Phytoparasitica (2002) 30 (3) - Combining biocontrol agents ...

Ruth Guetsky, Y. Elad, D. Shtienberg, E. Fischer and A. Dinoor (2002)
Combining biocontrol agents with several different mechanisms to improve biological control
Phytoparasitica 30 (3)
The 23rd Congress of the Israeli Phytopathological Society - February 11-12, 2002
Abstract: Two biocontrol agents, a yeast (Pichia guilliermondii) and a bacterium (Bacillus mycoides), were tested separately and together for suppression of Botrytis cinerea on strawberry leaves and plants. We reported recently that the combination of these two biocontrol agents reduced variability and improved efficacy of B. cinerea suppression. Scanning electron microscopy revealed significant inhibition of B. cinerea conidial germination in the presence of P. guilliermondii, whereas B. mycoides caused breakage and destruction of conidia. When both biocontrol agents were applied in a mixture, conidial inhibition and destruction were more severe. The modes of action of each of the biocontrol agents were elucidated and the relative quantitative contribution of each mechanism to suppression of B. cinerea was estimated using multiple regression with dummy variables. The improvement in control efficacy achieved by introducing one (or more) mechanism(s) at a time was calculated. P. guilliermondii competed with B. cinerea for glucose, sucrose, adenine, histidine and folic acid. Viability of the yeast cells played a crucial role in suppression of B. cinerea and these cells secreted an inhibitory compound(s) that had an acropetal effect and was not volatile. B. mycoides did not compete for any of the sugars, amino acids or vitamins examined. Viable cells and the compound(s) secreted by them contributed similarly to B. cinerea suppression. The bacteria secreted volatile and non-volatile inhibitory compounds and activated the defense systems of the host. The non-volatile compound(s) had both acropetal and basipetal effects. A mixture of P. guilliermondii and B. mycoides resulted in additive activity, as compared to their application separately. The combined activity was due to the sum total of biocontrol mechanisms of both agents. This work provides a theoretical explanation for our previous findings of reduced variability in disease control with a mixture of P. guilliermondii and B. mycoides.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Yigal Elad, Dani Shtienberg

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
application technology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Botrytis cinerea	Strawberry (Fragaria)
Meyerozyma guilliermondii (antagonist)	Botrytis cinerea	Strawberry (Fragaria)
Bacillus mycoides (antagonist)	Botrytis cinerea	Strawberry (Fragaria)