Potential of different isolates of entomopathogenic fungi from Thailand as biological control agents against western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)Möglichkeiten der Verwendung verschiedener entomopathogener Pilze aus Thailand zur biologischen Bekämpfung des Kalifornischen Blütenthrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

The present study aimed to investigate the potential of 41 entomopathogenic fungal isolates, belonging to 25 species from 11 genera isolated from different hosts in Thailand, as biological control agents against the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). Firstly, pathogenicities of all isolates were assessed with single concentration against first instar larvae of F. occidentalis. The results showed that 37 out of 41 isolates, belonging to Akanthomyces sp., Aschersonia spp., Beauveria spp., Cordyceps sp., Hirsutella spp., Metarhizium spp., Paecilomyces spp., Torrubiella petchii and Verticillium spp., were pathogenic to F. occidentalis, while Hynennostilbe sp., Torrubiella tenuis, Hypocrella discoidea and Cordyceps pseudomilit were non-pathogenic. In general, the pathogenicities of all fungi varied significantly according to the fungal isolate, and could be classified into three pathogenicity levels. High pathogenicity level contained 14 isolates: six isolates of Beauveria, four isolates of Metarhizium, three isolates of Paecilomyces and one isolate of Cordyceps were identified as virulent isolates.