X is for Xylophage
Most A-Z lists start to struggle once they get to the letter ‘X’, as the range of words beginning with ‘X’ is somewhat limited. Xylophone is not a particularly flexible topic to work with when talking about World Heritage Sites or ecology. Luckily in the biological sciences there are plenty of X words to explore, so here is a favourite.
Xylophage is related to the word ‘xylem’, which refers to the vascular tissues (think blood vessels of the plant kingdom) that run through a plant’s system particularly in the ‘woody’ part of the plant stem. The xylem tissue is essential for transporting water and micronutrients around the plant to drive healthy growth and reproduction. A ‘xylophage’ is an organism that feeds on the xylem and woody parts of the plant, and biologists encounter these organisms all of the time! They would have been well known to the monks of Augustine’s Abbey and the monastery of Christ Church, as pests on their fruit trees, or the woodworm and death watch beetles eating away at timbers and choir stalls!
A common xylophage is the simple aphid, found everywhere, and feeding on everything from the roses in the Dean’s garden in the cathedral precincts, to the ancient trees in St Martin’s churchyard. Aphids are pests, and do significant damage to the plants they feed on, particularly due to their ability to transfer plant diseases from host to host in the same way a mosquito carries malaria between humans and other animals. Despite being considered a nuisance by plant lovers, the aphid is one of the most miraculous animals on the planet. Aphids are all female, born alive (rather than being laid as an egg), and when born are able to reproduce again within minutes. As a result, a single aphid could produce the weight of several 747 aeroplanes in ‘aphid biomass’ within a field season, a true miracle of reproductive success!
Not all xylophagous insects are troublesome though. The saproxylic insects are a particular group of xylophages that specialise on dead or decaying wood. Many saproxylic species, such as the famous stag beetle (nurtured by leaving piles of dead wood in the university’s campus), or the noble chafer beetle, that lives a cloistered life in the traditional orchards of Kent, serve essential functions within the ecosystem, breaking down and recycling nutrients as they feed. These insects also carry beneficial microbes in their guts which they use to break down complex molecules found in wood, and without them, dead wood falling to the forest floor would simply sit there for years without the nutrients being made available again for other plants to use. Needless to say, without saproxylic insects feeding in our woodlands, the nutrient cycle would almost certainly come to a complete halt.
Unfortunately many saproxylic insects are in decline across the world, part of the coming ‘insect apocalypse’ that has come into the spotlight in recent years. Over 40% of insect species are threatened with extinction, and the xylophage species are no exception to this. The main threats to insects are the conversion of land for agriculture and the introduction of agrochemical pollution, and, in Kent, specifically the loss of traditional orchards and ancient woodlands. These threats are exacerbated by climate change and the invasion of non-native species. Without a radical change to our environmental policies, these declines could be catastrophic for nature and humankind, since so much of our lifestyle is reliant on the natural ecosystem functioning correctly, including food production, water management and even biotechnology and medicine. Recent calls for a ‘Green New Deal’ from some politicians is encouraging, this could go some way into halting this drastic loss of biodiversity. Protecting nature, however, takes real political will and a serious investment for a renewable and sustainable future.
Dr Joe Burman is a member of the Ecology Research Group and university lecturer in the Life Sciences at CCCU, specialising in insect conservation. Follow him on Research Gate and twitter @TheMothSexGuy
The University will also be hosting a two-day conference on Canterbury and other UNESCO World Heritage Sites around the world on Friday 24 and Saturday 25 May at Old Sessions House, Longport.
