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THE VIRULENCE OF THE ENTOMOPHTHORALEAN FUNGUS PANDORA DELPHACZS TO THE BROWN PLANTHOPPER NILAPARVATA LUGENS 1)
Author(s) -
Xu Junhuan,
Feng Mingguang,
Xu Qian
Publication year - 1999
Publication title -
insect science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 45
eISSN - 1744-7917
pISSN - 1672-9609
DOI - 10.1111/j.1744-7917.1999.tb00117.x
Subject(s) - brown planthopper , conidium , biology , nymph , virulence , spore , inoculation , fungus , hypocreales , population , veterinary medicine , horticulture , botany , ascomycota , medicine , biochemistry , demography , sociology , gene
The entomophthoralean fungus, Pandwa delphacis (Hori) Humber, is a pathogen frequently causing epizootics of the brown planthopper, Nilaparvata lugens Stal, in rice growing areas of China. Two isolates (F95127 and F95129) of the fungus obtained from mycosis‐killed planthoppers collected in Zhejiang Province were bioassayed for their virulence to N. lugens . For inoculation, botches of 4– or 5‐in‐star‐old nymphs from a laboratory population were exposed to time‐varying spore shower from sporulating plates of fungal mass produced in Sabouraud liquid medium, resulting in 8 and 6 dosages for F95129 and F95127, respectively. The nymphs treated at each dosage were maintained on rice plants at 25°C and a photophase of 12L: 12D in growth chamber (nearly 100% RH) and were examined daily for mortality. The resulting data were well fitted to time‐dose‐mortality model, generating parameters of time and dose effects for estimation of virulence indices. The LD 50 values 6–8 d after exposure were 327, 122 and 46 conidia/mm 2 for F95129 and 409, 133 and 74 conidia/mm 2 for F95127, respectively. The LT 50 estimated for F95127 was 7. 6 d at 95 conidia/mm 2 whereas that for F95129 decreased from 6. 6 d at 172 conidia/mm 2 to 5. 6 d at 525 conidia/mm 2 . Based on these virulence indices and comparison of the slopes for dose effects from the model, the two isolates of P. delphacis had moderate virulence to N. lugens with insignificant difference to each other.