Rhynchophorus ferrugineus

Primarily due to the existence of numerous color forms across their ranges, the taxonomy and classification of red palm weevils has undergone a number of changes in understanding and circumscription. As such, the information in the literature should be viewed as a compilation of data which may apply to both species, depending primarily upon the biogeography; accordingly, the vast majority of publications presumably do refer to R. ferrugineus rather than vulneratus, as the former is by far the most widely invasive. The most recent genus-level revision in 1966 recognized two species of red palm weevil, ferrugineus and vulneratus, and for decades these were interpreted as separate taxa. A genetic study in 2004 concluded that vulneratus was not distinct from ferrugineus, and treated them as synonyms, a view that was accepted until 2013, when yet another genetic study came to the opposite conclusion, based on more comprehensive geographic sampling. Accordingly, the "red palm weevil" species that appeared in the US was vulneratus rather than ferrugineus, though the latter is the invading species in all of the other global introductions. ==Distribution==

Range The native range of this species is considered to include Bangladesh, Cambodia, China, India, Japan, Laos, Pakistan, Philippines, Sri Lanka, Taiwan, and Vietnam; records from Indonesia, Malaysia, Myanmar, Singapore, and Thailand largely or exclusively refer to R. vulneratus. The model of Ge et al 2015 predicts a wide area of invasion based on climate suitability, throughout the south, north to the east and west to central China. Oceania • Australia unassessed • absent from New South Wales • absent from the Northern Territory • Queensland unassessed • absent from South Australia • absent from Tasmania • absent from Victoria • absent from Western Australia • absent from Papua New Guinea This expansion has been due to the movement of infested planting material from contaminated to uninfected areas. All known hosts of R. ferrugineus as compiled from sources by CABI ISC are: Areca catechu, Arenga pinnata, Borassus flabellifer, Brahea armata, B. edulis, Butia capitata, Calamus merrillii, Caryota cumingii, C. maxima, C. urens, Chamaerops humilis, Cocos nucifera, Corypha umbraculifera, C. utan, Elaeis guineensis, Howea forsteriana, Jubaea chilensis, Livistona chinensis, L. decora, Metroxylon sagu, Phoenix canariensis, P. dactylifera (date palm), P. sylvestris, Roystonea regia, Sabal palmetto, Trachycarpus fortunei, Washingtonia filifera, and W. robusta. Lab studies have reared the insect on diets of Agave americana and Saccharum officinarum, but these findings have not been observed in the wild. There is evidence that the weevil prefers the 'Sukkary' cultivar of date palm to other cultivars. The palm species W. filifera and Chamaerops humilis may be moderately resistant to the red palm weevil, though both are known hosts. ==Life cycle==

This weevil usually infests palms younger than twenty years. While the adult causes some damage through feeding, it is the burrowing of the larva into the heart of the palm that can cause the greatest mortality of trees. The adult female lays approximately two hundred eggs on new growth in the crown of the palm, at the base of young leaves, or in open lesions on the plant. Oviposition After fertilization, the adult female can lay between 300 and 500 eggs. They lay in holes they produced while searching for food, or take advantage of the cracks or wounds in a recently cut palm. At oviposition, females bend upward and the tarsi are anchored to the tissue with the spines of the third pair of legs to push the ovipositor into the tough palm tissue. After laying, the female protects and secures the eggs with a secretion that rapidly hardens around the eggs. On average, females produce 210 eggs per clutch, most of which hatch over a period of 3 days. The eggs are white, cylindrical, glossy, oval shaped, and measure . The back of these eggs possess special 'gill cover' structures that provide the developing insect with oxygen. Larvae The neonate larvae are yellow-white, segmented, legless, and have a chitinous head capsule that is a darker brown than the rest of the body. They have powerful horizontal conical jaws which they use to burrow from the axils of the leaves to the crown, where they feed voraciously. Upon completion of larval development, the larva will sometimes emerge from the trunk of the tree, and build a pupal case of fiber extracted from the galleries inside the palm. The larva will then undergo metamorphosis into an adult. The larva will also weave a pupal case at the base of the palm fronds within the frond itself or at the centre of the base of the plant. While they prefer to attack palms that are already infested or weakened by other stresses, they will colonize healthy palms. ==Predators, diseases, and parasites==

R. ferrugineus is predated by Chelisoches morio, infected by a cytoplasmic polyhedrosis virus and Metarhizium pingshaense, and parasitized by Heterorhabditis indicus, Hypoaspis spp., Praecocilenchus ferruginophorus, Scolia erratica, Steinernema carpocapsae, and Steinernema riobravis. ==Behaviour==

Studies show that this insect is attracted by ethyl acetate, 2-methoxy.4.vinylphenol, gamma-nonanoic lactone, 4SSS-ferrugineol, 50H and 4me-9-5Kt. ==Symptoms of infestation==

The infestation of the pest can result in yellowing and wilting of palms, that may lead to the death of the affected plant. The crown wilts first, and lower leaves will follow, due to damage to vascular tissue. Major symptoms such as crown loss or leaf wilt are usually only visible long after the palm has become infested. Secondary infections of opportunistic bacteria and fungi may occur within damaged tissues, accelerating decline. By the time these external symptoms are observed, the damage is usually sufficient to kill the tree, and the infestation may have been present for six months or longer. In high-density infestations, sounds of the larvae burrowing and chewing can be heard by placing one's ear to the trunk of the palm. Recent research has been conducted using electronic listening devices or dogs trained to recognize the scent of weevils or palm decay to detect infestations at low densities earlier in the process. Image:Phoenix_canariensis_first_sign_of_infection_with_Rhynchophorus_ferrugineus.JPG|Canary Island date palm, with first obvious infestation signs Image:Phoenix canariensis destroyed by Rhynchophorus ferrugineus 1.JPG|Destroyed crown of CIDP Image:Phoenix canariensis destroyed by Rhynchophorus ferrugineus 4.JPG|Bases of palm leaves fallen from the crown of the tree, with burrows and extracted pupal cases Image:WeevilStrickenDatePalm-in-Kfar Saba-RJP.jpg|Date palm killed by weevils ==Control==

The main control method is through the application of a systemic insecticide. Insecticide is usually applied through a funnel about above the infested area of the trunk. The red palm weevil can be monitored using pheromone lures and alternative forms of control use field sanitation and mass trapping with traps baited with pheromone and plant derived semiochemicals. New alternative technologies using semiochemicals and bioinsecticides are being developed to attract the weevils to a point source and kill them. Another management technique is to drench the base of palm fronds with the entomopathogenic fungus Metarhizium robertsii (syn. M. anisopliae, Entomophthora anisopliae), or Beauveria bassiana. An Italian company claims to have developed a microwave collar that can be used to sterilize individual trees. For early detection, bioacoustic analysis may be implemented by inserting a sensitive microphone into the tree and recording any produced sounds. These sounds are analyzed by digital signal processing and artificial intelligence to decide whether they are generated by palm weevils. Palms' natural defense against this weevil is understudied. ==Prevention==

As the weevil prefers to lay its eggs in softer tissues, avoiding mechanical damage to plants can help to reduce infestation. Tarring wounds after pruning a plant of dead or old leaves can also reduce the probability of infestation. The movement of plant material such as husks, dead leaves, or untreated coir from infested to uninfested areas is not recommended. ==Culinary uses==

The larval grub is considered a delicacy in Vietnam. In Vietnam, the larvae are usually eaten alive with fish sauce. Other methods of cooking include toasting, frying and steaming. They are eaten with sticky rice and salad or cooked with porridge. The larvae are known in the Vietnamese language as đuông dừa ("coconut beetle-larva"). ==References==

• European Commission - Directorate-General for Health & Consumers (2011) The insect killing our palm trees. EU efforts to stop the Red Palm Weevil. • CISR: Red Palm Weevil Information • Red Palm Weevil Home • Red Palm Weevil Control & Tips • Red Palm Weevil Research Chair, King Saud University, Riyadh • Greek webpage dedicated to management • USDA information page