Seasonal fluctuation, phenology and turnover of chafer assemblages – insight to the structural plasticity of insect communities in tropical farmlands
1 Studies on chafer assemblages were conducted on two farmland sites in the Terai lowland of Nepal (200 m above sea level) using light traps. During the course of a 2-year field monitoring program, a total of 4503 specimens was captured and an unexpectedly high number of syntopically co-occurring species was found: 52 from Gunganagar (GN) and 36 from Gaindakot (GK), respectively. Highest species abundances and species numbers were found during April and May.
2 Species occurrence was strongly correlated with air temperature and the maximum soil temperature, at least during the pre-monsoon season. However, assemblage structure from the two sites showed significant qualitative and quantitative changes seasonally, as well as from 1 year to the next. Turnover rates between adjacent months were in the range 26–62% (GN) and 37–70% (GK), whereas the turnover from 2004 to 2005 was 25.8% (GN) and 21.4% (GK) respectively.
3 When only dominant and subdominant taxa are considered, the seasonal change in species composition was even more striking.
4 Strong fluctuation in chafer assemblage over time suggests: (i) a possible influence of patchy habitat types and soil working on seasonal assemblage structure and (ii) colonization of suitable habitats (fields) in great part by chance.
Document Type: Research Article
Affiliations: 1: Institute of Agricultural and Animal Sciences (IAAS) of Tribhuvan University, Rampur, Nepal 2: Department of Biology, University of Mississippi, MS 38677, U.S.A. 3: Department of Environmental Sciences, Institute of Biogeography, University of Basel, St Johanns-Vorstadt 10, CH-4056 Basel, Switzerland
Publication date: 2009-08-01