赣北二化螟卵寄生蜂寄生率动态及其对景观结构的响应

为探索南方稻区二化螟卵寄生蜂生防功能、评估卵寄生蜂在田间寄生动态并探讨对不同景观结构的响应，本文采用对比盆栽稻株叶片载卵、离体新鲜稻叶载卵和滤纸卵卡比对二化螟卵寄生蜂寄生率差异；利用盆栽稻株叶片载卵调查卵寄生蜂在稻田中的寄生率季节动态变化；在5月初、7月初和9月初分别调查了在不同景观样点二化螟卵寄生蜂寄生率，对不同空间尺度下（0.2，0.5，1.0，1.5，2.0 km）景观变量与卵寄生率进行模型分析，评估不同景观变量对卵寄生率的影响。结果表明，三种诱集方法差异显著，盆栽稻株叶片载二化螟卵被寄生的比率最高，其次为离体新鲜稻叶，滤纸卵卡效果最差。田间寄生动态调查表明，早稻卵被寄生比率偏低，中稻寄生率较高，在7月中旬二化螟卵被寄生率达到高峰（66.7%），8月下旬以后，晚稻寄生率逐步下降。对不同空间尺度下景观结构变量与卵寄生率分析表明，1.5 km尺度下的林地与二化螟卵寄生蜂有着密切关系。低于40%林地面积比例时，二化螟卵寄生蜂寄生率随林地面积增加而降低；而在高于40%林地面积比例时，二化螟卵寄生率随林地面积增加而增加。综上所述，对于中国南方的小规模稻田景观，林地比例与二化螟卵寄生率有关，但相关效应并非单一地增加或减少的线性响应。研究结果可为南方稻区二化螟卵寄生蜂提供简便、有效的评估方法，并为综合利用二化螟卵寄生蜂控害功能，发展二化螟生防策略提供参考依据。

Dynamics of Egg Parasitoids of Chilo suppressalis and Its Response to Landscape Structure in Northern Jiangxi

To explore the bio-control roles of egg parasitoids on rice striped stemborer (SSB) Chilo suppressalis in Southern rice planting areas, we evaluated the dynamics of egg parasitoids and its responses to different landscape structure. Potted rice plant, detached fresh rice leaf, and filter paper with SSB egg mass were compared for their efficiency as sentinel eggs. Field parasitism dynamics of egg parasitoids were investigated using potted rice plants with egg masses in different seasons. Further, parasitism of egg parasitoids in different landscape was investigated on May 6^th, July 1^st and September 7^th using potted rice plants with egg masses for analysis of the relationship between parasitism rate and landscape variables at five different spatial scales (0.2, 0.5, 1.0, 1.5, 2.0 km radius). The results showed that potted rice plants with SSB eggs were the best as sentinel eggs, seconded by detached fresh rice leaves with SSB eggs. Field parasitism was very low on early rice, significantly increased on middle rice, peaking at 66.7% on middle July. After late August, the parasitism rate on late season rice decreased gradually. A close relationship was detected between forest area and egg parasitism rate at 1.5 km scale. When the proportion of forest area was less than 40%, parasitism rate decreased with the increasing of forest area. In contrast, when forest area was more than 40%, parasitism rate increased with the increase of forest area. In conclusion, although proportion of forest area is related to the parasitism rate of C. suppressalis eggs, however, the related effect is not a linear response. The results of this study provide a simple and effective method for evaluation of egg parasitoids of C. suppressalis in Southern rice region, and serve as a reference for the development of integrated pest management strategies by using egg parasitoids of C. suppressalis.