Department of Evolution and Ecology, University of California Davis, Davis, California, United States of America.
PLoS One. 2012;7(7):e42238. doi: 10.1371/journal.pone.0042238. Epub 2012 Jul 31.
Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies, supporting previous suggestions that adult Drosophila vector yeasts to new substrates. However, larvae alone had dramatic effects on yeast density and species composition. When yeast densities were compared in pieces of the same fruits assigned to different treatments, fruits that developed low yeast densities in the absence of flies developed significantly higher yeast densities when exposed to larvae. Across all of the fruits, larvae regulated yeast densities within narrow limits, as compared to a much wider range of yeast densities that developed in pieces of the same fruits not exposed to flies. Larvae also affected yeast species composition, dramatically reducing species diversity across fruits, reducing variation in yeast communities from one fruit to the next (beta diversity), and encouraging the consistent development of a yeast community composed of three species of yeast (Candida californica, C. zemplinina, and Pichia kluvyeri), all of which were palatable to larvae. Larvae excreted viable cells of these three yeast species in their fecal pools, and discouraged the growth of filamentous fungi, processes which may have contributed to their effects on the yeast communities in banana fruits. These and other findings suggest that D. melanogaster adults and their larval offspring together engage in 'niche construction', facilitating a predictable microbial environment in the fruit substrates in which the larvae live and develop.
黑腹果蝇的成虫和幼虫，尤其是幼虫，对在香蕉果实中生长的酵母菌的密度和群落结构有深远的影响。暴露于先前喂食过果蝇条件性香蕉的雌果蝇的果实碎片比未暴露于果蝇的相同果实碎片发展出更高的酵母密度，这支持了先前的观点，即成年果蝇将酵母菌传播到新的基质上。然而，幼虫单独对酵母密度和物种组成有显著影响。当对暴露于不同处理的同一果实碎片中的酵母密度进行比较时，在没有果蝇的情况下酵母密度较低的果实，当暴露于幼虫时，酵母密度显著增加。在所有的果实中，与没有暴露于果蝇的同一果实碎片中发展出的酵母密度范围相比，幼虫将酵母密度调节在较窄的范围内。幼虫还影响酵母物种组成，显著降低了跨果实的物种多样性，减少了下一个果实之间酵母群落的变化（β多样性），并促使由三种酵母（加利福尼亚假丝酵母、齐氏假丝酵母和毕赤酵母）组成的酵母群落持续发展，所有这些酵母对幼虫都是可食用的。幼虫在其粪便池中排泄这三种酵母的有活力的细胞，并抑制丝状真菌的生长，这些过程可能有助于它们对香蕉果实中酵母菌群落的影响。这些和其他发现表明，黑腹果蝇成虫及其幼虫后代一起进行“生态位构建”，促进幼虫生活和发育的果实基质中可预测的微生物环境。
