3种竹笋夜蛾生态位及其种间竞争的研究

竹笋夜蛾是竹林笋期最主要的害虫之一,应用昆虫种群生物学理论对早园竹、红竹和淡竹笋上3种夜蛾种群动态及生态位进行了研究.结果表明:淡竹笋夜蛾和笋秀夜蛾在种群数量上明显占优,前者发生高峰期集中于4月底至5月初,约7 d,后者集中于5月中旬,约10 d,二者在发生时间上相互分离;竹笋禾夜蛾发生数量少,危害相对较轻.淡竹笋夜蛾的时间生态位宽度在3种夜蛾中最小,竹笋禾夜蛾和淡竹笋夜蛾的生态位相似比例较高(>0.7),种间竞争系数高达0.907 3,说明二者在利用时间资源上发生重叠,二者存在明显资源竞争,最终导致淡竹笋夜蛾种群密度和数量比例显著高于竹笋禾夜蛾.竹笋禾夜蛾的生态位宽度和笋秀夜蛾接近.3种竹笋夜蛾共存同一株竹笋的情况不存在,即使是2种夜蛾共存于同一竹笋的几率也很低,平均值也仅为0.97%.

N iche of Three Dom inant Shoot boring Noctuids andTheir Interspecific Competition

Shoot boring noctu ids are the most importan t pests in bamboo shoot periods. In th is paper, insectpopulat ion b iology theory w as used to ana lyze quantitatively the niches of three dom inant shoo t boring noctu ids.These noctuids w ere investigated on three bamboo spec ies, Phy llostachy s praecox, P. iridescins and P. glauca,respectively. Itw as found that the popu lation density ofK umasia kumaso and Apamea ap am eoides w ere the ma inspec ies. The former reached the peak from late A pr il to early M ay, exper ienc ing seven days or so, and the latteraggregated on m id M ay, lasting about ten days. These tw o spec ies occurred separately. Oligia vulgaris w erecaptured few er in the field and observed to be less infested than the prev iousmentioned tw o species. Analysis fromeco log ica l ind ices show ed that temporal n ich breadth ofK. kumaso w as the narrow est among three noctu ids. Thetempora l n iche sim ilarity be tw een Oligia vulgaris and Apamea kumaso w as h igher than 0. 7 w hile the interspec ificcompetition coefficient w as 0. 907 3. The results ind icated tha t the competition betw een O. vulgaris andK. kumasoeventua lly resoulted in the sign if icantly h igher populat ion density ofK. kumaso than O. vulgaris. The temporaln iche breath ra lues ofK. kumaso and A. apam eoides w as very sim ilar. It had never observed that three spec iescoex isted on the same shoots. The coex istence rat ios of tw o o f them w as only 0. 97%.