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article imageWine going off? Blame the wasps

By Tim Sandle     May 6, 2017 in Environment
Sour rot disease, a scourge of wine industry and there is likely to be more than one vector. A new problem with transmission of the rot has come to light: a small wasp called the paper wasp.
The wasp is an invasive European paper wasp called Polistes dominulus. New research shows how the wasp plays a role in facilitating sour rot disease in the absence of other insects. The wasp is one of the most common species of social wasp. The body is colored entirely yellow and black. These insects are called paper wasps due to the construction of their nests. Paper wasp nests are made from plant material combined with saliva and appear to be made from paper.
The native range of P. dominula covers much of southern Europe and North Africa, and temperate parts of Asia as far east as China. However, the wasp has also recently been introduced into the U.S.
For growers of grapes, wine makers need to spot signs of a common but devastating threat at harvest season. This is a black mold that comes with a distinctive acidic smell. These signs are a signal of grape sour rot disease. This is a disease of economic importance; it is an incurable condition that leads to the decomposition of infected berries. If unchecked, it also degrades wine quality. Because of this, and given the contribution of the wine sector to the economy, considerable effort and research is put into combating the disease. The disease is caused by more than one microorganism for a both a fungus and an acid-loving bacterium are thought to be involved.
That the fungus and bacteria that cause the rot might also be spread by the paper wasp is a relatively new finding and it has come from research conducted at Tufts University. According to Dr. Anne Madden: “The research showed that these wasps carry the polymicrobial community of sour rot and are capable of dispersing live microorganisms when foraging.”
She adds: “This suggests that wasps are playing a role, which had not been previously identified, and may help shed light on more effective management strategies or treatments to curtail these annual losses.”
Further study has shown a rise in the presence of the wasps in vineyards during late summer. Here the insects are attracted to forage on sugar-rich foods like ripe grapes. Studies where vines were quarantined and only exposed the wasps revealed the winged-insects to be an additional contributor to the sour rot disease. This suggests that new strategies are required to protect vineyards,.
The findings are published to the journal Peer J. The research paper is headed “The emerging contribution of social wasps to grape rot disease ecology.”
More about paper wasps, Wine, wine rot, Fungus
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