Gastromermis kolleonis n. sp. (Nematoda: Mermithidae), a Parasite of Midges (Chironomus sp. Chironomidae) from Argentina

Gastromermis kolleonis n. sp. (Nematoda: Mermithidae) is described from the Arroyo Saldan River in Córdoba, Argentina. This species parasitizes midges of the genus Chironomus (Chironomidae: Diptera). It is distinguished from other members of the genus by the presence of six longitudinal chords, vulval flaps, degree of ventral displacement of the mouth, and size and shape of the spicule and amphids.     

Parasitism of Kenyan Mosquito Larvae (Diptera: Culicidae) by Romanomermis culicivorax (Nematoda: Mermithidae)

The ability of Romanomermis culicivorax to infect, develop, and emerge from Kenyan mosquito hosts was evaluated in the laboratory. Host species tested were Aedes aegypti, Ae. dentatus, Ae. hirsutus, Anopheles arabiensis, An. coustani, An. funestus, An. gambiae, An. pharoensis, Culex duttoni, Cu. ethiopicus, Cu. poicilipes, Cu. quinquefasciatus, Cu. tigripes, Cu. univittatus, Coquillettidia metallica, Mansonia africana, Ma. uniformis, Mimomyia splendens, Mi. uniformis, Toxorhyncites brevipalpis, and Uranotaenia balfouri. R. culicivorax penetrated all the host species tested and developed and emerged from most of the hosts. Both penetration and some development, but not nematode emergence, were observed from all instars of Ma. uniformis. T. brevipalpis exhibited signs of resistance in the form of melanization of R. culicivorax within 48 hours of infection in all four instar stages. Nematode melanization, especially in older hosts, was observed in Ae. dentatus, Ae. hirsutus, Cu. duttoni, Cu. tigripes, and Mi. splendens. When melanization occurred, the melanized carcass of the nematode was passed on from instar to instar. The implications for field release of R. culicivorax in Kenya are still good, especially in habitats where different mosquito species occupy the same niche at different times, which would allow for nematode recycling.     

Description of the Male of Ogma cobbi and Juveniles of Bakernema inaequale (Nematoda: Criconematidae)

Juveniles ofBakernema inaequale and the male of Ogma cobbi are described and illustrated for the first time. Juveniles of Bakernema inaequale lack the cuticular spines characteristic of the adults. The annules of first-stage and fourth-stage juveniles are smooth, whereas those of the second-stage and third-stage juveniles have faint, bead-like ornamentation either throughout the body or in the anterior or posterior part only. Detailed morphometric data of O. cobbi males and all juvenile stages and females of B. inaequale are given.     

Anatomy of the Pre-Parasitic Stage of Hydromermis conophaga (Mermithidae: Nematoda)

The anatomy of the preparasitic juvenile of Hydromermis conopophaga (Mermithidae: Nematoda) has been examined with the light and electron microscope. The alimentary tract consisted of an onchiostylet, pharyngeal tube, stichosome, and intestine. Paired penetration glands were associated with the anterior half of the stichosome. A total of 16 sensory papillae were found in this stage. Certain features, such as the character of the stylet and the attachment of the pharynx to the intestine, show that the preparasitic juvenile more than any other stage in its life cycle closely resembles a free-living dorylaimoid nematode.     

Heydenius araneus n.sp. (Nematoda: Mermithidae), a parasite of a fossil spider, with an examination of helminths from extant spiders (Arachnida: Araneae)

Abstract. A mermithid, a parasite of a spider (Araneae: Thomisidae) in Baltic amber (40 mya), is described as Heydenius araneus n.sp. (Nematoda: Mermithidae) and represents the first fossil record of a nematode parasite of an arachnid. After a critical examination of reports of naturally occurring helminths of extant spiders, I conclude that although mermithid parasitism is well established in this host group, previous reports of hairworm parasites of spiders are "nomina dubia," putative records, or refer to mermithid nematodes.     

Four New Species of the Genus Hemicriconemoides (Nematoda:Criconematidae)

Four new species of the genus Hemicriconemoides (H. californianus n.sp., H. taiwanensis n.sp., H. annulatus n. sp., and H. nitida n.sp.) are described. The range of total length of H. mangiferae is increased on the basis of specimens collected in Israel, Observations on H. mangiferae and H. litchi support the validity of H. litchi as distinct from H. mangiferae.     

Contribution to the Knowledge of the Pre-imaginal Stages of Neotropical Hydrobiosidae (Trichoptera): Metachorema griseum Schmid

Mature larvae and pupae of Metachorema griseum Schmid are described for the first time. The known distribution of the genus includes the province of Neuquén in Argentina and central and southern Chile. The distinctive characters of the larvae of this genus are: (1) prothoracic sternite consisting of a wide subrectangular central sclerite and a pair of elongated lateral sclerites, (2) anterior femora with a narrow basodistal process, (3) anterior tibia and tarsus fused and (4) anal prolegs with a short lateral sclerite with basal spine and claws simple with ventral spine and two ventral setae.     

Host range of the parasite Strelkovimermis spiculatus (Nematoda: Mermithidae) in Argentina mosquitoes

Strelkovimermis spiculatus ( Poinar and Camino 1986 ) is a nematode parasite of mosquitoes isolated from the Neotropical region. We investigated the host range of this parasite in mosquito populations for a better understanding of the dynamics of temporary breeding sites. Five grassy‐pool habitats filled by rainwater were sampled from the summer 2007 through the fall 2008. Eight mosquito species were collected: Anopheles albitarsis, Culex chidesteri, Culex dolosus, Culex maxi, Aedes albifasciatus, Psorophora ciliata, Psorophora cyanescens, and Psorophora albigenu. Six of these species were parasitized: Cx. chidesteri, Cx. dolosus, Cx. maxi, Ae. albifasciatus, Ps. ciliata, and Ps. cyanescens. The occurrence of this mermithid in natural mosquito populations was increased from the end of winter to the end of the spring. Prevalence ranged from 11% to 100%. High levels of infections were registered only in Ae. albifasciatus larvae, the most abundant mosquito species (95%), followed by Cx. dolosus (2.7%). Strelkovimermis spiculatus completed its development in all infected mosquito larvae. The presence of S. spiculatus in six natural mosquito populations increases the number of susceptible species to 24.     

Strelkovimermis spiculatus n. sp. (Mermithidae: Nematoda) Parasitizing Aedes albifasciatus Mac. (Culicidae: Diptera) in Argentina

Strelkovimermis spiculatus n. sp. (Mermithidae: Nematoda), a parasite of the mosquito Aedes albifasciatus Mac. in Argentina, is described. Diagnostic characters of this species include a ventrally shifted mouth opening and spicules fused at the tips. The mermithid has been reared on Culex pipiens L. larvae in the laboratory.     

Hybridization studies of Haemonchus contortus (rudolphi, 1803) and H. placei (place, 1893) (Nematoda: Trichostrongylidae)

Hybridization experiments between Haemonchus contortus from sheep and H. placei from cattle indicate that the H. placei vulvar morph type and the inability of the eggs to hatch and develop at 11°C were inherited as dominant traits in the hybrids. The size of the third stage larvae was similar to H. placei in hybrids from the mating of male H. placei × female H. contortus while larvae from the reciprocal mating were intermediate in size. Hybrids produced by the mating of thiabendazole resistant female H. contortus × non-resistant male H. placei were also resistant. The F₁ males of the mating between male H. contortus and female H. placei were sterile. Male sterility did not occur in the reciprocal cross until the F₂ generation. Female hybrids from these generations had a low level of fertility when backcrossed to males of either parent species. Cytological studies of the hybrid males indicated that sterility was due to several kinds of meiotic disturbance and that spermatogenesis stopped during metaphase I. The chromosomes in eggs of unfertilized females did not undergo meiosis and polar body formation; instead they increased in number by a process of endomitosis. Unfertilized eggs in the faeces were characterized by uneven cytoplasmic division and abnormal shape. It is proposed that hybrid sterility can lead to the local eradication of one species of Haemonchus by the other. Furthermore, the outcome of which species is eradicated can be influenced by such variables as initial population sizes, climate, and the local ratio of sheep to cattle.     

Introduction to the Rhizocephala (Crustacea: Cirripedia).

Knowledge about the Rhizocephala (parasitic barnacles) has increased exponentially over the past two decades. This introduction broadly reviews this progress, touching on rhizocephalan morphology, life-cycles, larval biology, and the effects on the crustacean hosts. Members representing both orders, the Kentrogonida and Akentrogonida, are discussed. The recent discovery regarding the vermigon stage further highlights the intricacy of the kentrogonid life-cycle. Because rhizocephalans are found in most world regions, occurring on their respective hosts from the deep ocean to freshwater, their importance is now being recognized.     

Susceptibility of cockroaches (Gromphadorhina portentosa,Nauphoeta cinerea and Blaptica dubia) exposed to entomopathogenic nematodes

Cockroaches are major pests, vectors of pathogenic bacteria and induce allergies. Current control methods use chemical pesticides, but they can be ineffective and costly and there are reports of resistance in the field; hence new control methods are needed. There are conflicting reports about the susceptibility of cockroaches to entomopathogenic nematodes (EPNs); so we investigated if EPNs could kill several diverse cockroach species, including the Madagascan hissing roach (Gromphadorhina portentosa), the Lobster roach (Nauphoeta cinerea) and Blaptica dubia. Female adult cockroaches were exposed to either commercial products containing Steinernema kraussei or a combination of Heterorhabditis spp. and Steinernema spp. at 50 and 150 nematodes per cm² for 21 days. We also monitored feeding and the numbers of infective juveniles that were produced from each cockroach corpse. We found that S. kraussei were harmless to all cockroach species (at both doses) but when exposed to a mixture of Heterorhabditis spp. and Steinernema spp. B. dubia died after 6 days and its feeding was strongly inhibited. We also found that the mixture of Heterorhabditis spp. and Steinernema spp. could proliferate in the cadavers of B. dubia whilst S. kraussei could only reproduce in G. portentosa and B. dubia but not N. cinerea. In conclusion, S. kraussei was harmless to all three cockroach species but B. dubia was killed when exposed to Heterorhabditis spp. and Steinernema spp., highlighting the differences in the host range of EPNs.     

Ultrastructure of the anterior sense organs of adult Gastromermis boophthorae (Nematoda: Mermithidae)

The amphids of adult Gastromermis boophthorae exhibit an organization unlike any previously reported. Each amphid consists of a distal cuticular channel which opens to the exterior, and a proximal amphidial gland. The cuticular channel is double and 15–18 cilia are held in a tight bundle by the inner channel. The amphidial gland contains an extensive reticulum, and the nerve axons which give rise to the amphidial cilia are arranged around the outside of the gland; anteriorly these axons are characteristically flattened. A granular secretion is produced by the amphidial gland and passes via the reticulum to the double cuticular channel, thus bathing the ciliary bundle. The ultrastructure of the amphids is discussed in relation to functional considerations.     

A Taxonomic Review of the Genera of the Aphelenchoidea (Fuchs, 1937) Thorne, 1949 (Nematoda: Tylenchida)

This generic level taxonomic review of the nematode superfamily Aphelenchoidea is based upon a study of specimens from 24 of the 28 described genera. The diagnoses of these genera are presented, and some are emended with new information. One new genus, Huntaphelenchoides, and five new combinations are proposed. The families Paraphelenchidae and Anomyctidae are placed in synonymy with Aphelenchidae and Aphelenchoididae, respectively. The genera Asteroaphelenchoides and Pseudaphelencboides are placed in synonymy under the genus Aphelenchoides. Rare male and/or female specimens of Peraphelenchus, Anomyctus, Laimaphelenchus, Aphelenchus, Cryptaphelenchoides, Megadorus, Tylaphelenchus, and Entaphelenchus, are redescribed and illustrated. Four plates, containing 106 original drawings of the males, females, stylets, and spicules of representatives of 22 aphelenchoid genera, are presented.