Donald M. MacLeod

Spontaneous formation of protoplasts by a species of Entomophthora

Abstract Conidia of a species of Entomophthora isolated from the eastern hemlock looper, Lambdina fiscellaria fiscellaria, were germinated in Graces insect tissue culture medium. Two germ tubes were normally formed per conidium, and when these reached a length of approximately 100–150 μ, the protoplasm was spontaneously released from the tip of the germ tube as a viable protoplast. The subsequent development of the protoplast is described. Two-day-old protoplasts were highly pathogenic to a number of lepidopterous larvae upon intrahemocoelic injection, death of the insects ensuing within 4–5 days. The Entomophthora species could be reisolated from the killed insects.

Isolation and growth of the grasshopper pathogen, Entomophthora grylli

Abstract Entomophthora grylli was isolated and grown in pure culture in protoplast form. Cultures were obtained by germinating conidia collected from naturally infected adult Carolina grasshoppers, Dissosteira carolina , in Graces tissue culture medium supplemented with 5% fetal bovine serum and an aqueous extract of grasshopper tissue. Grasshopper extract was not necessary for subsequent growth and subculture of the protoplasts. Healthy adult grasshoppers could be reinfected with the fungus by injection of a protoplast suspension.

Entomophthora bullata as a pathogen of Sarcophaga aldrichi

Abstract Adults of Sarcophaga aldrichi killed by Entomophthora bullata were found in the field 7 days after emergence. Resting spores were not found until 6 days later, although conidia were formed from the first incidence of mortality. It is suggested that the life cycle of the fungus involves alternating generations of conidia and thick-walled overwintering resting spores.

A taxonomic proposal regarding Delacroixia coronata (Entomophthoraceae)

Abstract It is recommended that the microconidium-producing entomophthorous fungi described under the names Delacroixia Sacc. and Syd., Entomophthora Fres., and Conidiobolus Bref. be grouped together within the genus Conidiobolus to comprise the subgenus Delacroixia (Sacc. and Syd.) Tyrrell and MacLeod stat. nov.

In vitro germination of Entomophthora aphidis resting spores

On germination, resting spores of Entomophthora aphidis produce a septate sporogenous germ tube, which in turn gives rise to two or occasionally three germ conidia, one conidium being formed by the terminal cell and the others from cells lower down the tube. The resting spores possess sufficient endogenous nutrient reserves to complete the germination process.

Rediscovery of Tarichium megaspermum (Entomophthoraceae) in Canadian cutworms (Noctuidae)

Abstract The fungus Tarichium megaspermum has not been reidentified conclusively in the literature since its original description by Cohn in 1870. It was a major cause of disease of the red-backed cutworm in British Columbia, Canada, in 1957 and 1959 and a minor cause of disease of the dark-sided cutworm in Ontario, Canada, in 1971. Populations of both host species were also infected with the conidial state of a fungus identified as Entomophthora virescens. It is possible that T. megaspermum and E. virescens represent the resting spore and conidial states, respectively, of a single fungus species, Entomophthora megasperma, but experimental proof by cross infection was unobtainable. Modern descriptions and photographs of the fungi are given.

Entomophthora echinospora (Phycomycetes: Entomophthoraceae), a fungus pathogenic on the neotropical cicada, Procollina biolleyi (Homoptera: Cicadidae)

Abstract Entomophthora echinospora (Phycomycetes: Entomophthoraceae) has been identified as a major pathogen of the neotropical cicada Procollina biolleyi (Homoptera: Cicadidae). Mortality levels in teneral adults ranged from 40 to 70% during the peak period of adult eclosion at Bajo la Hondura, Costa Rica, in 1971.