Consumption evaluation of weed seeds by Notiobia (Anisotarsus) cupripennis (Germ.) (Coleoptera: Carabidae)

The food preference of Notiobia cupripennis among seeds of eight weedy spring-summer species (Sp-Su) and six autumn-winter (Av-Wi) species more common in the agroecosystems of the South of Santa Fe Province, Argentina, was estimated in this study. The seeds of the species of each group were offered simultaneously and in pairs to adults individually placed. The relation (damaged seeds/available seeds) x 100 of each species was considered as a food preference index. The data were analysed by analysis of variance and Duncan's Multiple Range Test and by a paired difference test, previous arcsine-square-root transformation. The seeds of the Av-Wi species were more damaged (27.65%) than the Sp-Su ones (10.40%). Highly significative differences in the percentage of damaged seeds among the different species were found; dicotyledones were preferred over gramines. The food preference ranking was maintained when the insects were forced to choose between the seeds of two weed species. The food preference would be attributed to differences in seed size, tegument toughness and chemical composition of the seeds in relation to the ability of handling the seeds and the nutritional requirements of the insect.En este trabajo se estimó la preferencia alimentaria de Notiobia cupripennis por semillas de ocho especies de malezas primavero-estivales (Pr-Es) y de seis especies otoño-invernales (Ot-In) más comunes en los agroecosistemas del Sur de la provincia de Santa Fe, Argentina. Las semillas de las especies de cada grupo fueron ofrecidas en conjunto y de a pares a adultos confinados individualmente. La relación (semillas dañadas/semillas disponibles) x 100 de cada especie fue considerada como índice de preferencia alimentaria. Los resultados fueron analizados mediante análisis de la variancia y test de rangos múltiples de Duncan y mediante un test de diferencia de medias, previa transformación arcoseno de los datos. Las semillas de las especies Ot-In fueron más dañadas (27,65%) que las Pr-Es (10,40%). Se encontraron diferencias altamente significativas en el porcentaje de semillas dañadas entre las diferentes especies; las dicotiledóneas fueron más preferidas que las gramíneas. El orden de preferencia alimentaria se mantuvo cuando los insectos fueron obligados a elegir entre semillas de dos especies de malezas. La preferencia alimentaria se atribuiría a diferencias en el tamaño, la consistencia del tegumento y la composición química de las semillas en relación con la habilidad de manipulación de las mismas y los requerimientos nutricionales del insecto.The food preference of Notiobia cupripennis among seeds of eight weedy spring-summer species (Sp-Su) and six autumn-winter (Av-Wi) species more common in the agroecosystems of the South of Santa Fe Province, Argentina, was estimated in this study. The seeds of the species of each group were offered simultaneously and in pairs to adults individually placed. The relation (damaged seeds/available seeds) x 100 of each species was considered as a food preference index. The data were analysed by analysis of variance and Duncan's Multiple Range Test and by a paired difference test, previous arcsine-square-root transformation. The seeds of the Av-Wi species were more damaged (27.65%) than the Sp-Su ones (10.40%). Highly significative differences in the percentage of damaged seeds among the different species were found; dicotyledones were preferred over gramines. The food preference ranking was maintained when the insects were forced to choose between the seeds of two weed species. The food preference would be attributed to differences in seed size, tegument toughness and chemical composition of the seeds in relation to the ability of handling the seeds and the nutritional requirements of the insect