Edward A. Steinhaus

Crowding as a Possible Stress Factor in Insect Disease

The significance of aggregation (huddling) in laboratory mice, as an ecological factor, has been studied at three different ambient temperatures. Food consumption per gram of body weight and absolute food consumption were checked in three groups of MAf/Sp male mice with 1, 2 and 5 animals per cage in groups I, II and III respectively. 1 l has been demonstrated that the food consumption per gram of body weight by laboratory mice kept in bare cages varies inversely with the number of animals in the group. As the ambient temperature is lowered there is an increasing divergence in amount of food consumed by the different groups. The data support the hypothesis that crowding is an important ecological factor at lowered, as well as at room temperatures. REFERENCES

TAXONOMY OF INSECT VIRUSES

Although there is evidence that viruses unassociated with demonstrable inclusion bodies do cause infection in insects, the best-known insect viruses today are those characterized by the presence of either polyhedral or granular inclusions in the infected cells of the host. These viruses constitute a group of agents in many ways distinct from most other animal viruses and from plant viruses. Their location within the polyhedral or the granule-like inclusions, the occurrence of many of them in uniform bundles of several virus particles each, or regularly as individual rods, and their relatively large size (generally about 40 millimicrons in width and from 250 to 360 millimicrons in length), aid in distinguishing them from most other viruses. This distinctiveness and the rapid progress being made in demonstrating them has enhanced the need and desire to arrange them according to some scientifically valid, yet convenient system of nomenclature and classification. Acknowledging earlier contributions made toward the nomenclature and classification of insect viruses, I attempted to take a step in the direction of obtaining a satisfactory taxonomic arrangement of these agents with the publication, in 1949, of certain provisional concepts along this line. The foremost general classification of viruses a t that time, as now, was that presented by Holmes (1948) in the sixth edition of Bergeys Manual of Determinative Bacteriology. In my 1949 paper, certain errors, weaknesses, and inadequacies in the Holmes treatment of the insect viruses were recognized and pointed out, *but I did acknowledge and accept the thesis that the binomial system of nomenclature could be applied to properly described insect viruses as well as it could to rickettsiae, bacteria, and other microorganisms. Despite initial and continuing mild disagreement in some quarters, I remain convinced of the validity of this position. Basic difficulties with regard to virus nomenclature have been greatly ameliorated since the recent adoption of the International Bacteriological Code of Nomenclature. There appears to be general agreement that the Code, as stated therein, legitimately concerns viruses as well as bacteria and related organisms. Most of the difficulties, a t least as far as the insect viruses are concerned, lie with matters of classification and phylogenetic arrangement. A beginning toward solving the problems of classification has been made, however, and we have every reason to believe that, by the gradual processes of evolution rather than by edict, we can attain the taxonomic goals we seek. The tendency of many bacteriologists and virologists, especially those who disdain systematics, to demand a rigid, completed, and final classification and list of names of the agents with which they work, reflects a lack of appreciation for the slow, gradual, revisional process by which such information and knowledge is evolved and established. Also to be guarded against is any tendency on the part of international organizations and committees (as valuable as these bodies may

Teratology of the beetle Tenebrio molitor I. Gross morphology of certain abnormality types

Abstract Gross teratological forms of the yellow mealworm, Tenebrio molitor, are recorded. The principal teratologies observed involved abnormalities in wings and elytra, legs, antennae, segments, and other structures. Of special interest is an abnormality (pupal-winged adult) in which the adult insect retains the wings and elytra of the pupal stage. It is intended to study this particular teratology in depth. Comparisons of the abnormalities found in the colony studied are made with similar abnormalities found by other investigators in Tenebrio and in other insects. Beetles suffering major teratological changes were definitely shorter lived than were normal or slightly deformed specimens. At least three external factors contribute to the reduced longevity: dehydration, loss of coordination, and cannibalism. Wing, elytral, and some leg abnormalities occurring spontaneously in our colony could be produced in adults by exposing pupae and late larvae to ultraviolet irradiation.

Selective Bacteriostatic Action of Sodium Lauryl Sulfate and of “Dreft.”

The bacteriostatic action of various soaps has undergone a considerable amount of study by many investigators. Recently, a somewhat related class of substances, the sodium alkyl sulfates, has been synthesized. These substances have also been made use of as detergents in such preparations as “Dreft,” “Drene” and other commercial products. The alkyl sulfates are half-esters of sulfuric acid. In this respect they differ from soaps which are combinations of fatty acids and alkalis. In both cases, however, the alkyl chain probably determines its bactericidal effectiveness. Sodium lauryl sulfate is a sodium alkyl sulfate containing 12 carbon atoms. The similarity of these substances to soaps suggested the possibility that similar bacteriostatic action might be exhibited by them. Accordingly, sodium lauryl sulfate as such, and “Dreft” which contains a large amount of sodium lauryl sulfate were tested for their bacteriostatic action. Twenty-one strains of Gram positive bacteria, 20 strains of Gram negative bacteria and 6 strains of common molds were used in these studies. In general, all tests were made on Difco standard nutrient agar to which the test substances had been added in varying amounts so as to make concentrations of 1.0% sodium lauryl sulfate and of 1.0, 0.5, 0.25, and 0.1% “Dreft”. The plates were streaked with heavy suspensions of the organisms and then incubated at appropriate temperatures for 48 hours. The effects of sodium lauryl sulfate and of “Dreft” on the growth of the 41 strains of bacteria and 6 strains of molds studied in this investigation are shown in Table I. It is evident that the Gram positive organisms were prevented from growing, whereas the Gram negative bacteria grew as freely as, on the nutrient agar controls. There were 3 exceptions to the latter statement: Vibrio comma, Alcaligenes fecalis, and Neisseria catarrhalis were definitely inhibited in their growth.

Teratology of the beetle Tenebrio molitor: II. The development and gross description of the pupal-winged adult☆

Abstract A teratology characterized by the retention of essential aspects of the pupal wing in the adult mealworm, Tenebrio molitor is described. The developmental sequence which leads to the emergence of the abnormal adult was studied in the pupa, and the significance of the general state of health of the pupa in the emergence of the abnormal beetle is considered. By an observation of the various normal and abnormal pupae, the following became evident: (1) Morphologically normal pupae emerge as morphologically normal, or, in rare instances, very minimally defective adults. (2) The type of pupal abnormality is not as significant in the emergence of a pupal-winged adult as is the extent of the abnormality and the resulting general state of health of the pupa. (3) Size, flatness of the abdominal area, and the subcuticular blackened areas in the head and prothoracic area contribute significantly to the retention of the pupal wing by affecting the state of well-being of the pupa, while the condition of the wing itself plays only a secondary role inasmuch as it affects the general health of the insect. (4) There is often a rapid deterioration in the condition of the pupa prior to emergence of the pupal-winged adult. This is evidenced by a general softness and swelling of the abdominal area followed by a loss of response to tactile stimuli and a collapse of the abdomen. There is a depletion of internal moisture and reduction in the amount of fat body.

Teratology of the beetle Tenebrio molitor V. Ultrastructural changes and viruslike particles in the foregut epithelium of pupal-winged adults☆

Additional ultrastructural changes associated with the pupal-winged adult teratology of Tenebrio molitor are presented. Crystalline inclusions found in the nuclei of the foregut are described, and their possible mode of development is considered. Small, viruslike particles found both in crystals and free within nuclei are described, and their possible significance to the nuclear and cellular pathology of the foregut is discussed.

Teratology of the beetle Tenebrio molitor: IV. Ultrastructure of the necrotic fat body and foregut associated with the pupal-winged adult

Abstract The present paper presents further electron-microscopic observations of internal abnormalities seen in the pupal-winged adults of the beetle Tenebrio molitor . (The teratology was described in detail, and its developmental sequence was discussed, in previous communications.) Areas of necrosis found in the anterior foregut region, characterized grossly by liquefaction and discoloration of the foregut, and discoloration of fat body adjacent to it, are described. Ultrastructurally, the gut tissue is seen to be completely destroyed in the central necrotic region, with the presence of degenerating cells predominating at its periphery. The fat body, which makes up the major part of the discolored area, contains a proliferation of normally present, large, darkly staining granules presumed to have a high pigment content, and responsible for the brown-black color of the abnormal area. Several types of nuclear degeneration within the fat cells are also described. Comment is made on the enzootic protozoan infection, as well as a possible virus infection, present in the colony of Tenebrio used.

Teratology of the beetle Tenebrio molitor: III. Ultrastructural alterations in the flight musculature of the pupal-winged adult

Abstract The present report deals at an ultrastructural level with some of the internal aspects of a malformation or teratology (“pupal-winged adult”) found in the beetle Tenebrio molitor . The flight muscle of two types of pupal-winged adults was examined, and the pattern of muscular degeneration in the teratological insects is presented. By comparison with normal Tenebrio flight musculature, it is seen that, while externally the wing of the pupal-winged adult is pupal in form, the ultrastructural characteristics of the flight muscle are those of an adult beetle. The fine structural alterations in the flight muscle of the teratological insects include disorientation and dissolution of myofilaments, alterations in the Z lines, hypertrophy of the sarcoplasmic reticulum, glycogen abnormalities, and swelling, enlargment, and destruction of mitochondria. The possible metabolic dysfunctions that lead to, or result from, the ultrastructural alterations are considered.

Observations on a previously undescribed type of cellular degeneration in hydra

Abstract A form of cellular degeneration in the fresh-water hydra Pelmatohydra pseudoligactis Hyman is described, and its relationship to the depression phenomenon is discussed. The normal ultrastructure of characteristic cell types in each of the two epithelia (ectoderm and endoderm) is presented; the progress of degeneration is followed through successive stages in an attempt to ascertain the morphological pattern of this abnormal condition. The type of deterioration described shows some similarity to, but appears to be basically different from the phenomenon known as “depression”.

Insect Microbiology@@@Insect Microbiology: An Account of the Microbes Associated with Insects and Ticks with Special Reference to the Biologic Relationships Involved

Insect microbiology: an account of the microbes associated with insects and Ticks with special reference to the bioogic relationships involved , Insect microbiology: an account of the microbes associated with insects and Ticks with special refer... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی