Pathogenicity Of Fusarium Species From Red Clover

Author : Anis S. Lestari
Publisher :
ISBN 13 :
Total Pages : 81 pages
Book Rating : 4.:/5 (945 download)

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Download or read book Isolation and Pathogenicity of Naturally Occurring Entomopathogenic Fungi to Clover Root Borer (Coleoptera : Curculionidae: Scolytinae), a Pest of Red Clover Seed Crops written by Anis S. Lestari and published by . This book was released on 2016 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: Entomopathogenic fungi are cosmopolitan microbial pathogens that cause fungous diseases in a wide range of insects via spore infection. Due to their natural enemy status, they have tremendous potential for use as microbial control agents against insect pests, especially subterranean pests for which few management options are available. The clover root borer (Hylastinus obscurus Marsham) develops belowground, attacks the roots of red clover (Trifolium pratense L.) and causes a drastic reduction in seed yield. Hylastinus obscurus was controlled with organochlorine pesticides but their use was prohibited due to hazardous effects on the environment, and non-target organisms including humans. Subsequently, no alternative pest management strategy was developed for this pest. Meanwhile, little is known about impacts of entomopathogenic fungi on clover root borer. The current study was conducted to isolate naturally occuring entomopathogenic fungi and assess their pathogenicity against the clover root borer. More than 150 isolates were collected from infected clover root borers and root zone soil samples from five red clover seed production fields in western Oregon. Based on morphologic characters and phylogenetic analyses using ITS sequence data, these belonged to six species - Beauveria bassiana, B. pseudobassiana, Metarhizium brunneum, Isaria fumosorosea, I. farinosa and Lecanicillium muscarium. A laboratory experiment showed that two species of field isolated fungi - B. bassiana and I. fumosorosea were as effective in killing clover root borer adults as commercial sources of M. brunneum and I. fumosorosea when exposed to these fungi in petri dishes with sterile white sand. Subsequently, H. obscurus adults were exposed to four spore concentrations of B. bassiana and M. brunneum separately in cups filled with field collected unsterilized and sterilized soil. There were no significant mortality differences on either sterilized and unsterilized soil. However, at the highest concentration, more than 80% of clover root borers died with M. brunneum while with B. bassiana, the mortality was not significantly different due to high mortality in the negative control. Based on the study, at least six species of entomopathogenic fungi occur naturally in red clover seed production fields in western Oregon, and field isolated fungi are as virulent as commercial fungi against the clover root borer. Further research is needed for evaluation of the pathogenicity of these entomopathogenic fungi under field conditions.