David Tyrrell

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.

Pathogenesis of Entomophaga aulicae: I. Disease symptoms and effect of infection on weight gain of infected Choristoneura fumiferana and Malacosoma disstria larvae

Abstract Larvae of the eastern spruce budworm, Choristoneura fumiferana, and the forest tent caterpillar, Malacosoma disstria, infected with strains of Entomophaga aulicae gained weight at the same rate as uninfected control larvae and larvae injected with sterile culture filtrates in which E. aulicae had been grown, until the day prior to their death. At this time, infected insects lost weight and exhibited a marked reduction in frass production. No evidence for toxic substances was found in culture filtrates of E. aulicae grown under a variety of environmental conditions nor in homogenates of near or freshly dead E. aulicae-infected budworm larvae. External symptoms of fungal infection on spruce budworm larvae, which first became evident about 4 hr prior to death of the larvae, are described.

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.

The fatty acid composition of some Entomophthoraceae. IV. The occurrence of branched-chain fatty acids in Conidiobolus species.

The presence of branched-chain fatty acids was confirmed in 6 of 18 Conidiobolus species examined. Amounts varied from about 9% of total fatty acids in C. parvus to about 73% in C. adiaeretus, and in all cases included acids of the even-carbon-numbered iso series and the odd carbon-numbered anteiso series.

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.