Endophytic fungi, Beauveria bassiana and Metarhizium anisopliae, confer control of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), in two tomato varieties.
Background: The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is an important pest of tomatoes that reduces yield and fruit quality resulting in losses of up to 100%. The pest has developed resistance to chemical insecticides, therefore necessitating alternative control measures. The entomopathogenic fungi (EPF) Beauveria bassiana and Metarhizium anisopliae have been exploited extensively for biological control of the insect pests of economic importance. Results: The potential of B. bassiana (Bals.) Vuillemin (Hypocreales: Cordycipitaceae) (BbC1) and M. anisopliae (Metchn.) Sorokin (Hypocreales: Clavicipitaceae) (M150) to persist as endophytic EPF in two tomato varieties, Matina and Harzfeuer, which spread within host tissues and protect plants against larval attack of S. frugiperda was evaluated. Tomato seedlings were inoculated by dipping roots in either BbC1 or M150 spore suspensions (108 spores/ml). The qPCR analyses revealed the presence of both fungi in > 65% of the tested samples. Second-instar larvae of S. frugiperda were introduced onto inoculated plants that revealed the presence of fungal DNA and non-inoculated plants, 14 days after inoculation. Treating tomato plants with the EPF resulted in reducing weights and slowing larval development of Spodoptera. Larvae fed on BbC1 and M150-treated Matina significantly reduced weights than those treated with Harzfeuer tomato plants. The tomato variety Matina conferred enhanced level of resistance to the S. frugiperda larvae, further aggravated by the presence of both fungi through dietary stress resulting in slow development and reduce larval weight. Conclusion: These results may serve the tomato production systems and the S. frugiperda integrated management programs.