Changes in Thiol Content, Glutathione and Hydrogen Peroxide Levels as a Measure of Oxidative Stress in Periplaneta Americana Treated with Metarhizium Anisopliae Spp.

Periplaneta americana (American cockroach) treated with conidia of entomopathogenic fugal isolates of Metarhizium anisopliae revealed a decrease in the thiol content and an increment in the levels of oxidized glutathione as well as hydrogen peroxide (H2O2). T-SH levels decreased to 48% and 50% at 24 hours and 48 hours post treatment respectively at LC90 of M20 isolate. Low virulent isolate M48, on the other hand, recorded a decrease of 76% and 78% in the T-SH levels at 24 and 48 hours post treatment respectively with LC30 treatment. Remarkable increase of 200% in the levels of H2O2 recorded at LC90 of M20 and 102% increase at LC30 of M19 was remarkable and focuses on the extent of oxidative stress induced by the fungal infection. Dynamics in the levels of GSH, GSSG, H2O2 and thiols in the insects treated with different fungal isolates in a time and dose dependant manner reveals oxidative stress induced by the fungal infection and the information would facilitate to explore the antioxidant defense system in augmented resistance or susceptibility of cockroach against entomopathogenic fungal conidia.

In-Vitro Evaluation of the Entomopathogenic Fungal Isolates of Metarhizium Anisopliae for Compatibility with Pesticides, Fungicides and Botanicals.

Isolates of the entomopathogenic fungus Metarhizium anisopliae were tested for their compatibility with insecticides, fungicides and botanical pesticides, which are being used in the field, as a prerequisite for developing as mycopesticides and their use in IPM programmes. Three concentrations (0.1X, 0.5X and 1X) of each chemical were evaluated in the laboratory based on the recommended dose for field application by food poison technique. Variation in vegetative growth and sporulation of M. anisopliae appeared to be related to the chemical nature of the formulations, its concentration and the fungal isolates in study. M19 and M48 isolates showed compatibility with imidacloprid at 0.5X and 0.1X and with fungicide sulphur at all the concentrations tested. All the four botanicals tested were found to be compatible to all the four fungal isolates and neem gold displayed maximum tolerance, at all the concentrations. M19 displayed an enhancement in the vegetative growth with imidacloprid (2%) and HIT (2-18%). 2% increase in the spore output was also recorded by M19 with chloropyrifos and sulphur. M19 and M48 isolates demonstrated compatibility with pesticides, fungicides and botanicals as well as with a cockroach management pesticide, HIT. The two isolates of M. anisopliae tested emerged as prospecting candidates for use as mycopesticide component in the combined application with pesticides like imidachloprid and fungicide, sulphur as well as botanicals in the IPM programmes.

Isozyme markers for virulence in the entomopathogenic fungal isolates of beauveria species against spodoptera litura.

Twenty nine pathotypes of Beauveria bassiana (Bals.) Vuill and one of Beauveria brongniartii (Sacc.) petch were characterized according to virulence towards second instar larval stage of Spodoptera litura and isozyme variations. Biological differences were found among the isolates. LT50 values ranged from 4.2 to 9.6 days based on which the isolates were characterized as virulent and less virulent. Electrophoretic polymorphisms of esterase and acid phosphatase were performed to differentiate the isolates. Cluster analysis revealed a demarcation among the virulent and less virulent isolates of B. bassiana from that of B. brongniartii species.