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Southern Pine Beetle
2008 Southern Pine Beetle Forecast for Florida
The 2008 Florida survey was conducted using from one to three traps (Lindgren funnel traps baited with alpha- and beta-pinene and the primary SPB aggregation pheromone frontalin) in each of 26 counties, with each trap located in a different stand of susceptible forest type. The 26 counties surveyed included those that are most likely to experience SPB problems based on historical outbreaks and/or their relative abundance of loblolly pines.
As in previous years, effort was made to place traps in stands containing sawtimber size loblolly pine or areas where loblolly pine is most abundant. Traps were distanced at least 40 feet from any pine tree and checked weekly by DOF foresters from in March and April. Numbers of SPBs and their clerid beetle predators (Thanasimus dubius) were counted for each of the four weekly collections per trap. Numbers of SPB/trap/day and the %SPB were then applied to the Modified SPB Prediction Chart model (Ron Billings, Texas Forest Service) to provide a forecasted level of SPB activity for the remainder of the year. Forecasted activity was based on a relative scale of Low, Moderate, High, or Outbreak.
2008 Trapping Results and Discussion
The 2008 results suggest that SPB populations remain low at all trap locations in the 26 counties surveyed across northern Florida. Of the 37 traps deployed statewide, none caught sufficient numbers of SPBs to warrant predictions above a “low” level of SPB activity for the coming year (Fig. 1).
The total %SPB figure was similar to that of 2007 (Table 1). The %SPB is an expression of the number of SPBs relative to the number of clerid predators; “50% SPB” would indicate equal numbers of SPBs and clerids trapped. In general, in those areas in which the highest (although still low) numbers of SPB were trapped, similar or higher numbers of clerid beetles were also trapped, suggesting that there is an adequate population of these natural predators to help moderate SPB populations.
As in previous years, all counties in DOF Districts/Centers 1-12 have been asked to conduct an initial aerial SPB detection survey. Procedural guidelines for aerial surveys, ground checking, and reporting are available to Division of Forestry foresters. Confirmed SPB spots should be controlled as quickly as possible, preferably through cut-and-remove techniques. See links to SPB control information.
Because of limited survey inputs, a vast resource of potential habitat, and the limitations of the predictive model, the forecast presented here cannot be expected to be 100% accurate. Low/Static SPB predictions do not guarantee that troublesome infestations will not develop on a local or limited basis in some counties. Activity predictions are likely to be more accurate for the 5-mile radius region around each trap than for the county as a whole. Given the limitations of the forecast, the small increase in SPB activity seen in 2007 (particularly in central Marion, northern Alachua, and southern Columbia Counties), and the potential for environmental conditions to change after the survey, areas of suspicious pine mortality should be promptly inspected for evidence of SPB in the coming months.
Sincere thanks to all the foresters who were involved in installing traps, making weekly collections, and submitting jars for sample processing.
Authors: Jeffrey Eickwort, Forester, and Bud Mayfield, Forest Entomologist
Florida DACS Division of Forestry
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