Efficacy of Metarhizium anisopliae and Beauveria bassiana against Tuta absoluta (Lepidoptera: Gelechiidae) eggs under laboratory conditions.
Tuta absoluta Meyrick (pinworm), is a seriously crucial leaf mining, stalk borers and fruit damaging pest of solanaceae plants. Among solanaceous plants, tomato is considered to be the most preferred host to T. absoluta. Infestations caused by pinworm lead to reduction in tomato yield and its worldwide export. The current study has been conducted to evaluate effectiveness of two entomopathogenic fungi; Beauveria bassiana and Metarhizium anisopliae against eggs of T. absoluta under laboratory conditions. The potential of the two fungi was also assessed as an instrument of integrated pest management system through biological control. Eggs of T. absoluta were treated with four different conidial concentrations of each entomopathogenic fungus. These fungi were evaluated for their toxicity at four different conidial concentrations (4x105, 6x105, 8x105 and 1.0x106 conidia/mL). Twenty-one days post treatment, spore concentration 1.0x106 conidia/mL, resulted in the highest death rate: 50 and 37.6% with eggs when treated by B. bassania and M. anisopliae, respectively. The lowest mortality 33.6 and 25.6% of eggs was observed when T. absoluta eggs were treated with 4x105 conidia/mL of B. bassania and M. anisopliae, respectively. Mortality values resulted from the experiments indicated that B. bassania showed superiority over M. anisopliae regarding its effect on controlling of T. absoluta eggs. In addition, 4x105 conidia/mL showed the minimum mortality effect among the two fungi used in the bioassay. Mortality and spore production on the eggs were significantly higher with the higher spore concentrations (8x105 conidia/mL) of M. anisopliae and B. bassiana. Our findings suggest that the moderate (8x105 conidia/mL) and the higher (10x105 conidia/mL) spore concentration/ml of B. bassania and M. anisopliae are potent entomopathogenic and have the potential to be developed as effective and potent bio-control agents hostile to T. absoluta eggs in IPM programs. Keywords: Biological control, Tuta absoluta Eggs, Beauveria bassania, Metarhizium anisopliae.