Integrated Control of Plant-Feeding Mites IOBC/wprs Bulletin Vol. 50, 2009 pp. 69-79 Predator-prey dynamics and strategies for control of the red palm mite (Raoiella indica) (Acari: Tenuipalpidae) in areas of invasion in the Neotropics Jorge E. Peña1, Jose Carlos V. Rodrigues2, Amy Roda3, Daniel Carrillo1 and Lance S. Osborne4 1 University of Florida, Tropical REC, Homestead, FL 33031, USA; 2 University of Puerto Rico, 1193 Calle Guayacan, San Juan 00926 Puerto Rico; 3 USDA, APHIS, Plant Protection & Quarantine, Miami, FL 33158, USA; 4University of Florida, Mid-Florida- REC, Apoka, FL., 32703, USA Abstract: The red Palm mite, Raoiella indica (Acari: Tenuipalpidae) invaded the new world around 2004 and is now reported from the Caribbean islands, Florida, USA and northern South America (Venezuela). Surveys to determine generalist fauna prior to its arrival during the end of 2007 in Florida, reported the predators Amblyseius largoensis, Stethorus utilis, Chrysoperla spp., Aleurodo- thrips fasciapennis and Bdella distincta in association with diaspidids, aleyorids and tetranychids. Predator density increase was not observed until 6 months after the arrival of R. indica in Florida. Studies on predator composition after the initial detection in 2006 of R. indica in Trinidad and Tobago, indicated that the predaceous mite, A. largoensis increased its densities as the red palm mite grew and spread to new locations. Other reported predators were A. fasciapennis, Bdella spp., Cheletomimus sp., and species of the families Cecidomyiidae and Chrysopidae. Amblyseius largoensis, while preying on the red palm mite in Puerto Rico, has not substantially reduced the high numbers of R. indica. Studies to find exotic and more effective predators of the red palm mite should be intensified. Key words: coconuts, red palm mite, phytoseiid mites, biological control Introduction The red palm mite (RPM), Raoiella indica Hirst, (Acari: Tenuipalpidae), also known as the coconut mite (Somchoudhury & Sarkar, 1987), coconut red mite (Jalaluddin & Mohana- sundaran, 1990), red date palm mite (Elwan, 2000), leaflet false spider mite (FAO, 2005), frond crimson mite, scarlet mite (Gassouma, 2005) is an important pest of coconuts, date palm, other palm species (PROSEA, 2006), and bananas, beans, and durian in different parts of the world. Previous to its arrival in the New World, the mite was found in India, Philippines, Mauritius, Reunion, Malaysia, Israel and Egypt. Raoiella indica was found in Martinique and St. Lucia in 2004. During 2005, RPM was found in Dominica and during 2006 on the islands of Trinidad, Guadeloupe and Saint Martin (Kane et al., 2005; Etienne & Fletchmann, 2006), and in Puerto Rico (Rodrigues et al., 2007). The mite was discovered in Florida during December 2007 (Peña et al., 2008). Damages to coconut, ornamental palms and bananas are extensive. It is considered that the pest has serious consequences for the coconut, ornamental palm and banana industries of the Caribbean islands. Damage to coconuts results in a 70% yield reduction and possibly job losses, which lead to a major socio-economic problem for some of the islands (Mr. Philippe Agostini, President Trinidad and Tobago Coconut Growers Assoc., Pers. Comm). In Florida, cost of regulatory actions, such as precautionary sprays before shipping R. indica hosts to other states, will represent an 69 70 additional production cost of more than half a million dollars to palm nursery producers per year. Raoiella indica is found on the underside of the leaves of the host plant in very large numbers. On coconuts, attacked leaves display on the upperside uneven dark patches that correspond with the area where the mites are located, this is followed by necrosis of the patches; when seen from a distance, the fronds become yellowish to bronze-orange, followed by necrosis. Heavy mite infestations result in the death of young plants. Management programs for this mite in areas where it is present, as well as preventative programs for areas where it has not yet arrived, are urgently needed. Past chemical control tactics against R. indica were proven inefficacious and costly in India and Egypt, but they are considered necessary for regulatory purposes in infested palm exporting areas (Florida & Puerto Rico). Biological control is one of the most important alternatives to conventional pesticide use in pest management. Classical biological control, or the introduction of natural enemies from the areas of origin for R. indica has been initiated under the auspices of APHIS, PPQ (Marjorie Hoy, pers. comm.), resulting in the quarantine screening of one classical biocontrol candidate. Prior to release of any exotic predator, it is necessary to put greater emphasis on other areas of biological control, such as natural enemy conservation and augmentation. The objectives of this study were 1) to determine the density of predators and herbivorous micro-arthropods associated with palms and bananas in Florida before the arrival of R. indica and record the response of the current beneficial fauna to the invading mite in Trinidad, Puerto Rico and Florida. Materials and methods Generalist fauna prior invasion by the red palm mite in Florida A survey for natural predators infesting palms and bananas was carried out in South Florida, where most of the palm, Musa, gingers and heliconid production is concentrated. Monthly surveys were conducted in Miami-Dade and Monroe counties in the landscape on coconut palms and on bananas from the end of 2005 until 2008. Twenty pinnae per frond were collected per palm species while 20 sections (ea. ~ 60 cm2) were removed from a banana leaf. Samples were taken to the laboratory, where densities of microarthropods, i.e., tetranychids, tenuipalpids, diaspidids, phytoseiids, bdellids and others were recorded, labeled and mounted and sent for identification by specialists. Predator composition in Trinidad and Tobago. A study was conducted at the St. Andrews Estate coconut plantation,-Cedros, Trinidad, to determine the distribution of R. indica and predators in the canopy of a coconut tree. Fronds were collected from the upper (leaf 3), mid (leaf 9) and lower (leaf 13) canopy from 5 trees and 9 pinna from each frond representing the top, middle and base were sampled. All motile RPM and predators were counted under a steromicroscope. A predator was determined by having observed it to feed on R. indica. Predator abundance in Puerto Rico Samples were taken monthly in 8 different sites around Puerto Rico by collecting 10 leaflets, 3 replicates per site, and washing them in 80% ethanol. Ethanol wash samples were then inspected in the laboratory under a stereomicroscope to record presence and abundance of red palm mites and potential predators. 71 Naturally occurring generalist predators currently preying on R. indica in Florida Eight coconut palms were selected in two areas in West Palm Beach (26°42′54″N 80°02′22″W) and Broward (26°07′28″N 80°14′58″W). Once each month, since the time of the discovery of the R. indica invasion on December 2007, a single pinna was collected from each of two fronds per palm, totaling 16 samples per site. Each pinna was placed in a plastic bag, sealed and placed in a refrigerated cooler, and frozen before evaluation. Each sample was examined under the microscope, and number of red palm mite, tetranychids, diaspidid scales, whiteflies, mealybugs and different predaceous arthropods (Phytoseiidae, Neuroptera, Thripidae, Coccinellidae) was recorded. Preliminary tests to determine the efficacy of commercial predators that show potential for control of R. indica Several commercially produced predators will be tested for efficacy to feed, survive and reproduce on R. indica (i.e., Amblyseius swirskii, Phytoseiulus persimilis, Neoseiulus longipes, N. californicus, Galendromus occidentalis). The predator Amblyseius swirskii was selected for a preliminary trial under laboratory conditions. The arena consisted of a 5 cm petri dish placed inside of a 12 cm petri dish. Water was added to the larger petri dish to prevent predator or prey escape from the arena. A 4 cm2 section of a coconut frond that held a known number of different stages of R. indica was added. Then, presumably mated 1 to 2 day old single females were individually placed inside of the arena. The number of eggs, nymphs and adults consumed daily was calculated and new food sources added daily. Results and discussion Generalist fauna prior to invasion by the red palm mite in Florida The scale, Aonidiella orientalis (Newstead) (Heteroptera: Diaspididae), the whitefly, Aleuro- canthus woglumi Ashby (Heteroptera: Aleyrodidae) and the spider mites, Tetranychus spp., Tetranychus gloveri Banks (Acari: Tetranychidae), were the most common microarthropods inhabiting coconuts, while Tetranychus sp., and Brevipalpus spp., were the most common inhabiting bananas from 2006 to 2008 in areas before the arrival of RPM (Figures 1 and 2). On coconuts, the predators, Amblyseius largoensis (Muma) (Acari: Phytoseiidae), Stethorus utilis (Horn) and Chrysoperla spp., (Neuroptera: Chrysopidae) were the most common predators followed by Bdella distincta (Barker and Bullock) (Acari: Bdellidae) and Aleurodo- thrips fasciapennis (Franklin) (Thysanoptera: Phlaeothripidae). On bananas, the predators Amblyseius spp., and Stethorus utilis were recorded (Figures 3 and 4). Amblyseius largoensis was the only phytoseiid on coconuts, while the identification of the Amblyseius sp. found in bananas is pending. Amblyseius largoensis is a generalist feeding