Andropogon bicornis (Poales, Poaceae): a hibernation site for Pentatomoidea (Hemiptera: Heteroptera) in a rice-growing region of Southern Brazil.

Tussocks of Andropogon bicornis (Poaceae) make up a significant part of the landscape of the rice-growing region of south Brazil. However, little is known about their role in maintaining insect diversity in anthropized regions. We tested the hypothesis that A. bicornis is a hibernation site for Pentatomoidea (Hemiptera: Heteroptera) by analyzing the composition, structure, and diversity of pentatomoid assemblages over the course of a year. A total of 208 tussocks were removed at fortnightly intervals from April 2010 to March 2011. We collected 3,423 pentatomoid specimens belonging to 22 species distributed in 13 genera of three families, Pentatomidae, Scutelleridae, and Thyreocoridae. The most common species was Tibraca limbativentris Stål, the main rice pest in southern Brazil, followed by Oebalus ypsilongriseus (De Geer) and Edessa meditabunda (Fabricius). Abundance and species richness were the lowest in January, February, and March and the highest in July, August, and September. A combination of high species diversity observed during the colder months, including several unrelated to rice, and the absence of immature specimens in the tussocks strengthens the hypothesis that A. bicornis is a hibernation site for pentatomoids in the region.