Charles F. Reichelderfer

Migration in Heterogeneous Environments: Differences in Habitat Selection Between the Wing Forms of the Dimorphic Planthopper, Prokelisia Marginata (Homoptera: Delphacidae)

The planthopper, Proklisia marginata, feeds selectively on the intertidal grass, Spartina alterniflora. Populations contain two adult wing forms that vary in proportion from one local area to the next. There are short—winged flightless individual (brachypters) and individuals with fully developed wings (macropters) that fly. Differences in the ability of the two wing forms to select high quality habitats in a heterogeneous environment are measured to elucidate further the advantages of migration (macroptery). Adult planthoppers (both wing forms) occur most abundantly on the parts of individual plants, seed heads in particular, that contain the highest percent crude protein. The percent crude protein in stands of S. alterniflora and the frequency of flowering plants are used as measures of habitat quality and vary considerably over the marsh surface. There is a significant positive relationship between the densities of both wing forms and habitat quality. However, the slope of the regression line for macropters is significantly steeper than for brachypters suggesting that macropters are better able to move from low— to high—quality patches. The relative mobility of wing forms is further documented by the inability of brachypters to colonize small defaunated plots of grass compared to macropters. We suggest variation in habitat quality is unpredictable, that high—quality patches of vegetation may be separated by distances greater than the ambit of brachypters, and that macropters can more effectively track spatial oscillations in habitat quality.

Effects of Bacillus thuringiensis var. kurstaki δ-endotoxin on isolated lepidopteran mitochondria☆

Abstract An investigation was undertaken to determine the effects of Bacillus thuringiensis var. kurstaki δ-endotoxin on mitochondria isolated from Bombyx mori midgut epithelium. Using manometric and colorimetric techniques, the investigation revealed that toxic polypeptides had stimulatory effects on mitochondria oxygen uptake and inhibitory effects on ATP production. These results indicated that B. thuringiensis δ-endotoxin could act as an uncoupler of oxidative phosphorylation. Loss of ATP production caused by the action of the δ-endotoxin would lead to metabolic imbalance and possible cell death.

Accumulation and persistence of a nuclear polyhedrosis virus of the cabbage looper in the field

Abstract A nuclear polyhedrosis virus of the cabbage looper, Trichoplusia ni, was applied to foliage of Fall-planted broccoli and cabbage plants. Soil bioassays demonstrated that appreciable quantities of active virus accumulated in the upper 1 cm of the soil of plots sprayed with 10, 20, and 100 larval equivalents (LE)/acre as well as in unsprayed plots. After completion of the spray program, soil from plots treated with 8 foliar applications of 10 LE/acre contained only slightly more virus than the soil from unsprayed plots, but considerably more virus accumulated in plots treated with 20 and 100 LE/acre. The accumulation of virus continued after the completion of spraying and considerable quantities of active virus persisted through the winter.

Some genetic aspects of the resistance of Spodoptera frugiperda to a nuclear polyhedrosis virus

Abstract A probit analysis of the dosage-response of two isolates of Spodoptera frugiperda to a single nuclear polyhedrosis virus revealed a greater than 5-fold difference in the LD50. The response of F1 progeny of reciprocal crosses between the two parental isolates demonstrated that resistance to the virus is not sex-linked. The LD50 values of F1 and F2 backcrosses suggest that the major variation in resistance is due to a single gene or genes that lack dominance.

Characteristics of the Non-Occluded Form of a Nuclear Polyhedrosis Virus

Non-occluded virions of a nuclear polyhedrosis virus of the alfalfa looper, Autographa californica, found in the medium of cell cultures of infected fall armyworm, Spodopter frugiperda, and in the hemolymph of infected S. frugiperda larvae were partially characterized by biological, chemical and physical methods. Also, the rate of appearance of the virions was studied in cell culture and the host insect to determine maximum virion production. Virions obtained from both sources were heat-sensitive, acid-labile and inactivated by several organic solvents. The non-occluded virions found in the insect cell culture fluid and in the hemolymph were identical, and both were enveloped nucleocapsids. Visualization of the fragilely enveloped nucleocapsid was accomplished only after fixation with glutaraldehyde. Differences between the non-occluded and occluded virions of nuclear polyhedrosis viruses are discussed.

A hemagglutinating antigen from a nuclear polyhedrosis virus of Spodoptera frugiperda

Abstract The 100,000 g supernatant from an alkaline dissolution of polyhedra isolated from an NPV of Spodoptera frugiperda was found to agglutinate adult chicken erythrocytes in a p H range of 5.5–6.9. Optimal conditions for active hemagglutination and hemagglutination-inhibition, with antisera prepared against polyhedron protein, occurred at p H 5.8 with an incubation temperature of 37°C and a solublization time of 45 min at p H 11.2 Minimum quantities of antigen detectable were at 2–4 μg/ml of protein.

The effect of soil pH on the persistence of cabbage looper nuclear polyhedrosis virus in soil

Abstract The persistence of singly embedded Trichoplusia ni nuclear polyhedrosis virus in Norfolk A loamy sand of various p H was studied under laboratory conditions. Virus extracts of the treated soils were bioassayed at three monthly intervals and showed that virus residues are affected by soil p H. Within the range of soil p H tested (4.83-7.17), the lower the p H, the more rapidly the virus was inactivated. The practice of liming fields for maintaining favorable physiological characteristics as well as for nutritional reasons, enhances the persistence of the virus in the soil.

The effect of 3-methylcholanthrene treatment on the virulence of a nuclear polyhedrosis virus of Spodoptera frugiperda

Abstract Four treatments of a nuclear polyhedrosis virus with 3-methylcholanthrene resulted in a 9-fold increase in virulence. The activity of one treated suspension remained unchanged after storage for over 10 months at 4°C. A significant decrease in the LT 50 was observed during bioassays comparing treated and untreated virus. Similar results were obtained with three other compounds.

Differentiation of Trichoplusia ni MEV and Autographa californica MEV by macrophage migration inhibition tests

Abstract The macrophage migration inhibition test (MMI), an in vitro correlate of delayed hypersensitivity, was found to be an effective means of differentiating Trichoplusia ni and Autographa californica multiple embedded nuclear polyhedrosis viruses (NPV). Peritoneal exudate cells from guinea pigs sensitized to virions of T. ni NPV demonstrated significantly different MMI when challenged with T. ni vs A. californica virions. Similarly, when virions of A. californica NPV were employed as the sensitizing antigen, different percentages of MMI were observed in the homologuus versus heterologous challenges. The susceptibility of the fall armyworm, Spodoptera frugiperda, to these two pathogens was very similar as revealed by a comparison of LD50s, slopes, and fiducial limits of dose-mortality regression lines. In contrast, the cabbage looper, T. ni, was much more susceptible to A. californica NPV. The polyhedral sizes, shapes, and virion occlusion patterns of the two species of NPV were virtually indistinguishable.

Some biochemical effects of the microsporidian Nosema whitei on the blood components of Tribolium castaneum using disc electrophoresis

Abstract Disc electrophoresis was used to study the effects of a protozoan ( Nosema whitei ) infection of several metabolic macromolecules in the 6th instar larvae of the red flour beetle Tribolium castaneum . The electrophoretic patterns of the macromolecules consisted of the following: 1. 1. Thirteen basic fractions of proteins. 2. 2. Two isoenzyme fractions of lactic acid dehydrogenase (MDH). 3. 3. Six isoenzyme fractions of lactic acid dehydrogenase (LDH). 4. 4. Six isoenzyme fractions of glucose-6-phosphate dehydrogenase (G-6-PDH). 5. 5. Five distinct fractions of gycoproteins. 6. 6. Five fractions of phospholipids. 7. 7. Four fractions of lipoproteins. 8. 8. Except for the enzyme G-6-PDH, T. castaneum larvae infected with N. whitei generally showed a significant decrease in the fractions of the macromolecules.