A. Glenn Richards

INTRACELLULAR SYMBIOSIS IN COCKROACHES. I. PRODUCTION OF APOSYMBIOTIC COCKROACHES

1. The trans-ovarial inheritance of fat-body intracellular symbiotes in the German cockroach was prevented by subjecting the parent insects to high temperature or by feeding the parents aureomycin or sulfathiazole.2. The most certain and simple method of obtaining aposymbiotic nymphs is by feeding the parents ground dog biscuit plus 0.1% aureomycin all of their lives.3. Aposymbiotic nymphs are practically incapable of growth on a natural diet which is adequate for symbiotic nymphs.4. The addition of large amounts of dried brewers yeast to the diet enabled the aposymbiotic nymphs to grow to maturity in two to three times the period required by normal nymphs.5. Adult aposymbiotic cockroaches suffered impaired reproductive ability. The males were affected as well as the females.6. The second and third generations of aposymbiotic roaches are similar to the first in both histology and behavior.

AN AUTORADIOGRAPHIC STUDY OF THE RELATION BETWEEN HEMOCYTES AND CONNECTIVE TISSUE IN THE WAX MOTH, GALLERIA MELLONELLA L

1. The hemocyte count of Galleria mellonella during the prepupal and early pupal stages varies from 4000/mm.3 to 15000/m3 as a function of age. The number of freely circulating cells can be approximately doubled within 6-24 hours by bleeding the insect.2. Using tritiated thymidine and autoradiography it was found that there is a hemocyte differentiation sequence of prohemocyte → plasmatocyte → adipohemocyte. This differentiation requires about three days at 35° , and the labeled cells have disappeared in another three days. The life expectancy of these cells, at least in prepupal and early pupal stages, is then less than six days.3. Transfusion of labeled hemocytes, followed by autoradiography of sections, confirmed the previous suggestion that adipohemocytes have some role in the destruction of the larval neural lamella, but that no blood cells are involved in the formation of the connective tissue around the adult nervous system.

STUDIES ON ARTHROPOD CUTICLE. VIII. THE ANTENNAL CUTICLE OF HONEYBEES, WITH PARTICULAR REFERENCE TO THE SENSE PLATES ,

1. The epicuticle on honeybee antennae differentiates in correlation with sclerotization to give qualitatively different reactions on different parts.2. The procuticle of the antennae shows a novel and unorthodox sequence of sclerotization involving two stages. The first stage begins at the outer surface and spreads inwardly, the second begins at the inner surface and spreads outwardly (Figs. 40-46). As a result the entire thickness of cuticle becomes sclerotized but still shows reducing power for osmic acid and ammoniacal silver nitrate. In contrast, the cuticle of thorax and abdomen shows the orthodox sequence of sclerotization proceeding from the outer surface inwardly.3. Argentophile granules disappear during sclerotization from epidermal cells of areas that undergo sclerotization. Large numbers of argentaffin-positive granules remain in the cell cluster under the sense plates.4. In the strip containing sense plates, the antennal cuticle develops a dark brown color in its inner half. This browning, wh...

CORRELATION BETWEEN THE POSSESSION OF A CHITINOUS CUTICLE AND SENSITIVITY TO DDT

1. Throughout the animal phyla there is a correlation between the presence of a chitinous cuticle and susceptibility to external applications of DDT. Those aquatic animals with a chitinous cuticle (arthropods and certain coelenterates) are highly sensitive to external applications of DDT, other animals are not so susceptible although there is considerable variability.2. The correlation to a chitinous cuticle is supported by studies on various coelenterates, on adsorption, and on temperature coefficients. Coelenterata with respectively a complete, partial, and no chitinous perisarc are respectively highly sensitive, somewhat sensitive, and nearly insensitive to DDT. DDT can be adsorbed by chitin and chitinous cuticles and at low concentrations shows a negative temperature coefficient for toxicity to arthropods.3. From these data a hypothesis is proposed that chitinous cuticles facilitate the entry of DDT into the animal body by selectively concentrating the compound by adsorption phenomena.4. This is the f...

STUDIES ON ARTHROPOD CUTICLE. II. ELECTRON MICROSCOPE STUDIES OF EXTRACTED CUTICLE

1. Chitin purifications alter the structure of cuticular membranes of insects more or less extensively.2. Our data agree with the x-ray diffraction studies of Fraenkel and Rudall in showing:(a) The cuticle cannot be viewed as a rigid chitin framework iii the interstices of which other components are deposited.(b) Protein extraction methods have no value for localization of membrane components.(c) Purified chitinous membranes have no significance for studies on the permeability of arthropod cuticle.3. Several but not all types of membranes after purification yielded microfibers of chitin which after drying have diameters of < 100 to 300 A< 0.01 to 0.03 µ). It is suggested that these values may represent chitin micelle diameters.4. Unexpected diversity in chitin patterns was obtained. Possible interpretations are discussed, and it is suggested that chitin cross-linkages vary considerably from one type of membrane to another type.5. Chloroform and acetone remove the lipid epicuticle without affecting the str...

INFECTION OF COCKROACHES WITH HERPOMYCES (LABOULBENIALES). I. LIFE HISTORY STUDIES

1. Herpomyces stylopygae Speg. is shown to be distinct fromH. periplanetae Th. by host specificity tests.2. Spores of H. stylopygae are found all over the surface of oriental cockroaches but mature plants are mostly found on the antennae, seldom on palpi and only rarely elsewhere. They grow on setae or on hard or soft cuticle but only on a living cockroach. Infections are heavier on males and on adults and experiments show the infection is disseminated by contact.3. The ascus contains 8 spores which it liberates within the perithecium through a terminal perforation, leaving the ascus as a fluid-filled ghost.4. Spores are ejected from the perithecia in various numbers, not just in pairs (Table I). Mostly the groups protruding from the subterminal apertures of the perithecia (Fig. 2) consist of 1-4 spores but groups as large as 12 spores were found. The presence of single, paired and multiple spore groups protruding from perithecia and found on the surface of hosts is correlated with the presence of single,...

Ultrastructure of the atypic muscles associated with terminalial inversion in male Aedes aegypti (L).

Two sets of opposed, crossed muscles are present in the rotating region of the abdomen in male A. aegypti. These muscles undergo changes during rotation of the genitalia that suggest they function as the driving force for rotation. During this rotation, one muscle of each set contracts and the opposed one becomes elongated. The contracting muscles are atypic physiologically. They contract from 300 mum to about 69 mum, and this requires a period of 18 to 24 hours. They shorten only once and those muscle fibers still present after the completion of rotation remain in a contracted condition at least for two weeks. The elongated muscles never shorten; they become stretched to approximately 2.5 times their original length and disappear soon after rotation is completed.

INFECTION OF COCKROACHES WITH HERPOMYCES (LABOULBENIALES). IV. DEVELOPMENT OF H. STYLOPYGAE SPEGAZZINI

The development of male and female plants of the dioecious fungus Herpomyces stylopygae on cockroach antennae is described. Cell lineage is fundamentally different for male and female plants. The gross structure and apparent cell lineage are different for female plants growing on setae in contrast to ones on the body wall. An interpretation in terms of developmental plasticity and geometric limitations of the hosts surface is suggested for the two types of growth of female plants.