Synergistic Effects of Combining Three Commercial Bioproducts Against Tuta absoluta (Meyrick) Larvae (Lepidoptera: Gelechiidae)

Abstract

Background and Objective: The use of entomopathogenic agents for crop pest management is a viable alternative to synthetic chemical pesticides. Beauveria bassiana (Bals.) and Metarhizium anisopliae (Metsch.) are fungi considered the most promising extensively widely applied bio-control agents in protecting a wide range of economic crops. Fungal toxins are thought to play a crucial part in the pathogenicity process during insect infestation. The bioinsecticides' synergy could help to control the invasive pest more safely and effectively. Materials and Methods: Suspensions of Beauveroz ( Beauveria bassiana) and Metarhoz-P ( Metarhizium anisopliae), were evaluated as to their virulence against T. absoluta larvae at 3 different doses. As a comparison, Abamectin was utilized as a positive control, while water was used as a negative control. Results: All the commercial compounds caused significant mortality among T. absoluta larvae, with approximately 52% mortality after 5 days of the treatment. Over 5 days, mortality of T. absoluta larvae when exposed to a combined treatment of B. bassiana, M. anisopliae and Abamectin reached 92%. The results under field conditions, showed significant differences (p<0.001) among these products while adding the surfactants increased the mortality larvae. Combined treatments of these 3 commercial compounds showed a synergistic effect acceded the effect obtained using each compound alone. Bio-pesticides, B. bassiana and M. anisopliae formulations caused mortality rates among T. absoluta larvae similar to the Abamectin treatment. Conclusion: Observations indicated that both fungus candidates and Abamectin proved effective against T. absoluta larvae. The combined use showed a high potentiality indicating a positive synergistic effect.