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灰稻虱为华北稻区主要害虫之一,在天津地区每年发生4-5代,以第4代或第5代的3-4龄若虫在稻田沟边、荒地杂草、土缝、稻茬内越冬;10月中旬能出现第6代的卵期,但由此孵出的若虫至11月中旬相继死去,故第6代若虫能否安全越冬尚待进一步考查。各代的发生期间互相重迭。 当春天2月末越冬若虫迁到杂草上取食、活动;4月末羽化为成虫迁入返青麦田,并在麦田内繁殖第1代;5月末以羽化后第1代成虫转入秧田,6月初至7月初移到本田,9月中水稻收获后转到荒地或新麦苗上为害。 灰稻虱卵期平均5.5-19.5天,若虫有2-7龄,一般为5龄,各龄期随不同世代而异:平均第1龄期3.1-8.9天,第2龄期2.6-8.8天,第3龄期2.2-11.1天,第4龄期2.2-10.1天,第5龄期3.5-6.8天,第6龄期3.3天,第7龄期2.5天。成虫有长翅型及短翅型两类,在天津地区—般可见短翅型雌虫而短翅型雄虫却极为稀罕。短翅型雌虫的发生和温度及饲料有关:高温和以稗子、三棱草为饲料者,短翅型雌虫发生较多。不同翅型在不同时期的成虫其产卵量不同:长翅型成虫平均每雌产卵119.2粒,而短翅型为158.1粒。 灰稻虱在本田中的消长与水稻生育期中的温湿度有关:其发生高峰处于水稻抽穗期及乳熟期。下雨后,高温有利于灰稻虱的发生。 灰稻虱每年在大田中发生数量的多寡可能受当年7-9月份降雨量?
Gray flies are one of the major pests in the rice fields of North China. They occur 4-5 generations per year in Tianjin area. The 3rd or 4th instar nymphs of the 4th or 5th generation are found near the paddy fields, weeds, soil seams, Winter in mid-October; the 6th generation can occur in mid-October, but the hatched nymphs will die one after another in mid-November, so the 6th generation nymphs can survive for further investigation. Generations overlap each other. In the spring of February, the overwintering nymphs migrate to the weeds for feeding and activity. At the end of April, the adults migrate into the rejuvenated wheat fields and propagate the first generation in the wheat fields. At the end of May, the first generation adults emerge into the seedlings after eclosion, Moved to Honda in early July, September mid-season rice turned to wasteland or new wheat seedlings harmed after harvest. Gray louse egg period average 5.5-19.5 days, nymphs 2-7 age, usually 5 age, each age varies with different generations: the average age of 3.1-8.9 days of the first, the second instar 2.6-8.8 days , The third instar 2.2-11.1 days, the fourth instar 2.2-10.1 days, the fifth instar 3.5-6.8 days, the sixth instar 3.3 days, the seventh instar 2.5 days. Adults have long-winged and short-winged two types, in Tianjin area - as short-winged females and short-winged males are extremely rare. Short-winged females and the occurrence of temperature and feed-related: high temperature and to barnyard grass, Sansevieria for feed, short-winged females occur more. The fecundity of adults with different wing types at different stages was different: the long-winged adults averaged 119.2 eggs per female and the short-winged ones were 158.1 grains. The growth and decline of the gray flies in Honda were related to the temperature and humidity during the growth period of rice. The peak occurred at heading and milking stage of rice. After raining, high temperature is conducive to the occurrence of the gray flies. The amount of annual occurrence of the gray flies in the field may be affected by the rainfall in July-September of the same year.