In vitro, the compatibility of eight vegetable oils, used as components in formulation, was studied in conidia of entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, based in three parameters that are been evaluated: germination rate, vegetative growth and conidiogenesis. Almond oil and gingelly oils at 1, 2 and 3% concentrations showed compatibility with B. bassiana as well as M. anisopliae. Mustard oil and eucalyptus oils at all three concentrations proved toxic to B. bassiana and M. anisopliae except at 1% concentration. Sunflower oil, olive oil, coconut oil and castor oils displayed compatibility with M. anisopliae and toxic to B. bassiana except olive oil and castor oil at 1% concentration. Conidiogenesis appear to be more affected than germination for the sample which displayed toxicity. Compatibility classification in to toxic, moderately toxic and compatible enabled assessment of the tested oils for use in formulations. Conidial formulations of B. bassiana and M. anisopliae with almond oil/olive oil/gingelly oil/castor oil were used for bioassaying against Spodoptera litura. All the four formulations displayed higher mortalities of the target pest compared to unformulated conidia.

This article examines the development of strain-specific sequence-characterized amplified region (SCAR) molecular markers in two strains of Beauveria bassiana and Metarhizium anisopliae, as well as their use for tracking pathogens in coinfected insect pests. The markers were designed based on the polymorphic introns of the large subunit region of the ribosomal DNA. These markers were used to distinguish between two strains of Beauveria (B55 and B51) and two strains of Metarhizium (M20 and M48). The entomopathogenic strains demonstrated synergistic increase in mortality against Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) larvae when infected with the coformulated M. anisopliae strain M20 + B. bassiana strain B55, particularly at a 2:1 proportion of LC 50 concentration. The study revealed a disparity between intergeneric and interstrain coformulations. In intergeneric coformulations, one strain appeared predominant over the other strain at 1:2 and 1:4 proportions, both under in vivo and in vitro conditions. On the other hand, in interstrain coformulations, both strains survived and formed heterokaryons. Molecular studies revealed that the heterokaryons were unstable and reverted back to any one of the parent strains after 3 or 4 generations.

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