Anybody visiting tourist resorts in the Mediterranean today will likely encounter large numbers of dying and dead palms.
What is the reason for this ‘palmageddon’ in the Mediterranean? The culprit is a large Asian beetle called the red palm weevil (Rhynchophorus ferrugineus) – the most important pest in the World of date palm, coconut and certain ornamental species. Their larvae develop inside the main trunk, hollowing it out and eventually killing the plant. It is difficult to detect the larvae protected inside the trunk and by the time the palm is showing symptoms, it is usually too late to save the plant.
I first encountered the beetle while on a family holiday in Greece, where my children delighted in capturing attractive beetles that were active in the warm evenings.
The adults are large, about 35 mm long and 10 mm wide, with a long rostrum (easily mistaken for a nose) – a characteristic of the weevil family. They are reddish-brown in colour with variable dark markings on the middle section of the body (pronotum) and are the largest weevils found in Europe.
I have subsequently seen their handiwork (dead palms) in Montenegro and southern Italy. In Naples, scores of majestic Canary Island date palms (Phoenix canariensis) have been cut down for health and safety reasons following a series of tall palms collapsing and damaging vehicles.
I have also seen large numbers of weevils caught in pheromone traps in China, where the giant larvae are collected as food. The weevil originates in southern Asia and has spread widely in Asia, the Pacific Region, Europe and the Mediterranean. Long distance dispersal results from the movement of infested plants in trade.
Why the concern in the UK? The red palm weevil has been moving northwards in Europe and was found in the UK for the first time in October 2016. Numerous larvae and a few adult beetles were found inside a round-leaf fountain palm (Saribus rotundifolia) in Essex. The palm had been imported from the Netherlands in March 2016. The infested palm was destroyed, and the surrounding area surveyed by the Plant Health and Seeds Inspectorate (PHSI).
The weevil has the potential to survive outdoors in the warmer parts of southern England and in large cities such as London, wherever suitable host plants are found. Palms are probably more common outdoors in southern England than most people realise. Specimen palms are grown in many coastal resorts in south-west and south-east England and the botanical gardens in Tresco (Isles of Scilly) have a spectacular palm collection. Two of the most popular species grown in the UK, Chusan palm (Trachycarpus fortunei) and dwarf fan palm (Chamaerops humilis), are suitable hosts. The beetle has devastated ornamental palms in many areas of the Mediterranean, completely changing the landscape, and it is essential that we prevent the introduction of this major pest into the UK.
If you suspect the presence of red palm weevil, please report it to your local PHSI. Further information can be obtained from Defra’s UK Plant Health Information Portal.
If the beetle eventually gains a foothold in the UK, perhaps some entrepreneur could follow the lead of our Asian colleagues and open a restaurant serving the larvae as food.
Larvae kebab anyone?!