Taking shortcuts to measure species diversity: parasitoid Hymenoptera subfamilies as surrogates of species richness

Abstract

When trying to assess entomological diversity, identifying taxa at levels higher than species is much easier and may provide a wider vision of other ecological features. In this work, we used the data from several samplings made in across six cacao farms in Mérida state (Venezuela). Farms fell into two categories according to intensity of perturbation. In these samplings we identified all parasitoid Hymenoptera families. All individuals belonging to families Ichneumonidae, Braconidae and Chalcididae were sorted to subfamilies and then to morphospecies. The accuracy of subfamilies richness to predict the species richness and to detect differences in the conservation status of plantations was tested. The species aggregation according to the sampling size was also explored. The three families this study was focused on represented 23 % of the total sampling, comprising 40 subfamilies and 393 morphospecies. Results showed a significant high positive correlation between subfamilies and species richness, and species/subfamilies ratio was about 4.5:1, with logarithmic relationship with sampling size tending to stabilisation at sizes greater than 15 individuals per sampling day. Subfamily richness detected the nearly-significant differences in plantations with the same accuracy as species richness, and therefore surrogacy effectiveness of parasitoid Hymenoptera subfamilies richness may be accepted for cacao plantations.