Potential value of the fibre nettle Urtica dioica as a resource for the nettle aphid Microlophium carnosum and its insect and fungal natural enemies

The perennial stinging nettle (Urtica dioica L.) is a wild plant that provides resources for aphid natural enemies and can therefore benefit crop protection. Stinging nettles producing approximately three times more fibre than Standard nettles are under commercial development for fibre production. Here we assess the relative value of Austrian Clone 2, a high fibre nettle variety, as a resource for the nettle aphid Microlophium carnosum (Buckton) and its associated natural enemies. The intrinsic rate of increase of M. carnosum cultured on Clone 2 was not different to that on a Standard nettle nor was there an effect of nettle variety on the susceptibility of this aphid to the entomopathogenic fungus Pandora neoaphidis (Remaudière and Hennebert) Humber. The development time of the aphidophagous predator Chrysoperla carnea (Stephens) was not affected by the nettle variety on which M. carnosum was cultured whilst the parasitoid Aphidius ervi (Haliday) fed on honeydew produced by M. carnosum infesting both varieties of nettle. Fibre nettle Clone 2 is therefore able to support non-pest aphids and their natural enemies and, if grown widely in the future, may be useful within conservation biological control and a tool within integrated pest management.