我国西南稻区白背飞虱,褐稻虱的迁飞和发生特点

MIGRATION AND OCCURRENCE OF WHITE-BACKED PLANTHOPPRS AND BROWN PLANTHOPPERS IN SOUTHWEST CHINA

由于西南稻区的地理位置、地势、地形、气候和水稻种植制度等因素的影响,白背飞虱和褐稻虱的迁飞和发生情况与我国东部稻区相比较,有其不同的特点: 迁飞特点有:贵州东南部迁入期较早,全区迁入虫量大,白背飞虱为春季迁入的优势种;云南境内,从南向北地势逐步抬升,迁入期和主要为害时期亦逐渐推迟,虫种由褐稻虱较多而变成白背飞虱为优势虫种;四川盆地迁入始期和主要迁入期由东向西推进;主害代的迁入虫源路径多;夏季短、中距离的迁飞频繁,有的年分在中稻上常造成两次主害时期等。发生特点有:常年三省的东、南部地区发生程度重,三省的西、北部地区发生程度轻;近期迁入虫量是中稻或晚稻上主害代的主要虫源;虫量相应集中,加重为害程度;另方面天敌种类多,数量较大,对飞虱种群数量有一定的抑制作用。上述迁飞和发生特点可作为拟定西南稻区对两种稻飞虱预测预报和防治策略的理论依据。

In southwest China,migration and occurrence of white-backed plan-thoppers (Sogatella furcifera Horvath) and brown planthoppers (Nilapar-vata lugene Stal)have different features from those in eastern part of Chinaas a result of the combined effect of different geographic location,to-pography,climate,cultural system,etc. Characteristics of migration,the planthoppers immigrated abundantlyinto the southeastern part of Guizhou province at an earlier season thewhite-backed planthoppers being the predominent species. In Yunnan province,immigration appeared first in the southern partand then in the north,and the predominent species was first the brownplanthoppers and then the white-backed planthoppers.In Sichuan provin-ces,the immigration appeared first in the eastern part and then in thewest.The immigratory paths of that generation,which caused majordamage,were various,and the migrations of short and middle distanceoccurred frequently in summer.So that,there were two major damageperiods on middle rice in some years. Characteristics of occurrence.In normal years,planthoppers usuallydo more serious damage in eastern and southern parts of the abovethree provines,than in western and northern parts.The nearestplanthopper populations were the principle sources of emigration doingharm to middle and late rice.It has been found that the planthoppercould be checked by the various kinds of natural enemies.