Epizootiology of Erynia phytonomi (Zygomycetes: Entomophthorales) and Beauveria bassiana (Deuteromycetes: Moniliales) Parasitizing the Egyptian Alfalfa Weevil (Coleoptera: Curculionidae) in Southern California

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Abstract
The incidence of Erynia phytonomi (Arthur) and Beauveria bassiana (Balsamo) in southern-California populations of the Egyptian alfalfa weevil, Hypera brunneipennis (Boheman) (Coleoptera: Curculionidae) was determined during 1979 and 1980. E. phytonomi infection normally occurred as a single epizootic in March or April after latewinter rains, and was typified by the results in the 1979 survey. Although incidence was relatively high, the epizootic occurred too late to prevent damage to the crop by feeding larvae. Abnormally heavy rainfall early in the year, such as occurred in 1980, initiated an earlier, longer epizootic, and seemed correlated with lower larval densities. E. phytonomi survived temporary dry periods occurring during the epizootic in dried host larvae, called resting larvae, on which the fungus sporulated when suitable conditions resumed. B. bassiana incidence was less affected by rainfall. Harvesting of the field, resulting in exposure of surviving larvae to soil-borne inoculum, increased the incidence of B. bassiana. Complete harvesting of the field seemed to have an immediate adverse effect on incidence of E. phytonomi, but levels of the fungus later reached new peaks.