灰飞虱与褐飞虱种内和种间密度效应比较

在人工气候室内比较研究了灰飞虱和褐飞虱在汕优63和秀水11上的种内和种间密度效应对其主要生物学参数的影响，结果表明两种稻飞虱均存在显著的种内竞争，主要表现为随着密度增加，若虫发育历期延长、若虫羽化率下降、雌成虫寿命缩短、每雌产卵量下降。种内密度效应与稻飞虱种类和寄主品种有显著互作关系，灰飞虱种内竞争较褐飞虱明显，二者在适宜寄主上种内竞争更为明显。同时，两种稻飞虱存在着显著的种间密度效应，主要表现为异种存在时的促进作用，即异种共存时若虫历期缩短、若虫羽化率提高、雌虫寿命延长、每雌产卵量增加。种间密度效应也与稻飞虱种类和寄主品种有显著互作关系，两种共存对灰飞虱的有利作用显著大于对褐飞虱的有利作用，在欠适宜寄主上种间互利效应更为明显。最后，本文对稻飞虱种内和种间密度效应的机制和进化意义进行了讨论。

Comparative study on density related intra-and inter-specific effects in Laodelphax striatellus (Fallen) and Nilaparvata lugens (Stål)

Small Brown Planthopper (SBPH) Laodelphax striatellus (Fallen) and Brown Planthopper (BPH) Nilaparvata lugens (St?l) have been the major insect pests in Chinese rice ecosystem at different times since 1960s, but simultaneously caused serious damage at the heading stage in the Yangtze Delta area in the recent years. To understand the ecological mechanisms of simultaneous outbreaks of the two rice planthopper species in the area, the density related intra- and inter-specific effects for SBPH and BPH on their main biological parameters, including nymphal development duration, emergence rate, longevity and fecundity of female adult, were studied in the laboratory using indica hybrid Shan You 63 and japonica Xiu Shui 11 as host plant varieties. The results showed that there was significant intraspecific competition, as well as interspecific facilitation, for both planthopper species. Intraspecific competition resulted in prolonged nymphal development duration, lower emergence rate, shorter longevity and lower fecundity of female adult as initial density was increased. In contrast, the interspecific facilitation resulted in shorter nymphal development duration, higher emergence rate, prolonged longevity and higher fecundity of female adult when the two species were coexisted. Both intra- and inter -specific effects were significantly interacted with planthopper species and host variety. The density related intra- and inter-specific effects on L. striatellus is higher than those on N. lugens. The intra-specific competition on a relative suitable host variety was higher than that on the other variety, but the inter-specific facilitation on the relative unsuitable host variety was higher than that on the other host variety. Findings are discussed in relation to underlying mechanisms and evolutionary significance, as well as the possible interaction between interspecific facilitation and simultaneous outbreak of SBPH and BPH.