Selection of global Metarhizium isolates for the control of the rice pest Nilaparvata lugens (Homoptera: Delphacidae).
BACKGROUND
This study was initiated to search for fungal candidates for microbial control of brown planthopper (BPH) Nilaparvata lugens Stål, to which little attention has been paid in the past two decades.


RESULTS
Thirty-five isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and M. flavoviride Gams & Rozsypal from different host insects worldwide were bioassayed for their lethal effects against third-instar BPH nymphs at 25 degrees C and a 14:10 h light:dark photoperiod at ca 1000 conidia mm(-2). On day 9 post-treatment, mortality attributable to mycosis ranged from 6.5 to 64.2% and differed significantly among the tested isolates with no apparent relationship to their host origin. Only two BPH-derived M. anisopliae isolates from the Philippines (ARSEF456) and Indonesia (ARSEF576) killed >50% of the nymphs. Both isolates were further bioassayed for time-concentration-mortality responses of the nymphs to the sprays of 19-29, 118-164 and 978-1088 conidia mm(-2) in repeated bioassays. The resultant data fitted a time-concentration-mortality model very well. Their LC(50) values were estimated as 731 and 1124 conidia mm(-2) on day 7 and fell to 284 and 306 conidia mm(-2), respectively, on day 10.


CONCLUSIONS
The two M. anisopliae isolates are potential biocontrol agents of BPH for further research. This is the first report of the lethal effects of global Metarhizium isolates on the rice pest.
Jin
Shao-Feng
SF
Institute of Microbiology, College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China.
Feng
Ming-Guang
MG
Chen
Jue-Qi
JQ
D000818:Animals; D005843:Geography; D006430:Hemiptera / Q000382:microbiology* / Q000502:physiology; D052981:Metarhizium / Q000302:isolation & purification* / Q000502:physiology; D012275:Oryza; D010572:Pest Control, Biological / Q000379:methods*; D010935:Plant Diseases