Recent concerns about worldwide decline of pollinators and the possible ecosystem wide consequences highlight the importance of understanding how native and non-native pollinators and plants interact. Pollination webs provide information on how these systems function and change. To understand the role of native and non-native pollinators in a Hawaiian dry forest ecosystem containing several endangered endemic plants, I have constructed a pollination web to answer the question of whether natives interact more closely with natives, and non-natives with non-natives. When the web is separated into native pollinators and non-native pollinators, native pollinators visit almost exclusively native plants, visiting only three non-native plants. In comparison, non-native pollinators visit both native and non-native plants. Compartmentalization of the web is dependent on perspective. From the native pollinator perspective, there is strong compartmentalization since they almost exclusively visit native plants. From the non-native plant perspective there is also strong compartmentalization because the majority of visitors are non-native. Native plants, by contrast, do not show compartmentalization, as they are visited by both natives and non-natives. However, honey bees, which are by far the most ubiquitous flower visitor in the system, visit almost every plant regardless of group or density, including four species of invasive plants which are visited by no other pollinators. Thus, while honey bees visit native plants and presumably enhance their reproduction, they may be even more important for the reproduction of some invasive species, and so may be facilitating invasion meltdown within the dry forest system.
