An appraisal of sampling methods and effort for investigating moth assemblages in a Fijian forest

Abstract

AbstractThe moth assemblages in forest ecosystems are often used as indicators of forest quality and to monitor the effects of habitat degradation or ecological restoration and management. However, to provide meaningful data on nocturnal moth faunas, it is important to evaluate the efficacy of available sampling methods and identify the minimum number of samples needed to obtain a reliable estimate of moth diversity. This study compared three light‐based collecting methods to sample nocturnal moths in Colo‐i‐Suva Forest Reserve, a lowland mixed forest 8 km north of Suva, Fiji Islands. On average, over eight nights collecting, a mercury vapour light (MV) with manual capture obtained approximately 14 times more individuals and five times more species than a white fluorescent light with automatic capture and ultraviolet light with automatic capture. Of the 84 moth taxa recorded in total, only two were not obtained by the MV trap, suggesting the moth assemblages obtained by the fluorescent light and ultraviolet light methods were subsets of the larger MV collection. Using a bootstrap method to estimate the total species collected after successive nights sampling, we found that after four nights almost 90% of the predicted total moth species would be obtained by the MV method. These results identify the MV method as a high‐performing technique to investigate nocturnal moth diversity in Fijian forests, and that a minimum of four nights sampling with this protocol would produce reliable data for use in habitat evaluation.