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Biological Control : A Guide to Natural Enemies in North America Anthony Shelton, Ph.D., Professor of Entomology, Cornell University

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Entomophaga grylli
Zygomycetes: Entomophthorales

With contributions by Mark Ramos, Plant Protection, USDA-ARS, 331 US Plant Soil Nutrition Laboratory, Cornell University.

E. grylli is a species complex that has two distinct pathotypes in North America: Entomophaga macleodii and Entomophaga calopteni. In addition, another complex member, E. praxibuli has been introduced from Australia. They all attack grasshoppers which are major pests of crops and rangeland in the Western United States and Canada. In 1986, approximately 55 million acres of western rangeland were infested by grasshoppers and the economic cost is estimated at over $400 million per year. A Grasshopper Integrated Pest Management Program was initiated in 1986-1992 by USDA-APHIS researching integrated approaches to managing grasshoppers preferable to application of expensive insecticides over vast areas of rangeland.


Entomophaga grylli is easily identified in the field. Shortly before death, infected grasshoppers crawl to the top of plants and die with their heads pointing upward and their legs wrapped tightly around the stalks where they may remain for several days.


Rangeland and cropland, predominantly in the Western U.S. and Canada.


Grasslands where E. grylli might be found

Photo: R. Carruthers
Typical habitat of E. grylli

Photo: R. Carruthers

Pests Attacked (Host Range)

E. macleodii infects grasshoppers in the subfamily Oedipodinae, including band-wing grasshoppers. E. calopteni infects grasshoppers in the genus Melanoplus. E. praxibuli infects both Oedipodinae and Melanoplus species in the United States.

Life Cycle

The members of this species complex can be separated principally by differences in vegetative growth patterns, the formation or lack of primary conidia, the size of and number of conidial nuclei, isozyme polymorphism profiles, and host and geographic ranges.

E. calopteni is monocyclic forming only overwintering resting spores allowing disease cycles to occur in subsequent years. E. macleodii and E. praxibuli are polycyclic, characterized by forming asexual conidia and overwintering resting spores. Under proper environmental conditions, (high humidity and rainfall) large numbers of conidia are formed on individual grasshopper cadavers and forcibly discharged, resulting in several additional disease cycles per season and dramatic increases in infection levels.

Relative Effectiveness

Periodic and widespread epizootics of grasshoppers in North America have been attributed to E. grylli. In Australia, E. praxibuli has caused epizootics in grasshopper populations under fairly dry conditions, a consideration in its introduction into the many arid rangeland areas where grasshoppers are pests.

Presently, the E. grylli complex has limitations as a biological control agent. It cannot be mass produced, and it is weather-dependent. In addition, there are over 600 species of grasshopper in North America and it is not feasible to test all of these for susceptibility. However, the introduction of E. praxibuli was part of a project involving the study of other biological control agents including viruses, parasitoids and the fungal pathogen, Beauveria bassiana. In an integrated approach, the E. grylli complex would seem to have a niche.

Commercial Availability

Entomophaga grylli is not commercially available.

Taken from:

Ramos, Mark (1993) The isolation, implementation and evaluation of Entomophaga praxibuli as a potential biological control agent of North American grasshoppers. A project report submitted to the faculty of the Graduate School of Cornell University in partial fulfillment for the degree of Master of Professional Studies (Agriculture).

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Sporulating grasshopper cadavers.

Epizootic of E. grylli in clear-winged grasshoppers.

Top: Sporulating grasshopper cadavers.

Bottom: Epizootic of E. grylli in clear-winged grasshoppers.
Note cadavers congregated at tops of stems.

Photos: M.Ramos

Grasshopper cadavers at tops of stem.

Grasshopper cadavers at tops of stem.

Photos: M.Ramos

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