A mutualism is a symbiotic relationship in which each organism benefits. The mutualism between the pollinating fig wasp, Pleistodontes imperialis and the fig tree, ficus rubiginosa is a form of an obligate mutualism where one cannot simply survive without the other. Here we report that seed set in the fig tree Pleistodontes imperialis is affected by parasatoid wasp numbers and that the obligate mutualism is kept intact by the parasatoid wasps.
In the study we collected fig fruits from two locations in the New England area of NSW and counted the number of seeds, pollinating wasps, non-pollinating fig wasps, male and female flowers in the fruits from two locations and compared the results. The results showed that where there was a greater presence of parasatoid (non- pollinating fig wasps) the seed count present in the fruit was higher, and concluded that parasatoid wasps are beneficial to the obligate mutualism by stopping the pollinating wasp species Pleistodontes imperialis out competing the fig tree by using up all available ovules of the fruit, therefore preventing seed set and reproduction of the fig tree ficus rubiginosa.
Introduction.
Theory predicts that mutualisms should be vulnerable to invasion by cheaters, yet mutualistic interactions are both ancient and diverse. What prevents one partner from reaping the benefits of the interaction without paying the costs? (Jander, K.C., & Herre, E.A., 2010).
The fig tree (ficus rubiginosa) is a species of fig that requires a form of mutualism to survive and reproduce. Mutualisms are interspecific ecological interactions characterised by reciprocal benefits to both partners, (West et al., March 2007). The one species of wasp that is part of the mutualism is the female wasp of the species Pleistodontes imperialis. This wasp pollinates the fig tree by entering the syconium of an unripe fig through an opening called the osteole. This wasp when entering the fig is pollen laden and whilst laying its eggs pollinates the flowers inside the fruit.