Taxonomic name: Raoiella indica (Hirst)
Common names: coconut mite, coconut red mite, frond crimson mite, leaflet false spider mite, red date mite, red palm mite, scarlet mite
Organism type: arachnid
Raoiella indica (the red palm mite) is a parasitic mite invasive in the Caribbean region; it poses a serious threat to many plant industries. Its recent invasion is referred to as the biggest mite explosion in the Americas. Already taking serious tolls on coconut, ornamental palm and orchid crops, its infestation of new species and spread to new locations makes it one the most menacing pests to the Western tropics.
Raoiella indica is a bright red mite that parasitizes many important plant species, principally palm and banana species. It can be found on the undersides of their leaves. R. indica resembles the common pests spider mites (Family:Tetranychidae) only with longer spatulate setae and lacking their web spinning ability. Adult females are about 0.32mm long and have dark patches on their abdomen. They are larger than males which have more triangular abdomens. Nymphal stages look similar only smaller with less pronounced setae. The mites are visible with the naked eye and usually congregate in clusters of 100-300, and are surrounded by their white exuvial remains (cast skins). (Kane, 2006; Welbourn, 2007).
Red palm mites live on the abaxial, or underside, surfaces of leaves. They have been found to parasitize a wide range of plants located in tropical and subtropical climates, and typically inhabit USDA hardiness zones 9-11. Population growth is found to positively correlate with crude protein and nitrogen levels and leaf moisture, however, heavy rains result in a significant decline (Pena, 2006; APHIS 2007).
Raoiella indica feeds on the deep tissue layers of leaves, most likely the mesophyll, which results in necrosis, cell death, and substantial chlorosis, leaf yellowing. Mites can number from 30-100 million per host plant (Pons & Bliss, 2007). Severly effected plants exhibit entirely dead leaves, especially on the lower third of the plant (EPPO, 2006). Symptoms are often confused with that of lethal yellowing, a prevalent disease of palms (Pena, 2006). R. indica's most signifcant damage has been on the coconut (Cocos nucifera), date palm (Phoenix dactylifera), areca palm (Dypsis lutescens ), and banana (Musa spp.). It is considered a high risk invasive species (Pons & Bliss, 2007; APHIS, 2007). For example, a farmer in Trinidad expects a 50% reduction in coconut production (Pena, 2006).
Red palm mites parasitize a wide range of plants also including: Everglades palm (Acoelorraphe wrightii), Christmas palm (Veitchia merrillii), multiple crown palm (Aiphanes spp.) betel nut palm (Areca catechu), coco macaco (Bactris plumeriana), Bismark palm (Bismarckia nobilis), fishtail palm (Caryota mitis), chamaedorea palm (Chamaedorea spp.), princess palm (Dictyosprema album), triangle palm (Dypsis decaryi), African oil palm (Elaeis guineensis), Licuala palm (Licuala grandis), Chinese fan palm (Livistona chinensis), Canary Island date palm (Phoenix canariensis), Senegal date palm (Phoenix reclinata), pygmy date palm (Phoenix roebelenii), Fiji fan palm (Pritchardia pacifica), buccaneer palm (Pseudophoenix sargentii), Cacheo (Pseudophoenix vinifera), solitaire palm (Ptychosperma elegans), Macarthur palm (Ptychosperma macarthurii), lady palm (Rhapis excelsa), royal palm (Roystonea borinquena), queen palm (Syagrus romanzoffiana), arikury palm (Syagrus schizophylla), fan palm (Washingtonia filifera), Mexican fan palm (Washington robusta), parrot flower (Heliconia psittacorum), wild plantain (Heliconia caribaea), lobster claw heliconia (Heliconia rostrata), Macaw flower (Heliconia bihai), sweet basil (Ocimum basilicum), screw pine (Pandanus utilis), bird of paradise (Strelitzia reginae), traveler's tree (Ravenala madagascariensis), red torch ginger (Eltingera elatior), and red ginger (Alpina purpurata) (Welbourn, 2007; EPPO, 2006).
Raoiella indica was first described in India in 1924 (Pons & Bliss, 2007; CariPestNet, undated). It has been reported in Egypt, Israel, Mauritius, Réunion, Sudan, Iran, Israel, Oman, Pakistan, Philippines, Sri Lanka, United Arab Emirates, Dominica, Dominican Republic, Guadeloupe, Martinique, Puerto Rico, Saint Lucia, Trinidad and Tobago (Trinidad island), US Virgin Islands (St Thomas) . (EPPO, 2007)
Introduction pathways to new locations
Host: The most common means of introducing Raoeilla indica to new locations is by the transport of infected plant material (APHIS, 2007) .
Transportation of habitat material: Raoeilla indica can be carried to new locations along with crafts made from woven palm leaves (APHIS, 2007).
Local dispersal methods
Host (local): Movement of host plants also spreads Raoeilla indica locally (APHIS, 2007).
Other (local): Raoeilla indica ride wind currents (Pena, 2006).
Preventative measures: Surveys for potential infestation of Raoiella indica are being periodically performed in many coastal areas in Florida (Feiber, 2007). Intensive outreach of flyers and educational materials have been distributed throughout the Caribbean and Florida to the public indicating the threat of Raoiella indica (Feiber, 2007). Also, flowers, crafts made from palm leafs, and other potential vectors for the mite are prohibited from being brought into the U.S. unless first bleached, dyed, painted or shellacked (APHIS, 2007).
The European and Mediterranean Plant Protection Organitzation (EPPO) has included the mite on its Alert list (EPPO, 2007). The EPPO Secretariat felt that it could be added to the Alert List considering that it could be a threat to the palm nursery industry and date palm production in the EPPO region.
Chemical: Current knowledge of chemical control of R. indica is based on research performed in India or the Near East, and in most cases is not yet applicable to Western Hemisphere infestations. However, there have been several effective controls. The spraying of neem oil mixed with sulfur from above infested coconut palms 5-6 times a year resulted in a decrease of red palm mite populations and a 25% increase in yield. Several systemic insecticides have proven toxic to R indica. These include: Phosphamidon, which is most effective, monocroptophos, dimethoate, formothion, and dementon-methyl. Most of these products are not registered for use on coconuts or bananas in Florida and Puerto Rico. A full evaluation before use on commercial food crops is required. Additionally, petroleum oil, pyridaben, fentbutatin-oxide, dicofol, and high rates of sulfur have been successful in controlling other members of the family Tenuipalpidae (Pena, 2006).
Biological: Natural predators may provide a means of controlling red palm mite populations. However they have not been used in practice and more research is necessary. Those in India include the phytoseiid mite (Amblyseius channabasavanni), lady beetle (Stethorus keralicus), and (Stethorus parcempunctatusi. In Mauritius, Amblyseius caudatus preys on red palm mites in coconut palms. In the Western Hemisphere, Neoseiulus longipinosus, also native to the East, has been found to prey on R. indica in the Caribbean. Also, there are several conccinellid and phytoseiid potential, endemic predators that are found preying on similar species in the Western Hemisphere (Hoy, 2006). The USDA Bee Research Laboratory has searched for predators by looking for a sequenced portion of R. indica DNA in the guts of potential candidates. They have found lacewings (Chrysopidae spp.) to be good predators and intend to use a chemical isolated from catnip-oil to attract them to prey on R. indica populations (Pons & Bliss, 2007). Another possibility lies in predatory beetles of the Chrysomelidae family (Welbourn, 2007). Utilizing arachnid pathogens such as fungi may prove to be yet another means of controlling R. indica. A fungus, possibly, Hirsutella spp. has been observed infecting the red palm mite. Similarly, other members of Tenuipalpidae have been documented has being infected by fungi (Hoy, 2006).
Raoiella indica is a phytophagus organism that feeds on the deep tissue layers of leaves, most likely the mesophyll. Indicated by the "yellowing" symptoms it inflicts rather than "silvering," which is caused by the feeding on epidermal tissue. Mites have been observed extending their stylets into leaf stomata to access this inner tissue (Kane, undated).
Oviparous. Sexual and Parthenogenetic. Fertilized eggs develop into females while unfertilized eggs become male. Fertilized females produce an average of 22 eggs while unfertilized females produce about 18, laying about 2 eggs a day. Sexual ratio ranges from 11.4 male to female from April to May, to 2.3 male to female from October to November. Males demonstrate pre-copulatory mate guarding by attaching to the rear of female deutonymphs and remaining in tandum. High temperature and daylength have a positive correlation with reproduction while rainfall and relative humidity have a negative correlation (APHIS, 2007; CariPestNet, undated; Kane, undated; Pena, 2006; Welbourn, 2007).
Eggs are atteched to leaves by a stipe and hatch after an average of 6.5 days. The larvae are bright orange and develop into eight-legged protonymphs in 5-10 days and larger deutoronymphs in 5-7 days. Deutoronymphs then molt into adults after about 4-11 days. Immatures are smaller with shorter dorsal and lateral setae and lack protruding setal bases. Female pre-oviposition period ranges from three days in the summer to seven days in the winter. According to Pena, Nagesha-Chandra and Channabasavanna (1984) found longevity of females to be 50.9 days and males 21.6 days (Pena, 2006; CariPestNet, undated; Kane, undated).
Reviewed by: Expert Review underway: Dr. Ronald Ochoa, Research Entomologist (Acarologist) USDA, ARS, Systematic Entomology Laboratory USA
Principal sources: APHIS, Animal and Plant Health Inspection Service. United States Department of Agriculture. 2007. Red Palm Mite.
Hoy, M.A., Pena, J, and Nguyen, R. 2006. Red palm mite Raoiella indica. Florida Department of Agriculture and Consumer Services, Division of Plant Industry.
Kane, E.C. and Ochoa, R. 2006. Detection and Identification of the Red palm mite Raoiella indica Hirst (Acari: Tenuipalpidae). Systematic Entomology Laboratory. United Stated Department of Agriculture. Beltsville, Maryland.
Pena, J.E., Mannion, C.M., Howard, F.W., and Hoy, M.A. 2006. Raoiella indica (Prostigmata: Tenuipalpidae): The red palm mite: a potential invasive pest of palms and bananas and other tropical crops of Florida, University of Florida.
Pons, L. and Bliss, R.M. 2007. A tiny menace island-hops Caribbean. Agricultural Research. May/June.
Welbourn, C. 2007. Pest Alert: Red palm mite Raoiella indica Hirst (Acari: Tenuipalpidae). Florida Depatment of Agricutlure and Consumer Services, Division of Plant Industry.
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Last Modified: Friday, 11 January 2008