Comparison of hand‐netting and pan‐trapping methods for estimating hover fly (Diptera: Syrphidae) diversity in the tropical agroecosystems of East Africa

Abstract Monitoring hover fly populations is essential for establishing richness and diversity and their potential links to ecosystem service provision. While pan traps and hand netting are widely used in monitoring insects in natural habitats, their comparative performance in estimating hover fly (Diptera: Syrphidae) diversity in Afrotropical agroecosystems remains understudied. This study assessed the effectiveness of yellow pan traps and hand netting in estimating the richness and diversity of hover flies over two consecutive years (2022–2023) in a cucurbit agroecosystem in Morogoro, Tanzania, across two contrasting landscapes (plateau and mountainous zones). Weekly sampling was conducted for eight consecutive weeks during both the rainy (April–June) and dry (September–November) seasons across 20 cucurbit plots. In each plot, nine yellow pan traps were deployed for 48 h, and hand netting was conducted along three 15‐m transects for 45 min per session. Hand netting consistently recorded higher hover fly diversity than pan traps across all Hill numbers— q = 0 (species richness), q = 1 (Shannon diversity) and q = 2 (Simpson diversity). Species accumulation curves reached asymptotes more rapidly with hand netting, indicating greater sampling efficiency and community coverage. Although more labour‐intensive, hand netting provided a more comprehensive estimation of hover fly richness, abundance and diversity in both agroecological zones. In contrast, pan traps captured only a few additional low‐abundance species overlooked by netting, which are unlikely to contribute significantly to ecosystem service provision. Therefore, the study provides evidence that hand netting is the most robust and cost‐effective method for monitoring hover flies in this agroecosystem context, offering practical guidance for selecting appropriate sampling methods for monitoring insect species delivering ecosystem services in tropical agricultural landscapes.