A Quick Sniff and She's Off

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Science  26 Feb 2010:
Vol. 327, Issue 5969, pp. 1060
DOI: 10.1126/science.327.5969.1060-a

Insects often use their sense of smell to locate food; some carry disease-causing pathogens, and in general, being infected makes an organism smell more strongly. Several pathogens have evolved to exploit these odor-tracking behaviors to entrain their life cycles in advantageous ways. Mauck et al. show that infection by cucumber mosaic virus increases the amount of aphid-attracting volatiles emitted by their plant hosts. Despite the delectable odors, virus infection makes the host plant less palatable, and consequently the aphids don't feed for long. For cucumber mosaic virus, fickle visitors are not a problem because it happens to be a nonpersistent virus—one sip of infected sap is enough to imbibe an infectious dose. The repellent host hastens the vector's departure and the transmission of the virus to a new host. In contrast, persistent viruses, such as barley yellow dwarf virus, induce both sweet odors and juicy fruit, which encourage their aphid vectors to prolong their visits. This allows the virus to complete a lengthy replicative cycle within the insect, after which onward transmission occurs.

Proc. Natl. Acad. Sci. U.S.A. 107, 10.1073/pnas.0907191107 (2010).

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