Spatial distribution and niche partitioning in the Ooencyrtus spp. complex parasitizing the eggs of Stenozygum coloratum

摘要

The way in which species coexist is an important ecological question. Often, several parasitoid species may share a common host species. Five species of Ooencyrtus Ashmead (Hymenoptera: Encyrtidae) co-inhabit the egg clusters of Stenozygum coloratum Klug (Hemiptera: Pentatomidae), in the East Mediterranean region. Their relative abundance and spatial and seasonal occurrence were investigated. Parasitism and parasitoid male ratios gradually increased to about 50 and 26.8 %, respectively, from May to October. O. telenomicida Vassiliev was dominant in Mediterranean climatic regions and absent from arid areas, O. fecundus FerriSre and VoegelS dominated semi-arid areas, and O. near nigerrimus was the commonest in hot-arid areas. O. near fecundus occurred everywhere but was most abundant in the more extreme weather conditions. O. pityocampae Mercet was uncommon in most areas and absent from arid ones. O. telenomicida abundance was positively, and that of O. fecundus negatively, correlated with annual rainfall. O. near fecundus and O. near nigerrimus abundance was positively correlated with temperature extremes. The results display a clear picture for climatic based spatial niche partitioning, although there is evidence that interspecific competition also plays a significant role in the frequency of occurrence of the studied Ooencyrtus spp.