桃蛀螟在玉米、高粱和向日葵上发生为害与播期的关系

Relationship between sowing date and occurrence of the yellow peach moth,Conogethes punctiferalis,on corn,sorghum and sunflower crops

【目的】为了更好地掌握桃蛀螟的田间发生规律,明确播期对桃蛀螟在玉米、高粱和向日葵上发生为害的影响。【方法】分别在北京和河北廊坊,分3个播期种植玉米、高粱、向日葵,采用5点取样法调查桃蛀螟在不同播期3种作物上的产卵部位、产卵量;作物收获前剖秆调查桃蛀螟幼虫数量、被害部位和被害株率。【结果】从7月中下旬到10月,田间一直可查见桃蛀螟卵,成虫产卵的时期长,世代重叠严重。在玉米田,成虫产卵多在玉米的抽雄期、灌浆期和乳熟期,产卵部位主要为雄穗、花丝、叶鞘、雌穗上部叶片;在向日葵田,成虫在花盘抽出之后一直产卵,产卵的时期较长,卵主要产在苞片、蜜腺盘及萼片和管状花上。对同一播期的不同作物来说,桃蛀螟对向日葵的为害最重,其次是高粱,为害最轻的是玉米;不同播期,桃蛀螟对同种作物的为害程度不同,这与作物的生长感虫期能否避开桃蛀螟的发生高峰期有关。桃蛀螟在玉米上主要为害果穗,也钻蛀茎秆为害,在高粱上主要为害高粱穗部,在向日葵上则主要为害向日葵花盘。【结论】本研究明确了播期对桃蛀螟在玉米、高粱和向日葵上发生为害的影响,为桃蛀螟的监测预报与防控策略制定提供了科学依据。

[Objectives]To clarify the occurrence of the Yellow peach borer(YPB),Conogethes punctiferalis,in the field,and determine the impact of sowing date on the amount of damage inflicted by this pest on corn,sorghum and sunflower crops.[Methods]Corn,sorghum,and sunflower seeds were sown on three different dates in Beijing and Langfang,Hebei Province.The five-point sampling method was used to locate oviposition sites and the number of eggs laid.Before harvest,the number of larvae,damaged plant parts and the plant damage rate,were determined by dissecting plants.[Results]Eggs could be observed from mid-late July to October and the prolonged oviposition period resulted in considerable overlap between generations.Females mostly lay eggs during the tasseling,filling and milking stages of corn,and prefer to lay on the tassel,silks,sheath and leaves above the level of the ear.Females mainly lay eggs on the bracts,nectary glands,sepal and tubiform florets of sunflower plants.Among different crops with the same sowing date,sunflower was the most severely damaged,followed by sorghum,and corn was the least damaged.The degree of damage to the same crop sown on different dates,was proportional to the degree to which the growing and pest-sensitive period of the crop were synchronous with the peak of YPB abundance.YPB mainly damage the ears of corn,the heads of sorghum and the sunflower flower plate.[Conclusion]These findings confirm that sowing date affects the amount of damage inflicted by the YPB on corn,sorghum and sunflower crops.This information should help improve the monitoring,forecasting,and management,of this pest.