Our results suggest patterns of host cultivation are strongly associated with parasite adaptation to local host communities (Q1; Fig. 3A-C). Using crop harvest data to approximate relative host abundance (Fig. 2), we found that S. hermonthica emergence was highest on the host species most commonly grown at location of origin of parasite populations (Table S3).  This pattern satisfies the ‘home vs. away’ criterion described by Kawecki & Ebert (2004), as mean fitness of the parasite is highest in its ‘home’ host environment compared to ‘away’ hosts.  Although ‘home vs. away’ patterns sometimes conflict with ‘foreign vs. local’ genotype contrasts when one environment is relatively higher quality, we did not see evidence for such a conflict. Instead different parasite populations performed best on different hosts. Higher fitness on ‘home’ hosts was apparent despite the fact that we were not able to find high resolution crop distributional data prior to the year 2000, whereas empirical studies were based on S. hermonthica populations from field and pot trials that were sampled or tested 12-25 years earlier. This may be because host community composition (relative area planted to each host crop) remained roughly constant in East and West Africa during this period, although total area harvested increased dramatically (Fig. S1).  Evidence supporting a link between specialization and patterns of parasite occurrence on different hosts (Q2) was weaker, likely due to the small number of parasite records with host annotations that were also near the origin of S. hermonthica populations tested in experiments (Fig. 3D-F).