Raoiella indica

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Authors: Espinosa, A. and A.C. Hodges Unversity of Florida

Contents

Introduction and Distribution:

Red palm mite is also known as coconut mite, coconut red mite, red date palm mite, leaflet false spider mite, frond crimson mite or scarlet mite.

This mite is apparently widespread in the tropical and subtropical regions throughout the Eastern Hemisphere. It has been reported as a palm pest in Egypt, India, Iran, Israel, Mauritius, Oman, Pakistan, Philippines, Reunion, Saudi Arabia, Sri Lanka, Sudan, Thailand, and United Arab Emirates. It was first reported in the Western Hemisphere in 2004 in the Caribbean island Martinique. Then, in 2005 it was reported in the islands of Saint Lucia and Dominica. In 2006 it was again reported as established in the Dominican Republic, Guadeloupe, Puerto Rico, Saint Martin and Trinidad-Tobago. As of 2007, US Virgin Islands, Granada, Haiti and Jamaica have also reported red palm mite establishment. Later that year it was reported in the state of Sucre in Venezuela. In the U.S. it was first confirmed to be present in Palm Beach County on December, 2007. Since then it has been reported in Broward, Miami-Dade, and Monroe Counties.

All these reports continue to occur in the subtropical areas of the United States, tropical areas of Central and South America, and the rest of the Caribbean.

Hosts:

This mite has been reported in 32 palm species. Within the palm hosts are the coconut, areca palm, date palm, among other palms. Currently it is important to consider all palm species as host plants for this mite. In the Caribbean, it has shown to cause severe damage to bananas and plantains. Heliconias, gingers, bird of paradise, and screw pine are also hosts of red palm mite. The following is a list of the common names of palms and other plants susceptible to red palm mite:

Everglades Palm Manila Palm Christmas Palm Multiple Crown Palm
Ruffle Palm Betel Nut Palm Coco Macaco Prickly Pole
Bismarck Palm Fishtail Palm Chamaedorea Palm Coconut Palm
Princess Palm Hurricane Palm Triangle Palm Areca Palm
Golden Cane Palm Butterfly Palm African Oil Palm Licuala Palm
Ruffled Fan Palm Chinese Fan Palm Canary Island Date Palm Date Palm
Senegal Date Palm Pygmy Date Palm Roebeleniin Palm Fiji Fan Palm
Buccaneer Palm Red Ginger Jungle King/Queen Solitaire Palm
Alexander Palm Macarthur Palm Lady Palm Bamboo Palm
Royal Palm Queen Palm Arikury Palm Fan Palm
Foxtail Palm Macaw Flower Wild Plantain Balisier
Parrot Flower Lobster Claw Heliconia Edible Banana Plantain
Wild Banana Red-Flowering Banana Red Banana Screw Pine
Bird of Paradise Crane Flower Traveler’s Tree Red Torch Ginger

Potential Economic Impact and Description of Damage:

Red palm mite colonies get established on the underside of the leaf along the midrib. They feed on leaf cell content that is accessed through the stomata or by piercing the plant tissue with their stylet-like mouthparts. Palms that appear to be affected with this pest show scattered yellow spots on both sides of the leaves. These spots are followed by yellow patches that are usually located towards the midrib of the leaf. High feeding mite densities cause localized leaf yellowing, and finally, death of leaf tissue. On coconut leaflets, symptoms start as small yellow spots that later develop into larger chlorotic spots, followed by abortion of the flowers or small nuts. Both young and old coconut palms are severely affected. Under high populations leaves turn from bright green to pale green to yellow, and then finally a copper brown that indicates some tissue death is occurring.

It is important to keep this pest in mind as a suspect, as damage may resemble nutrient deficiencies or might even be confused with lethal yellowing, a non-related but very serious palm disease. Lethal yellowing also causes widespread chlorosis of the lower leaves.

One of the major modes of dispersal appears to be through the transport of infected plant material or landscape utensils, such as pruning shears. Wind dispersal, as might occur with tropical storms, is also a possibility. This pest has been found to be present on Caribbean palm souvenirs such as hats, baskets, rugs, bowls, purses, etc. therefore it is important to consider not obtaining those souvenirs to prevent red palm mites from being introduced into the U.S.

Red palm mite is a serious threat to Florida, and other subtropical to tropical U.S. states with palms. In general, palm nurseries, landscape palms and horticultural gardens will be seriously affected by this new pest. In the Caribbean, some growers have reported 50% losses to coconut production.

Identification Characteristics:

Red palm mite is usually visible with the naked eye. It is bright red, with a roundish flat body, long body hairs, and some water-like droplets at the tip. All life stages, including the eggs are red. Adult females frequently have dark markings on their backs after feeding.

Red palm mite can easily be distinguished from most spider mites by their bright red color and absence of webbing; they do not produce silk, which is common in most spider mites. Red palm mites are also slow moving mites when compared with spider mites.

Although field characteristics may leave you with strong suspects for red palm mite, remember that a diagnostic lab must confirm your identification. This is particularly important for new state or county records. Links to the NPDN diagnostic labs are available at: http://www.npdn.org/ . Refer to the FDACS-DPI hotline listed below, for reporting red palm mite in Florida.

Other Interesting Details:

Studies have shown red palm mites prefer hot and dry temperatures.

Reporting Red Palm Mite in Florida

“If you suspect a red palm mite infestation, you should contact your local University of Florida County Extension Office (http://directory.ifas.ufl.edu/Dir/searchdir?pageID=3&pl=05), or call the Florida Department of Agriculture & Consumer Services' Division of Plant Industry help line at 1-888-397-1517. Live samples should not be removed from your property. Place the mites or a small piece of the infested plant in a container with rubbing alcohol. A sample is necessary for identification and confirmation. Record as much information as possible about the plant type and location. A good digital picture may be useful.”

Life History:

Eggs are smooth and measure 0.12 long by 0.09 wide mm. They are deposited in colonies and are attached individually to the lower surface of the leaf. Colonies usually include between 110 to 330 individuals. It may take them between 6 and 9 days to hatch (it will take longer for fertilized than for unfertilized eggs to hatch). Unmated females produce male progeny and mated females produce female progeny. About 24 hours before hatching, eggs turn opaque white.

Recently hatched mites are called larvae. They measure between 0.18 and 0.20 mm in length and have only three pairs of legs. Often they have a tiny black spot on their back after feeding. Larvae will continue to feed for about three to five days and then they will stop feeding for about one or 2 days before they molt into the protonymphal stage.

The protonymph emerges with four pairs of legs, they continue to feed for two to five days before they stop feeding and enter a resting stage. Females have an oval body in contrast to the more triangle-shaped body of males. They will continue in this resting/non-feeding stage for one to four days and then they will emerge as deutonymph.

The last nymphal stage is very similar to the previous one; the only difference is the size. They will feed between two and five days before they go back to their last resting stage that lasts from two to four days prior to becoming adults.

The nymphal stages of red palm mite look like smaller versions of the adults. In general it takes between 23-28 days for females and 20-22 days for males.

Adult females are approximately 0.32 mm (0.01 inch) long, and live for about 30 days. Each female typically lays between 28 and 38 eggs. Males are smaller than females, more active, live for about 26.5 days, and have a distinctive triangular body. Once adult males and females emerge, they are sexually mature. Females during the deutonymph stage actually produce a sex pheromone that attracts males so they will settle close to them and wait for that female to molt and become adult.

Management:

On adult palms, the use of acaricides for chemical control is difficult and it becomes impractical because of the size of the palms. In general, biological control agents that maintain low population levels would be the preferred long-term strategy in the landscape. Biological control agents that have shown to be effective in the Eastern Hemisphere are predatory mites (Phytoseiidae), predatory beetles (Chrysomelidae), lacewings (Chrysopidae), and predatory mites.

Researchers are still working to identify the best long-term management plan for red palm mite in the U.S. If you are a Florida resident, the following management guideline found at: http://mrec.ifas.ufl.edu/lso/RPM/RPM.htm is recommended if you suspect you have red palm mite.

Cultural Control:

If necessary, prune most affected plants and double bag all plant material before disposing. Place double bags in the garbage; do not move that plant material to prevent spread. If a commercial tree or lawn maintenance company prunes your landscape, be sure that they follow these same guidelines and that they cover their vehicles before leaving your property.

Biological Control:

USDA, University of Florida, and FDACS-DPI are investigating potential predators that might help manage this pest. Stay tuned with information from your local cooperative extension service at: http://www.csrees.usda.gov/Extension/ to determine recommended options for biological control.

Homeowner Chemical Control:

There are very few pesticides that are available for homeowners use. In general, broad-spectrum insecticides may have a more negative impact on beneficial insects and mites rather than red palm mites. Insecticidal soaps and horticultural oils typically are only effective if the mite has been contacted directly. Application of insecticidal soaps or oils to large palms could be problematic. Some options for chemical control may be available through private pest control companies. Florida-based questions regarding management of red palm mite in the landscape should be directed to your county extension office. You can find it at: http://solutionsforyourlife.ufl.edu/map/

Image Gallery:

For images of Red Palm Mite please go to the following links:

References:

  • Pena, J.E., C.M. Mannion, F.W. Howard, and M.A. Hoy. 2006. Raoiella indica (Prostigmata:Tenuipalpidae): The Red Palm Mite: A Potential Invasive Pest of Palms and Bananas and Other Tropical Crops of Florida. Found at: http://edis.ifas.ufl.edu/IN681
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