Evaluation of Some Entomopathogenic Fungi for Controlling the Green Shield Bug, Palomena prasina L. (Heteroptera: Pentatomidae)

Abstract

Green shield bug, Palomena prasina L. (Heteroptera: Pentatomidae) is a common pest species in Turkish hazelnut orchards. It feeds on hazelnut fruits and causes premature nut dropping in early season and later kernel damage during nut development. Controlling P. prasina is currently done by spraying insecticides that looks like the only option. Since hazelnut covers quite a large area in the country, possibility of using microbial control agents for controlling P. prasina is rather important. In this study, firstly hazelnut orchards were surveyed and 8 entomopathogenic fungi isolates were obtained from insects. Virulance of these isolates was evaluated against P. prasina nymphs in laboratory at 25 degrees C and 90+/-5 RH. Isolates included 2 Simplicillium lamellicola, 4 Lecanicillium muscarium and one Beauveria bassiana and one Isaria fumosorosea. Isolates were bioassayed against nymphs. Dead individuals were counted daily following treatment for 12 days. Lethal time values (LT50 and LT90) for entomopathogenic fungi were calculated. LT50 and LT90 values for the experimented isolates ranged from 3.20 to 8.48 days and from 9.32 to 40.30 days, respectively. At the end of 12 days post treatment, mortality rates were above (83%) at all treatments. Highest mortality rates (98.00 and 95.00%) were observed in at the isolate of L. musacarium and B. bassiana, respectively. Entomopathogenic fungi could be promising agents for controlling P. prasina.