Communities of Galling Insects on Neoboutonia macrocalyx Trees in Continuous Forests and Remnants of Forest Fragments in Kibale, Uganda

The responses of Afrotropical galling insects to habitat fragmentation are poorly understood. We studied the influence of fragmentation and fragment characteristics on communities of galling insects on Neoboutonia macrocalyx trees, in six forest fragments around Kibale National Park, Uganda. Insect galls were collected from six randomly cut tips of branches from each of 10 randomly selected trees in every forest five times over a 10-month period.Atotal of 6090 individuals representing five galler species were recorded. The species richness, density and community composition of gallers were significantly different among the forests. Continuous forest areas showed similar community characteristics but some fragments were similar to continuous forests and others differed from them. None of the fragment characteristics measured (size, host-tree density, distance from continuous forest boundary and from nearest neighbour) explained differences in community measures (species richness and density) of gallers. Our results indicate that habitat fragmentation can lead to a decline in the galler species richness and to changes in the density and composition of galling insects, emphasizing the need to maintain large continuous forested areas as a long-termstrategy for their conservation. However, the similarity of community measures of gallers of some fragments and continuous forests suggest that the preservation of fragments might provide an important complement to the conservation of galling insects, highlighting the need to include also these habitats in management and conservation priorities. However, our study did not identify habitat characteristics to predict which fragments have a high value for gallers, indicating that processes that produced high-value fragments might have been stochastic. Our results caution against making generalizations on the use of easily measureable fragment characteristics (e.g. size and distance of isolation) when designing and planning conservation areas.