Biological and ecological consequences of Diolcogaster sp. (Hymenoptera: Braconidae) parasitizing Agaraea minuta (Lepidoptera: Arctiidae) and the effects on two Costus (Costaceae) plant species in Brazil

Costus spicatus (Jacq.) Sw. and Costus spiralis (Jacq.) Roscoe var. spiralis (Costaceae) are economically important plants due to their pharmacological and medicinal properties and ornamental value. These plants are natives from the Brazilian Atlantic Rainforest and are fed upon by Agaraea minuta Schaus, 1892 (Lepidoptera: Arctiidae). This study describes the damage done by A. minuta on C. spicatus and C. spiralis and the biological and ecological aspects of parasitism of A. minuta by Diolcogaster sp. (Hymenoptera: Braconidae). Twenty stems of C. spicatus and C. spiralis with 100 last-instar caterpillars of A. minuta, were collected per plant in each of two years. The stem heights (F, P > 0.05), leaf lengths (F, P > 0.05), leaf widths (F, P > 0.05) and the number of leaves per stem (F, P > 0.05) of both plant species; number of pupae obtained from caterpillars of A. minuta (F, P > 0.05), adult emergence of this defoliator (F, P > 0.05) and of Diolcogaster sp. (F, P > 0.05) were similar during the two study periods. Agaraea minuta has potential to defoliate C. spicatus and C. spiralis plants, although it damages the former more severely than the latter. The parasitoid, Diolcogaster sp., could suppress populations of A. minuta, which could result in increased plant biomass.