PESTS - Rhyncophorus ferrugineus
Rhynchophorus ferrugineus (commonly referred to as red palm weevil) is a beetle belonging to the super-family Curculionoidae and the family Dryophthoridae.
This parasite, native from Indonesia and the coasts of southern India, is responsible for serious damage to palm plantations. Measuring 3 to 4 centimeters long in adulthood, this insect swarms by flying short distances from palm to palm.
It was with the help of humans and the transit of infected palms that individuals were able to reach the Arab Emirates in the 1980s and from there the species spread to the Middle East and in the countries of the Mediterranean basin.
In 1994, the first specimens were reported in Spain and in 2006 in Corsica and the Côte d'Azur.
The female lays eggs in the hundreds (between 100 and more than 500), which she deposits at the level of the central palms of the heads of the palms. The larvae feed on the living tissue of the base of the fins and dig galleries to finally reach the terminal bud causing the death of the palm.
In a year, a female, can theoretically produce 4 generations and generate nearly 4,000,000 individuals!...
THE ADULT (IMAGO)
Males and females can live up to 90 days.
Adult flight under our climate is observed from April to November, an adult has a flight capacity of 50 kilometers.
Its activity will be to reproduce and feed (unlike the palm butterfly that will live on its reserves).
The sexual pheromone involved in the reproduction of red weevils has been isolated and studied, the latter is used in trapping devices.
Each female once fertilized can lay up to 200 eggs.
The spawning procedure differs from the palmivorous butterfly: the female must dig with her rostrum a cavity in the soft tissues of the palm, to incorporate her egg so that it turns into a larva that will migrate to the inside of the palm.
The female also uses wounds that could be induced either by the size or by the damage of the palmivorous butterfly (the palmivorous butterfly prepares and facilitates the infestation of the red weevil!).
It is now known that wounded palms emanate from kairomones (odors) that attract palm pests specifically, so it is important to follow a preventive protocol when pruning a palm tree, especially during the pests pairing season.
In addition, we also know that an infested palm has a potential for attraction, this explains the finding of a pest relentless, the latter acting by successive over-infestations of the same sick palm, to its final withering.
DAMAGES SPREAD BY THE RED PALM WEEVIL
In Saudi Arabia palms trees are attacked either in the head (apical bud and meristeme) or at the base or on the first meter of the stipe.
1 – ATTACK IN THE APICAL BUD
At first asymptomatic, infestation can only become evident at a late stage.
The first symptoms correspond to an unusual change in the crown of the tree, which takes on a flared appearance of open umbrella.
The infestation then evolves with the progressive loss of the leaves, until the final collapse of the plant.
At this latter stage, colonies of parasites leave the attacked plant and migrate to adjacent palms.
2 – ATTACKS ON THE STIPE
In Saudi Arabia, most farmers collect offshots at the base of trunks for transplanting into neighbouring plots.
This technique generates wounds whose smell attracts parasites. The adults of Red Palms Weevils come to lay on these wounds and the larvae grow in the trunk.
The galleries caused by these larvae can be extremely important to hollow out part of the trunk.
The palm tree thus weakened progressively decays and can even break.