The UV-A and UV-B wavelengths of solar radiation may seriously reduce viability of Metarhizium anisopliae conidia,a fungus used extensively in Brazil for insect pest control.The conidial tolerances to UV-A and UV-B ra...The UV-A and UV-B wavelengths of solar radiation may seriously reduce viability of Metarhizium anisopliae conidia,a fungus used extensively in Brazil for insect pest control.The conidial tolerances to UV-A and UV-B radiation were studied for one isolate(IBCB 425) commercially available product produced on rice grains.Aqueous or oil emulsion conidial suspensions were irradiated for 0(control),2,or 3 h using the solar simulator filtered with diacetate filter to remove UV-C radiation which afforded 652 mW·m-2 in the spectral range of 280～370 nm.The UV tolerance was based on conidial germination(viability) and virulence to Diatraea saccharalis larvae.Conidia formulated with oil emulsion had higher survival after 3 h of UV exposure,but the virulence of the conidia previously exposed to 2 h of UV radiation were similar when oil formulated or not.The mortality of D.saccharalis caterpillars exposed to non-UV-irradiated conidia was greater than that of larvae exposed to irradiated conidia,and the LT50 values were lower for the non-irradiated suspensions than for those irradiated.This apparent reduction in virulence was directly related reduction in viability or delay of germination of UV-irradiated conidia.展开更多
文摘The UV-A and UV-B wavelengths of solar radiation may seriously reduce viability of Metarhizium anisopliae conidia,a fungus used extensively in Brazil for insect pest control.The conidial tolerances to UV-A and UV-B radiation were studied for one isolate(IBCB 425) commercially available product produced on rice grains.Aqueous or oil emulsion conidial suspensions were irradiated for 0(control),2,or 3 h using the solar simulator filtered with diacetate filter to remove UV-C radiation which afforded 652 mW·m-2 in the spectral range of 280～370 nm.The UV tolerance was based on conidial germination(viability) and virulence to Diatraea saccharalis larvae.Conidia formulated with oil emulsion had higher survival after 3 h of UV exposure,but the virulence of the conidia previously exposed to 2 h of UV radiation were similar when oil formulated or not.The mortality of D.saccharalis caterpillars exposed to non-UV-irradiated conidia was greater than that of larvae exposed to irradiated conidia,and the LT50 values were lower for the non-irradiated suspensions than for those irradiated.This apparent reduction in virulence was directly related reduction in viability or delay of germination of UV-irradiated conidia.
