Palm Trees & The Red Palm Weevil Infestation

The Red Palm Weevil, Rhynchophorus ferrugineus Olivier (RPW), is the most deleterious pest of palm spreading rapidly in palm growing countries around the globe.
It was accidentally introduced into the territory of the European Union. Its presence was reported by Spain in 1996 and this was followed by reports from Italy in 2004, Greece in 2005, Cyprus and France in 2006, Malta and Portugal in 2007, and Slovenia in 2009. Nowadays it has spread among all Mediterranean Member States.

So what the RPW looks like and what damage it can cause
The RPW is about 3 cm long, has a characteristically long-curved rostrum of reddish-brown color. Its larvae weaken the host plant till the final destruction by excavating holes in palm trees’ trunks up to more than one meter long. The RPW normally has three generations per year. Females lay about 300 eggs and it takes about four months for the new generation of adult beetles to emerge. And there is a possibility for one palm tree to simultaneously host hundreds of insects at various stages of development.

Lifecycle of the RWP 

Why has RPW become one of the most important pests of palm trees in the world?
The popularity of the insects is caused by the number of several factors such as:
• Strong ability to fly long distances;
• Uninterrupted dispersal distances from more than 1km and up to 7 km away in short time after being released;
• Larvae’s developing within the tree trunk by destroying its vascular system and causing the collapse and death of the tree.

How to detect the RPW:
At the early stage of infestation symptoms are hardly visible so it is very difficult to detect one. But when the symptoms become visible later, it might mean that adult beetles have often already left the tree. Moreover, at the same time on the same tree all stages of developing such eggs, larvae, pupae and adult insects can be found.
The main damage is caused by the larvae which makes tunnels and large cavities. That means that the larvae can be found anywhere within the palm. They feed on the growing tissue in the crown of palms, often destroying the apical growth area and causing the eventual death of the palm.

There are several methods used for detection of the RPW:
•       Bioacoustics method. Bioacoustics is a very useful tool for the early detection of RPW. An automated approach has been researched and implemented by the Consortium based on capturing and automatically recognizing the acoustic emission resulting from typical behaviour such as the feeding of the target pests.
•       Visual method. In the early stages of infestation, a brown viscous fluid oozes out from the tunnels in the trunk and base of the frond petiole. This liquid solidifies upon exposure to air and some brown flakes can be seen. Another symptom is the presence-boreholes of chewed-up fibres. These fibres give out a very foul smell, characteristic of RPW damage. This is a real confirmation of the presence of fresh damage inside the palm. Other symptoms include yellowing and/or dried central “heart” leaves, damage of leaves’ bases, and damaged leaves that are under partial or total slope resembling an open “umbrella”. Other evidence for RPW presence is the cocoons found in damaged leaves/type/ground close to the host, and the pest itself. Overall, the slope of the palm tree and the sight of damage (penetration) on the trunk reminds the increased state of danger.