Local species richness of parasitoid wasps (Ichneumonidae: Pimplinae) in Ugandan tropical forest

Abstract

It has been suggested that the highly species-rich Ichneumonidae family of parasitoid wasps has an anomalous latitudinal diversity gradient, peaking in species richness outside the tropics. Extensive studies of the family in the tropics, especially in the Afrotropics, are scarce. Here, I study the local species richness and biological composition of pimplines (Ichneumonidae: Pimplinae) in the Afrotropics. The samples were collected 9/2014–9/2015 with 32 Malaise traps in four forest types and farmland in Kibale National Park, Uganda. They are a subset of 108.5 trap months of the total sample size of 373.5 trap months. I produced species rarefaction curves of sorted species to model species accumulation rates by habitat type and biological pimpline group. A total of 1,925 pimplines in 112 species were collected. Trapping accumulated species slower in farmland than in forest types. Species accumulation rates differed between all four biological pimpline groups, with the accumulation rates of species of koinobiont ectoparasitoids of spiders differing between forest types. Few rarefaction curves were near stabilizing, suggesting that the local fauna was incompletely sampled. These are the first results of the species richness of pimplines caught with extensive Malaise trapping in the Afrotropics. The biological composition of the local fauna was typical, with most collected species being idiobiont parasitoids of weakly concealed hosts. At a given number of individuals sampled, only a few pimpline collections in the Neotropics surpass the observed species richness. The observed richness lends no support to the purported anomalous latitudinal diversity gradient of the family.