Ecological and socio-economic impacts of the red import fire ant, Solenopsis invicta (Hymenoptera: Formicidae), on urban agricultural ecosystems

Abstract

The agricultural impacts of the Red Imported Fire Ant, Solenopsis invicta Buren 1972, have been well studied in North America, but have received less emphasis in Asia where the species was first detected in the early 2000’s. Simultaneously, with urbanization rapidly expanding in Asia, S. invicta impacts on the socio-economic benefits of urban farming are to this point unknown. Our study focuses on establishing a baseline on the geographic distribution of the S. invicta spread in Hong Kong urban agroecosystems and its potential impacts on native ant communities and farmers through a series of field surveys and interviews. Our results show that in 15 years, S. invicta has invaded half of the Hong Kong urban agroecosystems, with infestation levels slightly varying in farming practices (organic vs. traditional) but greatly among the different types of cultures. Ecologically, the presence of S. invicta and its increased abundance were associated with a decrease in ant community species richness and evenness. Economically, the farmers’ perception indicated that S. invicta could have impacts on crops production ranging from 10% to 80%, as well as important public health issues associated to indirect economic costs due to the aggressive stinging and consequences on other educational activities. Finally, all control methods used were mainly inefficient and maladjusted to these environments. With dense infested farm locations and current management, S. invicta prevalence and its cost are expected to expand. This prospective situation requests the development of professional guidance and management plans to impede S. invicta spread and rising impacts.