Comparison of Sampling Methods for Determining Relative Densities of Homalodisca vitripennis (Hemiptera: Cicadellidae) on Citrus

Abstract

Four sampling methods that included A-Vac, D-Vac, pole-bucket, and beat-net devices were evaluated for estimating relative densities of glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) nymphs and adults on citrus (Citrus spp.) trees. All four methods produced similar temporal and spatial distribution profiles, although significant differences in quantities of H. vitripennis adults and nymphs caught by each device were observed. The four sampling methods also showed a consistent male bias in adult populations across a range of densities, suggesting that previously reported male-biased sex ratios in H. vitripennis adult populations are real and not a product of sampling bias. A strong relationship (R2 = 0.95) between the monitoring methods we evaluated and yellow sticky trap catches of female H. vitripennis adults suggest that yellow sticky trap catches may provide a good relative index of infestation levels in citrus trees. Based on quantitative analyses examining precision and cost, the pole bucket was the most efficient method for sampling nymphs, and it was as efficient as the beat-net method for sampling adults and both stages combined. In addition to these analyses, consideration of other sampling characteristics such as added flexibility in sampling and higher sensitivity in detecting infestations within individual trees helped to fortify the conclusion that the pole bucket was the best overall sampling method of those tested.