Molecular characterization, virulence and horizontal transmission of Beauveria pseudobassiana from Dendroctonus micans (Kug.) (Coleoptera: Curculionidae)

Abstract

The great spruce bark beetle, Dendroctonus micans (Kugelann) (Coleoptera: Curculionidae), has been a potential threat for Turkey and the entire Eurasian spruce forests for many years. Control strategies which have been applied so far are still insufficient to prevent its damage. A previous study has shown that a Beauveria isolate (ARSEF 9271) proved to be an efficient microbial control agent against the great spruce bark beetle. In this study, this isolate was identified as B.pseudobassiana based on the partial sequence of EF1- and ITS sequence. A conidial suspension (1x10(8)/ml) of this fungus caused 100% mortality on both larvae and adults of D.micans within 5 and 6days, respectively. Also, it caused 100% mycosis value on both larvae and adults. Mortality values of horizontal transmission experiments between larvae and adults which were contaminated with 1x10(6)/ml spore suspension at 25%, 50%, 75% and 100% rates were determined as 100% after 15days at 20 degrees C under the laboratory conditions. We also determined the decrease of the damage in spruce wood block (15x25cm) when the contamination rate of the larvae was increased. Our results indicate that B.pseudobassiana ARSEF 9271 seems to be a very promising biocontrol agent against D.micans.