Department of Agriculture & Consumer Services Florida Coordinating Council on Mosquito Control
Subcommittee on Imperiled Species
February 13, 2008 – Vero Beach, Florida
Florida Medical Entomology Laboratory University of Florida/IFAS 200 9th St. SE, Vero Beach, FL 32962 (772) 778-7200
Develop recommendations to the Council regarding conduct of mosquito control that will: 1) allow for management and recovery of imperiled species by state and federal agencies and 2) allow the Mosquito Control Districts to continue to provide mosquito control as required by State Law under Chapter 388 of the Florida Statues. Introductions Comments on the FR Notice Concerning Mosquito Control on NWRs (Dwinell) (Dwinell)
The Florida Coordinating Council on Mosquito Control agreed to provide comments to the October 15, 2008 Federal Register (FR) notice titled “Draft Mosquito and Mosquito-Borne Disease Management Policy Pursuant to the National Wildlife Refuge System Improvement Act of 1997.” At the Council meeting last October, the Council voted 9 - 2 in favor, of the following language serving as the Council’s formal comment to the proposed policy revisions: “The Council recommends, consistent with the need to protect public health and well-being from excessive mosquito populations that might move from managed refuge land into adjacent residential areas, that, when requested by a local mosquito control agency, plans to manage such mosquito populations through sound mosquito control practices be prepared by National Wildlife Refuge System in consultation with the local mosquito control agency.” Subsequent to the comments submitted to the U.S. Fish and Wildlife Service (USFWS), the deadline for submissions was extended an extra 60 days (expired the end of January). E-mail me if you would like a copy of the FR notice and/or comments submitted by the Coordinating Council (firstname.lastname@example.org).
Recommendations for Upcoming Miami Blue Trials on North Key Largo
Dr. Zhong is pursuing additional grant opportunities from FDACS since funding has run out and additional trials (at least 3) are needed to fill in the data gaps. More replicates are needed since the initial trials were performed at an altitude of 100 ft while last year’s trial was done at 150 ft for safety reasons.
Although there were enough butterfly larvae for two trials last year only one was performed due to adverse weather conditions.
Comments: Tim Bargar mentioned that the residues found on the filter paper and yarn has not correlated well with residues found on the plants which would affect exposure to the larvae. He recommended adding one additional plant (two total) for each sample station to be sampled for residues. Harry commented that for site 5 (where there was larvae mortality) leaf residues did correlate well with yarn residues. The use of additional plant material will be dependent on available resources. Also it is not possible to determine actual exposure concentrations from vegetation without knowing the weight of collected vegetation. Someone recommended using a hole punch. However, this would be difficult with the complex leaf shape of the nickerbean plant (compound pinnate with small leaflets). Max Feken asked if it would be possible to add additional sample stations (without larvae) to collect data on residues. Harry stated that this would require additional manpower that is not available. Collecting residue and fixing samples in a timely manner is very difficult since naled breaks down very rapidly in the field.
Current Status of the Miami Blue Reintroductions
Fish and Wildlife Commission (FWC) and University of Florida (UF) are planning on scaling back reintroduction efforts for the Miami blue as previous efforts have proven unsuccessful. This year they will focus on trying different reintroduction methods including releasing different life stages in an effort to determine the most successful method. Overall, fewer larvae will be needed for the reintroduction efforts which should free up some additional larvae for the adulticide trials.
Currently, FWS has three proposed studies to look at exposure and effects of mosquito adulticides on imperiled species. The first study looking at field residues is the only one that has been initiated. 1. The first study is focused on residue collection within Refuge lands on Big Pine Key. The work, in collaboration with the Florida Keys Mosquito Control District, involves looking at the drift of aerial applications of naled in the National Wildlife Refuge. Only one trail has been completed (?) Residues of permethrin from truck sprays have also been collected (?) 2. The second study will measure the toxicity of currently used mosquito adulticides on various life stages of several butterfly species that could be used as surrogate species for federally listed and candidate listed species found on the Florida Keys. 3. The third study (proposal sent with these meeting notes) will look at exposure and impacts of surrogate caged butterflies in the field during mosquito control activities. USFWS has yet to coordinate with the Keys District for this particular study. Tim Bargar also mentioned that he has resigned from the USFWS to take a job with USGS in Gainesville, FL. He will continue to pursue the above research while at USGS.
Rare Butterflies of the Keys
The presentation form Marc Minno is available upon request.
Dr. Minno provided an overview of the status of several rare butterflies found in the Keys including some that have been recently been extirpated (Zestos skipper, Rockland grass skipper and the nickerbean blue). There is a great deal of concern over the possible loss of the Palatka skipper which feeds on sawgrass. Also very concerned about the Bahamian swallowtail, Florida white (which used to be common like the Miami blue), Bartram hairstreak (recent Candidate species) and Florida leafwing (another Candidate species that may already be extirpated). The only federally listed butterfly species, the Schaus swallowtail, seems pretty stable in Biscayne National Park. Bartram’s hairstreak and Florida leafwing larvae feed on the pineland croton that is found in pine rockland habitat. Most of this South Florida habitat has been developed and can now only be found in the lower Keys and Everglades. This habitat is currently being lost rapidly due to development and lack of fire. In some cases, the exact causes for the dramatic losses of the other imperiled butterflies are not known. Many blame pesticides used to control mosquitoes for the decline of many of these species; however, many are disappearing from areas that do not receive mosquito control. Why are reintroductions not taking in areas that do not receive mosquito control and yet have habitat that appears to be suitable? Why are areas that contain suitable habitat devoid of these butterflies (e.g., Long Key State Park)? Is it predacious ants? Fire ants? Mexican twig ant (Pseudomyrmex gracilis)? Lack of symbionts (e.g., tending ants)? As an example, Miami blues are doing well on the most isolated islands – Marc thinks this is primarily a result of lack of exotic predators. Overall, Marc feels confident we can save the Palatka skipper – the others we just don’t know enough about what is ultimately causing their declines.
Comments: Ricardo Zambrano provided some information on the new workgroup on Imperiled Butterflies of South Florida. The goal of the multidisciplinary workgroup is to developed management strategies to increase or stabilized imperiled butterfly populations in South Florida. The group met on February 8, 2008. The topic of mosquito control and potential impacts to imperiled butterflies will remain with the Subcommittee on Imperiled Species while the workgroup will focus on other management issues dealing with imperiled butterfly populations in South Florida. There was a question concerning fire management in pine rocklands in the lower Keys and the effects on the two candidate species, Bartram’s hairstreak and Florida leafwing. The larvae plant for both species is a croton that is found in pine rocklands. Pine rocklands require fire or else they become overgrown with vegetation resulting in hardwood hammock type habitat. Anne Morkill would like input concerning the fire management plans for the Key Deer National Wildlife Refuge and their role in enhancing habitat for the Bartram’s hairstreak and Florida leafwing while limiting short-term destructive impacts on
populations (this would be a good topic for one of the subcommittees of the Imperiled Butterflies of South Florida Workgroup).
Current Mosquito Control Practices on Key Deer NWR
(Hribar and Leal)
Andrea Leal gave a presentation on how, when and why truck adulticide operations are performed by the Florida Keys Mosquito Control District. Slides are available upon request. All vehicles are tracked using GIS tracking system. Truck sprays are not routine but are scheduled according to surveillance (landing rates or traps) and/or complaint calls. The current aldulticide used is Biomist 30:30 (permethrin : piperonyl butoxide). Application rates are calculated using a 300-foot swath width (actual effective width is dependent on wind speed/direction and physical obstructions). 300 feet is the standard used based on the width of a city block. Rates are also calibrated with the appropriate truck speed (5 to 9 mph); sprayer shuts off >10 mph Sprays are aimed directly behind truck. Big Pine Key and No Name Key are unique in their patchwork of private, state and federally owned parcels. The potential for drift from truck sprays onto public lands is very likely in this type of patchwork of land use scenario.
Comments: How long are the treatments effective? Depends on weather and migration of mosquitoes. For Big Pine most of the problem mosquitoes migrate to the area. How many aerial missions? Only one mission was flown on Big Pine last year. There is year round larviciding including into no-spray-zones (no spray zones for adulticiding) per the agreement between the District and the Refuge. Anne Morkill mentioned that the no-spray-zones were originally developed to protect the Stock Island tree snail which is found in tropical hardwood hammocks. Most of the pine rocklands (where the two candidate butterflies are found) on Big Pine and No Name Keys are not covered by the nospray-zones. Can a nozzle be directed? No, they cannot. Only wind speed and direction control the movement of the droplets. Is it possible to limit the number of applications per year? Possibly, but it would be difficult to keep track of since areas could be split up and sprayed during different operations – specific areas would have to be delineated. Does the droplet deposit onto the ground or leaf surfaces? Eventually they do deposit. Where is dependent on the wind and size of the droplet. Optimal sizes are 15-20 microns; deposits can occur between 300 to 500 feet under typical conditions. by saying the no one has ever bothered to collect and freeze the insects for analysis – so these reports are just anecdotal.
Randy Grau mentioned reports of dragonflies being killed by ground sprays. Mike Spoto responded
Discussion on the Following Items (taken from National Key Deer Refuge Letter)
Since initiation of the integrated adulticiding/larviciding program, has the program been effective at reducing the total amount of adulticide used on Refuge lands?
Anne mentioned that the District sends in annual reports to the Refuge on larvicide applications. Overall, the data suggest that the program appears to be successful in reducing the number of aerial applications over refuge lands. Not sure if there has been a reduction in truck sprays. Data on truck sprays are not compiled within the report to the Refuge. The District and the Refuge will need to decide if data on truck sprays should be included in the annual report to the Refuge.
Discuss the issue of naled (aerial) and permethrin (ground) applications that occur off the Refuge but may drift onto Refuge lands and potentially impact imperiled species?
Even though there appears to be fewer aerial applications over Refuge lands, aerial applications remain a concern since no-spray-zones on both Big Pine and No Name Key do not cover most of the pine rocklands where the two candidate butterfly species are found. In addition, truck sprays do enter into the Refuge lands, particularly in areas where there is a mosaic of private and public parcels adjacent to one another (Big Pine Key). Data from the proposed FWS study (#3) may help to determine if drift from truck sprays will have impacts to imperiled butterflies. In the meantime, the Refuge would like to, as much as practical, limit drift into the Refuge lands. Questions raised: If the wind direction is toward the Refuge or Park lands would the District still spray? Likely yes, as the public would be upset otherwise. Overall, this is up to the driver and is, therefore unpredictable. Can we change this practice? Can the drivers who are licensed and trained to apply pesticides make the necessary assessment, based on wind direction, to spray or not to spray? This is possible, but it will require educating homeowners on why they may not receive spray applications. Citizen complaints are a real concern here, which the group acknowledges. Jeff Stivers recommended using wind streamers along Refuge and Park lands so that drivers can see whether the wind is blowing toward those areas. Most agreed that using wind streamers and educating homeowners on spray drift mitigation would go a long way in preventing unnecessary drift into protected areas. Education and outreach will need to be a joint effort between the public land managers and the Keys MCD. Everyone agreed.
Evaluate feasible alternatives to further reduce or eliminate adulticide applications on Refuge lands to minimize exposure to non-target species while controlling mosquitoes to an acceptable level.
The subcommittee agreed that there should be a management policy between the District and the Refuge that addresses efforts to minimize drift of ground applications onto Refuge lands including the use of wind streamers (if considered feasible) along Refuge boundaries and a joint effort to educate homeowners that live adjacent to these parcels on the importance of mitigating spray drift to non-target areas. In addition, the Refuge and District shall continue discussion on possibly expanding the current no-sprayzones to include areas of pine rocklands which contain habitat essential for the survival of the Bartram’s hairstreak and Florida leafwing, two federal candidate species.
Identify information gaps and research needs.
Aside from the data gaps that the field research is attempting to fill, some additional data gaps were identified during the meeting: 1. Is the increase in larviciding in the Keys reducing the number of truck applications? 2. If the current no-spray-zones on Big Pine Key and No Name Key are expanded to include pine rockland habitat, will this impact mosquito abundance on adjacent residences? Additional surveillance of the number and types of mosquitoes on pine rocklands is needed as this habitat may be harboring (?) areas. Finally, Dr. Zhong gave a brief presentation on the Challenges of Protecting Non-target Organisms when controlling mosquitoes. Dr. Zhong gave a brief description on some of the work that he has performed looking at non-target effects in the field. A copy of his presentation is available upon request.