2007 Florida CAPS Red Palm Mite Survey Interim Report Trevor R
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2007 Florida CAPS Red Palm Mite Survey Interim Report Trevor R. Smith and Wayne N. Dixon1 Introduction Red palm mite, Raoiella indica Hirst (Fig. 1), was first detected in the Western Hemisphere in Martinique in 2004. It quickly spread throughout the West Indies, with the most recent detections in Venezuela and Florida (Fig. 2). Red palm mite (RPM) has been found on many different palms as well as several other plants in the Caribbean (Table 1) but seems to concentrate on coconut palms, Cocos nucifera L. Symptoms of RPM damage include severe yellowing and chlorosis of the leaves which can lead to leaflet drooping when the mite population is high. This damage can significantly lessen the ornamental value of palms. Caribbean coconut growers anticipate as much as a 50% loss in coconut production. The Florida Cooperative Agricultural Pest Survey (CAPS) program determined that the RPM posed a significant threat to Florida’s palm industry as well as to several of the state’s native palms. South Florida is particularly at risk due to the high volume of offshore plant material brought into its many ports as well as its close geographic proximity to the RPM-infected Caribbean Islands. Coconut seeds, plant material, tropical weather systems and palm handicrafts were viewed as likely pathways for RPM to be transported into Florida from the Caribbean (Fig. 3). The first RPM survey was initiated in late October, 2006. Objectives The primary objective of this project was to survey in and around “hot zones” high risk areas that have the highest potential for exotic pest introduction in Florida for the presence of RPM. This survey also afforded scientists the opportunity to identify predatory mites occurring in this area which may be useful as biological control agents for the RPM in the future. In addition, it enabled the recording of naturally occurring mite populations on palms, especially in the event that RPM displaces them. All CAPS personnel, both federal and state, worked along with collaborators from many other agencies and organizations. Survey and Monitoring The hot zone areas chosen for RPM surveys were found in the central and southern parts of the state of Florida. These areas have the largest numbers of host plants as well as a large number of people traveling to and from the Caribbean islands. Nurseries with high numbers of palms were chosen with preference given to those bringing in coconut seeds for propagation from Jamaica. Due to several interceptions of RPM on coconut seeds, the CAPS team treated any nursery importing coconut seeds as a “hot zone.” One island in the southern Bahamas, Great Inagua, was also chosen for survey due to its close proximity to areas where RPM has been found (Hispaniola and possibly Cuba). Field Surveys The survey technique consisted of a CAPS team (usually two people) selecting three to five evenly distributed sites within a section (one square mile or 640 acres) to survey with 1 CAPS State Survey Coordinator and Bureau Chief, respectively 2 priority given to “hot zones” (ports of entry, marinas, suspect plant nurseries, etc.) within the section (Fig. 4). Coconut palms were the preferred host for the survey, although other hosts, preferably Christmas palm, Adonidia merrilli (Becc.) Becc. or banana, Musa spp. were surveyed when coconut palms were not available. Two fronds were selected for inspection from each palm, the focus being placed on the lower fronds. Four leaflets from each selected frond were examined for mites. This often was accomplished without the removal of any leaf tissue. Selection of leaflets started from the middle of the frond, working towards the petiole. The frond was pulled into the light to inspect the entire underside of the leaflets. Red palm mite colonies are usually circular and located near the mid-vein (Fig. 5). All life stages of this mite are red which makes the older life stages very visible and easily seen on the underside of leaves. Leaflets with mites on them were removed from coconut palms and other pinnate palms for closer examination. On palmate palms, the suspected mite colony was removed by cutting the part of the leaf around the colony. Suspect mites were collected from any leaflet. Inspections at each site were limited to about 15 minutes. If a plant was examined and no mites were in evidence then no sample was taken and the site was recorded as a negative. Infested or suspect plant material was collected in a one gallon, re-sealable plastic bag with a paper towel to absorb moisture. Samples were retained in coolers during daily survey activities. These samples were refrigerated until sent to the Division of Plant Industry, Entomology Section, Gainesville for identification. CAPS personnel were trained to identify RPM and related mites by FDACS/DPI, USDA/APHIS/CPHST and UF/IFAS specialists. Mite samples that were considered highly suspect were placed in alcohol before shipping to Gainesville. Photographs of the plants as well as plant material were sent to the Botany Section in Gainesville for host verification. Several photos were taken of diagnostic portions of the plants such as leaf scars, spines, swelling of the stem, hastula, roots, and flowers as well as a photograph of the entire tree. The plant samples were placed in separate re-sealable bags. PDAs, copilot GPS devices and ESRI ArcPad application facilitated data collection and management and allowed spatial geographic information to be available in the field. Locations of private marinas and commercial palm nurseries were available to surveyors both as printed aerial maps and on PDAs. Aerial maps allowed surveyors to focus on high-risk areas and the use of ArcPad allowed them to relate their real-time position via the global positioning system (GPS) to high risk locations. GPS points were automatically captured and linked with data supplied by the surveyor. Many changes have been made in the application and the survey protocol as a direct result of the first surveys. Permanent inspection sites or “sentinel sites” were selected throughout Florida (Table 2). Sentinel sites were located in areas related to a potential pathway for the RPM to enter Florida. Typically, sentinel sites were chosen in areas that were easily accessible (parks with open admission, public waterways, etc.), have several host plants for inspection, contain palm trees with fronds that can be reached by the surveyor, and are in or around a point of entry. These were checked at least once a month and will be surveyed extensively after major weather events such as hurricanes and tropical storms. 3 Coconut Washing The most efficient way to examine coconut seeds for mites was to wash each coconut in an alcohol bath. The technique for washing coconuts can be carried out by one person; however, due to the volume in which coconuts seeds arrive in Florida a team of 3-4 persons with several washing stations was better. A 2-3 gallon plastic bucket with a lid was filled to about 25% of the total volume of the container with 70-75% isopropanol. If alcohol is not available then water with a small amount of non-foaming detergent or 2-3 pellets of sodium hydroxide in it can be used. One or two coconuts were placed in the container and the lid was placed over the top. The bucket was then agitated for 30 to 60 seconds before the coconuts were removed. After 10-12 coconuts (fewer if coconuts were particularly dirty) were washed, the liquid was poured through a strainer or sieve (mesh size no smaller than 600 μ) which was used to remove large debris from the washing liquid. The strainer was rinsed thoroughly to wash any mites attached to the debris into the liquid. This liquid was then poured through a wet washing sieve (Humboldt) and the contents of the sieve were washed back into a small jar for shipping. The filtrates from all of the coconuts washed at one site on the same day were combined into one sample. The sieves were thoroughly cleaned after completion of a coconut wash at one location. Fixed screen sieves were thoroughly back-washed with water and a soft brush was used to clear the screen. The Humboldt wet washing sieves were disassembled and washed very carefully. Shipments of propagative coconut seeds typically arrived twenty to a bag with an average shipment size anywhere from 7,500 to 15, 000 coconuts. The “2-2 formula” was used to determine how many coconut seeds from a shipment must be washed, i.e., two coconuts from 2% of the bags in a shipment were washed. Prior to accessing commercial or residential areas, attempts were always made to contact the owner or manager. Door hangers about the CAPS program and RPM, as well as a “Red Palm Mite Information Sheet”, were provided when surveying these types of settings. Current Results The preliminary RPM survey took place in Miami-Dade County. The Miami area has long been a general “hot zone” for the introduction of invasive species. Particularly important to the potential introduction of RPM, this area has one deep water port (Port of Miami), a number of marinas and many palm nurseries. A pilot survey was conducted October 24 - 26, 2006 and used to develop a more universal surveying technique for RPM. Four sites in three TRSs were surveyed. A much more extensive Miami-Dade County survey took place May 21-25, 2007. For this survey, coastal TRSs as well as TRSs with a large number of palm nurseries within them were chosen for survey. Personnel from CAPS, DPI, and UF-IFAS conducted the survey. In total, 158 sites were surveyed in 62 TRSs (Fig.