Effectiveness of passive trapping and sweep netting for insect pollinator sampling in turf communities

Abstract

Pollinator communities in urban and peri-urban turfgrass remain poorly characterized despite the ubiquity of lawns and growing interest in management practices that enhance floral resources within these otherwise resource-limited environments. To address this gap, we evaluated the effectiveness of active (sweep netting at multiple times of day) and passive (molasses traps and blue, white, and yellow pan traps) sampling methods for surveying insect pollinators in forb-enhanced bermudagrass plots in Mississippi and Georgia. Eight replicate plots were sampled over the course of one week at two sites, using a randomized complete block design. We identified 4,638 insect pollinator specimens representing 153 distinct taxa. Overall, sweep netting captured more individuals but tended to be biased toward larger, social taxa (e.g., Apis , Bombus ), whereas pan traps collected greater per-sample species richness and disproportionately sampled smaller, solitary taxa. Molasses traps yielded comparatively few individuals and low taxonomic diversity relative to other methods and were therefore excluded from final comparative analyses. Community composition differed significantly among sampling methods. These results demonstrate that no single method adequately captures full pollinator assemblages in forb-enhanced turfgrass systems; a complementary protocol combining sweep netting and pan trapping is recommended for comprehensive pollinator surveys in managed turf landscapes. Implications for Insect Conservation: Although conventional turfgrass monocultures generally provide limited value for insect pollinators, turfgrass-dominated landscapes are widespread in urban and peri-urban environments and therefore represent an opportunity for targeted enhancement through the incorporation of flowering forbs. However, realizing this potential requires unbiased, efficient, and reliable pollinator surveying methods that are specifically tailored to forb-enhanced turf. Here, we provide analyses that quantify the method-specific biases, temporal effects, and complementary strengths of active and passive surveying methods for monitoring pollinator abundance, richness, and community composition.

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