Occurrence of Diapause and the Role ofAndropogon bicornis(Poaceae) Tussocks on the Seasonal Abundance and Mortality ofTibraca limbativentris(Hemiptera: Pentatomidae)

Abstract

The rice stalk stink bug, Tibraca limbativentris Stål (Hemiptera: Pentatomidae), is a major pest of rice crops throughout Latin America. We investigated the occurrence of diapause in T. limbativentris, as well as the role of West Indian foxtail, Andropogon bicornis L.(Poaceae), in its seasonal abundance and mortality. This plant grows spontaneously in grasslands from Mexico to Argentina, including at the edges of rice fields in southern Brazil. Tussocks of A. bicornis were collected in Eldorado do Sul, State of Rio Grande do Sul, Brazil throughout one yr and examined to sample rice stalk stink bugs. We collected in 2,355 T. limbativentris adults from 208 tussocks, totalling 2,205 live and 150 dead individuals. Live insects were dissected to determine the reproductive stage and to assess the presence of the fat body. We describe the occurrence of imaginai diapause and the use of A. bicornis as a shelter for this rice pest. Overwintering lasted 7 mo; arrival at the refuge occurred in early autumn (late Mar); the permanence period began in Jun, and extended to the end of Sep. From Oct the population decreased gradually until total departure from the tussocks in Jan. Thus, here we highlight the role of A. bicornis as an hibernation site for T. limbativentris in southern Brazil.