渭北旱原油菜茎象甲生物学及生态环境的研究

A Study of Biology of Rapeseed Stem Weevils and Their Ecological Environment on Weibei Rainfed Highland

渭北旱原油菜茎象甲1年发生1代,以成虫在寄主田中越冬。成虫产卵于寄主茎秆里,幼虫3龄,均在茎中活动取食,老熟后脱秆入土化蛹,各虫态历期:卵10～12d,幼虫30～36d,蛹17～19d,成虫300～306d。多点调查结果表明,白菜型油菜比甘蓝型油莱受害重,油菜密度越高受害率也越高,成直线回归关系;含水量低的坡地和播娘蒿、荠菜等杂草较多的油菜田受害较重。

Rapeseed stem weevils occur only to have one generation a year.Adults overwinterover the host plants in the fields.Adults produce eggs in the main stems of the hostplants.3-week age larvas all have their activities and eating in the stems.After they be-come adults,they leave away the stems and get into the ground to hatch the pupas.Eachperiod of the life cycle of weevils are:eggs:10～12 days;Larvas:30～36 days;pupas:17～19 days;and adults:300～306 days.The results of investigations at many pointsshowed that the Chinese-cabbage type rapesseeds suffered greater damage than that ofcabbage-type rapeseeds;the higher the rapeseed density,the greater the damage is sothat the percentage bettween density and damaged crops was in relation of linear regres-sion.Rapeseeds in the slope lands with low moisture contentss fuller greater damage.The rape seed fields with more weeds including Capsella Bursapastoris Medic,suffer se-vere damage.