Effect of land use change on Melolonthidae (Coleoptera: Scarabaeoidea) beetle communities in the deforestation arc of the Brazilian Amazon

Although the Amazon provides crucial goods and ecosystem services for humanity, the alarming conversion of its original ecosystem due to agricultural activities challenges the maintenance of biodiversity in this rainforest. Beetles from the family Melolonthidae serve as a proxy for assessing the effect of land use change on biodiversity. In this study, we evaluated the effect of land use changes on the entire Melolonthidae community (species richness, abundance and biomass) and on each subfamily (Rutelinae, Melolonthinae and Dynastinae). Peach palm Bactris gasipaes Kunth (Arecaceae) plantation, coffee Coffea canephora Pierre ex A. Froehner (Rubiaceae) plantation, pasture Urochloa decumbens Stapf. (Poaceae) and forest remnants had their Melolonthidae communities assessed in the southern Amazon region. Forest remnants encompassed a higher species richness of the entire Melolonthidae family and Rutelinae subfamily compared to coffee plantations. Pasture areas had a higher abundance of the entire Melolonthidae family and the subfamilies Dynastinae and Melolonthinae, as well as a higher biomass of the Melolonthidae family and Melolonthinae subfamily. Coffee plantations presented the lowest species richness, abundance and biomass for all taxonomic levels studied. The results provide evidence that the Melolonthidae beetle community, especially Rutelinae, is negatively affected by land use change in the Amazon, reinforcing the role of these beetles in conservation studies. Pasture areas are favourable habitats for some species of the Dynastinae and Melolonthinae subfamilies, which suggests that they may be pests in this ecosystem. Future population studies are necessary to broaden our understanding of this group of insects.