Efficacy of endophytic Beauveria bassiana (Balsamo) and Metarhizium anisopliae (Metchnikoff) against nymph of Nilaparvata lugens (Stål) infesting Oryza sativa plants

Certain entomopathogenic fungi (EPF), such as Beauveria bassiana and Metarhizium anisopliae, are highly pathogenic to arthropod pests and are able to colonize plant tissue as endophytic entomopathogenic fungi (EEPF), thereby requiring more extensive research on potential mycopesticides in rice. In this study, the entomopathogenic fungal (EPF) Beauveria bassiana (2) and Metarhizium anisopliae (3) isolates were artificially inoculated onto rice using the seed immersion technique. The successful colonization of rice by Beauveria bassiana and Metarhizium anisopliae isolates was demonstrated, and the endophytic and direct effects of the EPF against the third instar brown planthopper, Nilaparvata lugens (Stål), were assessed. Endophytic colonization of the plant by the EPF was shown by re-isolating the EPF from the leaf lamina and leaf sheath+culm of the rice plant that were not the initial site of inoculation. The results indicated that significant differences (at p=0.05) were obtained in mean % successful re-isolation of the EPF from the leaf lamina and leaf sheath + culm at 21 and 28 days after inoculation (DAI). Interestingly, DNA sequence data revealed that the recovered fungal isolates from EEPF-inoculated rice tissues showed 100% nucleotide similarity with the B. bassiana and M. anisopliae published by the National Center for Biotechnology Information (NCBI), indicating successful endophytic colonization of all the EPF in rice seedlings. Exposure of third instar BPH nymphs to 21-day-old EPF-inoculated rice seedlings resulted in 61-74% mortality recorded for 7 days compared to uninoculated rice plants. In conclusion, this research provides evidence, for the first time, of the endophytic action of B. bassiana and M. anisopliae against the third instar N. lugens and the ability of the EPF-B. bassiana and M. anisopliae to colonize the internal tissues of O. sativa plants.