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England’s trees at risk due to invasive oak processionary moth caterpillars


The oak moth arrived in the UK after infected trees were imported from mainland Europe. Credit: Ralph Gaith/Shutterstock

An insect that can be dangerous to human health is spreading across the south east of England.

Oak moth larvae are becoming more common as warming temperatures help them spread to new areas.

New rules have been introduced to control the invasive moth that harms oak trees in the UK.

The oak procession moth was accidentally introduced to London in imported oak trees around 2006, and has since spread throughout the Southeast. In addition to being a pest of oaks, their larvae can cause irritation and, in serious cases, allergic reactions to people and animals.

with the Caterpillar is now widespread Across D.C., the government has introduced new legislation regarding the movement of oak trees across the country to try to stem the species’ spread.

A buffer zone was set up across the heart of England has been expandedwhile a new designated area has been created around the buffer zone and established areas to allow limited movement of trees.

Professor Nicola Spence, UK Chief Plant Health Officer, says: “Healthy oak trees are a vital component of biodiversity and a thriving landscape. They are the most important tree in Great Britain for species biodiversity, supporting more than 2,000 species of birds, fungi, mammals, invertebrates and bryophytes and lichen.

“This is why it is essential to protect the health of our oak trees, that we have regulations in place for the movement of large oak trees within areas and boundaries designed to manage the oak moth.”

What is the oak procession moth?

The acorn moth, Thometopoea parade, is a small brown moth native to southern Europe. Adults are short-lived, gray insects that do not feed, and are difficult to obtain in the wild.

However, most concerns focus on its distinctive black and white hairy larvae, whose behavior gives the species its name. They move in groups, tracking chemical and tactile cues on oak trees or the ground to find and consume leaves.

This gives them security in numbers, and their defense is further enhanced by their covering of fine hairs. Known as setae, they contain a toxic protein known as thaumetopoein that can cause skin rashes, irritation, and breathing difficulties in humans and animals.

For this reason, it is recommended to avoid getting close to the caterpillars and especially their nests.

“While the larvae are a danger in their own right, their nests are even worse,” says Alessandro Giusti, senior curator of Lepidoptera at the Museum. This is because they contain not only the larvae, but also their larvae, which means that if the nest is disturbed, it can cause damage. In a more serious reaction.”

UK oak parade moths

The oak moth first arrived in the UK in the early 2000s, with establishments in 2005 and 2006. It is believed that the caterpillars were imported as part of the plant trade, possibly transported on oak trees brought to the UK from South Africa. Europe.

After first arriving in London, the caterpillars spread to the surrounding areas of Surrey, Essex and Kent. Some have now spread even further, reaching areas as close as Colchester, Reading and Milton Keynes.

In large enough numbers, the caterpillars are able to consume a large amount of leaves, and in extreme cases defoliate an entire oak tree. This limits the tree’s ability to photosynthesize, making it weaker and more vulnerable to other threats, such as acute oak decline diseases and sudden oak death.

Invasive oak moth larvae are causing concern for England's trees

Adult oak moths are common in south-west London. Credit: Gyorgy Csoka, Hungarian Forest Research Institute, Bugwood.org, licensed under CC BY-SA 3.0 United States via Wikimedia Commons

Their spread is also being accelerated by climate change, which helps them expand their range into suitable areas.

“The fact that it’s warm will help the moth feel at home here, because it’s used to the Mediterranean climate,” says Alessandro. “The movement of plants and humans, in combination with climate change, is helping their spread.”

Rising temperatures in the south of England are thought to be one reason for the insects spreading through Surrey and into Hampshire, where there is currently an isolated population near Romsey. Meanwhile, the lack of predators is another matter.

“While their hair gives them good protection, there are still animals that feed on acorn moths,” says Alessandro. “Parasitic wasps Flies, for example, are not deterred by their hair, nor are some birds. And cuckoos are known to feed on them regularly, as is the wasteland.”

“As the oak procession moth is a relatively recent arrival in the UK, any potential predators haven’t had much time to identify them. This means that the caterpillars are able to spread faster than they would otherwise.”

What can be done about oak moths?

The main way to target oak procession moths is to find them early in their life cycle. They start emerging from their eggs in April and May, and this is when they are at their weakest.

In general, infected trees are treated by spraying with insecticides. These are applied in a targeted manner so that they do not affect other wildlife in the vicinity.

Insecticide treatment is supported by removing nests from trees to reduce the possibility of future reinfestations. These can be difficult to find, however, and other methods are used to track down the elusive caterpillars.

“Oak moth nests are easy to find when they are fresh, as the white silk with which they are made stands out against the branches and foliage,” explains Alessandro. “However, they quickly get darker which makes them hard to spot.”

“Pheromone traps can help with this, as they attract adults from the vicinity and narrow down nesting spaces. This can also help disrupt the moth’s reproductive cycle.”

How to identify an oak moth

While infestation treatment should be left to professionals due to the health risks involved, members of the public can help tackle their infestation by identifying oak moths in their area.

Before making a report, it is important to realize that there are many species other than the oak moth that have hairy larvae. Species such as the yellowish-tailed moth and the brown-tailed moth are often erroneously reported.

Oak moths can be identified by their black heads and bodies that are covered in long white hairs. They are found almost exclusively in oak trees, and only venture into other trees if there is a shortage of oaks.

Their nests can be a range of different shapes and sizes, but they tend to be the same dome or teardrop; It is about the size of a tennis ball. These tend to be built on the trunks and branches of trees, and are not found among oak leaves.

Similar species may only group together rarely, be found on trees other than oaks, or not build nests at all. Comprehensive ID guide What looks like the oak procession moth can be found on the Forest Research website.

If a suspected oak procession moth is identified, it should be reported to forestry research through TreeAlert service. Alternatively, members of the public can email opm@forestrycommission.gov.uk or call 0300 067 4442.

Provided by the Natural History Museum

This story is republished with permission from the Natural History Museum. Read the original story here

the quote: Invasive oak moth larvae cause concern for trees of England (2023, June 9) Retrieved June 9, 2023 from https://phys.org/news/2023-06-invasive-oak-processionary-moth-crawillars.html

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