Population trends of insect pollinators in a species-rich tropical rainforest: stable trends but contrasting patterns across taxa

Recent reports of insect decline have raised concerns regarding population responses of ecologically important groups, such as insect pollinators. Additionally, how population trends vary across pollinator taxonomic groups and degree of specialization is unclear. Here, we analyse 14 years of abundance data (2009-2022) for 38 species of native insect pollinators, including a range of Coleoptera, Lepidoptera and Hymenoptera specialists and generalists from the tropical rainforest of Barro Colorado Island, Panama. We estimated population trends across taxonomic groups to determine whether specialist species with a narrower range of interacting mutualistic partners are experiencing steeper population declines under environmental change. We also examined the relationship between climate variables and pollinator abundance over time to determine whether differences in sensitivity to climate predict differences in population trends among pollinator species. Our analyses indicated that most pollinator populations were stable or increasing, with few species showing evidence of decline, regardless of their degree of specialization. Differences in climate sensitivity varied among pollinator species but were not associated with population trends, suggesting other environmental factors at play for tropical insect pollinators. These results highlight the need for long-term population data from diverse tropical taxa to better assess the environmental determinants of insect pollinator trends.

Polypore fungus beetles (Coleoptera: Tetratomidae) in a remnant of semi-deciduous forest of the Brazilian Cerrado: checklist and the description of a new species of Eustrophopsis Champion, 1889

Tetratomidae Billberg, 1820 is a small family of tenebrionoid beetles that primarily feed on polypore fungi. Their Neotropical diversity remains poorly known, with most recent studies concentrating on Nearctic and Palearctic species. The few records from the neotropics are from samplings in the Atlantic Forest or Amazon Rainforest. Here we present illustrations of genitalia and photos of two species of Eustrophopsis Champion, 1889, E. laurae sp. nov. and E. bilunulata Pic, 1912. The samplings were carried out with malaise traps in the Parque Estadual Altamiro de Moura Pacheco (PEAMP), Goiás, Brazil, a remnant Cerrado mostly covered by semi-deciduous forest. These species represent the first records of Tetratomidae for the Brazilian Cerrado since their original descriptions, elucidating the paucity of studies on the fauna of Coleoptera in Brazil. This research is part of our ongoing efforts to better understand the insect diversity of this region, especially in current scenarios of rapid deforestation and biodiversity loss.

Diversity of Insect Flower Visitors of Xylopia aromatica (Magnoliales, Annonaceae) in a Brazilian Savanna

Small beetles are important pollinators of Annonaceae whose flower chambers are small and have diurnal and/or nocturnal anthesis. The pollinators of these flowers belong to the families Nitidulidae, Staphylinidae, Chrysomelidae, and Curculionidae. In this study, the first conducted in the Cerrado of Chapada dos Guimarães, Mato Grosso, Brazil, the behavior of the insect flower visitors of Xylopia aromatica was observed, in both the field and the laboratory. The chambers of 253 flowers were collected from 11 plants, and the biological aspects of their visitors were analyzed quantitatively and qualitatively. The most abundant visitors were thrips and beetles. Coleoptera was represented by four morphospecies occurring frequently in the floral chambers (>70% of individuals). Among beetles, one species belonged to Nitidulidae (Cillaeinae, Conotelus sp. 1) and two belonged to Staphylinidae (Aleocharinae sp. 1 and Aleocharinae sp. 2). These three morphospecies of small elongate beetles have setae where pollen may adhere. In addition, they were present on both male and female phases of the flowers, indicating potential cross-pollination. In the study area, X. aromatica possesses mixed pollination promoted by Thysanoptera and small Nitidulidae and Staphylinidae beetles. This study brings the first record of Lamprosomatinae (Chrysomelidae) and, especially, of Conotelus (Nitidulidae) in the flower chambers of X. aromatica, with new information on behavior of floral visitors coupled with their morphological traits that may promote cross-pollination in this plant species.