The Effects of Temperature on the Mosquito Pathogenic Fungus Culicinomyces.

Abstract

The optimum temperatures for germination and growth in culture of an Australian isolate of Culicinomyces were 27.5 and 25ºC respectively. At 30ºC the fungus germinated but did not grow. Larvae of Anopheles amictus hilli and Culex fatigans in water containing conidia were killed when incubated at temperatures ranging from 15 to 27.5ºC but not at 30ºC. At 30ºC conidia adhered to the normal infection sites of the foregut and the gut cuticle was penetrated, but hyphae did not invade the haemocoel and the infection was discarded at the next moult. The fungus was lethal to larvae maintained at 30ºC for 8 h and at 25ºC for 16 h each day, but not to those reared at 30ºC for 16 h and at 25ºC for 8 h per day. Temperature should not limit the utilization of Culicinomyces for mosquito control, provided that the temperatures of breeding sites are below 30ºC. The fungus might not be effective against larvae living continuously at 30ºC, but it might be effective if the temperature were at this level during only part of each day.