An approach to the control of Hyalesthes obsoletus, vector of Bois Noir, using entomopathogenic agents

The planthopper Hyalesthes obsoletus Signoret (Homoptera, Cixidae) is vector of the grapevine yellow Bois Noir, one of the most important phytoplasmosis in Europe. Reduction of phytoplasma associated diseases incidence relies on the control of the insect vectors and on the eradication of affected host plants. Management of Bois Noir is especially difficult because both the vector and the phytoplasma can develop also in plants other than grapevines; the overwintering younger instars of the insect live underground feeding on the roots of wild plants normally nearby vineyards (like nettle and bindweed) and chemical interventions are ineffective and unsustainable. The aim of this trial was to evaluate the possibility to control the young forms of the leafhopper by means of entomopathogenic agents applied to nettle roots. During summer, hundreds of wild H. obsoletus adults were captured and allowed to breed in a greenhouse with nettle pots; the following late spring groups of young leafhoppers obtained from the pots were treated by sprinkling the ground with strains of entomopathogenic fungi (Beauveria bassiana and Paecilomyces fumoseroseus) and nematodes (Heterorhabditis bacteriophora and Steinernema feltiae). The mortality of H. obsoletus was recorded on day 3, 7, 14 after the treatment. The positive results obtained in the experiment suggest that microbiological control of the vector could represent a promising option for the integrated management of Bois Noir.