Isolation and Identification of Fungi Associated with the Sawtoothed Grain Beetle, Oryzaephilus surinamensis and Their Potential Use in Biological Control of the insect pest

Abstract

This study included the isolation of fungi associated with the saw-toothed grain beetle and the use of these fungi (Beauveria bassiana, Aspergillus flavus and Fusarium semitectum) isolated from dead insects, for the control of the beetle. In addition, plant extracts of Lawsonia inermis, Nerium oleander, and Conocarpus erectus in three concentration 1, 1.5, and 2% and at three time periods after treatment (24, 48 and 72 hours) were tested for their ability to control the beetle. Results obtained showed that the fungus Beauveria bassiana was isolated with the highest frequency and appearance rate of 45.04% and 48.09%, respectively, and the lowest frequency and appearance rate was for the fungus Fusarium semitectum at 10.16% and 12.5%, respectively. The entomopathogenic fungus B. bassiana produced the highest mortality rate of adults (49.02%) and was significantly higher than the mortality rate caused by the fungi F. semitectum and Aspergillus flavus. Furthermore, the mortality rate of the saw-toothed grain beetle adults by applying the alcoholic extract of Conocarpus erctus reached 46.61%, followed by the henna alcoholic extract (40.91%), and the oleander alcoholic extract (37.71%). In addition, the 1% extract concentration achieved the highest mortality rate (47.45%), and the lowest mortality (38.08%) was obtained with the 1.5% concentration. Results obtained also showed that the alcoholic extract of the oleander plant had a repellent effect at all concentrations (1.0, 1.5 and 2.0 %) with an effect coefficient of 0.14, 0.10 and 0.7, respectively, whereas the alcoholic extract of the Conocapris plant had an attractive effect at all three concentrations with an effect coefficient of 0.8, 0.11 and 0.12, respectively.

Keywords:

Fungal suspension, B. bassiana, A. flavus, F. semitectum, saw-toothed grain beetle, alcoholic plant extracts, Oryzeaphilus surinamensis.