Monocystid Gregarine Parasites of Nigerian Earthworms

SYNOPSIS Seven monocystid gregarine parasites including 6 new species are described from the perivisceral coelom and seminal vesicles of Nigerian earthworms, which have not been so far investigated for monocystid parasites. The new species are: Apolocystis iridodrilii sp. n. from Iridodrilus preussi and Iridodrilus roseus ; Apolocystis libyodrilii sp. n., Monocystis abegbei sp. n., Monocystis libyodrilii sp. n., and Zygocystis violacea sp. n. from Libyodrilus violaceus ; and Nematocystis bunmii sp. n. from Heliodrilus lagosensis. Apolocystis herculea (Bosanquet) was recorded from Libyodrilus violaceus.     

Parasites of British Earthworms

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The Life Cycle of Ganymedes oaklandi n. sp., an Acephaline Gregarine of Gammarus fasciatus (Say)*

SYNOPSIS. Ganymedes oaklandi n. sp. (Ganymedidae) from the intestine of Gammarus fasciatus (Say) is described, and its life cycle is given. In the trophic stage the gregarine is acephaline, with an elongated cylindrical body slightly tapered anteriorly, and is up to 298 × 64 μ. The gametocysts are up to 121 × 99 μ, and are covered with a secreted thick sticky gelatinous coat. The spores are released from the gametocyst by rupturing of the cyst wall. The spore body is spherical, approximately 6 μ in diameter, and has 4 episporal rays about 20 μ long.     

Escape from Gregarine Parasites Affects the Competitive Interactions of an Invasive Mosquito

When a species is introduced into a new location, it may escape, at least temporarily, from its natural enemies. In field surveys, we found that when the exotic, invasive mosquito, Aedes albopictus, invades new sites, it initially experiences reduced infection by its gut parasite, Ascogregarina taiwanensis. To determine the effect of this escape from parasitism on the competitive ability of A. albopictus, we performed a laboratory competition experiment in which infected and uninfected A. albopictus larvae were reared in microcosms alone and in competition with larvae of the native mosquito, Ochlerotatus triseriatus. We analyzed the effect of parasitism by A. taiwanensis on A. albopictus performance when subjected to intra- and interspecific competition across a range of larval densities, as well as the effect of A. albopictus parasitism by A. taiwanensis on the competitive impact of A. albopictus on O. triseriatus. At a density of 30 O. triseriatus larvae, O. triseriatus survivorship was significantly reduced by the addition of 30 unifected A. albopictus, but not by addition of 30 infected A. albopictus, and not by addition of 15 A. albopictus whether infected or uninfected. Although estimated finite rate of population increase (') showed similar trends, and was significantly affected by treatments, no pairwise differences in rate of increase were significant. Infection by A. taiwanensis also significantly prolonged A. albopictus female development time and reduced the intraspecific competitive effect of increased density of A. albopictus, but did not affect A. albopictus survivorship, mass, or estimated finite rate of population increase. Thus, when A. albopictus escapes from this parasite as it colonizes new sites, this escape may give it a small, but significant, added competitive advantage over O. triseriatus, which may facilitate range expansion of A. albopictus and enhance A. albopictus's initial impact on resident species.     

The Gregarine Infection in Different Species of Odonata from the Same Habitat

A qualitative and quantitative study of eugregarine parasites in different dragonfly species was performed around a breeding site at Bergen (Western Norway). Dragonfly larvae were never found to harbour gregarines. As a general rule, the number of dragonflies infected and the number of gregarines present in each individual host increased during the flying season. In the zygopterans Coenagrion hastulatum (Charp.), Enallagma cyathi-gerum (Charp.), and Pyrrhosoma nymphula (Sulz.), the majority became heavily infected. Discoloured, feeble specimens captured in the field exhibited extensive damage to the midgut, probably progressing to bacterial septicaemia. The histopathology of the midgut wall has been recorded from scarcely visible alterations to massive disruption of the epithelium. In these species, gregarine infection apparently reduced the longevity of adults. The population of Lestes sponsa (Hansem.) was moderately infected and injuries of the midgut seldom occurred. In the only infected anisopteran, Sympetrum danae (Sulz.), gregarines seemed unimportant and caused no damage to their hosts. Each gregarine species seemed to thrive in several dragonfly hosts, and a host could harbour at least two different gregarine species at the same time. The pattern of infection is discussed against the background of climatic and edaphic conditions.     

Acephaline Gregarines of Earthworms—Additions to the British Records

SYNOPSIS. 30 acephaline gregarines, including 4 new species, were identified and described from the perivisceral coelom and vesiculae seminales of 13 British earthworm species. The newly described monocystids were Apolocystis megagranulata n. sp. and Nematocystis dendrobaenae n. sp. from Dendrobaena rubida f. subrubicunda and D. mammalis, Monocystis mammaliae n. sp. from D. mammalis, and Zygocystis ictericae n. sp. from Allolobophora icterica f. typica. These 3 earthworm hosts have not been previously examined for monocystids in Britain.     

The Biochemistry of Parasites

HPLC-analysis of the reaction products of a series of 4-methylumbelliferyl glycosides from cello-oligosaccharides, used as substrates of a cellobiohydrolase from Trichoderma reesei, proves the lack of specificity for terminal cellobiosyl groups. Also, different reaction patterns are observed for this CBHI and for an endocellulase, when acting on these same substrates. 4-Methylumbelliferyl β-D-lactoside is an unexpected substrate for CBHI, yielding only lactose and phenol as reaction products. The binding characteristics of p-nitrobenzyl 1-thio-β-D-lactoside for this enzyme are determined by a dia-filtration technique, yielding 1 binding site and an association constant of 4.0 × 10⁴ M^?1.     

Checklist of the species of the aseptate Gregarine family Urosporidae

A checklist is given of the 45 named species of the family Urosporidae (phylum Protozoa, subphylum Apicomplexa, class Sporozoa, subclass Gregarinia, order Eugregarinida, suborder Aseptatina) together with their synonyms, the names of their hosts, their locations in the hosts, their known geographic distribution, and key references. Another list is given of synonyms, lapsi calami, nomina nuda, etc. associated with the genera of this family. The following taxonomic-nomenclatural innovations are introduced—NEW NAME: Gonospora good-richae nom. nov. in the polychaete Arenicola ecaudata; NEW COMBINATIONS: Urospora grassei (Changeux, 1961) in the sea cucumbers Holothuria spp.; Urospora schneideri (Mingazzini, 1891) in the sea cucumbers Holothuria spp; Gonospora gonadipertha (Djakonov, 1923) in the sea cucumber Cucumaria frondosa; Gonospora stichopi (Lützen, 1967) in the sea cucumber Stichopus tremulus.     

The Fine Structure of the Gregarine Lankesteria culicis Parasitic in the Yellow Fever Mosquito Aedes aegypti

SYNOPSIS. The fine structure of the eugregarine Lankesteria culicis from the larvae of the mosquito Aedes aegypti was examined by light and electron microscopy and compared with that of other gregarines. The cell organelles found in L. culicis included a nucleus, mitochondria, Golgi-complexes, endoplasmic reticulum, vesicles, droplets, granules and lipid bodies.
The surface of L. culicis was composed of a highly differentiated membrane-cortex, differing slightly from that of other eugregarines. This complex was limited by a unit membrane, the plasmelemma, and underlying cortical laminae which appeared to be composed of several layers. The homogeneous electrondense layer present in Pyxinoides balani was greatly diminished or absent in L. culicis.
A series of laminar folds supported by ground substance and longitudinal subpellicular fibrils gave the organism's surface a ridge-like appearance. Permanent cytostome-like openings in the surface, which appeared to be supported by a narrow band of thickened cortex, were present as specializations of the surfacemembrane complex. The structural composition of the parasite appeared quite striking in that it was made up almost entirely of vesicles, granules, and droplets which were absent only in the area of the protomerite. The mitochondria were usually found just beneath the surface or near the nucleus. Mitochondria were also seen in the region of demarcation between the protomerite and deutomerite.     

Development and Dehiscence of Gametocysts of the Gregarine Pyxinia crystalligera Frenzel

SYNOPSIS. Association of gamonts of Pyxinia crystalligera takes place in the midgut of its beetle host, Dermestes vulpinus. At 25°C. the development of gametocysts to the point of liberation of sporocysts is completed between about 15 hours and 27 hours after the gametocysts are deposited with fecal material. Dehiscence is favored by relative humidities of 0% to 90%, but is not favored by a relative humidity of 100%. During the early development of the gametocysts outside the host, the crystals and paraglycogen granules in the cytoplasm of the associated gamonts become concentrated in large masses. The gametes are formed at the periphery of the gamonts. After fusion of the gametes takes place and the sporoblasts begin to develop, the residual cytoplasm containing the inclusions moves outward to form a continuous layer next to the gametocyst envelope, so that the sporoblasts become crowded into a central core. A few hours before dehiscence is initiated a clear area appears on the upper side of the gametocyst. The contents of the gametocyst begin to shrink away from the envelope except in the region of the clear area. Eventually the sporocysts emerge through the clear area and press against the envelope of the gametocyst, causing formation of a conical papilla in the envelope. With continued pressure from the sporocysts, the papilla ruptures at its tip, and the sporocysts emerge in a continuous thread until dehiscence is completed. The thread of sporocysts may attain a length of about 11 mm.     

Parasites and Pathogens of the Honeybee (Apis mellifera) and Their Influence on Inter-Colonial Transmission

Pathogens and parasites may facilitate their transmission by manipulating host behavior. Honeybee pathogens and pests need to be transferred from one colony to another if they are to maintain themselves in a host population. Inter-colony transmission occurs typically through honeybee workers not returning to their home colony but entering a foreign colony (“drifting”). Pathogens might enhance drifting to enhance transmission to new colonies. We here report on the effects infection by ten honeybee viruses and Nosema spp., and Varroa mite infestation on honeybee drifting. Genotyping of workers collected from colonies allowed us to identify genuine drifted workers as well as source colonies sending out drifters in addition to sink colonies accepting them. We then used network analysis to determine patterns of drifting. Distance between colonies in the apiary was the major factor explaining 79% of drifting. None of the tested viruses or Nosema spp. were associated with the frequency of drifting. Only colony infestation with Varroa was associated with significantly enhanced drifting. More specifically, colonies with high Varroa infestation had a significantly enhanced acceptance of drifters, although they did not send out more drifting workers. Since Varroa-infested colonies show an enhanced attraction of drifting workers, and not only those infected with Varroa and its associated pathogens, infestation by Varroa may also facilitate the uptake of other pests and parasites.