The impact of bush honeysuckle (Lonicera maackii) removal on forest insect diversity

Bush Honeysuckle (Lonicera maackii) is an exotic, invasive species out-competing native plants through shading and the release of allelopathic chemicals, though little is known about the effects of this species on other trophic levels. Lonicera maackii has invaded Cherokee and Seneca Parks in Louisville, Kentucky and eliminated many other plant species in the understory of invaded sites. To determine the impact of Bush Honeysuckle on the insect community in these areas, an observational study and honeysuckle removal experiment were performed. Two invaded sites and one restored site were compared by collecting beat stick samples and pit fall trap samples. The total numbers of insects and species richness were significantly lower in invaded sites than in the restored site, suggesting a relationship may exist between lower insect diversity and the presence of L. maackii. A manipulative experiment removed L. maackii from one half of ten paired-plot sites in January, 2009. Pitfall and sticky trap samples were collected in the ten pairs of invaded and removal sites in April, July, and August of that year. Pitfall traps and summer sticky trap arthropod abundance and species richness was not significant between removal and invaded plots. Sticky trap sample insect abundance was significantly higher in invaded sites during the spring and removal sites in the fall. In the fall, insect morpho-species richness was also significantly greater in removal sites using sticky traps. Possible mechanisms explaining these patterns may include more understory plant biomass in invaded areas, or greater light availability in removal areas.