Evaluation of Metarhizium anisopliae (Metsch) Sorok. to target larvae and adults of Capnodis tenebrionis (L.) (Coleoptera: Buprestidae) in soil and fiber band applications

The aim of this work has been to evaluate in the laboratory the potential of entomopathogenic fungi against adults and larvae of Capnodis tenebrionis (L.) (Coleoptera: Buprestidae) through fiber band application and a potted plant bioassay with soil application, respectively. Our previous findings revealed that Metarhizium anisopliae EAMa 01/58-Su isolate was the most virulent against neonate larvae of the buprestid. In the present work, M. anisopliae EAMa 01/58-Su isolate has been also shown to be highly virulent against adult beetles by immersion in a conidial suspension; thus it was selected to accomplish our objectives. When adult beetles were stimulated to climb 100 × 200 mm non-woven commercial fiber bands impregnated with conidia of M. anisopliae EAMa 01/58-Su isolate, total mortality rates varied from 85.7% to 100.0%; whereas no significant correlation was detected between the time needed to cross the band (mean value 648.7 ± 22.4 s) and the time of death, with mean average survival time ranging between 10.3 and 16.0 days, compared to 28 days of the controls. Potted seedlings (5-6 months old) of cherry plum (Prunus myrobalana Lois.), a commonly used apricot rootstock, were used to study the efficacy of soil treatment with M. anisopliae EAMa 01/58-Su isolate against neonate C. tenebrionis larvae. The soil inoculation with M. anisopliae EAMa 01/58-Su isolate had a significant effect on the mean number of dead larvae recovered from the roots, with mean mortality ranging from 83.3% to 91.6%; whereas no significant differences were detected between the three fungal doses. In all cases, dead larvae found within roots exhibited external signs of fungal growth. Hence, it may be possible to use M. anisopliae EAMa 01/58-Su isolate in a biocontrol strategy targeting both adults and larvae of C. tenebrionis.