and wax compounds on PGPR application is related to the changes of DBM responses.