Coping with Seed Parasitism: A Possible Response by Protasparagus aethiopicus

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Abstract
Seeds of Protasparagus aethiopicus berries are subject to heavy parasitism by a lepidopteran larva. The level of parasitism increases with an increase in seed number per fruit. One-seeded berries have the highest probability of escaping parasitism (0.97), whereas two- and multi-seeded (three seeds or more) berries have lower probabilities for escaping (0.42 and 0.25, respectively). Since the seeds are in all cases similar in size, one-, two- and multi-seeded berries possess different seed-to-pulp ratios, with multi-seeded berries having the highest seed-to-pulp ratio. Successful larval development is inversely related to seed number, with a 97% larval mortality on one-seeded berries, 86% in two-seeded and 17% in multi-seeded berries. A mechanism for limiting successful parasitism in Protasparagus aethiopicus berries ws examined at four study sites and at three stages of the fruiting. The ratios of one-, two- and multi-seeded berries were found to vary both seasonally and at different sites, whereas parasitism of multi-seeded berries remained consistently high.