The impact of habitat fragmentation on the interaction betweenCentaurium erythraea(Gentianaceae) and its specialized seed predatorStenoptilia zophodactylus(Pterophoridae, Lepidoptera)

Abstract

AbstractHabitat fragmentation can affect plant population characteristics and plant traits, which in turn can change biotic interactions, such as plant–insect interactions. Because of this, habitat fragmentation can affect reproductive success and survival of both the plant and seed predators, especially when the predator is rare and specialized. This study focuses on the level of fruit predation inCentaurium erythraeaby its specific seed predator, the plume mothStenoptilia zophodactylus, in a fragmented coastal dune landscape. To investigate the consequences of habitat fragmentation, we assessed the effect of population and plant characteristics of 25C. erythraeapopulations on fruit predation byS. zophodactylus. Although the distribution of this specialized predator is poorly documented, our results show thatS. zophodactylusoccurred frequently in most of the studiedC. erythraeapopulations. We found a strong correlation between the spatial isolation of the host plant and the level of fruit predation, with low predation in isolated populations, most likely due to the limited dispersion capacity of the plume moth.C. erythraeaindividuals experienced a higher risk of fruit predation when showing a large floral display size, presumably because they are more attractive. However, at fruit level, the risk of predation decreases with increasing floral display at individual plant level, representing a sort of dilution effect. Our findings indicate that maintaining and restoring large, dense and rather connected populations ofC. erythraeawill be beneficial for the sustainable conservation of the rare specialist seed predatorS. zophodactylus, without increasing the predation pressure on the host plant.