Edaphic entomofauna associated with coconut crops in the eastern Amazon

Abstract

In the Eastern Amazon is the largest continuous coconut crop area in the world. This region is known for its high precipitation levels and an ecosystem of extensive insect biodiversity. It is important to know the local entomofauna and to know whether there is a balance between the different insect groups. This study aimed to understand the influence of seasonality on the dynamics of edaphic insect families, comparing the environment as a whole and in different commercial coconut crop areas and riparian forests in the Eastern Amazon. Forty pitfall traps were installed in the ground at an average distance of 1 m from the coconut stipe. They were filled with 200 ml of an aqueous solution of liquid neutral soap and 70% alcohol. Traps were installed in eight areas: an area of riparian forest (A1) and seven in commercial coconut crop areas (A2 to A8), in the Amazon dry and rainy season. The similarity between the insects was measured using Euclidean distance. The abundance of families in each collection area used qualitative similarity. For family dominance, quantitative similarity was used. Diversity analyses were performed to justify the similarities of the clusters through the Shannon and Simpson Indices. In total, 252,313 individuals, 118 families, and 9 orders were collected. There were many Formicidae in both climatic periods because it is a social insect and has edaphic habits. The families with the most individuals in the collections were Drosophilidae, Staphylinidae, Bostrichidae, Phoridae, Nitidulidae, Scolytidae, Tenebrionidae, Scarabaeidae, Ceratopogomidae, and Platyogastridae. The riparian forest area (A1) showed the greatest diversity and least dominance. The oldest cultivated areas A2 and A3 (7 years) showed the greatest diversity in the dry season. In the rainy season, the most diversified areas were those with the highest land slope (A6 and A7). The most dominant areas were A5 and A8, where the largest number of Solenopsis spp. were found. This study showed the importance of obtaining basic information about coconut entomofauna and conducting research on insect dynamics in agricultural crops in the Amazon region.