Nest characteristics and associates of Dolichovespula (Hymenoptera, Vespidae) in Central Finland

In social vespine wasps, the nest characteristics and associates vary intra- and interspecifically. I studied the nest characteristics and nest associates of three Dolichovespula wasp species in boreal Finland. The average number of combs and cells per nest was similar among D. media, D. saxonica and D. norwegica, and similar to Dolichovespula in the temperate zone. Most D. media and D. saxonica colonies produced both gynes and males, whereas D. norwegica produced mainly either one. The average colony lifespan of D. saxonica was a bit over two months, i.e. shorter than documented for Dolichovespula in the temperate zone. The proportion of nests parasitised by the ichneumonid wasp Sphecophaga vesparum was 36% in D. saxonica and 50% in D. media; S. vesparum has not been recorded from D. media before. The proportion of parasitized cells was 0.6–11% for D. saxonica and 0.2–22% for D. media. The proportion yellow, overwintering cocoons of S. vesparum was highly variable among the nests. The proportion of nests parasitised by the moth Aphomia sociella was 36% in D. saxonica and 13% in D. media. Sphecophaga and Aphomia were not recorded from D. norwegica colonies, which supports studies in the temperate zone. The study adds up to the previous research on the nest structure and nest associates of vespines, and together they indicate that there is geographical variation within Europe and globally in the host use of Sphecophaga.