| Abstract: | The acaropathogenic fungus Hirsutella kirchneri (Rostrup) Minter , Brady and Hall grew best and produced most mycelia on a medium containing yeast extract , dextrose and agar; conidial production , however , was maximal or potato dextrose agar (PDA) . The best growth on both media was at 25 C and conidial germination was high within a wide range of temperatures (10 - 35 C) . Colony growth , mycelial mass production and conidial yield were best under alternating dark and light regimes . Maximal germination occurred under dark conditions . When grown in continuous light the fungus produced synnemata (compacted conidiophores) which remained viable for 22 weeks . Of six species of phytophagous mites assayed , three spider mites and a rust mite became infected by the fungus , as did , to a limited degree , a parasitic mite . Another four mites , including two pests , a scavenger and a predator , were unaffected . The fungus grew on and sporulated from heat - killed cadavers of a dead mealybug (Homoptera) . Conidial germination and penetration into live mites , under saturation condi tions , were affected little by temperatures . Intra - host growth was temperature dependent , with mite death beginning on the second or third day post - infection . Maximal sporulation from infected mites took place at 25 C . Mortality was quickest at 25 C when mites were held under saturation conditions , but some death also occurred at lower relative humidities . These data are discussed with a view to using H. kirchneri in the biological control of plant mites . |
