Larvicidal activity against Plutella xylostella of cordycepin from the fruiting body of Cordyceps militaris.
The insecticidal activities of methanol extracts of Cordyceps militaris Link (Ascomycotina: Clavicipitaceae) cultured on fresh pupae of Bombyx mori L against 3rd-instar larvae of Plutella xylostella L were examined using direct contact application. The larvicidal activity was more pronounced in an extract of C militaris fruiting body than in an extract of the pupae separated from the culture. The biologically active constituent of the Cordyceps fruiting body was characterized as cordycepin (3'-deoxyadenosine) by spectroscopic analysis. Responses varied according to dose, exposure time and application method. In a leaf-dipping test, cordycepin at 500 mg litre-1 caused no mortality at 1 DAT (day after treatment) but 78 and 100% mortality at 2 and 4 DAT, respectively, whereas 34 and 88% mortality at 3 and 5 DAT, respectively was observed at 300 mg litre-1. Cordycepin caused body colour change from pale green to dark brown and eventually body lysis. These results suggested that the larvicidal action may be attributable to a direct effect rather than an inhibitory action on chitin synthesis. There was a significant difference in insecticidal activity of cordycepin between leaf dipping (500 mg litre-1) with 100% mortality and topical application (10 micrograms per larva) with 0% mortality, suggesting that cordycepin has stomach action. Cordycepin merits further study as a potential P xylostella control agent or as a lead compound.
Kim
Jun-Ran
JR
School of Agricultural Biotechnology, Research Center for New Bio-Materials in Agriculture, Seoul National University, Suwon 441-744, Republic of Korea.
Yeon
Sung-Hum
SH
Kim
Ho-San
HS
Ahn
Young-Joon
YJ
D000818:Animals; D032661:Cordyceps / Q000737:chemistry*; D003839:Deoxyadenosines / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects*; D015394:Molecular Structure; D009036:Moths / Q000187:drug effects* / Q000254:growth & development; D010944:Plants; D013997:Time Factors
D003839:Deoxyadenosines; D007306:Insecticides; C058120:cordycepin