EUROPEAN AND MEDITERRANEAN PLANT PROTECTION ORGANIZATION 10-15862 PPM, point 7.1 Draft Data Sheet – Extensive version Diocalandra frumenti IDENTITY Name: Diocalandra frumenti (Fabricius, 1801) Syst. Elenth. 2:438 Synonyms: Calandra frumenti (Fabricius, 1801) Sitophilus frumenti (Fabricius) Schoenherr, 1838:982 Diocalandra frumenti (Fabricius) Faust, 1894:354 Calandra bifasciata Boisduval, 1835: 445 Calandra montrouzieri Chevrolat, 1882: CXXVIII Sitophilus subfasciatus Boheman, 1838: 971 Sitophilus stigmaticollis Gyllenhal, 1838: 972 Diocalandra frumenti var. stigmaticollis (Gyllenhal) Kolbe, 1910: 46 Sitophilus subsignatus Gyllenhal,1838: 973 Sphenophorus cruciger Motschulsky, 1858:69 Calandra punctigera Pascoe, 1885: 305 Callandra sechellarum Kolbe,1910:46 Taxonomic position: Insecta: Coleoptera: Curculionidae: Rhynchophoridae: Diocalandrini Notes on taxonomy and nomenclature: The above taxonomic determination and the following notes follow a general scheme of classification used by E. C. Zimmerman in his 8 volume series of Australian weevils. Zimmerman (1993) raised the Rhyncophoridae to Family status within the super family Cuculionoidea and proposed a new tribe, the Diocalandrini to include the genus Diocalandra with Arecaceae as hosts but excludes the seed feeding genus Sitophilus. Diocalandra are small, slender weevils but the loss of sternite 9 in male specimens separates them from Sitophilus that they closely resemble. Morimoto (1978) has recognized and produced a key to 9 species of Diocalandra. D. frumenti was originally described by Fabricius in 1801 as Calandra frumenti but since the adults vary greatly in size, colour and maculation (Zimmerman, 1993), the species has been redescribed many times (see above synonomy). Zimmerman (1993) indicated that this species closely resembles D. taitense (Guèrin-Mèneville) from the central and eastern Pacific islands with which it is often confused and he produced a key to separate the two species. Common names: Palm weevil borer (English), four spotted coconut weevil (English), lesser coconut weevil (English), small weevil (Taiwan). Bayer computer code: DIOCFR Phytosanitary categorization : HOSTS D. frumenti has been collected from at least 17 genera of Arecaceae, with most of these being economically important palm species cultivated for food, oil, housing or landscape plants. Major hosts include coconut (Cocos nucifera) and landscape palms such as Phoenix canariensis and its hybrids (Kahlshoven, 1981, Salomone Suárez et.al., 2000b). Minor hosts include date palm (Phoenix dactylifera), oil palm (Elaeis guineensis), attap (Nypa fruticans) and a large number of other landscape palm species. The literature records include Archontophoenix alexandrea, Bismarkia sp., Caryota sp., Chrysalidocarpus lutescens, Dypsis lutescens, Dypsis lucubensis, Howea belmoreana, Mascarena verchaffeltii, Metroxylon sagu, Phoenix loureirii, Phoenix roebelenii, Ptychosperma macarthurii, Ravenea rivularis, Roystonea regia, Sabal palmeto, Washingtonia spp. and Wodyetia bifurcata (AVA, 2006; Lepesme, 1947; NGIA, 1998; Salomone & Caballero Ruano, 2008). It is possible that the species has only recently adapted to the ornamental species in the genus Phoenix. Howard et. al. (2001) who cited Lever (1979) as a reference, indicated that species in the Areca and Borassus genera in addition to Sorghum were also attacked by this weevil. Although D. frumenti has been raised under artificial conditions on sugar cane, the EPPO Expert Working Group for the Pest Risk Analysis of Diocalandra frumenti concluded that the pest is attracted to decaying tissues, but did not consider Poaceae as hosts, as there is only this record. GEOGRAPHICAL DISTRIBUTION “CABI map 249” provides a distributional map of Diocalandra frumenti. EPPO region: Spain (Canary Islands) Africa: Madagascar, Mauritius, Seychelles, Somalia, Tanzania (including Zanzibar). Asia: Bangladesh, India, Indonesia, Japan, Malaysia, Myanmar, Philippines, Singapore, Sri Lanka, Taiwan, Thailand. Oceania: Australia (Northern Territory, Queensland, Western Australia), Guam, Palau, Papua New Guinea, Samoa, Solomon Islands. South America: Ecuador. Note: In Spain, the species was found in 1998 in the south of Gran Canaria, Canary Islands (González Núñez et al., 2002). In Japan, the species was discovered in 1977 on Okinawa, Ryukyu archipelago from palm trees introduced from Taiwan (Morimoto, 1985). BIOLOGY The life cycle was outlined by Hill (1983) to take 10-12 weeks, and included 4-9 days as eggs, a larval development of 8-10 weeks and a 9-10 day pupation period (in the wild). More recently, Liao & Chen (1997) reported a similar life cycle duration with individual stages for egg, larvae and pupae as 6-10; 35-40; and 10-16 days respectively. They indicated that adults survived 15-22 days. The life stage durations are similar to these found by González Núñez et al. (2002) in laboratory trials (25 ±1°C, 70%±10 HR) using sugar cane as a food source. Adult D. frumenti weevils are attracted to sap exuding from wounded palm tissue (Kalshoven, 1981) or from flower bases (Lepesme, 1947) and lay eggs in various sites: inflorescences, the bases of petioles or peduncles, or in cracks near adventitious roots at the base of the stem. In Taiwan, female D. frumenti drill holes with their mouthparts to lay eggs near the surface of an unopened leaf sheath on the palm Mascarena verchaffeltii (Liao & Chen, 1997), whereas González Núñez et al. (2002) reported that in experiments with sugarcane as the food source, D. frumenti laid eggs 1.0-2.5 mm deep, and that no sign of oviposition could be seen from the exterior of the cane. The average fecundity was 0.13 egg per female per day during experiments on sugarcane (González Núñez et al. 2002). They considered this low fecundity to be balanced by the high longevity of the adults, although Liao & Chen (1997) reported that the adults survived only 15-20 days. The larvae can bore galleries in any part of the palm: roots, petioles, inflorescences, fronds, leaf sheaths, fruits and to all heights of the trunk (González Núñez et al., 2002; Hill, 1983). They develop entirely within the palm tree. Gummy exudates are usually seen near the gallery entrance. Pupation takes place within the larval gallery but no cocoon is formed. González Núñez et al. (2002) found that on sugar cane, the pupation chamber is formed near the epidermis of the cane used as food, a circular hole of 1.5 mm of diameter being formed for exit of the pest. This hole is filled with debris, and the thin epidermis of the cane remains as a protection. Similarly, Liao & Chen (1997) indicated that the larvae move toward the edge of the leaf sheath to pupate. The adults remove the debris with their mouthparts to emerge. Liao & Chen (1997) indicated that 10 or more larvae could develop in each leaf sheath and Salomone Suárez et al. (2000b) estimated that hundreds of individuals could be found in a single palm tree. Picture: Eduardo Franquiz Alemán (2008) Galleries of D. frumenti in sugar cane. used as a food source. Attack of Phoenix canariensis by D. frumenti Picture by Francesco Salomone (2008) DETECTION AND IDENTIFICATION Symptoms Feeding damage by weevil larvae may cause premature yellowing and collapse of palm fronds, beginning with the exterior fronds and moving to the interior ones (Salomone Suárez et al., 2000b). Infestation is recognised by the emergence holes of 1 to 2 mm diameter in sound tissues of new and old fronds and in the leaf bases (NGIA, 1998; Salomone Suárez et al., 2000b). Attack is usually to old, weakened or injured parts of palms, especially to the edges of older fronds or wound sites (Zimmerman, 1993). Gummy exudates at the opening of galleries can be observed (Salomone Suárez et al., 2000b). In Australia, the stubs of fronds cut from the palm or broken by winds are frequently the areas initially attacked. The larvae bore distally from the petiole (NGIA, 1998; Howard et al., 2001). Another symptom may involve the premature shedding of fruits (NGIA, 1998). Vanderplank (1953) claimed that damage by D. frumenti larvae could cause gumosis and immature nutfall on coconut palms. However, it is possible that the weevils are attracted to the gelatinous exudates caused by wounding (Kalshoven, 1981) or damage by other insect species, such as Tirathaba (Lepidoptera: Pyralidae) (Lepesme, 1947) and are not the primary cause of the gumosis. Damage can occur on roots, fronds and fruit stalks (Howard et al., 2001). Death of mature Phoenix canariensis has been reported from Australia (NGIA, 1998) and this weevil is associated with palm deaths in Gran Canaria (Salomone & Ruano, 2008). Morphology The eggs are white, slightly elongate and about 0.9 mm long by 0.3 mm wide (Liao & Chen, 1997). Larvae are white, slightly curved and about 7 mm long when fully grown (9 larvae were measured by Stuart Smith, Biosecurity and Product Integrity Division, Department of Primary Industry, Fisheries and Mines, Northern territory, Australia). The dark brown mandibles are visible and they are slightly plumper at the distal end. Pupae are also white, and about 6-7 mm long. Adults are small (6-8 mm long), shiny to dull dark-brown to black weevils with four large reddish to brownish-yellow spots on the elytra. Sexual dimorphism is evident with females being considerably larger and by the shape of the posterior apex, and the length and thickness of the rostrum: the male rostrum being shorter, thicker, and more curved (Hill, 1983). Fronds of Phoenix canariensis attacked by D. frumenti Picture: Servicio de Sanidad Vegetal, Gobierno de Canarias (2008) Galleries of D. frumenti in fronds of Phoenix canariensis Picture: Servicio de Sanidad Vegetal, Gobierno de Canarias (2008) Trunck of Phoenix canariensis attacked by D. frumenti Picture: Servicio de Sanidad Vegetal, Gobierno de Canarias (2008) Galleries of D. frumenti Picture by Francesco Salomone (2008) Detection and inspection methods Infestation by D. frumenti can be recognised by the emergence holes on new and old fronds and leaf bases and should be the normal method of inspection (NGIA, 1998). Any palm with symptoms of premature yellowing of the fronds, particularly if the yellowing sequence is from the outside to the inside of the crown, or the collapse of palm fronds should be inspected for the presence of emergence holes and adult beetles or larvae associated with these galleries. Nevertheless, the species is cryptic and is therefore difficult to detect. MEANS OF MOVEMENT AND DISPERSAL Spread: No data is available on natural spread, but adults can move over at least small distances and this could occur in a nursery situation. Sale or exchange of infested palms can ensure spread of the pest over long distances. Pathway: Palms for planting from countries where D. frumenti occurs. Palm trees are grown around the Mediterranean for fruit production (Phoenix dactylifera) or ornamental purposes (Phoenix canariensis and many other species). PEST SIGNIFICANCE The precise status of this weevil as a pest is open to dispute; some entomologists believe that the damage is primary and results in appreciable crop losses, but other maintain that this damage is purely secondary (Hill, 1983). It is considered that the species is associated with palm deaths in both Australia and the Canary islands (NGIA, 1998; Salomone & Ruano, 2008). Economic impact Feeding damage by larvae may cause premature yellowing and collapse of palm fronds in the crowns (NGIA, 1998; Salomone & Ruano, 2008). Damage can occur on roots, fronds and fruit stalks which will reduce the vigour of the plant. The activity of D. frumenti allows the entry of the saprophitic micro-organisms. Gliocladium vermoeseni, Thielaviopsis paradoxa, Fusarium spp., Aspergillum spp., Cladosporium spp. and Pennicillium spp. were detected in tissue samples of palms damaged by D. frumenti in the Canary Islands (Salomone & Caballera Ruano, 2008). Hill (1983) listed D. frumenti as a major pest of coconut (Cocos nucifera) and oil palm (Elaeis guineensis). The larvae of D. frumenti may cause gumosis and nutfall of immature coconuts. D. frumenti has also been found attacking Phoenix dactylifera and its hydrids, though impacts on this crop are not detailed (Salomone Suárez et al., 2000b). Hill (1983) considered D. frumenti to be a minor pest of date palm. D. frumenti has the potential to damage a wide range of landscape palms (see above) and is known to have caused the death of mature ornamental palms of Phoenix canariensis in Queensland (Australia) (Giblin-Davis, 2001) and has been associated with palm deaths in Gran Canaria. Phoenix canariensis is by law the Canary Island vegetal symbol (Ley 7/1991 de Símbolos de la Naturaleza para las Islas Canarias) and is represented by over 5,000.000 natural palms in La Gomera (one of the smallest island of the archipelago), and by 55.000 palms in Gran Canaria where it is found in natural ecosystems (Salomone & Caballera Ruano, 2008). In Taiwan, Liao & Chen (1997) reported attacks of D. frumenti on Mascarena verchaffeltii, Roystonea regia with a damage comprised between 5 and 20%, while the damage on Phoenix loureiri was estimated lower than 5%. In Australia, damage by this pest is usually very minor, although where it is associated with another weevil pest, the sugarcane weevil borer Rhabdoscelus obscurus, the combined attack can cause significantly greater damage and even death of susceptible host palms (NGIA, 1998). In the Northern Territory, where the sugarcane weevil borer is absent, the impact is low and there is no effort to manage D. frumenti. Picture by Francesco Salomone. Damage caused by D. frumenti on young palms, Maspalomas, Gran Canaria December 2000 Control Control of D. frumenti is difficult because of its cryptic nature. Cultural control Excessive pruning, shaving of the trunk, inadequate fertilization and watering are believed to help the establishment of the species (Salomone & Caballera Ruano, 2008). Pruning should be avoided. NGIA (1998) recommended several cultural control methods against D. frumenti. These include removing and destroying old and dead fronds to reduce breeding sites and adult hiding places, protecting cut surfaces with an acrylic paint (or tar, Lever, 1969), and covering adventitious roots at the stem base with soil to prevent infestation as earlier recommended by Lever (1969). Chemical control There are no registered insecticides for this weevil in northern Queensland (NGIA 1998), but a chemical applied against another weevil pest there (chlorpyrifos) would also reduce the numbers of D. frumenti. It is likely that persistent contact chemicals would reduce D. frumenti attack to the base of palms if applied as a protectant insecticide as recommended by Lever (1969). Protecting the rachis of the frond and the frond bases would be more difficult even if such a chemical was registered for that use. Salomone Suárez et al. (2000a) have proposed several studies to test the efficacy of chemical treatments to D. frumenti and the possible interactions between this weevil and pathogens which may be involved in the serious damage and death of palms in the Canary Islands. A patent disinfection device for fumigating palms infected with D. frumenti has been submitted for assessment (Roca Michavila, 2006). Trapping Salomone & Ruano (2008) have outlined a project to determine whether this species produces an attractant pheromone or if attractant bait for the weevil could be developed. If the studies produce acceptable results, then the pheromone or bait could be integrated into a trap for the palm weevil borer. Biological control Several biological agents are known to attack D. frumenti but are unlikely to provide effective control if chemical treatments are also used. Vanderplank (1953) reported that in Tanzania, two species of ants, Anoplolepis custodiens and Oecophylla smaragdina would prey on this beetle in coconuts. Both adults and larvae of the histerid beetle Plaesius javanus and larvae of the rhagionid fly Chrysophilus ferruginosus are predators on D. frumenti larvae (Lever, 1969; Kalshoven 1981). Giblin-Davis (2001) (citing Lever, 1979) claimed that the same generalist predators of the sugarcane weevil borer would also attack D. frumenti. Lever (1969) reported that 40% of D. frumenti larvae were found to be parasitised by a braconid wasp Spathius apicalis. These species are not recorded in the EPPO region. It is possible that if these species or other generalist predators are present in an area, that they may maintain some control over this beetle pest and similarly, natural enemies of closely allied species such as D. taitense could be tested and perhaps introduced against D. frumenti (Salomone Suárez et al.,2000b). Phytosanitary risk The most likely pathway for D. frumenti to enter the EPPO region is through the import of palm plants for planting, derived from countries where D. frumenti occurs. The example of another serious palm borer Rhynchophorus ferrugineus that has recently been introduced to Spain and is currently spreading in the Near East has shown that this type of insect is likely to be moved unnoticed on palm material. PHYTOSANITARY MEASURES D. frumenti is listed in the Moroccan Bulletin official n°5022 of the 18 July 2002 as a pest for which introduction is prohibited. On 12 April 2002, the Republic of Korea sent a notification to the World Trade Organization Committee on Sanitary and Phytosanitary Measures stating that “as the result of Pest Risk Assessment (PRA), […] the Ministry of Agriculture and Forestry is proposing the addition of 24 species of quarantine pests such as Xylophilus ampelinus, Diocalandra frumenti, Lecanoideus floccissimus, etc. for susceptible host plants” (PMC (2002) G/SPS/N/KOR/111). To be completed after PRA ACKNOWLEDGEMENTS This datasheet has been prepared by the EPPO Secretariat on the basis of a text prepared by Stuart Smith from the Department of Regional Development Primary Industry, Fisheries and Resources in the Northern Territory of Australia. BIBLIOGRAPHY Anonymous (2008) CABI distribution maps of pests, Diocalandra frumenti, Map no. 249. CABI, Wallingford, UK. AVA (2006) AgriFood and Veterinary Authority of Singapore. p.40 of Annual Report 2005/06. The coconut palm weevil, Diocalandra frumenti Fabricius was found in a first report on Metroxylon sagu in Singapore. http://www.ava.gov.sg/NR/rdonlyres/0676D1EB-C401-4038-9D8D84A01B52DD27/11973/AVAAR0506corporate.pdf. Website visited November 2008. Bulletin officiel n° 5022 du 7 joumada I 1423 (18 juillet 2002) Maroc http://www.mcinet.gov.ma/mciweb/baseslegales/200.pdf http://www.eppo.org/ABOUT_EPPO/EPPO_MEMBERS/phytoreg/originals/PRF-MA02rev.doc Giblin-Davis RM (2001) Borers of palms. In: Insects on palms. Edited by FW Howard, Moore, D, Giblin-Davis RM, Abad, RG. CABI Publishing, Wallingford, GB, 287-288. González Núñez M, Jiménez Álvarez A, Salomones F, Carnero A, Del Estal P, Esteban Durán JR (2002) Diocalandra frumenti (Fabricius) (Coleoptera: Curculionidae), nueva plaga de palmeras introducida en Gran Canaria. Primeros estudios de su biología y cría en laboratorio. Boletín de Sanidad Vegetal Plagas 28(3), 347-355. Hill DS (1983) Diocalandra frumenti. In: Agricultural insect pests of the tropics and their control. 2nd Edition. Cambridge University Press, Cambridge, UK, pp. 478-479. Howard FW, Moore D, Giblin-Davis RM & Abad RG (2001) Insects on palms. CABI Publishing. 400 pp. Kalshoven LE (1981) Pests of crops in Indonesia. 2nd Edit., Van Hoeve Jakarta 1981. 701 pp. Lepesme P (1947) Les insectes des palmiers. Paul Lechevalier (Edit.) Paris. 904 pp. Lever RJAW (1979) Pests of the coconut palm. FAO Agric. Studies No 77. FAO Rome. 190 pp. Liao CT & Chen CC (1997) Primary study the insect pests, hosts and ecology of weevil attacking ornamental palm seedlings. Bulletin of Taichung District Agricultural Improvemnet Station 57, 43-48 (abst). Morimoto K (1978) Checklist of the family Rhynchopiridae (Coleoptera) of Japan, with descriptions of a new Genus and five new species. Esakia 12, 103-118. Morimoto K (1985) Supplement to the check-list of the family Rhynchophoridae (Coleoptera) of Japan, with descriptions of a new genus and four new species. Esakia 23, 67-76 (abst.). NGIA (1998) Web site of the Nursery and Garden Industry Australia. The nursery Papers, Issue no 1998/02. Getting control of weevil borers and leaf beetles in palms. hhtp://www.ngia.com.au/np/pdf/98no02.pdf PMC (2002) G/SPS/N/KOR/111 http://www.ipfsaph.org/cds_upload/kopool_data/WTOSPSNF_0/en_nkor111.doc http://www.ipfsaph.org/cds_upload/kopool_data/WTOSPSNF_0/fr_nkor111.doc Roca Michavila J (2006) Method for the curative treatment of Diocalandra frumenti infestations. http://www.wipo.int/pctdb/en/wo.jsp?WO=2007099191&IA=WO2007099191&DISPLAY=S TATUS Salomone F, Cabellero Ruano M (2008) New pest for Phoenix canariensis Hort. Ex. Chab. in its original habitat, the Canary Islands. Situation report. 2 pp. Salomone Suárez F, Gonzalo Bartolomé O, Hernández Hernández J, Rodríguez Rodríguez R, Muñoz Carpena R (2000a) Identificación y propuestas de control de factores bióticos y abióticos que producen depresión y mortalidad de palmeras naturales o implantadas en Canarias. Granja (eds. Cabildo de Gran Canaria) 7, 9-13. Salomone Suárez F, Carnero Hernández A, Marrero Ferrer M, González Hernández A (2000b). Presence in the palearctic zone of Diocalandra frumenti Fabricius, (Coleoptera, Curculionidae). Boletín de la asociación Espaňola de Entomología 24, 263-264. Vanderplank FL (1953) Causes of coconut nutfall and gumosis. Nature 172, 315 – 316. Zimmerman EC (1993) Australian Weevils (Coleoptera: Curculionidea). Vol. III: 99-102. CSIRO Publications, Australia.