马铃薯甲虫成虫田间扩散规律

Diffusion of colorado potato beetle,Leptinotarsa decemlineata,adults in field

马铃薯甲虫具有很强的自主扩散能力,为进一步明确马铃薯甲虫在田间自然条件下的扩散特性,采用"标记—释放—回捕"方法研究了农田生态系统下的马铃薯甲虫扩散规律。结果表明:随着释放时间的推后,回捕得到的虫口数量逐渐减少。田间的平均拥挤度、平均密度和拥挤度指标也逐渐减小,至释放后7 d,马铃薯甲虫的空间分布格局变化为均匀分布。在扩散速度上,马铃薯甲虫越冬代和第2代成虫扩散速度显著高于第1代成虫,而越冬代和第2代成虫的扩散速度差异不明显,雌虫的扩散速度大于雄虫。在扩散方向上,各世代成虫扩散没有明显的方向性,呈向四周随机扩散趋势。

The Colorado potato beetle （CPB）, Leptinotarsa decemlineata （Say）, is a highly destructive migratory pest on potato crops worldwide. It originated in the United States or Mexico and has now invaded more than 40 countries across North America, Europe, Australia, and Asia. This invasive pest dispersed from Kazakhstan into the Xinjiang Uygur Autonomous Region of China, where it was first discovered on potato crops in the Ill River Valley area in 1993. Since then, it has spread widely throughout the northern of Tianshan Mountain region. CPB can migrate independently, and its optimal survival strategy involving high reproductive rates and diapause have allowed it to spread eastward, where it now threatens to invade Gansu and the Inner Mongolia Autonomous Region, the main potato-producing regions of China. CPB can migrate both naturally and artificially. Although CPB can travel via running water, flight migration is more ecologically important. Several factors can affect CPB migration, including geographic blockages, overwintering conditions, host distribution, wind speed and direction, and level of CPB control; the first two are the most decisive factors. CPB adult flight is directly affected by environmental factors; starvation and high light intensity can both stimulate flight of CPB. Adults of the overwintered generation continue to store nutrients in their bodies, which helps them fly long distances to find an appropriate host. Therefore, understanding the diffusion pattern of this migratory pest is important for developing more efficient prevention and control measures. In this study, the diffusion of CPB was evaluated using the ＂mark-release-recapture＂ method in a potato field in Xinjiang Province, China, in 2012. Diffusion speeds and direction of adult CPB were compared among the overwintering generation, first summer generation, and second summer generation. We also analyzed the differences in diffusion patterns between females and males and compared the CPB adult densities between early release days and later periods in the potato field. Mean crowding was used to analyze the spatial distribution of CPB adults. The results showed that the number of recaptured insects decreased as release time increased. The congestion analysis showed that the distribution of CPB in the field was uniform, except after 1 d, 3 d, and 5 d, when the distributions were all clumped, and that the congestion index became smaller over time. Thus, diffusion process of CPB progressed from a clumped distribution to a uniform one. With respect to diffusion velocity, there were significant differences between generations; the overwintering and second summer generation adults had significantly higher velocities than the first summer generation, but the velocities did not differ significantly between the overwintering and second summer generation adults. In addition, there were significant differences between genders; female adult CPB spread more quickly than male adults; the velocity of female adults was （2.74±0.25） m/d, while that of males was （1.33±0.28） m/d. There was no significant directionality in any of the three adult generations in diffusion direction. After being released from the center of a potato field, adults spread randomly to their surroundings. Only in first summer generation CPB were there significant differences in recapture amounts and diffusion speeds among directions, while for overwintering and second summer generations adults, there were no significant differences among directions in recapture amounts and diffusion speeds scientific basis for the mechanism of CPB diffusion in fields, as well as help in of adults. The results of this study will provide a its comprehensive prevention and control.