de Vries Egbert J, Jacobs Gerrit, Sabelis Maurice W, Menken Steph B J, Breeuwer Johannes A J
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands.
Proc Biol Sci. 2004 Oct 22;271(1553):2171-8. doi: 10.1098/rspb.2004.2817.
Studies on bacteria in the gut of insect species are numerous, but their focus is hardly ever on the impact on host performance. We showed earlier that Erwinia bacteria occur in the gut of western flower thrips, most probably acquired during feeding. Here, we investigate whether thrips gain a net benefit or pay a net cost because of these gut bacteria. On a diet of cucumber leaves, the time to maturity is shorter and the oviposition rate is higher in thrips with bacteria than in thrips without (aposymbionts). When fed on cucumber leaves and pollen, aposymbionts develop faster and lay more eggs. So Erwinia bacteria benefit or parasitize their thrips hosts depending on the diet, which is in accordance with theoretical predictions for fitness of organisms engaged in symbiotic interactions. Possibly, the transmission of gut bacteria has not become strictly vertical because of this diet-dependent fitness variability.
关于昆虫肠道内细菌的研究众多，但研究重点几乎从未放在对宿主性能的影响上。我们之前表明，欧文氏菌存在于西花蓟马的肠道中，很可能是在取食过程中获得的。在此，我们研究蓟马是否因为这些肠道细菌而获得净收益或付出净成本。以黄瓜叶为食时，有细菌的蓟马比无细菌的蓟马（共生菌缺失型）成熟所需时间更短，产卵率更高。当以黄瓜叶和花粉为食时，共生菌缺失型发育更快且产卵更多。所以欧文氏菌对其蓟马宿主是有益还是寄生取决于食物，这与参与共生相互作用的生物体适应性的理论预测相符。可能由于这种依赖食物的适应性变异性，肠道细菌的传播尚未变得严格垂直。
