The tropical ichneumonid wasps are poorly sampled, particularly in the
Old World, despite their ecological importance and high species
richness. Existing inventories also tend to have had a taxonomic focus,
with trap placement reflecting the need for maximal sample size rather
than rigorous ecological comparisons. Here, we report the results of an
intensive sampling effort at Kibale National Park, Uganda, carried out
with randomised trap locations. We sampled ichneumonid faunas for a year
(2011–2012) with Malaise traps, in eight successional sites ranging
from clear-cut exotic plantations to primary rainforest. The traps were
situated in 10 random locations at each site and were moved between
locations once a week. The total sampling effort encompassed 231 trap
months (using traps smaller than the standard size), one of the largest
we know of from a single Afrotropical location.We sorted the collected
ichneumonids into subfamilies and investigated whether their community
composition differed between the sites. Ichneumonid faunas differed
between forest and former plantation sites, with both the overall
difference and that of four subfamilies significant. Our sample size was
unexpectedly small (1212 individuals), but we estimate that the
model-based analyses we used could still have given a significant result
with a smaller (954 individuals) sample. Overall, randomly placed
Malaise traps detected ecological patterns in Afrotropical ichneumonid
distributions. Our data also showed that there is a rich and at least
partly undescribed ichneumonid fauna still awaiting discovery in the
Afrotropical rainforests. Future inventories of this fauna may, however,
have to compromise on objective random trap placement in order to get a
large sample size.