Fig trees and fig wasps: their interactions with non-mutualists

Non-mutualist species that interact with mutualists occur commonly in nature. Non-mutualists associated with the mutualism between fig trees and their pollinating fig wasps include mites and nematodes. This thesis focusses on the interaction of nematodes with fig trees and fig wasps in South Africa and Indonesia, with additional investigation on how mites, nematodes and fig pollination respond to highly seasonal environments. The reproduction of monoecious Ficus burtt-davyi in Grahamstown, South Africa slows down but does not stop in winter. There are fewer fig pollinating wasps Elisabethiella baijnathi flying in the air during winter, but most figs are probably pollinated by locally-produced fig wasps. Elisabethiella g5baijnathi females transport mites (Tarsonemella sp. nr. africanus) and nematodes (Parasitodiplogaster sp.) between figs. Contrasting dispersion patterns and relationships with fig wasp foundress numbers indicate that the mites, but not the nematodes, disperse between figs after being carried there by the pollinators. Three nematode species (Caenorhabditis sp., Schistonchus centerae, and S. guangzhouensis) developed inside both male and female figs of dioecious F. hispida tree in Sumatra, Indonesia. Caenorhabditis sp. was transferred between figs as juveniles, whereas Schistonchus spp. were transferred mostly as juveniles, and occasionally as adults. The nematode community of eight species in Sumatran monoecious F.racemosa was the most diverse recorded anywhere. No mites were found in both species of fig trees. Peak nematode populations occurred in D-phase figs, when the fig wasp offspring are ready to emerge. The nematodes attach themselves to newly-emerged female pollinators, which then carry them away. Usually more nematodes attached on the first fig wasps to emerge. Entry into figs by early-emerging pollinators resulted in higher numbers of the next generations of nematodes within the figs. Details of the ecology of each nematode species may be different, but as a group they did not seem to significantly affect seed and wasp development in both F. hispida and F. racemosa figs.