Host Integument Research Articles

In vitro release of ecdysteroids by an endoparasitoid, Ascogaster reticulatus Watanabe

Ascogaster reticulatus larvae removed from their host Adoxophyes sp. and held in vitro released immunoreactive ecdysteroids into Grace's medium. Initially 20-hydroxyecdysone and an unidentified polar ecdysteroid were released, but ecdysone was also present after 24 h incubation. Regardless of the age of the host or size of the parasitoid larva, the maximal release of immunoreactive ecdysteroids occurred when a parasitoid larva developed opaque, fat body spots. We discuss the possibility of direct manipulation of the host haemolymph ecdysteroid titre and subsequent apolysis of the host integument, all initiated by the release of ecdysteroids by the parasitoid larva.

"AKENTROGONID" HOST INVASION AND AN ENTIRELY NEW TYPE OF LIFE CYCLE IN THE RHIZOCEPHALAN PARASITE CLISTOSACCUS PAGURI (THECOSTRACA: CIRRIPEDIA)

ABSTRACT Cyprid settlement and host invasion was studied in the rhizocephalan Clistosaccus paguri (Clistosaccidae) using transmission electron microscopy. Male and female larvae appear to be morphologically identical. The infestive kentrogon instar known from the Peltogastridae, Lernaeodiscidae, and Sacculinidae is absent in the Clistosaccidae. Instead, the cyprid itself uses an antennule to penetrate through the host integument. This is the same mechanism used by functional male cyprids to implant spermatogonia into juvenile female parasites, and it is the first demonstration of akentrogonid host invasion in the the Rhizocephala. The primordial parasite is not preformed in the cyprid, but develops from injected, undifferentiated cells almost directly below the site of settlement. The full clistosaccid life cycle without kentrogons is described in detail, and compared to that found in the classical kentrogonid rhizocephalans. It is concluded that the traditional classification of the Rhizocephala into the suborders Kentrogonida and the Akentrogonida should be reconsidered, since the Clistosaccidae was previously included in the former.

Susceptibility of sixteen species of Diptera to the fungal pathogenEntomophthora muscae (Zygomycetes: Entomophthoraceae)

Sixteen species of Diptera from eight families were inoculated with conidia ofEntomophthora muscae (Zygomycetes: Entomophthorales). The following species were susceptible and became infected at the rates indicated:Musca domestica (100%),Sarcophaga haemorrhoidalis (86%),Phaenicia sericata (44%),Scatophaga stercoraria (30%),Drosophila melanogaster (11%),Aedes aegypti (3%), andStomoxys calcitrans (2%). The following species were not susceptible under the conditions of this study:Phormia regina, Calliphora vicina, Rhagoletis pomonella, Eristalis arbustorum, Eristalis tenax, Toxomerus geminatus, Sphaerophoria scripta, Syrphus sp. andAllograpta oblique. Differences in susceptibility were not related to the taxonomic affinities of the taxa tested; however, susceptibility may be related to interspecific morphological differences of hosts, such as, scales and hairs on the host or the degree of sclerotization of host integument.

The life cycle of the Tantulocarida (Crustacea)

Four new species of parasitic crustaceans belonging to the class Tantulocarida are described, two of which are placed in a new genus,Onceroxenus. Three of them parasitize deep-sea tanaids, the other, a deep sea asellote.Microdajus langi, originally classified as an epicaridean isopod, is recognized as a tantulocaridan. It is reported from Scottish waters for the first time and from new host species. These records include the shallowest depth, 22 m, known for a tantulocaridan.Cumoniscus kruppia parasite of cumaceans, is also recognized as a tantulocaridan. The Tantulocarida now comprises eleven species and five genera, here assigned to the Basipodellidae and two new families, the Deoterthridae and Microdajidae. Several life cycle stages are described and arranged in two developmental sequences. Evidence for a possible third sequence was found. Male development involves a unique type of metamorphosis in which the free-living adult differentiates from a dedifferentiated mass of tissue contained within the expanded trunk of the tantulus larva. Throughout this metamorphosis the male is supplied with nutrients from the host via a tissue connection, the umbilical cord, and the permanently attached larval head. The non-feeding adult male lacks cephalic appendages but possesses two clusters of aesthetascs on its anterior margin. It is free swimming and has six pairs of large thoracopods without endites. The first two thoracic somites are incorporated into the cephalothorax. The abdomen bears a posteriorly directed, median stylet, interpreted as the intromittent organ. It originates on the first abdominal somite. The adult female has a large sac-like trunk attached by the larval head. The larval trunk is sloughed leaving a scar but no complete moult occurs. Eggs develop within the trunk sac and hatch directly at the infective tantulus larval stage. This extreme condensation of early ontogeny is compared with that of other crustaceans and is interpreted as an adaptation to parasitism in situations where a high dispersal ability is not advantageous. In some females the trunk sac forms behind the head but the larval trunk is retained. Small and large females of this type are described, the largest being 737 µm in length. These probably represent females in which sloughing of the larval trunk has failed but it is possible that each may have contained a free-living adult female of comparable size to the adult male. The tantulus larva is described in detail. Scanning electron microscopy reveals that the thoracopodal endites have a complex apical armature, including coupling spines which serve to link the members of a leg pair. Tantulocaridans are permanently attached to their host by the oral disc, presumably by means of an adhesive. In the centre of the disc they make a minute puncture (between 0.5 and 2.0 µm in diameter) through the host integument, probably with the aid of their cephalic stylet. This constitutes their only access to the body fluids of the host. The phylogenetic relationships of the Tantulocarida are discussed. They appear to be related to the barnacles (Thecostraca), both groups possessing a median penis derived from the seventh trunk limb. Their possession of a thorax of six somites and the location of the male gonopores on trunk somite seven suggests an affinity with a larger group containing the Thecostraca and the Copepoda.

Pathogenesis associated with philornid myiasis (Diptera: Muscidae) on nestling pearly-eyed thrashers (Aves: Mimidae) in the Luquillo Rain Forest, Puerto Rico.

Pathogenesis of myiasis due to the muscid fly Philornis deceptivus in nestling pearly-eyed thrashers (Margarops fuscatus) in the Luquillo Rain Forest, Puerto Rico was investigated. Philornid larvae penetrated the host integument, underwent a period of development and growth, and established, as third instar larvae, between the dermis and the body musculature. Movement into this location plus growth and development of the fly larva appeared to be linked to the ingestion of host tissues including red blood cells, mononuclear cells which infiltrated from focal accumulations adjacent to the lesion, and necrotic cellular debris which accumulated in the lesion. The resultant increase in size of the larvae greatly displaced the host integument. Following the evacuation of the larvae for the purpose of pupation, repair of the cavernous lesion was initiated with the production of an intense organized fibrinous exudate. Macrophages and plasma cells predominated with vascular congestion in surrounding tissues. Over the 21-day nest period, nestlings were subject to successive infestations of large numbers of larvae and host responses to these appeared to significantly debit an energy budget responsible for nestling development and growth. Nestling mortality and post fledging survivorship appeared linked to the impact of these energy demands.

Development of the Polyembryonic Parasite Copidosomopsis tanytmemus (Hymenoptera: Encyrtidae)1

Copidosomopsis tanytmemus Caltagirone is a polyembryonic egg-larva parasite of Anagasta kuehniella (Zeller). The parasite undergoes holoblastic cleavage, producing a morula whose cells divide repeatedly to form a large mass of undifferentiated embryonic tissue. This tissue, the polygerm, gives rise to as many as 200 larvae. The larvae are dimorphic. Precocious larvae, which constitute ca. 10% of the larva brood, dissociate from the polygerm in as early as 7 days, are extremely motile, have deeply sclerotized mandibles and cranial structures, neither molt nor pupate, and invariably die as larvae. Normal larvae are formed from the polygerm ca. 25 days later, have small, weakly sclerotized mandibles, apparently undergo 4 instars, and consume most of the host's tissues. Normal larvae pupate within the host integument in individual pupal chambers; females emerge in 50 or 51 days, 3 days later than the males. The average brood size is 88 for females, 76 for males. There is an emergence mortality of 20% in female broods and 17% in male broods. Mixed broods are common under laboratory conditions. Adults ordinarily live to 10 days but can survive to 25 days in the laboratory on a diet of honey and water.

Purification and infectivity ofEntomophaga grylli (Fresenius) Batko Pathotype 2 againstMelanoplus differentialis (Thomas) [Ort.: Locustidae

The life stages ofEntomophaga grylli (Fresenius) Batko Pathotype 2 were purified and separated by centrifugation in PercollR density-gradient medium. The ranges of buoyant densities for germinated resting spores, germ conidia, and resting spores respectively were: 1.040–1.050, 1.055–1.085, and 1.080–1.120 g/ml. Cuticular invasion by germinated germ conidia was the means by whichMelanoplus grasshoppers became infected. Scanning electron micrographs revealed germination of germ conidia on the visible host integument at 100% RH, but not at 90% RH. Significantly higher mortality (P<0.05) was obtained after 3 weeks with grasshoppers incubated in constant light than in constant dark for 24 h following treatment. The disease was not transmitted by ingestion of any life stage.

Ultrastructure and function Of the proboscis inMelanella alba(Gastropoda: Eulimidae)

The free living eulimid gastropodMelanella albaBowdich, 1822 is a temporary ectoparasite on echinoderms and, in Kilkerrin Bay on the west coast of Ireland, this species is found exclusively associated with the holothuroidNeopentadactyla mixta(Östergren), 1898.Melanellautilizes a highly specialized acrembolic proboscis to penetrate the integument and ingest the internal tissues of this holothuroid. That portion of the proboscis which penetrates integument bears a highly developed secretory epithelium composed of granular and goblet secretory cells. As the proboscis is unfolded into the host's integument by a combination of increased hydrostatic pressure and muscular movements, secretory material is released from this epithelium and appears to bring about a rapid loosening of the connective tissue elements of the host. The possible mechanism by which the integumental connective tissue is altered to allow unfolding of the proboscis into the coelomic cavity of the host is discussed.

Growth and migration of plerocercoids of Triaenophorus crassus Forel and pathology in experimentally infected whitefish, Coregonus clupeaformis (Mitchill)

The development, movement, and migration of the plerocercoid of Triaenophorus crassus in experimentally infected whitefish fry, Coregonus clupeaformis, were examined and the pathology of infection described. Plerocercoids penetrated through the stomach – pyloric caeca and anterior small intestine into the peritoneal cavity by 20 h postinfection (PI). Worms entered the muscle by day 5 PI and underwent a variety of migration patterns. Plerocercoid movement in muscle was aided by a series of peristaltic waves along the length of the worm. Plerocercoids underwent rapid growth during the first 2 months of infection and were wound extensively through the muscle by day 60 PI, at which time they occasionally penetrated into the peritoneal cavity or through the host integument. Migration of worms caused muscle necrosis resulting in formation of lesions by day 17 PI and granulomas by day 60 PI. Coincident with coiling of plerocercoids after day 60 PI was the formation of a host capsule around the worm and the initiation of plerocercoid hook development. Capsules and coiling of plerocercoids caused regional distortions in the body of the fish and displaced and (or) replaced large areas of muscle. Capsules containing live worms were recovered at 3 years PI. Mortality of infected whitefish was 21.7%, and 70.0% of this mortality occurred between days 48 and 59 PI. There was no difference in the rate of growth and the quantity of liver glycogen between infected and uninfected fish.

Ismaila Occulta, a New Species of Poecilostomatoid Copepod Parasitic in a Dendronotid Nudibranch From California

Ismaila occulta, new species, a poecilostomatoid copepod of the family Splanchnotrophidae, is described based on specimens recovered within the cerata of a giant red nudibranch, Dendronotus iris Cooper, collected from Alamitos Bay in Long Beach, California. Problems in uniting Ismaila, Micrallecto, Nannallecto and Splanchnotrophus under the Splanchnotrophidae and the systematic status of the family are discussed. The Splanchnotrophidae Norman and Scott, 1906 is a family of highly specialized poecilostomatoid copepods. According to Laubier (1964), this family contains only one genus, Splanchnotrophus Hancock and Norman, 1863, although Monod and Dollfus (1932) had included in it Briarella Bergh, 1876; Ismaila Bergh, 1867; and Chondrocarpus Bassett-Smith, 1903. Stock (1971, 1973), while agreeing with Laubier's opinion, suggested placing in this family two new genera (Micrallecto and Nannallecto) that were proposed by him. Members of the genus Splanchnotrophus are internal parasites of nudibranchiate molluscs. While the male lives free inside the host's body, the ovigerous female attaches (from inside) to the host's integument by penetrating through it with its posterior extremity, including the genital somite and the greatly reduced abdomen. Both Micrallecto and Nannallecto are monotypic genera with their species occurring as ectoparasites of gymnosome gastropods. In September, 1975, when Marine Biological Consultant, Inc., of Costa Mesa, California, was making a general survey of benthic animals in the Long Beach Harbor, a specimen of a giant red nudibranch, Dendronotus iris Cooper, 1863, caught in the trawl, was found infested with a bizarre copepod parasite. It lived within the hepatic diverticulum of the host's cerata. Because of the scarcity of specimens, it was not dissected for further study. Fortunately, six additional infested D. iris were later (in May, 1977) collected from the Long Beach Marina (Alamitos Bay). Dissection of a heavily infested nudibranch yielded 425 parasites (113 adults and 312 copepodids) from its five pairs of cerata. Examination of these parasites revealed that they represent a new species of Ismaila Bergh, 1867, a very poorly known genus of poecilostomatoid copepods. This report deals with only the adult forms; the larval stages will be reported separately in a later work. Ismaila occulta, new species Material Examined.-34 adult ? Y and 79 adult d d found in five pairs of cerata of a 57 mm long Dendronotus iris Cooper, 1863 caught in the trawl made in Alamitos Bay, Long Beach, California in May, 1977. Holotype Y (USNM 184044), allotype (USNM 184045), and 12 paratypes (6 Y 9 and 6 6 d) (USNM 184046) deposited in the National Museum of Natural History, Smithsonian Institution, Washington, D.C. Female.-Body (Figs. 1A-B) elongate, saclike and slightly depressed dorsoventrally, measuring from 2.38 to 4.46 mm long. Head globose, distinctly set off from trunk, bearing no processes except bulges on lateral and posteroventral surfaces.

Biologie de la Larve Planidium de Villa Brunnea, Diptère Bombyliide, Parasite de la Processionnaire du Pin. III. Le Début de la Vie Endoparasitaire du Planidium, les Réactions de l'Hôte et les Échecs du Parasitisme.

SummaryThe endoparasitic life of Villa brunnea in the pupae of the pine processionary moth, Thaumetopoea pityocampa, begins by a « fixed period », 25 minutes to 20 days long, during which the planidium stays joined with the host integument, generally does not eat, and undergoes important physiological transformations. At the beginning of this fixed period, the host pupa often reacts by siphonogenesis. A « reactive sheath » is then built round the planidium. The length of this sheath varies from 0 to 3,2 mm. Some planidia die during their fixed period or shortly later, because of a defective adaptation to their host or of superparasitism. Encapsulation goes generally together with their death, but it is only a consequence of a pre-existant and irreversible weaking of the larvae.

Studies on the host parasite relationship between the parasitic prosobranch Thyca crystallina and the asteroid starfish Linckia laevigata

A study of the Blue starfish Linckia laevigata in the Banda Islands, Moluccas, Indonesia, revealed 62% infestation by the molluscan prosobranch parasite Thyca crystallina. Infestation rate varies directly with the degree of water movement. A marked difference in settlement pattern according to parasite size is observed. The smallest limpets tend to settle on the upper surface of the distal parts of the arms and are randomly oriented. The largest parasites are found on the oral arm surface on the right hand side of the ambulacral groove and facing the starfish mouth. All of the attached parasites were female. Most of the large females had a dwarf male, one tenth the length, attached, under the mantle, at the anterior end. Amongst the small limpets, less than half had made a proboscis hole in the host integument and none had made an attachment disc lesion; of the large parasites 90% had the proboscis embedded in the host and 80% left an attachment disc lesion on the host. Small parasites can move very slowly over the host surface. Larger limpets are probably permanently attached. A detached parasite of any size is probably unable to reattach. There is evidence of an extended parasite breeding period and repetitive settlement on the hosts, which could cause the observed overdispersion without invoking a mature female parasite pheromone.

The fine structure of Entomophthora apiculata and its penetration of Trichoplusia ni.

The fine structure of conidia and immature resting spores of the entomogenous fungus Entomophthora apiculata is described. The two cell types contain comparable organelles and quantities of lipid, and possess a similar cell wall structure. The large quantity of stored lipid and numerous mitochondria in each cell type indicate a capacity for great metabolic activity. Numerous dense, microbody-like organelles were observed in conidia and resting spores, and their possible functions are discussed. Third instar larvae of the cabbage looper Trichopulsia ni were exposed to conidia of E. apiculata. Fungal germ tube formation and penetration of the host integument were observed. The germ tubes did not form appressoria and appeared to penetrate the epicuticle by enzymatic and physical means. After penetration of the epicuticle the germ tube often bifurcates, and expands as two or more digit-like projections parallel to the lamellae of the exocuticle. The hyphae gradually extend inward, cleaving the lamellae of cuticle, and eventually enter the host's body cavity.

The Epithelium of the Gut as a Barrier Against Encapsulation By Blood Cells in Three Species of Parasitoids of Bupalus Piniarius (Lep., Geometridae)

Three habitual parasites of the pine looper are generally not eliminated by the haemocytic defence reaction of their usual host, because the eggs are laid or the larvae settle behind the epithelium of the gut. This acts as a barrier against the passage of blood cells. This conclusion is supported by the observation that larvae of all three species are encapsulated during abnormally long stays in the host's body cavity. In two species this results from the parasitoid's failure to oviposit in the usual way, being either egg deposition at a less favourable site on the host's integument, or in a less suitable larval instar of the host. In the third species encapsulation results from the failure of the parasitoid's larva to enter the mid-gut due to some unknown factor(s) related to superparasitism.

Fine structure of the fungus Metarrhizium anisopliae infecting three species of larval Elateridae (Coleoptera). IV. Development within the host.

Metarrhizium anisopliae develops through three structural stages within the body cavity of elaterid larvae after penetration of the host integument. The fine structure of these stages is described. The penetrant hyphae give rise to hyphal bodies, which become distributed throughout the body cavity and give rise to secondary hyphae in all parts of the body. The third stage consists of discrete large, ovoid cells with abundant nutrient stores and few metabolically active inclusions. It is termed a chlamydospore stage to differentiate it from the hyphal body stage, the cells of which are also discrete and often ovoid. The suggestion is that the chlamydospores may maintain fungal viability within the body of the host for extended periods before surface sporulation.

Fine structure of the fungus Metarrhizium anisopliae infecting three species of larval Elateridae (Coleoptera) II. Conidial Germ tubes and appressoria

The fine structure of germ tubes of the entomogenous fungus Metarrhizium anisopliae, and of appressoria formed by them in contact with the host integument, is described. The abundance of mitochondria, dictyosomes, ribosomes, and endoplasmic reticulum in appressorial cells suggests a high level of secretory or metabolic activity. The wax layer of the host integument disappears at points of contact with appressoria, indicating possible utilization of this layer by the pathogen. A mucoid substance coats the appressorial cell walls, fills some of the spaces between adjacent appressoria, spores and germ tubes in infection cushions, and forms a thin layer between the appressorial cell walls and the integumental surface of the host where these are in close apposition. This substance is presumably secreted by the appressorial cells, and appears to serve as an adhesive. Bacteria occasionally were observed intermingled with fungal structures on the exterior of the host.

Some Aspects of Host Selection in Eucarcelia Rutilla Vill. (Diptera: Tachinidae)

Host finding, acceptance and suitability in Eucarcelia rutilla Vill. were studied in the field and in the laboratory. The literature on nomenclature, morphology of adult and larva, life history, hosts, synchronisation and geographical distribution is surveyed. The species is univoltine, well-synchronized with its two main hosts, Bupalus piniarius and Semiothisa liturata. It deposits macro-type eggs in which the maggots are ready to hatch. Descriptions and relevant aspects of the biology of pine dwelling caterpillars and Diprion larvae are also given. In the field gravid Eucarcelia females coincide mainly with Bupalus larvae in their second and third instar. Eggs were also found upon specimens of Semiothisa liturata, Ellopia prosapiaria, and Thera obeliscata. Superparasitism is not avoided under natural conditions. Host selection was studied experimentally. Attention was paid to detectability and acceptability. A preliminary study of factors involved in host finding reveals that visual stimuli play an important role. In host acceptance stimuli originating from the host's surface are involved. Some evidence was found that these stimuli are mediated through receptors on the tarsi and ovipositor. In experiments there was no discrimination between parasitized and non-parasitized hosts. Preimaginal conditioning in oviposition preference was not noticeable. The bigger the caterpillars, the greater the chance of detection and the greater the risk of parasitization. The resting position of the caterpillar upon the needle has a strong influence on its chance of being found by the parasite. Specimens resting at the base are almost exempt from attacks. The detectability and acceptability of nine species of Lepidoptera and six species of Hymenoptera were tested. Only 4 differed significantly in detectability from Bupalus, but 10 were wholly unacceptable for oviposition. The reaction of the hosts towards attacking females and their eggs differed markedly among species. Upon Bupalus piniarius, Thera obeliscata, T. firmata, and Hyloicus pinastri the eggs are deposited preferably on the thorax. In Semiothisa liturata, Ellopia prosapiaria, Panolis flammea, and Diprionidae other distributions were obtained. As regards the side of the host chosen, the wider its girth the less often the eggs are attached ventrally. The risk of destruction of eggs upon the host's integument varies widely among species: Panolis flammea and Eupithecia indigata remove almost all the eggs, whereas in Ellopia prosapiaria no eggs were dislodged, and in Hyloicus pinastri almost none. Bupalus piniarius, Semiothisa liturata, Thera obeliscata, and T. firmata demonstrate a moderate reaction towards eggs placed upon the abdomen. In Bupalus the instars II and III have a stronger reaction than the other instars. Eggs laid dorsally on abdominal segments as a rule run a greater risk than those placed ventrally. Eucarcelia can develop only in Bupalus, Semiothisa, and Thera obeliscata. In about 20% of the cases Thera firmata, too, can give rise to full-grown parasite larvae. Host suitability also depends on site of penetration. Posterior penetration into Bupalus lead to greater losses than anterior penetration. The frequencies of settlement of maggots in wall of the foregut (intima), mandibular muscles, subcuticular sites, segmental muscles, and haemocoel were recorded for the various instars of Bupalus. Maggots which have settled in intima or in subcuticular sites must migrate at each moult of the host. This migration takes the maggot outside the host's body which it re-enters by piercing the integument at a sharply defined spot mid-dorsally in the membrane between head-capsule and first thoracic segment. Its main function certainly is to prevent removal with the shed intima or cuticle. In addition it is conjectured that migration may help the maggot to avoid exposure to the host's hormones in concentrations which might cause it to moult prematurely. Mortality of maggots can be brought about by encapsulation by haemocytes or removal from the host. Larval mortality is higher in cases where more than one maggot has entered the host than when only one is present. Site of settlement exerts a considerable influence upon parasite mortality. Settlement in haemocoel or wall of the mid/hindgut is unfavourable. It is argued that the relatively high mortality of maggots penetrated into posterior segments of younger instars is due to lower suitability of the sites of settlement attained by these maggots.

SPECIALIZATION IN THE EGG STRUCTURE OF EXENTERUS (HYMENOPTERA: ICHNEUMONIDAE) IN RELATION TO DISTRIBUTION AND ABUNDANCE

AbstractLike all other Tryphoninae, the European species of Exenterus have eggs that are attached to the host by a stalk inserted into the host integument. Their eggs present an interesting series of evolutionary steps from the typical tryphonine condition in which the egg has a small single stalk with a knob-like anchor to an extremely specialized condition in which the stalk is doubled and its two parts migrate to opposite ends of the egg; the anchoring part of the stalk is concurrently enlarged until it half encloses the egg and functions as an extremely efficient organ of attachment to the host cuticle. In dry periods the simple type of stalk becomes brittle and easily broken, resulting in the death of the parasite. The specialized eggs with protected stalks are not subject to such hazards; thus species with specialized eggs can succeed in drier climates and can better survive droughty seasons. Correlated with these specializations is an increase in range of species, and greater abundance of individuals. The success of the European species introduced into North America for biological control has been roughly proportional to the amount of specialization in the egg structure. Little is known of the life histories of the American species of Exenterus but the few facts available do not appear to contradict the type of correlation exhibited by the European species.

Tissue Damage Inflicted by Lernaea cyprinacea Linnaeus, a Copepod Parasitic on Tadpoles

The site and extent of injury in 14 Rana pipiens experimentally infested with Lernaea cyprinacea were determined by the use of serial sections. Muscles and kidneys were the most frequent site of development of the anchor process, but lungs, liver, and spinal cord were also affected. The degree of injury was in part dependent upon the nature of the tissue invaded and in part upon the degree of development of the parasite. Injury to the host could be attributed to compression and destruction of tissues in contact with the expanding anchor process or to subsequent formation of connective tissue layers around the parasite. Although connective tissue was always found surrounding the portion of the copepod free in the coelom of the host, the tissues of the body wall failed to contribute to its formation. Thus, lesions on the integument of the host, common in fish infested with Lernaea cyprinacea, do not occur on infested Rana pipiens. Lernaea cyprinacea Linnaeus has been reported as parasitizing many different species of fishes throughout the world (Nakai, 1927; Tidd, 1934; Haderlie, 1953; Uzmann and Rayner, 1958; Haley and Winn, 1959; Huggins, 1959; Dogiel, Petrushevski, and Polyanski, 1961). Recently we have been finding specimens of Lernaea on tadpoles as well as fishes from central Ohio streams. This aroused our curiosity as to the part tadpoles might play as hosts to L. cyprinacea. We successfully infested laboratory-reared tadpoles of Rana pipiens with first copepodid larvae of L. cyprinacea (Tidd, 1962). Our observations of the deep penetration and development by the adult females in these hosts led us to make a study of the tissue sites and tissue damage resulting from these experimental infestations. MATERIALS AND METHODS Tadpoles of R. pipiens were laboratory raised from eggs obtained by induced ovulation. At the time of infestation these tadpoles were 25 mm long. They were divided into an experimental and a control group. Each tadpole in the experimental group was infested by the method outlined by Tidd (1962). The control tadpoles were treated the same in every respect except that they were not exposed to the larvae. The temperature of our laboratory during this experiment varied between Received for publication 2 October 1962. 22 and 28 C. We knew from past experience that 10 days after infestation the copepodid larvae mature to the point where some start a penetration of the host's integument and enter upon a period of metamorphosis. The body segments lengthen and the arms of the anchor process form as outgrowths of the cephalothorax. Ten days after penetration the metamorphosis of these parasites is complete or nearly so. Although all tadpoles were exposed to copepodid larvae of the same age, differences of 2 to 3 days in the time of penetration were common. Thus the copepods on any one tadpole may exhibit considerable differences in their degree of development depending upon the actual time of penetration. We divided our experimental and control tadpoles into three groups each. The first were killed 10 days after infestation, the second 15 days, and the third 20 days. Bouin's alcoholic reagent was used to kill and fix all specimens. The standard paraffin embedding method was used. Serial frontal and serial cross sections, 10 / thick, were cut from 14 of these infested tadpoles and their controls. The sections were stained with either Mallory's triple strain or a modification of Azocarmine-G (Hubschman, 1962). Effects of the development of the anchor process were determined by comparison with control tadpoles of approximately the same age.

Respiratory Pore Construction in the Host by the Nemestrinid Parasite Neorhynchocephalus sackenii (Diptera), With Notes on Respiratory Tube Characters

After penetrating the grasshopper host in the unsclerotized tissue just below the rows of spiracles, the parasitic larva punctures and enters the main tracheal trunks, wandering there and feeding on the inner surface for about 2 days. It then punctures the trachea again to make a partial exit just under the host's integument, through which it cuts its respiratory pore while still maintaining contact with the host's spiracular trachea, usually in an abdominal segment. Upon completion of the pore, the larva severs connection with the trachea, and, reversing its position, brings its metapneustic spiracles to the pore, which it plugs with the posterior end of its body. The respiratory tube which then begins to develop maintains the larva's contact with the pore as the parasite moves deep into the host's body cavity. When artificially parasitized hosts molted, the parasite's respiratory pore and tube were shed with the exuviae, and new ones were developed which differed in manner of formation, appearance, and position. Another North American nemestrinid, Trichopsidea clausa, makes no external pore but attaches its respiratory tube to the host's spiracular tracheae, usually in the first abdominal segment. The African T. (Symmictus) flavopilosa, parasitic in a much larger grasshopper, makes its pore within 1 mm. of the host's mesothoracic spiracle and develops respiratory tubes that may be twice as long as the larvae themselves.