Moyes C L, Raybould A F
Department of Biological Sciences, University of Liverpool, PO Box 147, Liverpool L69 3BX, UK.
Proc Biol Sci. 2001 Aug 7;268(1476):1567-73. doi: 10.1098/rspb.2001.1685.
To understand the ecological role of secondary plant compounds in host location by phytophagous insects it is important to consider attraction at different scales in natural populations. The cabbage seed weevil, Ceutorhynchus assimilis, which lays eggs in pods of crucifers where the larvae feed on seed, is attracted to purified extracts of specific glucosinolate-derived volatiles. We considered the possibility that C. assimilis adults are attracted to and preferentially attack patches of plants and/or individual plants producing these volatiles. Using discrete natural populations of Brassica oleracea and Brassica nigra, we found that oviposition was highest in populations of B. oleracea producing high amounts of 3-butenylglucosinolate. No links were found between the other glucosinolates, 2-propenylglucosinolate, 2-hydroxy-3-butenylglucosinolate, 1-indolylmethylglucosinolate or 1-methoxy-3-indolylmethylglucosinolate, and oviposition in B. oleracea. B. nigra, which contains only 2-propenylglucosinolate, was not attacked by C. assimilis. Within populations of B. oleracea, neither oviposition nor the number of seeds eaten was related to the glucosinolate profiles of individual plants. We suggest that C. assimilis adults use 3-butenylglucosinolate-derived volatiles to locate host populations, whereas other cues determine oviposition on individual plants. The consequences of these results for natural selection of glucosinolate phenotypes are discussed.
为了解次生植物化合物在植食性昆虫寻找寄主过程中的生态作用，有必要考虑自然种群中不同尺度下的吸引作用。甘蓝种子象鼻虫Ceutorhynchus assimilis在十字花科植物的豆荚中产卵，其幼虫以种子为食，该象鼻虫会被特定硫代葡萄糖苷衍生挥发物的纯化提取物所吸引。我们考虑了这样一种可能性，即Ceutorhynchus assimilis成虫会被产生这些挥发物的植物斑块和/或单株植物所吸引并优先对其发动攻击。利用甘蓝（Brassica oleracea）和黑芥（Brassica nigra）的离散自然种群，我们发现，在产生大量3-丁烯基硫代葡萄糖苷的甘蓝种群中产卵量最高。未发现其他硫代葡萄糖苷，即2-丙烯基硫代葡萄糖苷、2-羟基-3-丁烯基硫代葡萄糖苷、1-吲哚基甲基硫代葡萄糖苷或1-甲氧基-3-吲哚基甲基硫代葡萄糖苷与甘蓝的产卵之间存在联系。仅含有2-丙烯基硫代葡萄糖苷的黑芥未受到Ceutorhynchus assimilis的攻击。在甘蓝种群中，产卵量和被吃掉的种子数量均与单株植物的硫代葡萄糖苷谱无关。我们认为，Ceutorhynchus assimilis成虫利用3-丁烯基硫代葡萄糖苷衍生的挥发物来定位寄主种群，而其他线索则决定在单株植物上的产卵情况。本文讨论了这些结果对硫代葡萄糖苷表型自然选择的影响。
