Susceptibility of lucerne beetle [Gonioctena fornicata (Brüggemann) (Coleoptera, Chrysomelidae)] larvae to some local enthomopathogenic fungal isolates under laboratory conditions

Abstract

The infectivity of Beauveria bassiana (Balsamo) Vuillemin isolates from Hypera postica (Gyllenhal) (Coleoptera, Curculionidae) and Gonioctena fornicata (Brüggemann) (Coleoptera, Chrysomelidae) collected from alfalfa fields in Tokat Province, Turkey for G. fornicata larvae were evaluated under laboratory conditions. Ten B. bassiana isolates were used in single screening test to determine their efficacy against G. fornicata larvae at a concentration of 1 x 107 conidia/ml. In addition, dose-mortality tests were carried out with the isolates GN-8-2, GN-4, GN-8-1(2) and GN-12-3. They caused more than 90% mortality at 7 days post-treatment at doses of 1x105, 1x108 and 1x109 conidia/ml. In the dose-mortality tests, almost all isolates caused 100% mortality at 1x109 conidia/ml at 7 days. The LT50 and LT90 rates at 1×108 conidia/ml were also determined. In summary, the Gonioctena fornicata larvae were susceptible to all the B. bassiana isolates used in the dose-mortality studies.