The present research is aimed at a formulation of the entomopathogenic fungi, Beauveria bassiana (Bal.) Vuillemin and Metarhizium anisopliae (Metch.) Sorokin, in two types of diatomaceous earth dusts, fossil shield and Silico-Sec, are then applied against the adults of three species of stored-grain insects: Sitophilus oryzae L., Rhyzopertha dominica Fab. and Tribolium castaneum Herbs. Effect of the treatment was assessed by comparing the mortality percentage of the adults of the three insect species exposed to the formulated fungi with that of the adults exposed to the unformulated fungi or the diatomaceous earth dusts or the undisturbed control. Results obtained from these exposures have indicated that treatment of the adults with the formulated fungi resulted in a significantly higher mean mortality percentage compared to the treatment with the unformulated fungi or the diatomaceous earth dusts or the undisturbed control. A synergistic interaction between the effect of fungal species and the diatomaceous earth dusts was shown. Viability of conidia of both fungal species in diatomaceous earth dusts was assessed by calculating the germination percentage of the conidia over time. Results indicated a small loss of mean germination percentage for formulated conidia of both fungal species versus a high loss of mean germination percentage for the unformulated conidia, thus the diatomaceous earth dusts used in the formulation of both fungi demonstrated a negligible effect on the viability of formulated conidia compared to the unformulated.
Beauveria bassiana
Control of Main Stored-Grain Insects with New Formulations of Entomopathogenic Fungi in Diatomaceous Earth Dusts
Sun, 2013-02-17 19:08 — Yacoub A. M. Batta
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TwitterBiocontrol of Almond Bark Beetle (Scolytus Amygdali Geurin-Meneville, Coleoptera: Scolytidae) Using Beauveria Bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes)
Sun, 2013-02-17 19:00 — Yacoub A. M. BattaAims
To formulate the entomopathogenic fungus Beauveria
bassiana in invert emulsion, then apply it against adults of almond bark beetle
(Scolytus amygdali) under laboratory and field conditions.
Methods and Results
The effect of formulated B. bassiana in invert
emulsion against S. amygdali adults was shown by comparing the mortality
percentage of adults exposed to the formulated fungus using a Petri dish
treatment method and by field applications to infested peach trees with
mortality of adults exposed to the unformulated fungus or the untreated
control. Results obtained from both exposure methods have indicated that
treatment of S. amygdali adults with the formulated fungus resulted in a
significantly higher mean mortality percentage (P < 0.05) when compared with
the treatment with the unformulated fungus or the untreated control. This
mortality ranged from 81.2 to 100%, 10 days after treatment with the formulated
fungus when compared with 6.7 to 49.6% mortality, 10 days after treatment with
the control or the unformulated fungus, respectively. Viability of the fungus
conidia in invert emulsion was assessed by calculating the germination
percentage of the conidia over time. Results indicated a high storage stability
shown by a small loss of germination percentage for the formulated conidia of
both strains (5.8 to 8.4% over a 12-week period) vs a low storage stability
shown by a high loss of germination percentage for the unformulated conidia of
the same strains (58.9 to 61.0% over the same period). The presence of B.
bassiana in the galleries of beetles following the treatment of infested trees
was shown in the present research.
Conclusions
The results obtained have demonstrated a
significantly higher level of efficacy of formulated B. bassiana in invert
emulsion against S. amygdali adults under laboratory and field conditions. The
ingredients of invert emulsion used in the formulation of the fungus had a
negligible effect on the viability of formulated conidia when compared with the
unformulated.
Significance And Impact Of The Study
Results obtained in the present research are
promising and may be exploited commercially to control S. amygdali adults on
various species of stone fruit trees, especially peach trees. This type of
biocontrol of this insect may be used as an alternative means to chemical
control for management of the insect. No adverse environmental impacts of the
fungus or its formulation have been observed during application.
Investigations Into the Formulation and Efficacy of Entomopathogenic Fungi Against Larvae of Yellow Mealworm (Tenebrio Molitor L., Coleoptera: Tenebrionidae)
Sat, 2013-02-16 20:15 — Yacoub A. M. BattaA new invert emulsion formulation of entomopathogenic fungi was developed using non-toxic ingredients readily available in Australia and tested for compatibility with two Australian strains of Beauveria bassiana (Bals.). Laboratory bioassays were conducted to determine the efficacy of these fungi when applied in an invert emulsion formulation against yellow mealworm larvae, Tenebrio molitor L. The entomopathogenic fungi consistently caused higher mortality of T. molitor larvae when the invert emulsion was used compared with aqueous conidia suspensions. When B. bassiana strain BG1 was applied as an invert emulsion using different concentrations, the LC50 (measured as conidia mL-1) was > 600x lower than the LC50 of aqueous suspension of the conidia. The invert emulsion formulation tested improved the consistency and efficacy of the fungal strains tested against T. molitor under controlled conditions and has the potential to increase their efficacy when used on a commercial scale.
