Rhynchophorus ferrugineus or the red palm weevil is a sweet looking creepy-crawly, and yet for ornamental palm trees it is a dangerous pest. In its native habitat of Southeast Asia and Papua New Guinea, the larvae of the beetle – eaten raw or grilled – are a popular delicacy, rich in protein. The red palm weevil reached the Mediterranean region, including Portugal, through palm tree imports in the late 1990s via the Middle East and Morocco. Thousands of palm trees have already fallen victim to it, causing millions of Euros of damage.
Its preferred hosts are the Canary palm, the Washingtonia and the date palm. When the pest has found the object of its desire, it emits a scent that attracts both females and males. A few days after mating larvae hatch from the fertilised eggs and eat their way into the heart of the palm tree. After pupation (2-3 months) a new beetle generation hatches from the cocoons, which will remain within the host palm until it becomes overcrowded and is unable to provide enough food. There are different methods of treatment for infested palms. Microwave devices set up around the trunk are supposed to kill the brood with electromagnetic energy. Experiments have been made with essential oils and nematodes also known as roundworms that invade the larvae and beetles. The spores of the Beauveria bassiana fungus, in liquid form, are also used. Other palm tree owners swear by the use of soap suds, flushed into the crown with hot water devices. Success has been achieved with pheromone traps in Sicily and in the Côte d'Azur. However, "chemical warfare" in the form of Imidacloprid, a product from the Bayer Group, is the only measure that promises a high success rate. This insecticide comes under the trade names Admire, Confidor, Connect, Evidence, Gaucho, Leverage, Lizetan, Muralla, Provado and Trimax. Imidacloprid is a systemic insecticide, acting as a contact as well as stomach insecticide. According to the manufacturer, it is diluted with water and directly injected into the heart of the palm – in the middle of the upright palm leafs – and between the individual palm frond bases right down to where the trunk begins. It is best to avoid the use of high pressure, as the resulting spray would contaminate the surrounding area. Protective clothing and a proper breathing mask are mandatory in any case, as this agent is quite aggressive – but effective if properly dosed and applied. Attempts to inject chemicals through endotherapy are efficient, but very costly. With this method, a hole is drilled into the stem and the insecticide is pumped into the Palm’s interior through hoses.