Irvin M. Hall

Electron microscopy of a rod-shaped noninclusion virus infecting the citrus red mite

Abstract Thin sections of the citrus red mite, Panonychus citri , infected with a virus disease contained rod-shaped virions but no rods were found in healthy mites. The rods, which were present in midgut epithelial cells, were ca. 194 × 58 nm and were enclosed in an envelope ca. 266 × 111 nm. Some mites, both healthy and diseased, contained spherical particles, but these particles did not cause symptoms of the virus disease.

The influence of infections of nuclear-polyhedrosis virus on adult cabbage loopers and their progeny

Abstract The longevity, mating, and oviposition of adult cabbage loopers ( Trichoplusia ni ) infected with nuclear-polyhedrosis virus were not affected, even when high titers of virus were used; infection occurred only when the virus was injected into the hemocoel. Histological examination of diseased adults revealed infected nuclei in the tracheal matrix cells but rarely in the fat body, hypodermis, or other tissues that are infected at the larval stage. Viability of eggs was significantly reduced (to less than 10%) the first few days after treatment when 1-day-old female moths were injected with the virus, but this effect decreased with dilution. Also, the effect was less when the female was older at the time of infection. Examination of dead eggs showed that embryological development had commenced. The large numbers of progeny reared from moths that were injected with the virus rarely showed infection, indicating that transovarian transmission of the virus did not occur. In contrast, progeny of moths fed the polyhedra were often infected though the effect was unpredictable and could be eliminated by surface-sterilization of the eggs.

Influence of a cytoplasmic polyhedrosis on various developmental stages of the cabbage looper

Abstract When the relationship of infections with a cytoplasmic-polyhedrosis virus and the larval, pupal, and adult stages of the cabbage looper, Trichoplusia ni, were studied, the mortality of first-instar larvae was comparatively high and that of fourth-instar larvae was comparatively low. Also, infected larvae pupated as much as 5 days later than healthy larvae, and the pupal weight was lower. This decrease in weight was related to the time of pupation, the number of white fecal pellets excreted by a larva before pupation, the decreased rate of emergence, and the moth deformities. The importance of these effects in regards to prophylactic measures for rearing large numbers of insects is discussed.

Manipulated bacterial epizootics in Anagasta populations

Abstract Studies of self-perpetuating populations of Anagasta kuhniella (Zeller) in laboratory ecosystems have shown (1) that epizootics of a disease caused by Bacillus sp. can be created by overcrowding of the larval instars, (2) that the larval parasite Devorgilla canescens (Gravenhorst) can be rendered host-regulative by acting as a vector of the pathogen, (3) that transmission of the bacterium by the parasite creates uniformity in prevalence of disease within the ecosystem, (4) that the action of the egg-feeding mite Blattisocius tarsalis (Berlese) precludes bacterial epizootics, and (5) that Bacillus -caused disease is not in itself host-regulative.

Nosema costelytrae n.sp., a microsporidan parasite of larvae of Costelytra zèalandica (Coleoptera: Scarabaeidae) in New Zealand

Nosema costelytrae n.sp. is described from larvae of Costelytra zealandica collected at Maihihi, Takapau, and Te Awamutu, North Island, and Methven and Rakaia, South Island. The protozoan occurs in the fat body of 2nd‐ and 3rd‐instar grubs. Disease incidence appears to be relatively low; the degree of infection in a larva may be light to severe. When apparent in older larvae, symptoms are stunted growth and alteration of the normally white fat coloration to tannish‐grey. Marked differences in stages of the life cycle, in particular the much smaller size of the ovular spores, distinguish this species from N. takapauensis, with which it has been found associated.

Birefringent crystal formation in citrus red mites associated with noninclusion virus disease

Abstract Histological sections of citrus red mites, Panonychus citri , revealed that birefringent crystals, which are useful in diagnosis of the disease, are formed in the midgut. Crystals formed several days earlier in starved infected mites than in those free to feed; and fecal pellets, also birefringent, formed several days early in response to starvation. This correlation is discussed. About 95% of the infected mites cultured in the laboratory contained crystals, but transmission of the virus to other mites did occur when crystals were not present.

Protozoan parasites of species of Trogoderma in California

Abstract Diagnoses of diseases and/or parasite-host associations in populations of species of Trogoderma collected from locations throughout California were conducted between 1965 and 1968. The four species of parasites found associated with eight species of Trogoderma were members of the Protozoa, including the highly pathogenic Mattesia trogodermae, which was the most prevalent; an Adelina sp.; a cephaline eugregarine belonging to the genus Pyxinia; and an unidentified microsporidan. Data on host range of each parasite, distribution, and annual rates of parasitization over the 4-year period of the survey are presented.

Fungi attacking the blue-green lucerne aphid in New Zealand

Abstract The blue-green lucerne aphid, Acyrthosiphon kondoi, is attacked on lucerne in New Zealand by the entomophthoraceous fungi Entomophthora aphidis and E. ignobilis (= E. thaxteriana). E. aphidis appeared to be the most pathogenic of the two species, causing an epizootic in one of the sampled fields which was severely infested by the aphid.

New records of aphid hosts of Entomophthora aphidis and E. planchoniana in New Zealand

Examination of diseased aphids from the Christchurch area of New Zealand during summer 1974 established new records of Entomophthora aphidis and E. planchoniana attacking Macrosiphum hellebori and E. planchoniana parasitising Aulacorthum solani, plus the first record for New Zealand of E. aphidis infecting Myzus persicae.

Additional records of Entomophthora aphidis and E. planchoniana from aphids in New Zealand

Abstract The place of Entomophthora spp. in natural control of aphids in New Zealand was noted by Lowe (1973), who stated that the incidence of these pathogens in economically important aphids is not normally sufficient to control high-density populations. Nevertheless, it has been considered desirable to determine the species of fungi present, and to record the aphid species attacked and their host plants. Some such records were given by Hall et al. (1976), who also listed earlier references. The additional records tabulated below are from collections made at Christchurch by Lowe, unless otherwise indicated. Determinations of the two species of Entomophthora were by Hall, and of host plants by Botany Division, Department of Scientific and Industrial Research, Lincoln.