Comparative Overview of Community Structure and Functioning of The Flower-Visiting Insects on Physalis minima L. (1753) (Solanales: Solanaceae) and Sesamum indicum L. (1753) (Scrophulariales: Pedaliaceae) in Macha (Bambui, North-West, Cameroon)

Abstract

Background: Floral visitors play a crucial role in maintaining agro-ecosystem productivity, yet their dynamics in the highlands of North-West Cameroon remain poorly understood. The plant plays a crucial ecological role by offering alternative nectar and pollen resources, thereby contributing to the maintenance of local pollinator populations. Aim: This study investigated the entomofauna visiting Physalis minima L. (1753) (Solanales : Solanaceae) (a spontaneous herb) and  Sesamum indicum L. (1753) (Scrophulariales: Pedaliaceae) (a major oilseed crop) in Macha (Bambui) to evaluate their diversity, community structure, and interspecific interactions. Place and Duration of Study: Insect collections and observations were conducted during the 2013 and 2014 cultivation campaigns in Macha (Bambui, North-West, Cameroon). Methodology: Community structure was analyzed using diversity indices (Margalef, Berger-Parker, Shannon), rarefaction curves, and rank-frequency mathematical models (Zipf and Zipf-Mandelbrot). Interspecific correlations were tested to assess behavioral dynamics. Results: A total of 42 insect species were identified, with Hymenoptera (Apidae: 41.2%) being the dominant order. Amegilla sp. and Apis mellifera adansonii were the primary visitors, exhibiting clear niche partitioning: Amegilla sp. significantly preferred the tubular flowers of Se. indicum (44.9%), while A. m. adansonii favored Ph. minima (20.7%). Species abundance distributions (SADs) predominantly fitted the Zipf-Mandelbrot model, reflecting a "pioneer-like" system with high dominance and shared competition among leaders. Despite low overall species richness, communities were structured around a stable core of frequent visitors. Interestingly, all significant interspecific correlations were positive, suggesting behavioral tolerance and a synergistic network of floral exploitation. Physalis minima acted as a vital biodiversity reservoir, supporting 80.2% of useful pollinators and a refuge for biological control agents like Paragus borbonicus. Conclusion : The findings highlight the importance of maintaining heterogeneous floral resources (crops and wild weeds) to preserve a resilient pool of pollinators. Landscape-level management that integrates spontaneous flora is essential for the sustainability of subsistence agriculture and the stability of ecosystem services in the Cameroonian highlands.