Living With Turkey Oak

Humans use plants for a variety of purposes including for food, shelter, windbreaks, and ornamentals. The Turkey Oak, Quercus cerris, is widely cultivated in Europe and was introduced to the UK in the 1700s primarily as an ornamental and as a coastal windbreak. Oaks are notable as homes for cynipid wasps that form galls on the trees. Importation of Turkey Oak into the UK has allowed invasive species of Andricus gall wasps to colonize the UK. This includes the Knopper Gall Wasp which has been reported in the UK since the 1960s. The wasp has an asexual and a sexual reproductive cycle. Individuals in the asexual cycle can form galls on native oaks species during the summer and develop dense populations. The sexual cycle must occur on Turkey Oak. Without the introduction of the Turkey Oak, which is required for the wasp to successfully overwinter, Andricus gall wasps could not survive in the UK.

Oak Galls produced by a Cynipid wasp

Oak Galls produced by a Cynipid wasp

The gall wasps now thrive in the UK and in some years have outbreak populations. The large gall wasp populations can have ecological effects on native oaks and bird populations. Birds such as the Blue Tit and the Great Tit can open the galls and feed on the wasps. The wasps provide these birds with a food source early in the season before other insect food sources are available.

Global trade, including movement of plants and animals can have unanticipated effects on ecosystems. Scientists advise caution in the movement of species to new locations.

About jjneal

Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in by jjneal, Environment, Invasive Species. Bookmark the permalink.

2 Responses to Living With Turkey Oak

  1. Andrew M says:

    I have a Turkey Oak in my back garden that last year (2015) produced hundreds of, which I thought at the time were stunted acorns, these galls. I have noted already this year (May 2016) Gall wasps in the garden. There are English Oaks in adjacent gardens so are these of any concern warranting any action?

  2. jjneal says:

    The galls do not harm the tree any more than producing acorns that the galls replace. If you have building populations of gall wasps, you can rake the galls and dispose them in a distant location to reduce the next year’s population.

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