Biorhiza pallida

Range & Status

Hymenoptera: Cynipidae; widespread, sexual and agamic, but the only one of the genus in Britain.

Regional Distribution

Local, occurring in mid and east Cornwall. All records sexual stage with oak apples except where stated as agamic on roots. VC2: one record 20/46 1930 (agamic), two records SX16 and SX28 1972; five records since 1980: SX37 1985, SX26 1987, SX15 1988, SX45 1992. The only records for VC1 are from pre 1906 (agamic) and one record (sexual) from the Camel Trail 10/97 in 1989. Andricus kollari Oak Marble is often erroneously recorded as the oak apple in Cornwall.

Habitat & Ecology

Associated species: Quercus spp. Occurs in oak woodlands. Gall on twigs in the form of an apple and on the roots in an alternate stage (agamic) as ' berry root gall' . Several parasites and inquilines are known to occur in the Oak Apple, and a few parasites even reach the subterranean galls.

Threats

Oak trees have been affected and died in recent years; this may have been caused by drought brought on by possible global warming and/or the spread of Sudden Oak Death disease, Phytophthora ramorum . The decline of oak trees will cause a major negative environmental effect on all invertebrate species which depend on Quercus , not just those that form galls. The destruction of oak woodlands.

Conservation

Protection of habitat, planting of Quercus spp.