Orthoptera assemblages in subtropical paddy fields: role, effect of plant phenology, and cultivation area

Irrigated rice crops are considered artificial wetlands, with high productivity and biodiversity, especially in insect populations such as orthopterans. Although these predominantly herbivorous insects include several species of agricultural concern, their occurrence and dynamics in rice-growing systems remain insufficiently documented. This study aimed to analyse the composition and diversity of Orthoptera insects associated with subtropical paddy fields and to evaluate how rice phenology and field zone (edge vs centre) influence the structure of these assemblages. Sampling was conducted in Northeastern Argentina, the country's main rice-producing region. In total, 14 orthopteran species belonging to four families were recorded, with Conocephalus longipes (Redtenbacher, 1891) (Tettigoniidae) as dominant, representing 89.34% of total abundance. Crop phenology significantly affected the assemblage structure: species richness and diversity peaked during the vegetative stem elongation stage, whereas overall abundance was highest during the reproductive ripening stage. In contrast, no significant differences were detected in species richness or abundance between the field edges and centres. These findings are relevant because documenting the orthopteran community present in rice systems provides insights into whether current management practices align with principles of sustainable agriculture. Moreover, the marked predominance of C. longipes suggests that this species could play an important role as a potential pest, underscoring the need for continued monitoring and targeted research to assess its impact and inform future management strategies. This study contributes to a better understanding of insect biodiversity patterns in subtropical South American paddy fields and supports efforts aimed at promoting productive yet environmentally responsible agricultural systems.