Observations and experiments on Triplosporium floridanum (entomophthorales) attacking spider mites in Israel

Abstract

The fungus Triplosporium floridanum is common in various regions of Israel, attacking green and red forms of the two-spotted spider mite, Tetranychus telarius sensu lato. No resting spores have been found in this species in Israel. With dried, mummified, infected mites from the field, kept in vials for 6 weeks at 4°C, sporulation of associated T. floridanum was effected in moist chambers; after the dried mummies had been held for another 9.5 months at room temperature, the number of mites showing sporulating fungi in moist chambers remained very high. The fungus sporulated within an extremely wide temperature range, 4–37°C. Primary conidia were produced in less than a day at 6, 18, 27, 30, and 37°C, and anadhesive spores at 18, 27, and 30°C. After 2 days, anadhesive spores formed at 6°C as well. Heaviest sporulation occurred at 27† and 30°C. The longevity of the normal-appearing hyphal bodies within the mites after prolonged desiccation is considered to be a possible mechanism for tiding the fungus over periods during which the host is rare in the field.