Effect of pollen on Coleomegilla maculata (Coleoptera: Coccinellidae) population density, predation, and cannibalism in sweet corn
Effect of pollen on Coleomegilla maculata (Coleoptera: Coccinellidae) population density, predation, and cannibalism in sweet corn
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DOI：
10.1093/ee/27.6.1402
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发表时间：
1998-12-01
影响因子：
1.7
通讯作者：
Yeargan, KV
中科院分区：
文献类型：
--
作者：
Cottrell, TE;Yeargan, KV
斑纹鞘甲虫(Coleomegilla maculata，DeGeer)是玉米田中数量丰富的多食性捕食性天敌，仅以玉米花粉为食即可发育和繁殖。我们用的是甜玉米(Zea Mays L.)在田间实验中，研究了花粉丰度对斑纹夜蛾种群密度的影响，斑纹夜蛾对棉铃虫卵的捕食，以及斑纹夜蛾对卵的自相残杀。被指定为“无花粉地”的地块在开花前立即剥离，而在“花粉地”中的雄穗则保持完好。在两年中，当所有样地都没有花粉时(即开花前和开花后)，斑潜蝇的种群密度没有显著差异。在花粉区和非花粉区之间的玉米卵捕食，或斑点玉米卵自相残杀。在1996年开花期间，花粉区斑潜蝇的卵和幼虫密度显著高于非花粉区，但在1995年则不是这样。在1995年，花粉区对玉米卵的捕食量显著低于非花粉区，但在1996年不是这样。在这两年的开花期间，与非花粉区相比，花粉区的虫卵自相残食率较低，在1996年更是如此。当丰富的花粉导致花粉样地斑纹夜蛾幼虫种群增加时(即1996年)，捕食玉米卵和蚕食斑纹夜蛾卵的情况在花粉样地并不高。这表明丰富的花粉将斑点锦鸡儿从肉食性动物中分离出来。因此，即使在玉米开花期间，斑纹夜蛾种群数量可能会增加，但这种丰度的增加不太可能转化为对玉米卵的捕食增加。
Coleomegilla maculata (DeGeer) is an abundant, polyphagous predator in corn fields; it can develop and reproduce on a diet of only corn pollen. We used sweet corn (Zea mays L.) in field experiments to investigate the effect of pollen abundance on C. maculata population densities, predation by C. maculata on Helicoverpa zea (Boddie) eggs, and egg cannibalism by C. maculata. Plots designated as "no-pollen plots" were detasseled immediately before anthesis, whereas tassels were left intact in "pollen plots." In both years, when pollen was absent in all plots (i.e., before and after anthesis) there were no significant differences in C. maculata population density. H. zea egg predation, or C. maculata egg cannibalism between pollen and no-pollen plots. During anthesis in 1996, C. maculata egg and larval densities were significantly higher in pollen plots compared with no-pollen plots, but not in 1995. Predation on H. zea eggs was significantly lower in pollen plots than in no-pollen plots in 1995, but not in 1996. During anthesis in both years, egg cannibalism was lower in pollen plots compared with no-pollen plots and significantly so in 1996. EI en when abundant pollen led to increased C, maculata larval populations in pollen plots (i.e., in 1996), predation on H. zea eggs and cannibalism of C. maculata eggs was not higher in the pollen plots. suggesting that abundant pollen diverts C. maculata from carnivory. Thus, even though C. maculata populations may increase during anthesis in corn, this increased abundance is not likely to translate into increased predation on H. zea eggs.