Voltinism in the melanopline grasshopper Dichroplus elongatus Giglio-Tos (Orthoptera: Acrididae: Melanoplinae)

Abstract

Although Dichroplus elongatus is a common grasshopper of wide distribution and economic importance in southern South America, contradictory information still existed regarding its voltinism. Through captive rearing of individuals from an area where bivoltinism was recently postulated (Rafaela, Santa Fe province, Argentina) and either immediate subsequent incubation or incubation after refrigeration (4°C) of the resulting egg-pods, we determined that D. elongatus has obligatory embryonic diapause and one generation a year. Some previous reports of facultative diapause and bivoltinism may be attributed to other Dichroplus species that can be easily confused with D. elongatus.