Page 65 - Grapevine July-Aug 2020

Around The Vineyard

• The foraging of inoculated wasps increased the
incidence of filamentous fungi, black mold on
injured grapes, and the severity of disease in
injured grapes./

• The foraging of uninoculated wasps increased
the severity of disease and the average concen-
tration of acetic acid in grapes.

Sour rot disease microbial complex includes
yeasts, filamentous fungi and acetic acid bacte-
ria, but the acetic acid bacteria are responsible for
the worst of the disease symptoms. All inoculated
wasps were found to harbor acetic acid bacteria.

More than half (52 percent) of the wasp carried
sour rot associated yeasts. Eighty-eight percent of
the wasps tested harbored at least one of five dif-
ferent kinds of saprotrophic filamentous fungi. In
all, half the wasps contained the full complement of
sour rot microorganisms.

Madden noted that there was significant variability
in the presence of microorganisms. In some wasps,
the bacterial community was dominated by acetic
acid bacteria, while in others it was barely detect-
able.

“This variability suggests that rather than being
automatically associated with wasps, these micro-
organisms may be acquired from the local environ-
ment,” said Madden.

Journal Reference:

Anne A. Madden, Sean D. Boyden, Jonathan-
Andrew N. Soriano, Tyler B. Corey, Jonathan W.
Leff, Noah Fierer, Philip T. Starks. The emerging
contribution of social wasps to grape rot disease
ecology. PeerJ, 2017; 5: e3223 DOI: 10.7717/
peerj.3223

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