Passaloecus turionum Dahlbom,1844

Description and notes

A scarce and little known species in Britain, only recently added to the British list (Guichard 2002). It is very similar to the common P. gracilis and great care must be taken with determination as the characters are subtle. Ecological differences between the two species have been reported by Westrich & Schmidt (1983), who found that P. gracilis was foraging for aphids on herbaceous plants, whilst P. turionum was foraging for aphids associated with trees.

Distribution

South-east England, including Surrey, Berkshire, North Hants, West Sussex, East Sussex, West Kent and East Kent.

Probably a boreo-alpine species in Europe; it is common in Finland, for example (Lomholdt 1975-76). The species is adventive in North America, being found from Pennsylvania and New Jersey to Texas along the coast, and inland in Michigan, Indiana and Ohio. It was first collected in the 1940's but not identified until 1961 (Krombein 1961).

Status (in Britain only)

Not listed in Shirt (1987) or by Falk (1991) but its status clearly needs to be assessed.

Habitat

The few known British localities are mainly sandy heaths or mixed woodlands. The species is sparsely distributed in coniferous plantations in Denmark (Lomholdt 1975-76).

Flight period

Late May to early September.

Prey collected

Arboreal aphids are reported as prey by Westrich & Schmidt (1983).

Nesting biology

Falk has reared this wasp from beetle burrows in old Scots pine bark from Ambersham Common in West Sussex, and M Edwards collected one entering old beetle burrows in Scots pine bark in Rewell Wood, West Sussex (pers. comm.). Abroad, nests have been found in the galls of the moth Petrova resinella (Lepidoptera, Tortricidae) on Pinus species, including P. contorta and P. sylvestris (Lomholdt 1975-76). This moth also occurs in Britian and its galls may harbour P. turionum. Nest closures and an adult female are illustrated by Blösch (2000).

Flowers visited

No information available.

Parasites

The chrysidid wasps, Omalus biaccinctus (not British) and O. aeneus have been found as parasites/parasitoids in Europe (Lomholdt 1975-76).

Author of profile

G W Allen and  M Edwards

Year profile last updated

2002

Proofed: June 2012