Impact of boring insects on the reproductive success of Our Lord's Candle (Hesperoyucca whipplei)

Plants and herbivorous insects have a long evolutionary history; therefore we should be able to document insects’ impacts on plant fitness, if the plant is consumed by few herbivore species and the herbivores are monophagous. This study investigated the impact of stalk-boring insects on the reproductive fitness of Hesperoyucca whipplei by estimating the production of viable seeds and measuring stalk damage caused by stalk-boring insects. Since stalk-boring larvae tunnel through the flowering stalk, potentially affecting the flow of nutrients to the flowers and developing seeds, we predicted that stalk-boring insects would influence the reproduction of Hesperoyucca whipplei by increasing stalk damage, reducing seed, reducing germination success and the number of flowers producing pods. We found that as stalk damage increased germination success decreased. There was no evidence that stalk-boring insects reduced seed set (number of seeds), or the number of flowers producing pods.