Pathogenicity Assessment of Isaria javanica (Frider. & Bally) Samson & Hywel - Jones isolates against Spodoptera litura Fabr.

Author: Nguyen Thi Thanh, Nguyen Thi Thuy, Truong Xuan Sinh and Thai Thi Ngoc Lam

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Abstract

Eighteen Isaria javanica were collected in Pu Mat National Park, Nghe An province, Vietnam. Eighteen Isaria javanica isolates were used to develop a novel screening method aimed at selecting strains with the highest biocontrol potential. Based on five parameters: percent mortality, percent extrusion mycelium, average survival time, fungal life cycle duration and spore production. Only four strains merited further study: VN1472, VN1487, VN1801, VN1802. The life cycle of Isaria javanica on Spodoptera litura larvae includes pathogenesis phase and saprogenesis phase and has five steps. The pathogenesis phases begins with the formation of a germ tube, cuticle penetration and invasion throughout the insect body followed by death and has one step; the saprogenesis phase begins after the insect has died until spores begin to discharge and has four steps. They pathogenicity against Isaria javanica show that this fungus is a promising biocontrol agent to control of Spodoptera litura.

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Conclusion

(1) Isaria javanica caused high Spodoptera litura mortality. S. litura mortality was ranged between 45.40-81.48%. Based on five parameters percent mortality, percent extrusion mycelium, average survival time, fungal life cycle duration and spore production there are four strains show some potential as biocontrol agents on S. litura: VN1472, VN1487, VN1801, VN1802. (2) The life cycle of I. javanica isolates on S. litura which includes pathogenesis phase and saprogenesis phase, was completed in 12.46-17.42 days.

References

Fungus kills insects are a common phenomenon in nature. Along with other groups of natural enemies, entomopathogenic fungi have an important role in regulating the amount of this class of animals everywhere. Despite the focused, but the study and use of entomopathogenic fungi have not achieved desired results, the efficiency is low pathogenic and unstable. There are many reasons for this situation, the most visible problem is studied entomopathogenic fungi have only paid attention to the production and use of surface preparations without due regard to the basic study as infection, pathogenic of fungi parasitic on insects, the relationship between an entomopathogenic fungi and its host in relation to the relevant factors. There are the essential knowledge, science as a basis for the evaluation and selection of potential isolates as well as proposed measures to improve impact efficiency for entomopathogenic fungi. In the world, research on insect pathogenic fungi have gained certain ach

How to cite this article

Nguyen Thi Thanh, Nguyen Thi Thuy, Truong Xuan Sinh and Thai Thi Ngoc Lam (2017). Pathogenicity Assessment of Isaria javanica (Frider. & Bally) Samson & Hywel - Jones isolates against Spodoptera litura Fabr. Biological Forum – An International Journal