The red palm weevil is a beetle species curculionoideo , the curculionidae family, native to tropical Asia. Weevil is large , two to five centimeters. Its reddish ferruginous makes unmistakable. The larvae bore galleries over a meter in length logs. Their host plants are primarily family of plameras such as Cocos nucifera ( coconut palm ) , Elaeis guineensis ( palm oil ) and the genus Phoenix , including Phoenix canariensis ( Canary Island date palm ) and Phoenix dactylifera (date palm ), although attacks have been found in other species including Chamerops humilis palm . The plants , when they are affected by the plague , suffering yellowing and wilting , and can lead to death of the affected foot occur . Control of this pest is complicated and yet to lack of safe method , we proceed to the elimination of foot disease and suspected might be, to prevent the spread of the insect.
The red palm weevil has spread to many countries in Africa, Europe and America, outside their natural range due to anthropogenic transport.
The plague first appeared in 1994 in Spain , Almuñécar. Both this time and subsequent entries in various parts of eastern Andalusia , Murcia and Valencia , has come through infested palms from Egypt and other North African countries . The species is native to Southeast Asia.
It is currently affecting all aa palm of the most nearshore countries of southern Europe areas.
In 2005 , the pest was detected in the palm grove of Elche , considered the largest palm grove in Europe . In the Canary Islands threat Phoenix canariensis ( Canary Island date palm ) , jewel of the archipelago that could be jeopardized if the pest is progressing.
In summer 2011 the plague struck the city of Jerez de la Frontera , affecting more than 200 palm trees ; the Andalusian worked with the city to seek urgent measures against this insect.
After reaching the final stage , the larva is wrapped in a cocoon that builds fiber palm tree itself, where it becomes a pupa to complete their physical reorganization and become , after the process of metamorphosis into the adult insect. This process can take less than a week to several weeks, depending on environmental conditions.
The average life of this beetle in the adult stage , varies between 45 and 90 days, depending on environmental conditions : weather , food, etc. . Since egg hatches until his death has a half life of between 130 and 200 days.
The red palm weevil , complete their life cycle within the host, without changing palm until it has been completely destroyed , that is, until the animal is left without enough food for rearing the new breed or growth of the individual. The imago or adult individual manifests an intense daytime activity ; is when it goes in search of new specimens of palm tree and lay eggs infect new generations . Palm trees affected by this bug, usually the date palm ( Phoenix dactylifera ) , Canary Island palm ( Phoenix canariensis ) , coconut (Cocos nucifera) and Guinea palm ( Elaeis guineensis). Within a year this beetle is able to complete up to 3 biological cycles.
After fertilization , the adult female is capable of depositing 300 to 500 eggs in isolation through holes made by them in search of food or exploit the cracks or injury of the palm itself. These weevils are sensitive to kairomones exuded by palm trees as a result of wounds or pruning untreated , so do not find it very difficult to find new hosts . Spawning occurs in the terminal stems of the plant and in the soft tissue of the leaf bases . At oviposition , females bend the shanks up and anchored to the tissue with the thorns of the warm building on the third pair of legs until contacting the substrate with the ovipositor . After the eggs are protected and secured with a secretion produced by themselves. According MM T. Martin and Hair , females 211.1 average egg laying , of which 78.02 % hatch in a period of 3.35 ± 0.27 days leading to the legless larvae. The egg -white , cylindrical , bright color, has an oval shape and is about 1 to 2.5 mm . On the back of these eggs, structures called opercula appear .
Neonate larvae are whitish yellow , segmented , legless ( without legs ) have a chitinous head capsules , more brown than the rest of the body color. They consist of a horizontal conical powerful jaws with which burrow from the axils of the leaves to the crown , inside which feed voraciously . These insects remain in the larval stage an average of 95.53 ± 1.63 days , taking into account the results of the investigation, but may vary as this phase is strongly influenced by temperature. During the course of this period , the larvae undergo considerable growth because they spend measuring just 2 mm to 5 cm . The tone of the body also changes a bit , going to have a bright white to a dull yellowish white . Once completed larval development , build a cocoon fiber extracted from palm galleries , inside which undergo complete metamorphosis and go to the next state . The buds with a length of 4 to 6 cm and are located at the base of the trees .
The pupa , red , dark brown , is formed inside the cocoon formed by fibers of the palm. In that state, the weevil undergoes a metamorphosis , one last change before reaching the adult stage . This phase can last between 15 and 30 days. This value is similar to the 27.83 ± 3.13 days reported by MM Martin and T. Hair, but keep in mind again that these periods are determined by temperature. Once completed the period of pupation , the adult can stay a few more days within the fibrous cocoon.
The adult insect walking and flying moves , being able to reach long distances . However , it remains in the initially attacked palm if still available plant material for food. Otherwise, and attracted by the odors given off by palm trees with wounds, they colonize uninfested specimens . Thus began a new life cycle , more fertilization , other ovoposiciones , hatches , etc. will occur.
Remedies against the plague
Over 10 years ago that this plague came to Spain and Andalusia , Catalonia and Valencia in particular seem to be getting interested in studying solutions to the problem, but the evidence of effectiveness of the remedies are much longer and not yet found a definitive solution. Using parasites to end the red palm weevil demonstrates its effectiveness. The experts achieve a high mortality in the plague sweeping the palms of the municipality of Murcia. Today, following a suitable protocol and binding of several methods is achieved by reducing and completely recover the affected palms , with no cut in the bud the larvae. With the use by plant and foliar applications endotherapy showerheads and constant monitoring, very good results are obtained . Recently, it has made progress in controlling this pest by using innocuous biological agents to the environment through the use of the fungus Beauveria bassiana3.