Virus Incidence and Cultivation System
Converging studies, using distinct approaches and pathosystems, have linked the early emergence and radiation of plant pathogens to the modification of their environment (Stukenbrock and McDonald, 2008; Webster et al., 2007). In particular, the development of agriculture from the Eocene coincides with the dates of the radiation of RNA potyviruses, 6600 years ago (Gibbs et al., 2008b, 2008c) and DNA sobemo-viruses 3000 years ago (Fargette et al., 2008), as estimated by phylogenetic analyses. The changes induced by agriculture and human migration favored “new encounters between plants and viruses” leading to the increasing number of virus species. Similarly, the recent history of potyvirus diseases of vanilla typically exemplifies the close relationship between agro-systems and virus pressure (Table 7.2).
| Country | Year of the Survey | Proportion of Infected Plots | Proportion of Infected Vines | Cultivation System | Potyvirus Identified | Reference |
|---|---|---|---|---|---|---|
| Comoros | 2007 | 0/41 | 0% | UF/SI | None | Grisoni and Abdoul Karime (2007) |
| Fiji | 1989 | 20/36 | 1–49% | SI/UF | NA | Pearson et al. (1993) |
| India | 2000/01 | 9/35 | 0.2–5% | SI | NA | Bhai et al. (2003) |
| India | 2003 | 52/65 | 0.25–10% | SI | NA | Bhat et al. (2004) |
| Madagascar | 1997 | 0/21 | 0% | UF/SI | None | Grisoni et al. (1997) |
| Madagascar | 2000 | 0/29 | 0% | UF/SI | None | Leclerq–Le Quillec (2000a, 2000b) |
| Madagascar | 2004 | NA | 5% | SH | BCMV | Grisoni (2004) |
| Madagascar | 2009 | 45 | 0% | SH/SI | Grisoni (2009) | |
| Marquesas (FP) | 2003 | 5/29 | 0.5–90% | SI | WMV-DsMV | Grisoni (2003) |
| Mayotte | 2007 | 0/ | 0% | SI | None | Grisoni and Abdoul Karime (2007) |
| Reunion | 1998/99 | 14/17 | 0.3–14.4% | SH | NA | Benezet et al. (2000) |
| Reunion | 2000 | 9/25 | NA | SI/SH | NA | Farreyrol (2005) |
| Samoa | 2005 | NA | 6% | SI | WVMV | Grisoni et al. (2006) |
| Society Islands (FP) | 2000 | 18/32 | NA | SI/SH | NA | Farreyrol (2005) |
| Society Islands (FP) | 1998/99 | 27/49 | 0.6–97% | SI/SH | DsMV, WMV, BCMV | Grisoni et al. (2004) |
| Society Islands (FP) | 1986 | 9/30 | 0.3–47.9% | SI/UF | DsMV | Wisler et al. (1987) |
| Tonga | 1989 | 19/25 | 1–21% | SI/UF | NA | Pearson et al. (1993) |