Inverse density-dependent and density-independent parasitism in a solitary ground-nesting bee in Southeast Brazil

Abstract

Aspects of the population dynamics of a solitary ground-nesting oligolectic
bee, Diadasina distincta (Holmberg 1903) (Hymenoptera Anthophoridae), were
studied in relation to the number of parasitized nests in aggregations of different
sizes. Inversely density-dependent parasitism by bombyliid flies and densityindependent
mortality by fungi together explained most of the variation in population
size. There was a significant negative correlation between the number of
nests in an aggregation and parasitism by bombyliid flies. Bombyliids accounted
for 19.4% of mortality and two fungal species for an additional 19%. It is
hypothesized that male patrolling in larger aggregations accounted for lower
parasitism rates by bombyliid flies.
KEY WORDS: solitary bee, Diadasina distincta, Anthrax sp., nest aggregation, parasitism,
mortality, bombyliid flies, fungi.