A new device for auto-disseminating entomopathogenic fungi against Popillia japonica: a study case.

The Italian distribution range between Piedmont and Lombardy interested by the outbreak of the exotic Japanese beetle (JB) Popillia japonica Newman (Coleoptera Scarabaeidae) is getting wider. In the past, in the USA, where P. japonica is an exotic pest too, entomopathogenic fungi have been extensively used against larvae and adults of the Japanese beetle. We tested under laboratory and field conditions the effectiveness of a home-made 'attract-infect-release' device against P. japonica adults. The device was activated alternatively with the two commercial products (GranMet® and Met52®), available in Italy, containing Metarhizium brunneum Petch. During a series of fifteen-minute observations we recorded a mean permanence time of adult beetles inside the device of about 3 minutes with no difference between treatments. The number of P. japonica adult-borne conidia was assessed in the laboratory with no significant differences between treatments. For what concerns GranMet®, experiments on horizontal transmission showed 100% mortality by 19 days after treatment, while mortality associated with Met52® was 30-65%. In conclusion, our research showed that a 3-minute contact between a P. japonica adult and GranMet® was enough to permit the transmission of the infection to other individuals and eventually kill the insect. This result appears to be promising and, if confirmed in large field experiments, could add a new device for the biological control strategies against the Japanese beetle. [ABSTRACT FROM AUTHOR]