贵州省高粱田草地贪夜蛾幼虫发生及其空间分布研究

Occurrence and spatial distribution of Spodoptera frugiperda larvae in sorghum fields in Guizhou Province

【目的】草地贪夜蛾Spodoptera frugiperda是一种迁飞性的重大农业害虫,近年来在贵州高粱田发生为害严重。明确其在高粱田中的发生规律及空间分布,为制定有效的防治策略提供理论依据。【方法】于2022年6-7月在贵州省安顺、贵阳、黔西、金沙和仁怀5个地区开展田间调查,采用6个聚集度指标、Taylor幂法和Iwao聚集格局回归分析法,对草地贪夜蛾幼虫的空间分布进行分析。【结果】田间调查发现,在高粱6-9叶生长期,草地贪夜蛾幼虫主要啃食叶片,导致叶片出现不规则孔洞或缺损;5个调查地区高粱田中多为低龄幼虫(1-3龄),高龄幼虫(4-6龄)较少,且南部地区(安顺、贵阳)的幼虫数量和密度显著(P<0.05)高于偏北部地区(黔西、金沙和仁怀)。空间分布指数表明,草地贪夜蛾幼虫在高粱田中呈聚集分布。高粱植株受害率与幼虫数量呈极显著正相关(r=0.9729,P<0.01),回归方程为y=54.6460x+5.2328(R^(2)=0.9465)。基于空间分布型分析,提出幼虫密度的理论抽样模型N=(3.84/D2)(1.9458/x﹣0.6649),明确了在不同虫害密度和允许误差范围下的抽样高粱株数;根据幼虫密度防治指标,得出草地贪夜蛾幼虫的序贯抽样区间计算公式为T_(lwao(n))=0.27n±1.96√0.477n。【结论】在贵州高粱6-9叶期,草地贪夜蛾幼虫以1-3龄为主,呈聚集分布,南部虫害较为严重。研究还提出了基于虫害密度的序贯抽样模型和防治指标,为田间监测及防控措施提供了科学依据。

[Aim]To determine the occurrence patterns and spatial distribution of Spodoptera frugiperda,a significant migratory,agricultural pest,in sorghum fields in Guizhou.[Methods]Field surveys were conducted in the Anshun,Guiyang,Qianxi,Jinsha,and Renhuai regions of Guizhou Province and 6 aggregation indices,Taylor’s power law,and Iwao’s regression analysis were used to analyze the spatial distribution of S.frugiperda larvae.[Results]Field surveys revealed that S.frugiperda larvae primarily feed on leaves,causing irregular holes or other damage,during the 6th to 9th sorghum leaf stages.In the 5 surveyed regions,larvae were mainly 3rd instar larvae or younger,with few 5th and 6th instar larvae.The number and density of larvae were significantly higher in southern compared to northern regions.Spatial distribution indices indicate that larvae have an aggregated distribution pattern.There was a highly significant,positive correlation between the infestation rate of sorghum plants and the number of larvae(R=0.9729,P<0.01),which conformed to the regression equation y=54.6460x+5.2328(R²=0.9465).A theoretical sampling model for larval density was developed based on analysis of the spatial distribution pattern:N=(3.84/D²)(1.9458/x﹣0.6649).This model defines the number of sorghum plants that should be sampled under different larval densities and allowable error ranges.Based on the larval density control threshold,a sequential sampling interval calculation formula for larvae was derived:T_(lwao(n))=0.27n±1.96√0.477n.[Conclusion]During the 6th to 9th leaf stages of sorghum in Guizhou,Spodoptera frugiperda larvae are predominantly in the 1st to 3rd instar stages,exhibiting an aggregated distribution.Infestations are more severe in the southern regions.The study also introduces a sequential sampling model based on pest density,along with control thresholds,providing a scientific basis for field monitoring and integrated pest management strategies.