【摘要】 在室内调查了分别以2龄、3龄和4龄小菜蛾幼虫作寄主时,及20、26、28和32℃下菜蛾盘绒茧蜂和菜蛾啮小蜂间竞争结果.当2龄或3龄小菜蛾幼虫供2种蜂同时产卵寄生时,绒茧蜂的寄生率显著高于啮小蜂的寄生率;分别与其单独寄生时比,前者无显著差异,而后者则显著下降;二种蜂的合计寄生率与任一种蜂单独存在时的相比,以2龄幼虫作寄主时无显著差异,但以3龄幼虫作寄主时则显著提高.当4龄小菜蛾幼虫供2种蜂同时产卵寄生时,绒茧蜂的寄生率与啮小蜂的寄生率之间无显著差异;二种蜂的合计寄生率显著比绒茧蜂单独存在时的高,但与啮小蜂单独存在时的寄生率相比无显著差异.当2种蜂共存时,在所测试的4个温度下,绒茧蜂的寄生率均高于啮小蜂的寄生率,与其单独寄生时的相比,绒茧蜂的寄生率无显著变化,而啮小蜂的寄生率均显著下降.这些结果表明寄主龄期比温度对这两种蜂种间竞争的影响更大.更多还原

【Abstract】 Effects of host age and temperature on interspecific competition between Cotesia plutellae (Kurdjmov) and Oomyzus sokolowskii (Kurdjmov) were investigated in the laboratory, by exposing the 2nd, 3rd, or 4th instar larvae of Plutella xylostella (L) to and by exposing the 3rd instar larvae at 20 ℃?26 ℃?28 ℃ and 32 ℃ to the two parasitoids concurrently, or to one of two species at a time When the 2nd and 3rd instar larvae were exposed to the two parasitoids concurrently, the parasitism rates by C plutellae were significantly higher than those by O sokolowskii As compared with those exposures to one species at a time, the parasitism rates by C plutellae were not reduced by the presence of O sokolowskii while those by O sokolowskii were significantly reduced by the presence of C plutellae No significant differences were found between the parasitism rates done by the two species together and those done by either one of them alone when the 2nd instar larvae were exposed However, the parasitism rate by the two species together was significantly higher than those by either one species alone when the 3rd instar larvae were exposed When the 4th instar larvae were exposed to the two species of parasitoids concurrently, there was no significant difference between the parasitism rate by C plutellae and that by O sokolowskii, however, the parasitism rate by the two species together was significantly higher than that by C plutellae alone, but not significantly higher than that by O sokolowskii alone When the 3rd host larvae were exposed to the two parasitoids concurrently, the parasitism rates by C plutellae were significantly higher than those by O sokolowskii, under all four tested temperatures Parasitism rates by C plutellae did not differ but those by O sokolowskii were significantly reduced, compared with those exposures of host larvae to either one species at a time These results suggest that host stage is a more important factor than temperature in affecting the competition between these two species of parasitoids 更多还原