Insect feeding on cucumber mediated by rhizobacteria‐induced plant resistance

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.

Plant Growth Promoting Rhizobacteria of Cotton Affecting the Developmental Stages of Helicoverpa Armigera

“…However, the larval mortality was high in endosulfan treatment where the emerging adults were absent. Similar results were obtained by Zehnder et al (1997aZehnder et al ( , 1997b wherein the PGPR treated cucumber plants showed reduced consumption by cucumber beetles with reduction in the percentage of wilted vines both in the glasshouse and field experiments. The altered feeding behaviour of the insects was due to reduction in the palatability.…”

“…Chestnut sprayed with P. fluorescens resulted in 20% weevil mortality (Yaman et al 1999). Biological control of pests using bacteria has been demonstrated by several other researchers (Fahey et al 1991;Racke and Sikora 1992;Zehnder et al 1997aZehnder et al , 1997bRajendran 2003). Reduction in consumption of boll tissues of cotton treated with bioformulation of Bacillus by H. armigera has been observed (Bhuvaneswari 2005).…”

“…Zehnder et al (1997b) reported that cucumber beetles (Diabrotica undecimpunctata Howardi) transmitting the bacterial wilt disease Erwinia tracheiphila when fed to cucumber plants treated with PGPR strains in greenhouse experiments exhibited reduced consumption of stems and cotyledons leading to reduced wilt severity compared to non treated plants. Delivery of Pseudomonas fluorescens through seed, soil, root or foliage reduced the incidence of both sheath blight and leaf folder in rice.…”

Systemic Resistance Induced by Rhizosphere Bacteria

“…These results indicate that rhizobacteria-mediated ISR, like SAR, is effective against multiple diseases. Moreover, two recent reports describe that cucumber plants growing from PGPR-treated seeds in the field supported lower numbers of the spotted cucumber beetle, Diabrotica undecimpunctata, and the striped cucumber beetle, Acalymna vittatum (110,111). PGPR treatment resulted in greater beetle control than did weekly applications of insecticide.…”

Potential for the use of elicitors of plant resistance in arthropod management programs

“…Knowing that the bacterial wilt pathogen, Erwinia tracheiphila (Smith), is vectored by cucumber beetles (Agrios, 1978, Yao et al, 1996, the Auburn workers conducted greenhouse and laboratory experiments to determine whether PGPR-mediated protection against bacterial wilt resulted from ISR against the pathogen, the vector, or both (Zehnder et al, 1997b). Results showed that attenuated beetle feeding on PGPR-treated cucumber was associated with reduced concentrations of cucurbitacin, a secondary plant compound and cucumber beetle feeding stimulant.…”