稻虱跗(虫扇)的个体发生研究:生活史和寄生作用

稻虱跗蝙Elenchinus japonicus Esaki et Hashimoto属(捻翅目)跗蝙科,在稻田寄生于白背稻虱、褐稻虱和灰稻虱。稻虱跗蝙在母体血腔中发育、孵化产生三爪蚴,三爪蚴通过生殖沟、生殖孔、育道和育道开口离开母体。三爪蚴离开母体在稻株上活动。一旦靠近寄主,用足抓住寄主,爬在它们身上。它通过节间膜进入寄主,变成蛆状蚴,开始取食。幼虫在寄主体内继续发育,达到足够大小,它们羽化成虫。雌成虫留在寄主体内,仅露出“帽子”(即头胸部),雄虫离开寄主,自由飞翔、雄成虫寿命很短(<12小时),它们积极寻找雌虫,进行交配,发现交配位置在育道口,支配时间约1—2秒钟。雄成虫体长1.33mm;展翅约2.25mm;雌成虫体长1.6—2.6mm,宽0.88—1.35mm;头胸部长0.2mm;育道口宽0.15mm,卵在雌成虫体内形成,而卵母细胞在雌幼虫体内发育。卵长75μm×宽40μm。第1期幼虫(三爪蚴):体长0.2mm;尾须为体长1/3。第Ⅱ期幼虫(蛆伏蚴)足和附肢都退化;第Ⅱ期幼虫分成4个龄期,具口和消化道,蛹属围蛹。卵历期7—8天,而三爪蚴历期仅1天。蛆状蚴(2—5龄)历期10—11天,蛹历期约3—4天,雌成虫历期7—8天。在实验室,每世代历期约20—23天。稻虱跗蝙的寄生作用较低,由于三爪蚴找不到稻虱很快死亡。在浙江1983—1986年调查,稻虱跗蝙对白背稻虱成、若虫寄生

STUDIES ON THE ONTOGENY OF ELENCHINUS JAPONICUS ESAKI ET HASHIMOTO: LIFE CYCLE AND PARASITISM

Elenchinus japonicus Esaki et Hashimoto belongs to Family Elenchidae, Order Strepsip-tera, and parasitizes planthoppers Sogatella furcifera (Horvath), Nilaparvata lugens (Stal) and Laodelphax striatallus (Fallen) in the paddy fields. The eggs develop and hatch within the haemocoel of the mother to produce the triungulid larvae which come out through the female genital and brood canals. They move rapidly on the rice plants to search for the hosts. When it succeeds it climbs on the host body and penetrates into the body through the intersegmental membrane. It than transforms into a worm-like larva beginning to feed and develop. Thus the larva is polymorphic and has four instars in the second stage of larval development which takes 10 to 11 days. The triungulid larva is about 0.2 mm in body length and its circus measures one-third of the body length. It lives only for one day. The mature worm-like larva will transform into a puparium and the pupal stage lasts for 2-4 days. The sexes differ entirely in the adult life and the female remains in the host body with the cepholothaca exposed to the outside. The male leaves the host body and flies around to seek the female for copulation. It lives about 12 hours and copulation is effected in 1-2 seconds. The male measures 1.33 mm in body length with wing expansion of 2.25 mm and the female is 1.6-2.6 mm in body length with the cephalothorax 0.2mm long. The egg stage lasts for 7-8 days. The duration of each generation is about 20 to 23 days in the laboratory.The rate of parasitization on planthoppers was investigated and the observation in 1983 to 1986 revealed that it was 5-7% on the nymphs and adults of S. furcifera, 2% on L. striatallus and 1% on N. lugens in Zhejiang Province. Sometimes, however, the parasitization rate an S. furicifera was found as high as 20-40%.