Evaluation of entomopathogenic fungi against Psalmocharias alhageos (Kolenati) (Hemiptera: Cicadidae) under laboratory and semi-field conditions

The grapevine cicada, Psalmocharias alhageos (Kolenati) (Hemiptera: Cicadidae), has recently emerged as a significant pest in vineyards in the Middle East. The soil-inhabiting nymphal stages of this species cause substantial root damage, and their subterranean habitats enable them to evade prevalent control tactics. Entomopathogenic fungi “EPF”, a class of fungi that are naturally occurring in soil and pathogenic to insects, have demonstrated potential utility against a broad spectrum of soil-dwelling pests and some non-soil-dwelling pests. Efficacy of three EPF species, Beauveria bassiana, B. varroae and Metarhizium anisopliae, against the grapevine cicada were investigated. In laboratory Petri dish assays, M. anisopliae exhibited the highest virulence with an LC50 value of 106 conidia/ml, followed by B. bassiana with an LC50 of 7.2 × 106 conidia.ml− 1. Cumulative mortality of P. alhageos was higher in soil column than Petri dish assays. At the highest concentration tested (108 conidia/ml), M. anisopliae caused the greatest efficacy against cicada nymphs, resulting in 75%, cumulative mortality. Soil type significantly affected activity of M. anisopliae and B. bassiana against P. alhageos. M. anisopliae caused greater nymph mortality in loam and loam soil than that in sandy loam. Moreover, efficacy of M.anisopliae was higher in clay loam soil than in the other soil types evaluated. Temperature also affected fungal virulence; cumulative mortality caused by M. anisopliae was higher at 20˚C than at 25 or 30˚C. Additionally, MST increased with decreasing temperature. Evaluations of pure cultures of EPF suggest that these microbial agents, especially the promising candidate strain of M. anisopliae, could be useful for management of P. alhageos. However, further work is needed to explore mass production of these agents and their compatibility for integration with other tools. Future large-scale evaluations of M. anisopliae under field conditions are warranted.