Ovicidal Effect of Entomopathogenic Fungi on Emerald Ash Borer, Agrilus planipennis Fairmaire, Eggs

The emerald ash borer (EAB) is an invasive beetle that has killed hundreds of millions of ash trees throughout North America since its arrival. The use of entomopathogenic fungi as part of integrated pest management approaches is considered effective against a wide range of insect pests. The aim of this study was to screen and select locally adapted EAB-associated entomopathogenic fungi with ovicidal effect on EAB eggs under laboratory conditions. The pathogenicity of nine fungal strains, previously isolated from EAB galleries, and the commercial Beauveria bassiana strain GHA was tested. Three of these, Akanthomyces muscarius 48-27, Lecanicillium longisporum 66-14 Lecanicillium psalliotae 59-2, and GHA B. bassiana strain consistently showed significant ovicidal effects and a high percentage of inoculum recovery both from eggs and neonate larvae. The high levels of inoculum recovery from neonate larvae demonstrate that, even after emergence, larvae were infected. The possibility of disrupting EAB's life cycle at the egg stage through microbial control represents a potential management opportunity that should be explored in future field studies. Future work should also study the effect of EPF on neonate larvae survival and performance. To our knowledge, this is the first study to evaluate the effect of entomopathogenic fungi against the egg stage of EAB.