Bioassay and enzymatic comparison of six entomopathogenic fungal isolates for virulence or toxicity against green peach aphids Myzus persicae

Abstract

Myzus persicae is an economically important pest infecting more than 40 families of crops throughout the world. Six entomopathogenic fungal isolates, three each of Beauveria bassiana and Verticillium lecanii, were screened for pathogenicity test against the M. persicae to select high virulent isolate with the most suitable application and to determine the role of individual enzyme in its virulence. Two treatments that is, conidial shower (190±23 conidia/mm 2) and filtrate (3 ml filtrate per treatment from six days liquid broth culture of 1.0x10 8 conidia ml-1) were conducted for virulence or toxicity test and a comparison was made between treatments and among fungal isolates against the target pest. The percent mortality rates of filtrate at each day, after inoculation was found higher as compared to percent mortality of conidial showering. V. lecanii 3 showed highest virulence or toxicity against the target pest treated either with conidial (80.70%) or filtrate (88.36%) application while B. bassiana 70 and B. bassiana 76 showed high toxicity (77.14 and 80.86%, respectively) in filtrate application at 6 th day of incubation. The aphidicial activities of the fungal isolates were evaluated by correlating the enzymes (Chitinase, protease and lipase) activities with enzymes production. On the basis of enzymatic activities, lipase was assumed to participate more in the total virulence or pathogenicity as compared to protease and chitinase while protease was assumed to participate more than chitinase. The pathogenicity test reveals the selection, effective application of most virulent isolate and the role of individual enzyme to develop an alternative control agent against M. persicae.

In Vitro Pathogenicity of Some Entomopathogenic Fungal Strains against Green Peach Aphid Myzus persicae (Homoptera: Aphididae)

“…The results revealed that all tested strains of B. bassiana and L. lecanii could be effective biocontrol agents against aphids. These results are corroborated by the findings of previous studies reporting the efficiency of different strains of B. bassiana and L. lecanii against M. persicae and other aphid species [29,30].…”

Assessment of the virulence and proteolytic activity of three native entomopathogenic fungi against the larvae of Oryctes agamemnon (Burmeister) (Coleoptera: Scarabaeidae)

“…The obtained results were in agreement with those reported by Khan et al (2012). They screened the proteolytic activity of six EPF isolates, three isolates from each of B. bassiana and V. lecanii.…”

Identification and characterization of an insect toxin protein, Bb70p, from the entomopathogenic fungus, Beauveria bassiana, using Galleria mellonella as a model system

“…The original host of fungus is green peach aphid and geographical origin is Vladivostok, Russia (Khan et al, 2012). The fungus was maintained by culturing on potato dextrose agar (PDA) Petri plates (90 mm diameter) for 30 days at 26°C in dark.…”

“…Following the method of Khan et al (2012), 2 mL of 0.02% tween 80 solutions were added to the culture and the spores gently removed from the mycelium using a glass spreader. The spore suspension was collected using a 2 mL syringe and placed in an Eppendorf tube (1.5 mL).…”