Ultrastructure of spermiogenesis and spermatozoa of Discocotyle sagittata (Monogenea: Polyopisthocotylea: Discocotylinea).

Ultrastructural analysis revealed that the spermatozoon of Discocotyle sagittata (Leuckart, 1842) is composed of two parallel axonemes, mitochondrion, nucleus and cortical microtubules. The nucleus, which occupies a central/distal position and has an unusual crescent-shaped profile, is slightly shorter than the mitochondrial rod. The two axonemes, which are of unequal length, and the cortical microtubules (up to 68 forming a continuous ring in the principal region) extend almost the entire length of the spermatozoon. A fold of the plasma membrane creates a unilateral flange or undulating membrane. Epifluorescence microscopy indicated that spermatogenesis gives rise to clusters of 64 spermatids connected to a common cytophore. Spermiogenesis and the structure of the filiform sperm of D. sagittata conform to the typical polyopisthocotylean pattern.     

Experimental infection of Atlantic salmon (Salmo salar) with marine Eubothrium sp. (Cestoda: Pseudophyllidea): observations on the life cycle, aspects of development and growth of the parasite.

The life cycle of marine Eubothrium sp. (Cestoda: Pseudophyllidea), from Atlantic salmon (Salmo salar L.) was experimentally completed in one year and included only one intermediate host (Acartia tonsa Dana) (Copepoda: Calanoida). Adult cestodes were collected from farmed salmon, and ripe eggs released by the cestodes were fed to Acartia tonsa. Ingested eggs hatched in the gut and the larvae developed in the haemocoel of the copepod for 15 days at 16 degrees C. A total of 170 seawater-reared salmon were exposed to infected copepods and the total prevalence of Eubothrium sp. in the salmon after infection was 95.3%, with a mean intensity of 15.0 (range 1-87). The infected salmon were kept in the laboratory where the growth of the cestodes was studied for eleven months. Mean length of the cestodes increased with time, but a large variation among the cestodes was observed. Growth and maturation of the cestodes were dependent on host size and the number of worms present in the intestine. No evidence of mortality of Eubothrium sp. was observed during the experimental period.     

Plectanocotyle major sp. n. (Monogenea: Plectanocotylidae), a gill parasite of Chelidonichthys obscurus (Teleostei: Triglidae) from the Mediterranean Sea

Plectanocotyle major sp. n. (Monogenea: Polyopisthocotylea: Plectanocotylidae) is described from Chelidonichthys obscurus (Bloch et Schneider, 1801) collected from the Mediterranean coasts (Tunisia and France). The new species is compared to Plectanocotyle gurnardi collected on Chelidonichthys gurnardus and the only other valid species in the genus Plectanocotyle. The new species differs from P. gurnardi by the clamp size (137 microm vs 64 microm for clamp length and 110 microm vs 60 microm for clamp width, respectively) and the length of the male copulatory organ (107 microm vs 144 microm, respectively). Species of the Plectanocotylidae seem to be characterized by an oioxenic specificity.     

Description of Pseudorhabdosynochus seabassi sp. n. (Monogenea: Diplectanidae) from Lates calcarifer and revision of the phylogenetic position of Diplectanum grouperi (Monogenea: Diplectanidae) based on rDNA sequence data

Pseudorhabdosynochus seabassi sp. n. (Monogenea: Diplectanidae) from the gill filaments of Lates calcarifer Bloch, a marine teleost fish held in floating sea cages in Guangdong Province, China, is described based on morphological observations and molecular data. The shapes of the male copulatory organs (MCO) of Pseudorhabdosynochus spp. were the focus of this study. The typical proximal part of the MCO in most species of Pseudorhabdosynochus is reniform, heavily sclerotized, and divided into four chambers. However, the new species from L. calcarifer has a bulbous proximal region with four concentric layers of apparent muscular origin, instead of a reniform structure with four compartments. This organ is also different in Diplectanum grouperi Bu, Leong, Wong, Woo et Foo, 1999, being sclerotized, cup-shaped, wide proximally with four concentric muscular layers and tubular distally. The 3' terminal portion of the small subunit ribosomal RNA gene (ssrDNA) and the 5' terminal region (domains C1-D2) of the large subunit ribosomal RNA gene (lsrDNA) were used to reconstruct the phylogenetic relationships of P. seabassi and D. grouperi with related taxa utilizing maximum-parsimony and neighbour-joining methods. Phylogenetic analyses unequivocally placed D. grouperi amongst Pseudorhabdosynochus using either ssrDNA or lsrDNA data. All species of Pseudorhabdosynochus (including D. grouperi) used in this study clustered together, inferring monophyly. Based on molecular phylogenetic evidence, we propose that D. grouperi from Epinephelus coioides Hamilton be transferred to Pseudorhabdosynochus as P. grouperi comb. n.     

The effect of some herbicides on vesicular-arbuscular endophyte abundance in the soil and on infection of host roots

The effect of the herbicides di-allate, diquat, diuron, paraquat, tri-allate and trifluralin, at a range of application rates from 0.5 to 32 times that recommended by the manufacturers, on vesicular-arbuscular (V-A) endophyte spore abundance in the soil and on infection of wheat roots was investigated in field and glasshouse experiments. Paraquat and diquat had no measurable effect on V-A endophyte spore abundance. There was a slight trend to lower V-A endophyte spore numbers at high rates of application of di-allate and tri-allate but no trend for the other chemicals. Infection intensity (% root length infected) declined at high rates of di-allate and led to lower mycorrhizal root weights. The phosphorus content of the shoots was also reduced by di-allate. High doses of di-allate, diuron, tri-allate and trifluralin reduced most parameters of plant growth more than mycorrhizal parameters. It is therefore concluded that at normal application rates these chemicals are unlikely to affect adversely endomycorrhiza formation or function.     

The capsalidae (Monogenea: Monopisthocotylea): a review of diversity, classification and phylogeny with a note about species complexes

The Capsalidae are monogeneans parasitizing 'skin', fins and gills of marine fishes. Some capsalids are pathogenic to cultivated fish and a few have caused epizootic events. It is a cosmopolitan family with broad host associations (elasmobranchs and teleosts, including sturgeons). Approximately 200 capsalid species are placed in nine subfamilies and 44-46 genera, some of which are well known (Benedenia, Capsala, Entobdella, Neobenedenia). Sturgeons host two capsalid species (Nitzschiinae) and 15 species in five genera are reliably reported from elasmobranchs. The combination of ancient (shark, ray, sturgeon) and modem (teleost) host fish lineages indicates that capsalid evolution is likely a blend of coevolution and host-switching, but a family phylogeny has been lacking due to deficient knowledge about homologies. The current phenetic subfamilial classification is discussed in detail using a preliminary phylogeny generated from large subunit ribosomal DNA sequence data from representatives of five subfamilies. Monophyly of the Capsalidae is supported by possession of accessory sclerites. Hypotheses are proposed for the possible radiation of capsalids. A suggestion that Neobenedenia melleni, a pathogenic species atypical due to its broad host-specificity (>100 host teleost species from >30 families in five orders), may be a complex of species is supported from genetic evidence. This may explain peculiarities in biology, taxonomy, host associations and geographic distribution of N. 'melleni' and has implications for fish health. Holistic studies using live and preserved larval and adult capsalid specimens and material for genetic analysis are emphasised to further determine identity, phylogeny and details of biology, especially for pathogenic species.     

Bioinsecticidal effect of harmaline on Plodia interpunctella development (Lepidoptera: Pyralidae)

We have investigated the effects of harmaline, a plant secondary metabolic compound belonging to β-carboline alkaloids, on the 4th instar larvae of Plodia interpunctella (Lepidoptera). When incorporated into the diet, harmaline caused weight loss of larvae with a reduction in protein and glycogen contents and an inhibition of α-amylase activity. Using electron microscopy, we showed that harmaline provoked a severe cytotoxicity on the epithelial cells of the midgut resulting in marked vacuolization of the cytoplasm, appearance of numerous autophagic vesicles and lysosomic structures, fragmentation of rough endoplasmic reticulum cisternae, disruption of microvilli, rupture of the plasma membrane leading to shedding of the cytoplasm contents into the midgut lumen. The development of larvae to the pupal and adult stages was prevented and high mortality was recorded.     

Homing of Gyrodactylus salaris and G. derjavini (Monogenea) on different hosts and response post-attachment

In natural European waters, the congeneric monogeneans Gyrodactylus derjavini Mikailov, 1975 and G. salaris Malmberg, 1957 are primarily found on brown trout Salmo trutta L. and Atlantic salmon Salmo salar L., respectively. Interestingly, rainbow trout, Oncorhynchus mykiss (Walbaum), originating from North America, is as susceptible as brown trout to G. derjavini. However, the mechanisms involved in this host specificity are poorly understood but may include behavioural, mechanical and chemical factors affecting parasite attraction, attachment, feeding, reproduction and host responses. In the present laboratory work, this question has been studied. Detached parasites (either G. derjavini or G. salaris) were offered a choice in small aquaria between fry of rainbow trout, Atlantic salmon and carp Cyprinus carpio L. Within 48 hours more than 90% of G. derjavini colonised rainbow trout and left salmon almost uninfected. Some parasites were found on carp. During the same time span, more than 60% of G. salaris attached to salmon, the rest infected rainbow trout and none were found on carp. Following attachment, the parasites need appropriate stimuli to initiate feeding and reproduction but even such a successful specific colonisation can be followed by a host response. Both humoral and cellular elements have been suggested to participate in these reactions but in the present work it was demonstrated by immunoblotting and immunocytochemistry that no antibodies in host mucus and host plasma bound to any parasite structures or epitopes.     

The handling and fate of spermatophores in Neoentobdella diadema and N. apiocolpos (Monogenea: Capsalidae: Entobdellinae)

The elongated encased spermatophores of the capsalid (entobdelline) monogeneans Neoentobdella diadema (Monticelli, 1902) Kearn et Whittington, 2005 and N. apiocolpos (Euzet et Maillard, 1967) Kearn et Whittington, 2005 have been found attached by their proximal ends to the region of the vaginal opening, with the bulk of the spermatophore projecting from the vagina and therefore lying outside the body. In spite of previous reports, no spermatophores were found projecting from the common genital opening and if spermatophore exchange is as rapid as it is in the related entobdelline Entobdella soleae, then the chances of finding a spermatophore in this location are small. In N. diadema and N. apiocolpos it is likely that sperm enters the vagina through the open proximal end of an attached spermatophore, after which the empty spermatophore case is probably discarded. There is no evidence for a previous proposal that the whole spermatophore is engulfed by the vagina followed by digestion of the case to release the sperm. Three specimens of N. diadema were found each with two spermatophore cases projecting from the vagina and a specimen of N. apiocolpos carried three cases. Assuming that each parasite is able to donate or receive only one spermatophore at each mating, then the presence of one spermatophore does not prevent a further mating and acceptance of a fresh spermatophore. In spite of differences between the spermatophores of E. soleae and N. diadema/N. apiocolpos, the events of spermatophore exchange may be similar.     

An annotated list of parasites (Isopoda, Copepoda, Monogenea, Digenea, Cestoda and Nematoda) collected in groupers (Serranidae, Epinephelinae) in New Caledonia emphasizes parasite biodiversity in coral reef fish

Abstract: Over a 7-year period, parasites have been collected from 28 species of groupers (Serranidae, Epinephelinae) in the waters off New Caledonia. Host-parasite and parasite-host lists are provided, with a total of 337 host-parasite combinations, including 146 parasite identifications at the species level. Results are included for isopods (5 species), copepods (19), monogeneans (56), digeneans (28), cestodes (12), and nematodes (12). When results are restricted to those 14 fish species for which more than five specimens were examined and to parasites identified at the species level, 109 host-parasite combinations were recorded, with 63 different species, of which monogeneans account for half (32 species), and an average of 4.5 parasite species per fish species. Digenean records were compared for 16 fish species shared with the study of Cribb et al. (2002); based on a total of 90 parasite records identified at the species level, New Caledonia has 17 new records and only seven species were already known from other locations. We hypothesize that the present results represent only a small part of the actual biodiversity, and we predict a biodiversity of 10 different parasite species and 30 host-parasite combinations per serranid. A comparison with a study on Heron Island (Queensland, Australia) by Lester and Sewell (1989) was attempted: of the four species of fish in common and in a total of 91 host-parasite combinations, only six parasites identified at the species level were shared. This suggests strongly that insufficient sampling impairs proper biogeographical or ecological comparisons. Probably only 3% of the parasite species of coral reef fish are already known in New Caledonia.     

The microecology of dactylogyrids (Monogenea: Dactylogyridae) on the gills of wild spotted rose snapper Lutjanus guttatus (Lutjanidae) from Mazatlan Bay, Mexico

The spatial distribution and coexistence of monogenean dactylogyrids was assessed on the gills of 63 specimens of wild spotted rose snapper, Lutjanus guttatus (Steindachner), caught in the Mazatlan Bay, Sinaloa, Mexico. Five species are reported: Euryhaliotrema perezponcei Garcia-Vargas, Fajer-Avila et Lamothe-Argumedo, 2008, Euryhaliotrematoides sp., Haliotrematoides spinatus Kritsky et Mendoza-Franco, 2009, H. plectridium Kritsky et Mendoza-Franco, 2009, and H. guttati Garcia-Vargas, Fajer-Avila et Lamothe-Argumedo, 2008. All except E. perezponcei and H. guttati represent new geographical records for the Pacific coast. The most prevalent dactylogyrid species was E. perezponcei (100%), H. plectridium and H. spinatus had > 80% prevalence, and H. guttati and Euryhaliotrematoides sp. had the lowest prevalence. The mean abundance of H. plectridium and E. perezponcei was close to 60 parasites/fish, whereas Euryhaliotrematoides sp. and H. guttati had the lowest abundance. The dactylogyrid species exhibited a tendency for attachment to gill arch 2: 25% attachment occurring on gill arch 1, 30% on 2, 27% on 3 and 18% on 4, and showed a significant preference for the central sector of the gill (42%). Haliotrematoides plectridium had a preference for attachment to gill arches 2 and 3 and the central sector. Haliotrematoides spinatus tended to settle on the gill arches 2 and 3 and had a preference for the central sector. Euryhaliotrema perezponcei tended to settle on the gill arches 1 and 2 and the anterior gill sector. Euryhaliotrematoides sp. and H. guttati did not show a preference for any gill arch or sector. The intraspecific aggregation was stronger than the interspecific aggregation, indicating that all the dactylogyrid species on spotted rose snapper were aggregated, and there was no evidence of competition among the species.     

A review of Dendromonocotyle (Monogenea: Monocotylidae) from the skin of stingrays and their control in public aquaria

Dendromonocotyle species (Monogenea: Monocotylidae) are the only monocotylids to parasitize the skin of chondrichthyan hosts. Currently 11 species are recorded from the skin of ray species in the Dasyatidae, Myliobatidae and Urolophidae. There have been increasing reports of Dendromonocotyle outbreaks on rays kept in public aquaria. This paper provides a broad review of Dendromonocotyle that should assist taxonomists and aquarists with species identification and help decisions on potential control methods for Dendromonocotyle infections. The taxonomy and host-specificity of Dendromonocotyle are discussed and a key to current species is provided. We summarise what little is known about the biology of Dendromonocotyle including egg embryonation and hatching, feeding, camouflage and reproduction. The efficacy of freshwater baths, chemical treatments and biological control measures such as the use of cleaner fish for Dendromonocotyle is also discussed. We demonstrate that effective control of Dendromonocotyle on captive rays is hampered by the lack of basic biological data on the life cycle of the parasites. A case history is provided outlining the success of a public aquarium (Underwater World, Mooloolaba, Queensland, Australia) in managing D. pipinna infections on captive Taeniura meyeni without chemical intervention simply by taking measures to reduce host stress.     

噻虫嗪和吡虫啉拌种对马铃薯甲虫幼虫生长发育的影响

噻虫嗪和吡虫啉是具有触杀、内吸和胃毒活性的新烟碱类杀虫剂,对植食性害虫效果显著,近年来已成为新农药创制领域研究的热点。马铃薯甲虫Leptinotarsa decemlineata (Say)是国际公认的毁灭性检疫害虫,以成、幼虫取食茄科植物茎叶、花蕾和叶芽等部位。一般田块减产30%~50%,严重地块达90%以上。目前,我国马铃薯甲虫仅在新疆马铃薯种植区发生,但对其周边省份马铃薯生产构成威胁。本试验选用噻虫嗪和吡虫啉于马铃薯播前进行一次性拌种,探讨出苗90天后的叶片对马铃薯甲虫幼虫生长发育的影响。     

Aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) on citrus: Seasonal abundance, association with the species of host plant, and sampling indices

Samples were collected from southern Greece during 1996–2000 in order to investigate the presence of parasitoids onAphis gossypii Glover infesting several citrus species. The species of aphidiines found to have a significantly different preference forA. gossypii wereAphidius colemani Viereck,Aphidius matricariae Haliday,Diaeretiella rapae (M’Intosh),Ephedrus persicae Froggat,Lysiphlebus testaceipes (Cresson),Binodoxys acalephae (Marshall) andBinodoxys angelicae (Haliday). In another sampling experiment, the relative abundance of aphidiine parasitoids on aphids infesting orange and tangerine trees was studied in southern Greece (Nea Kios) in 1996 and 1997.A. gossypii constituted the largest part of the aphid population and was the only species parasitized.B. angelicae andA. colemani were the most abundant parasitoid species. The parasitization rate differed among the parasitoid species.B. angelicae had the highest colonization rate in centrally located and large host (A. gossypii) groups, whereasA. colemani was found in more isolated and relatively small host groups. The percentage of parasitism byB. angelicae was high mainly in large host groups, whenB. angelicae was the only parasitoid present. However, in cases of coexistence ofB. angelicae withA. colemani with hyperparasitoids, in the same sampling unit, the percentage of parasitism was relatively low. http://www.phytoparasitica.org     

Endogenous development of Hemolivia mauritanica (Apicomplexa: Adeleina: Haemogregarinidae) in the marginated tortoise Testudo marginata (Reptilia: Testudinidae): evidence from experimental infection

Six young tortoises Testudo marginata Schoepff, 1792 were experimentally infected with Hemolivia mauritanica (Sergent et Sergent, 1904). The prepatent period ranged from 6 to 8 weeks. Young, smaller, club-like forms (6-9 x 3-6 Am) of gametocytes appeared in the peripheral blood first, whereas mature, elongated, cylindrical forms (9-12 x 5-7 Am) were detected after 1-2 weeks and predominated during later patency. Three of the infected tortoises were euthanized and dissected to study the endogenous stages. Meronts occurred in the cells of the reticulo-endothelial system and in the erythrocytes; these were observed mostly in parenchymatous organs. Mature forms measured 14.2 x 9.3 microm and contained 7-12 merozoites. Cysts with two (exceptionally one) cystozoites were also found predominantly in parenchymatous organs and measured 14.8 x 7.9 microm. Pathological changes attributable to Hemolivia were mild and limited to liver and kidneys. The role of individual developmental stages of haemogregarines is discussed with respect to evolution of heteroxenous life cycle and long-term persistence of parasites in their intermediate hosts.     

Experimental verification of the effect of physical condition of Gobio gobio (L.) on the growth rate of micropopulations of Gyrodactylus gobiensis Gl?ser, 1974 (Monogenea)

It has been verified experimentally that the growth rate of G. gobiensis micropopulations is markedly affected by the physical condition of the host (Gobio gobio). If the fish were weakened by 50% oxygen deficiency and lack of food, the number of parasites increased much more rapidly than on the fish also unfed but kept in water with 100% oxygen content. If the fish weakened by oxygen deficiency were intensively fed, the growth of the parasite micropopulations started to slow down after 4-5 days. When the feeding was stopped, the number of parasites increased again after 10-11 days. These time shifts seem to be associated with the physical condition of the host improved by feeding or worsened by starvation.     

Experimental verification of the effect of the form (scaly or scaleless) of carp host (C. carpio L.) on the growth rate of micropopulations of Gyrodactylus katharineri Malmberg, 1964 (Monogenea)

It was demonstrated that the growth rate of Gyrodactylus katharineri micropopulations parasitizing the fry of Cyprinus carpio L. was effected by water temperature and by the form of the fish host (scaly or scaleless). At lower water temperature (12 degrees C) the number of parasites increased in both host forms approximately at the same intensity. In warmer water (18 degrees C), the parasites reproduced intensively only on the scaly form of fish, whereas no parasites were found on the scaleless form some days after infection.     

Experimental verification of the effect of constant and changing water temperature on the micropopulation growth in Gyrodactylus gobiensis Gl?ser, 1974 (Monogenea) parasitizing gudgeon (Gobio gobio L.)

It has been verified under laboratory conditions that constant and changing water temperature markedly affects the micropopulation growth in Gyrodactylus gobiensis parasite on the body surface of gudgeons (Gobio gobio L.). At a water temperature of 12 degrees C, the number of gyrodactylids gradually increased up to the mean value of 63 specimens per host, which was reached on days 27-28 after experimental infection. At a constant temperature of 18 degrees C, the parasites completely disappeared from the bodies of infected fishes on days 15-20 p.i. A similar effect was produced by gradually increasing temperature from 12 to 18 degrees C, while the decrease in water temperature from 18 to 12 degrees C resulted in an increase in the parasite number.     

Synthetic pyrethroids: Toxicity and synergism on dietary exposure of Tribolium castaneum (Herbst) larvae

The potency of six dietary pyrethroids, as toxicants and inhibitors of weight gain in first- and fourth-instar Tribolium castaneum (Herbst) larvae, decreased in the order of cis-cypermethrin and deltamethrin > trans-cypermethrin and cis-permethrin > fenvalerate and trans-permethrin. Dosages that reduced larval weight also delayed pupation and emergence, probably due to their antifeeding activity. Three oxidase inhibitors (piperonyl butoxide, O, O-diethyl O-phenyl phosphorothioate, and O-isobutyl O-prop-2-ynyl phenylphosphonate), at a dietary concentration of 100 mg kg^?1, had little or no effect on the toxicity of trans-permethrin, but strongly synergised the toxicity of cis-cypermethrin by about 3-, 3- and 10-fold, respectively. Piperonyl butoxide also synergised the toxicity of cis-permethrin, trans-cypermethrin and deltamethrin, but not that of fenvalerate. On the other hand, an esterase inhibitor, profenofos, did not enhance the potency of any of the α-cyano-3-phenoxybenzyl pyrethroids. Oxidases appear to be more important than esterases in pyrethroid detoxification by T. castaneum larvae.