The deadly red palm weevil

The red palm weevil (Rhynchophorus ferrugineus Olivier) is an insect of the Coleoptera order that causes major damage to palm trees. It is a reddish insect of about 2-5 cm in length that has a long snout and can be very fatal to various species of palm. The insect originates in Polynesia and it seems that it has reached the southern Europe in the ’90s. It originally attacked the coconut trees, but as it is very adaptable, it begun infesting the various forms of palm. In the recent years, from 2007 and on, there is a spread in Greece following an outbreak in Spain and in other countries of the Mediterranean, infecting mainly two types of palm trees, the Phoenix Dactylifera and the Phoenix Canariensis, although it does also attack others.

The insect can fly for a kilometre without stopping. It kills palm trees by eating from the bark and burrowing into the main stem. It then lays its eggs inside and the cycle repeats itself. The weevil lays some 200 eggs that take between two and 18 months to reach full development. In the Mediterranean where the winder is mild winters and the summer is hot and humid the mating cycle of the bug tends to be continuous.

It is difficult to detect the presence of a plague when they initially attack. Falling leaves and cocoons found in the bores in leaves can be initial signs of infestation. In a matter of weeks virtually the entire crown will be affected which will result in the death of the tree. In fact, it is often too late to save the tree after the first signs of infestation became visible. Unfortunately there is a lack of proven treatments and prevention measures. Insecticides, in the form of fumigation and injections, can be a solution but success in treating very much depends on how early it is detected. Also trees that are cured remain more susceptible to re-infestation due to the damage already caused.

According to the Catalunya Ministry of Agriculture the following measures must be applied:

  1. Severely affected or dead palm trees must be uprooted and burnt in order to prevent the adult insects from spreading.
  2. The plague tends to enter palm trees via wounds, such as those caused by pruning leaves, since the smell of sap attracts the beetle. As a result, it is advisable not to prune trees in areas near outbreaks. Pruning is best done in winter when the plague spreads less actively.
  3. Chemical treatments must be applied to the crown of the palm tree and on pruning wounds. This operation is strongly advised in areas surrounding the outbreak of the plague. The following compounds are especially recommended: Fenitrotion 40 CS, Fenitrotion 40% WP, Diazinon 24% CS, Fosmet 45% CS, Imidacloprid 20% SL, Thiametoxam 25% WG, Carbaril 50% WP and Carbaril 85% WP. Of these products, only Fenitrotion 40% CS and Imidacloprid 20% are authorized for use in parks and gardens. An adherent can be added to improve the persistence and other characteristics of these insecticide products.
  4. Ensure plentiful irrigation during the summer.

– You can download a document issued by the Ministry of Agriculture of Cyprus containing information and measures against the red palm weevil from here
– A useful resource about plant protection and the spread of dangerous pests in the Mediterranean is EPPO (European and Mediterranean Plant Protection Organization).