棉叶蝉(Empoasca biguttula Shiraki)迁飞的研究

Studies on the migration of cotton leafhopper Empoasca biguttula (Shiraki)

通过冬季田间调查和笼罩饲养、雌成虫卵巢解剖、发育积温和过冷却点等项测定 ,证实棉叶蝉 Empoasca biguttula是迁飞性昆虫。据起飞行为和起飞日节律观察及飞翔力测定 ,及起飞与环境条件和虫体本身状况的关系、各地棉叶蝉始见日及突增日与天气关系的分析 ,得出 :1棉叶蝉在湖南不能安全过冬 ,并基本上查明了在华南的主要越冬寄主。 2起飞发生于一定季节 ,有一定日节律 ,具特定的起飞行为 ,在成虫幼嫩期起飞 ,雌成虫在羽化后第 2天为起飞高峰日。“迁飞型”翅较长 ,“居留型”翅较短。光照强度、风速、温度及降雨等 ,对起飞有很大影响。3成虫有明显的异地同期突增现象 ,并与一定的天气条件相吻合。从此虫远距离迁移的天气图分析表明 ,其迁入天气有 2个类型 :a.迁入 型 :迁入地区处在冷锋 (静止锋 )和切变线南部 ,也处在槽前西南气流中 ;b.迁入 型 :迁入地区正处在脊前。

Cotton leafhopper, Empoasca biguttula ,is an important pest damaging cotton and aubergine in South China.Based on the field investigation in winter and feeding experiments with Malva crispa in laboratory,it was found that the nymphae of the insect began to die under 10℃ and the adult moved slowly under 15℃ and lost activity under 6℃.Neither the adult nor the nymphae could survive at 0.1℃.For the two stages of egg and nympha,the development threshold temperatures were estimated to be 13.2℃ and 16 8℃,and the thermal constants to be 94.3 and 69.5 day degrees,respectively.Generally,the air temperature can not exceed 16.8℃ stably till the middle or the last ten days of April in Hunan and the insect pest could not be found before that time.The adult always was the first to be observed in field in Hunan every year,which indicated that cotton leaf hopper has migrated from other places and could not over winter safely in Hunan. On the other hand,the insect could survive through winter in Nanning,Linshui and the suburb of Guangzhou and its main host plants in winter include cotton, Urena labata,Solanum melongena,S.lyratum,Atropa belladonna and Hibiscus rosasinensis,et al. In those areas such as Liuzhou and Guilin that Solanum melongena could not survive in winter,no cotton leafhopper could live over winter. The insect took off and migrated after sunset in summer and autumn.Required intensity of illumination for takeoff was 0～300 lx in summer.The takeoff threshold temperature is 17.1℃ and the insect does not take off when it was rain or the wind speed is over 1 m/s.The peak day of blastoff was on the 2 nd day after adult emergence.Its blastoff behavior was similar to that of brown planthopper, Nilaparvata lugens. Remarkable differences between migratory type and residential type in the mean fly times and the ratios of the length of wing to body were observed.For male and female adult of migratory type,the fly times were measured to be 238.8 and 189.8 sec,and the ratios to be 1.14 and 1.11,respectively.As for male and female adult of residential type,the fly times were 41.4 and 53.7 sec and the ratios were 0.97 and 0.98,respectively. Fourteen observing stations were distributed from Nanning to Luannan and the insect density was investigated every two or three days in each station.It was found that the adult density increased suddenly and simultaneously in different station and satisfied the weather change.Its immigration was divided into type Ⅰ,which immigration regions located in the South of the cold front(static front)and shear line,and in front of the trough of Southwest air current,and type Ⅱ,which immigration regions located in front of the ridge of and in back of the trough of North side air current.In January,the 10℃ isotherm,corresponded to Fuzhou Yongan Qujiang Liuzhou Yuxi Baoshan,was the Northernmost limit for cotton leafhopper over wintering safely in China.