Turchin Peter, Thoeny William T
Ecol Appl. 1993 Feb;3(1):187-198. doi: 10.2307/1941801.
Pest management decisions should take into consideration quantitative information on dispersal of insect pests, but such information is often lacking. The goal of this study was to measure intraforest dispersal in the southern pine beetle (SPB). We developed an analytical formula for interpreting data from mark-recapture studies of insect dispersal. The formula is obtained by postulating a simple model of diffusion with disappearance (e.g., as a result of death) for the spread of marked insects from the release point. Parameters of the model (assumed to be invariant in space) are estimated by fitting the curve to the cumulative number of recaptured insects as a function of the distance from release. We also derived an expression for the distribution of dispersal distances in terms of the fitted parameters. The proposed methodology was applied to a mark-recapture study of SPB dispersal Statistical analysis of recaptures-with-distance curves obtained in 11 replicate releases indicated that the proposed formula provided an accurate description of the data. There were no systematic departures from the functional relationship prescribed by the formula, and the model consistently outperformed another commonly used formula for fitting data on dispersal distances, the exponential curve. We explored the effect of spatial heterogeneity in the host distribution on SPB movement by regressing the deviation from the recapture rate predicted by the model in each trap on the pine basal area around the trap. This correlation was significantly greater than zero, indicating that beetles tended to aggregate in localities where pines were dense. This result suggests that a diffusion model with spatially varying parameters may provide a more accurate description of the redistribution process in the SPB. Quantitative results on SPB intraforest dispersal were summarized by calculatingradii of circles enclosing a given proportion of SPB dispersal distances. For example, we estimated that one half of released beetles dispersed >0.69 km. This result has important implications for evaluating the area-wide consequences of current or novel control tactics that rely on disrupting SPB movements, e.g., cut-and-leave and treatments with anti-congregation pheromone.
害虫管理决策应考虑有关害虫扩散的定量信息，但此类信息往往缺乏。本研究的目的是测量南方松材线虫（SPB）在森林内的扩散情况。我们开发了一个分析公式，用于解释昆虫扩散标记重捕研究的数据。该公式是通过假设一个简单的扩散模型得到的，该模型考虑了标记昆虫从释放点扩散时的消失情况（例如，由于死亡）。通过将曲线拟合到重捕昆虫的累积数量与释放点距离的函数关系来估计模型参数（假设在空间中不变）。我们还根据拟合参数推导了扩散距离分布的表达式。所提出的方法应用于SPB扩散的标记重捕研究。对11次重复释放中获得的重捕距离曲线进行统计分析表明，所提出的公式能够准确描述数据。与公式规定的函数关系没有系统偏差，并且该模型始终优于另一个常用于拟合扩散距离数据的公式——指数曲线。我们通过将每个诱捕器中模型预测的重捕率偏差与诱捕器周围的松树基部面积进行回归，探讨了寄主分布的空间异质性对SPB移动的影响。这种相关性显著大于零，表明甲虫倾向于聚集在松树密集的地方。这一结果表明，具有空间变化参数的扩散模型可能会更准确地描述SPB的重新分布过程。通过计算包含给定比例SPB扩散距离的圆的半径，总结了SPB在森林内扩散的定量结果。例如，我们估计，一半的释放甲虫扩散距离超过0.69公里。这一结果对于评估当前或新型控制策略（如砍伐留桩和使用抗聚集信息素处理）对SPB移动的区域影响具有重要意义。
