Diversity and Abundance of Ground Beetles (Carabidae: Coleoptera) in Eco-Friendly Home Gardens in Comparison with Conventional Home Gardens in Southern Dry Zone of Sri Lanka

Abstract

Insect diversity plays an important role in agro-ecosystem in relation to stability and productivity; therefore, conservation of biodiversity is important for long-term viability of agro-ecosystems. Biodiversity in farm lands is threaten by some practices carried out by the growers such as extensive application of non-selective weedicides, misuse of insecticides, extensive ploughing, burning of crop waste etc. In order to conserve the biodiversity, it is necessary to promote the eco friendly practices such as low or no use of pesticides, organic manure application, enhance plant diversity, and soil and water conservation. Biodiversity improvement through these practices has been recorded elsewhere but local data are scant. Hence, the objective of this study was to assess the biodiversity; diversity of carabid beetles in multiregional homegardens that were managed as eco-friendly, nutritional home gardens in comparison with conventionally managed home gardens. Field study was carried out during 2009-2012 in selected three villages: Kumaragama, Katuwanayaya and Elisonkanda in Hambantota district. Carabid beetles were sampled from four conventional and four eco-friendly nutritional home gardens in each village using pitfall traps. Of the insects collected, 164 carabids that were belonging to five genera: Bembidion, Cicindela, Harpalus, Pheropsophus, and Scarites were identified. Pheropsophus sp. were more abundant [36.5% ] followed by Scarites spp. [9.7% ]. Carabid abundance was significantly higher in eco-friendly homegardens [X2 =72.8 df=l p<0.001] than in conventional home gardens. Carabid species diversity also followed the same trend. There was a significant variation among the sampling locations: Katuwanayaya, Elisonkanda and Kumaragama in terms of total carabid number [X2 =16.9; df=2; p<0.001). The study revealed higher diversity and abundance of carabids in eco-friendly homegardens in compared to the conventional home gardens.