Insect feeding on cucumber mediated by rhizobacteria‐induced plant resistance

Abstract

Abstract Select strains of plant growth‐promoting rhizobacteria (PGPR) were evaluated in greenhouse experiments with cucumber for induction of resistance against cucumber beetle ( Diabrotica undecimpunctata howardi Barber) feeding and the beetle‐transmitted cucurbit wilt disease. When beetles were given a choice between PGPR‐treated and nontreated cucumber, their feeding on stems and cotyledons and the severity of wilt symptoms were significantly lower on PGPR‐treated plants. HPLC analysis demonstrated that cotyledons from PGPR‐treated plants contained significantly lower concentrations of the cucumber beetle feeding stimulant cucurbitacin than nontreated plants. These results suggest that a mechanism for PGPR‐induced resistance against cucumber beetle feeding may involve a change in the metabolic pathway for cucurbitacin synthesis.