ENTOMOPHAGA GRYLLI (FRESENIUS) INFECTIONS IN GRASSHOPPER (ORTHOPTERA: ACRIDIDAE) POPULATIONS IN SASKATCHEWAN AND ALBERTA, 1985–1986

Abstract

AbstractA survey of grasshopper populations in Saskatchewan and Alberta indicated that the fungal disease caused by Entomophaga grylli (Fresenius) pathotype II was present in melanopline grasshoppers in 1985 and 1986. The disease was more prevalent and widespread in 1986, being found at 44% of 128 survey sites in Saskatchewan compared with 11% of 190 sites in 1985. In Alberta a high incidence (≥ three per 100 m2) of infected grasshoppers was found at 6% of 1746 sites in 1986 as compared with less that 1% of 2055 sites in 1985. Levels of infection based on cadaver densities at sites with high incidence of disease in Saskatchewan were similar in both years ranging from 3 to 28% for the total population. Melanoplus bivittatus (Say) was the predominant host species for E. grylli pathotype II; M. sanguinipes (Fabricius) was less affected. Entomophaga grylli pathotype I was isolated from Camnula pellucida (Scudder) hosts from a few sites in both Saskatchewan and Alberta in 1986.