Acadia researchers discover a novel plant-insect interaction in an endangered NS plant

by Kristie, David

Research conducted by former Acadia Biology Honours student Emily Evans, and Acadia professors Dr. Kirk Hillier and Dr. Rodger Evans has been published in the online Nature journal, Scientific Reports. The paper entitled “Novel Insect Florivory Strategy Initiates Autogamy in Unopened Allogamous Flowers” describes a new insect-plant interaction which has never been described previously. 

What is Florivory? The consumption of flower parts, prior to seed formation, by herbivores.

What is Autogamy? Self-fertilization, ie the self-pollination of a flower.

What is Allogamous (Allogamy)? Cross-fertilization, ie flowers that are normally pollinated by pollen from another flower, usually from another plant.

This research involved a rare, endemic plant in Nova Scotia’s sand barren habitats, Crocanthemum canadense (Rockrose),  and exposed a florivory interaction that had not been observed previously. Larvae of Mompha cappella, a small moth species native to North America, were observed between the sepals and petals of Rockrose flowers, early in the development of the flowers. The larvae would consume the base of the petals, disconnecting them from sources of nutrients and water; thus the petals will never open to allow the flower to be pollinated by the bee or fly species that typically visit Rockrose flowers. As the petals start to desiccate, they form a cone of tissue around the male stamens that causes them to come into close contact with the stigma of the female pistil as the flower continues to develop. When mature, the stamens open and pollen falls on the stigma, resulting in self-pollination. As the fruit from self-pollination develops, the larva chews a small hole in the side of the fruit, enters, and consumes the developing seeds produced from its florivory of the petals.

The novel aspect of the observed interaction is that the larva, although causing damage to the flower, is very precise in that only the bases of the petals are modified such that the flower doesn’t open. While Rockrose plants do have the ability to self-pollinate, producing flowers without petals later in the season that never open and self-pollinate, the relatively few “showy” pataliferous flowers that are produced are necessary for outcrossing and maintenance of genetic diversity in the population. With a measured infection rate of ~50% of plants over the past 3 years, it would appear that Mompha’s activities may have a negative effect on the population dynamics of Rockrose.

Images by Dr. Rodger Evans

This research was funded in part by an Arthur Irving Research Grant in Environmental Science 

Read the full paper here

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