Identification and virulence of entomopathogenic fungi, Isariajavanica and Purpureocilliumlilacinum isolated from the whitefly, Bemisiatabaci (Gennadius) (Hemiptera: Aleyrodidae) in Malaysia

Background Three of entomopathogenic fungi, identified as Isaria javanica (Cjc-03 and Cjw-01) and Purpureocillium lilacinum (TS-01) were found naturally infecting the whiteflies, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) on chili and tomato plants. All the isolates were identified by morphological characterization and molecular identification (ITS region amplification). The virulence of the three isolates was evaluated against nymphs of B. tabaci at three different concentrations (1 × 10 6 , 1 × 10 7 , and 1 × 10 8 conidia/ml) under laboratory conditions and on adults of B. tabaci at one conidia concentration (1 × 10 7 conidia/ml) under laboratory and glasshouse conditions. Results Isaria javanica showed the highest virulence against B. tabaci nymphs and adults in both laboratory and glasshouse conditions. I. javanica exhibited the highest mortality in the laboratory against B. tabaci , nymphs at the highest concentration (1 × 10 8 conidia/ml) 8 days post-inoculation. Likewise, in the laboratory bioassay, B. tabaci, adults, Cjc-03 isolate exhibited maximum mortality (80.0%), followed by Cjw-01 isolate (77.5%), and TS-01 isolate (65.0%) at the concentration of 1 × 10 7 conidia/ml at 7 days post-inoculation. The highest mortality rate (63.45%) was recorded by the Cjc-03 isolate and TS-01 (54.22%) isolate at 3 days post-inoculation in glasshouse bioassay using the concentration of 1 × 10 7 conidia/ml of each of the 2 isolates (Cjc-03 and TS-01) against B. tabaci adults. Conclusion Overall, the findings showed that both isolates of I. javanica and P. lilacinum reduced the number of eggs, nymphs, and adults’ emergence of B. tabaci, following the application of 1 × 10 7 conidia/ml on tomato leaves in the glasshouse. The newly isolated strains could be developed as a potential commercial biopesticide for managing B. tabaci.