ARS | Publication request: 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

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2012
Publication Date: December 1, 2012
Citation: Tavares, W., Salgado-Neto, G., Legaspi, J.C., Serrao, J., Zanuncio, J. 2012. 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. Florida Entomologist. 95(4):966-970.

Interpretive Summary: The ginger plants, Costus spicatus and Costus spiralis, are plants of economic importance due to their pharmacological and medicinal properties as well as their ornamental value. They are native to the Atlantic Rainforest biome of Brazil. Caterpillars of Agaraea minuta feed on C. spicatus and C. spiralis plants and a parasite, Biolcogaster sp. attack the caterpillars. Because of recent interest in the expanded cultivation of Costus spp., Scientists with the USDA-Agriculture Research Service, Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, Florida, in collaboration with Brazilian colleagues, studied: 1) the damage that A. minuta caterpillars caused to C. spiralis and C. spicatus plants over 2 consecutive yr, and 2) mortality inflicted by Diolcogaster sp. on A. minuta. Agaraea minuta fed on both plants of C. spicatus and C. spiralis and Diolcogaster sp. was shown able to suppress caterpilar populations and increase crop biomass.

Technical Abstract: Costus spicatus and Costus spiralis 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 (Lepidoptera: Arctiidae). This study describes the damage done by this species on C. spicatus and C. spiralis and the biological and ecological aspects of its parasitism by Diolcogaster sp. (Hymenoptera: Braconidae: Microgastrinae). Twenty stems of C. spicatus and C. spiralis, together with 100 final-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 fed on both plants of C. spicatus and C. spiralis and Diolcogaster sp. was shown to be a parasitoid suppressor of populations of this defoliator, which could decrease plant biomass.