IECOS - Instituto de Estudos Costeiros/Campus Bragança

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/2228

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Acesso aberto (Open Access)
The current status of the new world monkey phylogeny
(2000) SCHNEIDER, Horacio
Four DNA datasets were combined in tandem (6700 bp) and Maximum parsimony and Neighbor-Joining analyses were performed. The results suggest three groups emerging almost at the same time: Atelidae, Pitheciidae and Cebidae. The total analysis strongly supports the monophyly of the Cebidae family, grouping Aotus, Cebus and Saimiri with the small callitrichines. In the callitrichines, the data link Cebuela to Callithrix, place Callimico as a sister group of Callithrix/Cebuella, and show Saguinus to be the earliest offshoot of the callitrichines. In the family Pithecidae, Callicebus is the basal genus. Finally, combined molecular data showed congruent branching in the atelid clade, setting up Alouatta as the basal lineage and Brachyteles-Lagothrix as a sister group and the most derived branch. Two major points remain to be clarified in the platyrrhine phylogeny: (i) what is the exact branching pattern of Aotus, Cebus, Saimiri and the small callitrichines, and (ii), which two of these three lineages, pitheciines, atelines or cebids, are more closely related?
Acesso aberto (Open Access)
Genetic differentiation of Macrodon ancylodon (Sciaenidae, Perciformes) populations in Atlantic coastal waters of South America as revealed by mtDNA analysis
(2003) SILVA, Simoni Santos da; SCHNEIDER, Horacio; SAMPAIO, Maria Iracilda da Cunha
The king weakfish (pescada-gó in Portuguese - Macrodon ancylodon (Sciaenidae), a demersal (bottom-feeding) species found in South America Atlantic coastal waters from the Gulf of Paria in Venezuela to Baia Blanca in Argentina, is an economically important species because of its abundance and wide acceptance by consumers. Because of its wide distribution this fish may be subject to geographic isolation and this may have resulted in distinct populations along its coastal range. Considering that this species represents an important economic resource, confirmation of whether M. ancylodon is a single species or there are different genetic stocks spread over its wide distribution would be an important contribution to conservation policies and population management of the king weakfish. To investigate differences between king weakfish populations we used the cytochrome b and 16S rRNA genes to characterize M. ancylodon specimens caught throughout its South American range from Venezuela to Argentina. Our results clearly distinguished two genetically different groups which show nucleotide divergence and genetic structuring patterns that strongly suggest they may be different species, disagreeing with the widely accepted traditional taxonomy that accepts only one species of Macrodon in the western Atlantic.
Acesso aberto (Open Access)
Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters
(2003) BARROS, Maria Claudene; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio
We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths and anteaters) and used these sequences along with GenBank sequences of both extant and extinct sloths to perform phylogenetic analysis based on parsimony, maximum-likelihood and Bayesian methods. By increasing the taxa density for anteaters and sloths we were able to clarify some points of the Pilosa phylogenetic tree. Our mitochondrial 16S results show Bradypodidae as a monophyletic and robustly supported clade in all the analysis. However, the Pleistocene fossil Mylodon darwinii does not group significantly to either Bradypodidae or Megalonychidae which indicates that trichotomy best represents the relationship between the families Mylodontidae, Bradypodidae and Megalonychidae. Divergence times also allowed us to discuss the taxonomic status of Cyclopes and the three species of three-toed sloths, Bradypus tridactylus, Bradypus variegatus and Bradypus torquatus. In the Bradypodidae the split between Bradypus torquatus and the proto-Bradypus tridactylus / B. variegatus was estimated as about 7.7 million years ago (MYA), while in the Myrmecophagidae the first offshoot was Cyclopes at about 31.8 MYA followed by the split between Myrmecophaga and Tamandua at 12.9 MYA. We estimate the split between sloths and anteaters to have occurred at about 37 MYA.
Acesso aberto (Open Access)
Sciaenidae fish of the Caeté River estuary, Northern Brazil: mitochondrial DNA suggests explosive radiation for the Western Atlantic assemblage
(2004) VINSON, Christina Cleo; GOMES, Grazielle Fernanda Evangelista; SCHNEIDER, Horacio; SAMPAIO, Maria Iracilda da Cunha
Sciaenids are fish which are normally abundant in tropical estuaries of the western Atlantic. Studies on the Caeté river estuary in the northern Brazilian state of Pará have revealed that in this area Sciaenidae is the dominant family, comprising almost 50% of all teleosts sampled. In this paper we present the results of the first phylogenetic study on South American estuarine sciaenids, during which we obtained mitochondrial gene 16S sequences from 15 species belonging to eight genera occurring in the Caeté estuary. Intergeneric nucleotide divergences varied from 5 to 15%, Lonchurus and Menticirrhus being the most divergent lineages. Nucleotide divergences were quite variable amongst species of the same genus, ranging from 1.2% (Stellifer microps x Stellifer naso) to 8.4% (Menticirrhus americanus x Menticirrhus littoralis). Cladograms based on maximum parsimony, minimum evolution and maximum likelihood depicted an explosive diversification pattern for the western Atlantic sciaenid assemblage. Our analysis further reveals a very close relationship between Bairdiella and Stellifer, a monophyletic clade which emerged during the more recent diversification events of the Sciaenidae family. The phylogenetic reconstruction suggests the need for a revision of the taxonomy and nomenclature of the Bairdiella/Stellifer group.
Acesso aberto (Open Access)
Food categories reconstruction and feeding consumption estimates for the Sciaenid Macrodon ancylodon (Bloch & Schneider), and the congeneric fishes Stellifer rastrifer (Jordan) and Stellifer naso (Jordan) (Pisces, Perciformes) in the Caeté Estuary, Northern Coast of Brazil
(2004-03) CAMARGO-ZORRO, Mauricio; ISAAC, Victoria Judith
A quantitative method to estimate fish feeding consumption and energy intake from different food categories through the reconstruction of ingested preys based on hard not digestible body structures is presented. In order to establish the equations of the functional relationships between preys weight and body structures, stomachs of 1.086 specimens of Macrodon ancylodon (Bloch & Schneider, 1801), Stellifer rastrifer (Jordan, 1889), and Stellifer naso (Jordan, 1889) fish species were dissected. Consequently, preys reconstruction enabled a quantitative evaluation of food categories consumption. Results indicate a marked difference in diet composition and energy requirements according to fish species ontogenetic development.
Acesso aberto (Open Access)
Larval development of Lepidophthalmus siriboia Felder & Rodrigues, 1993 (Decapoda: Thalassinidea) from the Amazon region, reared in the laboratory
(Instituto Nacional de Pesquisas da Amazônia, 2005) ABRUNHOSA, Fernando Araujo; PIRES, Marcus Alexandre Borges; LIMA, Jô de Farias; COELHO FILHO, Petrônio Alves
The complete larval development of the ghost shrimp Lepidophthalmus siriboia Felder & Rodrigues, 1993 was described and illustrated in detail from specimens reared in the laboratory. Ovigerous females were collected at Canela Island in the northeastern region of the State of Pará. The larvae hatch as a prezoea, in which they persist for less than 3 hours. The larval development consists of three zoeal stages and a megalopa. The zoeal development averaged from 69 to 111 hours. The period in the megalopa stage was about 185 hours (about 8 days). The percentage of individuals succeeding in molt into juvenile stage was 91,8%. The first juvenile stage was reached 254 hours (about 10 days) after hatching. Morphological comparisons and their relationship with larvae of congeneric species are briefly discussed.
Acesso aberto (Open Access)
New records of Fredius denticulatus (H. Milne-Edwards, 1853) and F. reflexifrons (Ortmann, 1897), and the eastern limits of the distribution of pseudothelphusid crabs (Crustacea: Decapoda) in Brazil
(Instituto Nacional de Pesquisas da Amazônia, 2005) MAGALHÃES FILHO, Célio Ubirajara; ABRUNHOSA, Fernando Araujo; PEREIRA, Milena de Oliveira; MELO, Marlon Aguiar
The occurence of Fredius reflexifrons (Ortmann, 1897), a pseudothelphusid crab widely distributed in the Amazon region and the Atlantic Guianas, is recorded from the state of Ceará, northeastern Brazil. Other records of this species and Fredius denticulatus (H. Milne-Edwards, 1853) from the Amazon region are also presented. A discussion is made on the eastern limits of the distribution of the family Pseudothelphusidae in Brazil.
Acesso aberto (Open Access)
Taxonomic implications of molecular studies on Northern Brazilian Teredinidae (Mollusca: Bivalvia) specimens
(2005-03) VALE, Sonia Maria Lima Santos do; TAGLIARO, Claudia Helena; BEASLEY, Colin Robert; SCHNEIDER, Horacio; SAMPAIO, Maria Iracilda da Cunha; SANTOS FILHO, Carlos; MÜLLER, Ana Cláudia de Paula
The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now no molecular studies of the phylogeny of this group have been published. In the present study the relationships between four genera of the subfamilies Teredininae and Bankiinae were established and the efficiency of the 16S rRNA gene in characterizing four Teredinidae species was tested. Phylogenetic trees support the grouping of Bankia fimbriatula with Nausitora fusticula and of Neoteredo reynei with Psiloteredo healdi, but the genetic distances do not justify the classification of these species into two distinct subfamilies. The results show that B. fimbriatula, N. reynei and P. healdi specimens from the coast of the Brazilian state of Pará have five distinct 16S rRNA haplotypes, with one N. reynei haplotype differing from the other haplotypes in respect to at least seven sequences sites, indicating the existence of two very distinct sympatric lineages.
Acesso aberto (Open Access)
Developmental morphology of mouthparts and foregut of the larvae and postlarvae of Lepidophthalmus siriboia Felder & Rodrigues, 1993 (Decapoda: Callianassidae)
(Instituto Nacional de Pesquisas da Amazônia, 2006) ABRUNHOSA, Fernando Araujo; MELO, Marlon Aguiar; LIMA, Jô de Farias; ABRUNHOSA, Jacqueline Pompeu
In this study, the gross morphology of the mouthparts and foregut of the ghost shrimp Lepidophthalmus siriboia were investigated from larvae and postlarvae reared in the laboratory. The mouthparts (maxillae and maxillipeds) of the zoeae have a reduced number of setae and spines (or is absent in some individuals), and the foregut, under developed, have few minute setae in the cardiac and pyloric chambers. In contrast, after the metamorphosis into megalopa stage, all feeding appendages have many setae and, the foregut shows a well-developed gastric mill with strong lateral teeth. In the juvenile stage occurs an increase of setae and spines in the mouthparts and the foregut becomes more specialized. These observations strongly suggest that a lecithotrophic development occurs during all zoeal stages but the megalopa and juvenile stages are feeding animals. The functional morphology of the feeding structures of L. siriboia and other decapods will be briefly discussed.
Acesso aberto (Open Access)
Molecular discrimination of pouched four-eyed opossums from the Mamirauá Reserve in the Brazilian Amazon
(2006) NUNES, Cláudia; AYRES, José Márcio Corrêa; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio
Previous cytochrome B (CytB) mtDNA studies have suggested four species for the opossum genus Philander (four-eyed opossums), three (P. mcilhennyi, P. andersoni and P. opossum) from the Amazon and one (P. frenata) from the Brazilian Atlantic forest. During a faunal survey nine specimens of Philander sp. and four of Didelphis marsupialis were collected in the Mamirauá Sustainable Reserve, Amazonas State, Brazil. Preliminary analyses based on morphology and geographical distributions were not conclusive, suggesting that Philander specimens could belong to either P. andersoni or P. opossum. In order to elucidate the relationship of this taxon to the remaining Amazonian taxa, seven Philander and two Didelphis specimens animals were sequenced for the cytB mtDNA gene and compared to other previously studied taxa. The maximum likelihood (ML), neighbor-Joining (NJ) and maximum parsimony (MP) consensus bootstrap trees depicted six groups: Didelphis., P. frenata, P andersoni, P. mcilhennyi, P.o. opossum and Philander sp. and Philander canus in a common assemblage supported by significant bootstrap values, suggesting that the Philander sp. from Mamiraua in fact belongs to the species Philander canus.
Acesso aberto (Open Access)
Tocantins river as an effective barrier to gene flow in Saguinus niger populations
(2006) SOUZA, Marcelo Nazareno Vallinoto de; SILVA, Juliana Araripe Gomes da; RÊGO, Péricles Sena do; TAGLIARO, Claudia Helena; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio
The Saguinus represent the basal genus of the Callitrichinae subfamily. Traditionally this genus is divided into three groups: Hairy, Mottled and Bare-face, however, molecular data failed to validate these groups as monophyletic units, as well as raised some subspecies to the species status. This is the case of the former subspecies Saguinus midas midas and S. midas niger, which are now considered as different species. In the present study, we sequenced a portion of the D-loop mtDNA region in populations from the East bank of the Xingu and from both banks of the Tocantins river, in order to test the effectiveness of large rivers as barriers to the gene flow in Saguinus. According to our results, the populations from the East and West banks of the Tocantins river are more divergent than true species like S. mystax and S. imperator. The Tocantins river may be acting as a barrier to gene flow, and consequently these very divergent populations may represent distinct taxonomic entities (species?).
Acesso aberto (Open Access)
The morphology of the foregut of larvae and postlarva of Sesarma curacaoense De Man, 1892: a species with facultative lecithotrophy during larval development
(Instituto Nacional de Pesquisas da Amazônia, 2006) MELO, Marlon Aguiar; ABRUNHOSA, Fernando Araujo; SAMPAIO, Maria Iracilda da Cunha
Previous study on the resistance of larvae of Sesarma curacaoense submitted to starvation has revealed a facultative lecithotrophy during zoeal stages, but megalopa and first juvenile stages are exclusively feeding stages. In the present study, the gross morphology and fine structure of the foregut of S. curacaoense were investigated during larval, megalopa and first juvenile stages. The foregut of the zoea I show specific setae and a filter press apparently functional. The foregut undergoes changes in the zoea II (last larval stage) with increment of setae number, mainly on the cardiopyloric valve and complexity of the filter press. After metamorphosis to megalopa stage the foregut become rather complex, with a gastric mill supporting a medial and two lateral teeth well-developed. The foregut of the first juvenile is more specialized compared to the previous stage, showing similar characteristics of the decapod adults. These results provide further evidence of facultative lecithotrophic development in the larvae of S. curacaoense.
Acesso aberto (Open Access)
Indução de calos em espécies amazônicas do gênero Theobroma
(2006-04) SILVA, Marivana Borges; RAMOS, Alessandra de Rezende; VENTURIERI, Giorgini Augusto
Many works have been done on cocoa (Theobroma cacao) in vitro culture, with few studies being published for other species of the same genus, as cupuassu (T. grandiflorum), whose planted area is increasing expressively, and others that could be used as a source of genes for those with recognized economical importance. Protocols to obtain in vitro somatic embryos from T. cacao,T. grandiflorum,T. speciosum and the hybrid T. grandiflorum x T. obovatum from two sources of explants, staminodes and petals (formed by ligues and cogules) were evaluated, using a primary callus growth medium made of DKW salts, supplemented with 20 g l-1 of sucrose, 250 mg l-1 of glutamine, 200 mg l-1 of myo-inositol, 0.2 mg l-1 of thyamine-HCl; 0.1 mg l-1 of nicotinic acid; 0.2 mg l-1 of glycine; 2 mg l-1 of 2,4-D; 2.2 g l-1 of Gelrite® and the pH adjusted to 5.8. To this media was added different concentrations of thidiazuron (0; 5 and 10 µg l-1). Cultures were maintained at dark for 14 days, at a temperature of 25 ± 2 ºC, and so transferred for the secondary callus growth, made with WPM salts, Gamborg vitamins, 20 g l-1 of sucrose, 2 mg l-1 of 2,4 D; 0.3 mg l-1 of cinetin, 50 ml l-1 of coconut milk, 2.2 g l-1 of Gelrite® and the pH adjusted to 5.8. Callus formation occurred in all species. Somatic embryos were obtained only for T. cacao. Callus formation was influenced by genotype and was higher on staminodes.
Acesso aberto (Open Access)
Spatial and temporal distribution in density and biomass of two Pseudodiaptomus species (Copepoda: Calanoida) in the Caeté river estuary (Amazon region - North of Brazil)
(Instituto Internacional de Ecologia, 2006-05) MAGALHÃES, André Luiz Perez; COSTA, Rauquírio André Albuquerque Marinho da; PEREIRA, Luci Cajueiro Carneiro; RIBEIRO, Marcilenia de Jesus da Silva; LIANG, Tsui Hua
Spatial and temporal density and biomass distribution of the planktonic copepods Pseudodiaptomus richardi and P. acutus along a salinity gradient were investigated in the Caeté River Estuary (North-Brazil) in June and December, 1998 (dry season) and in February and May, 1999 (rainy season). Copepod biomass was estimated using regression parameters based on the relation of dry weight and body length (prosome) of adult organisms. The Caeté River Estuary was characterized by high spatial and temporal variations in salinity (0.8-37.2). Exponential length-weight relationships were observed for both Pseudodiaptomus species. Density and biomass values oscillated between 0.28-46.18 ind. m-3 and 0.0022-0.3507 mg DW. m-3 for P. richardi; and between 0.01-17.02 ind. m-3 and 0.0005-0.7181 mg DW. m-3 for P. acutus. The results showed that the contribution of P. richardi for the secondary production in the Caeté River Estuary is more important in the limnetic zone than in other zones where euhaline-polyhaline regimes were predominant. However, it was not possible to observe a clear pattern of spatial and temporal distribution for P. acutus.
Acesso aberto (Open Access)
The larval development of Pinnixa gracilipes Coelho (Decapoda, Pinnotheridae) reared in the laboratory
(2006-06) LIMA, Jô de Farias; ABRUNHOSA, Fernando Araujo; COELHO, Petrônio Alves
Pinnixa gracilipes Coelho, 1997 is a small pinnotherid crab living in association with ghost shrimp Lepidophthalmus siriboia Felder & Rodrigues, 1993 in the northeastern region of Pará State, Brazil. Larvae of P. gracilipes were reared in the laboratory from hatching to the megalopa stage. The complete zoeal period averaged 24 days. Mean duration for each larval stage was 5, 4, 4, 5 and 6 days, respectively. In the present study, five zoeal and megalopal stages are described and illustrated in detail. Morphological comparisons with previous reported works on Pinnotheridae larvae are briefly discussed.
Acesso aberto (Open Access)
The complete larval development of Armases benedicti (Rathbun) (Decapoda, Sesarmidae), from the Amazon region, reared in the laboratory
(2006-06) LIMA, Jô de Farias; ABRUNHOSA, Fernando Araujo
The four zoeal and one megalopal stages of the wharf crab Armases benedicti (Rathbun, 1897) larvae reared in the laboratory are described and illustrated in detail. The mean duration for each larval stage was 3, 2, 4, 4 and 13 days, respectively. The duration of the larval period from hatching to the first juvenile was 26 days. Morphologically, A. benedicti is very similar to the reported species of genus. However, a small lateral spine is clearly observed in the carapace of zoeal stages of this species. This feature appears to be unique among the family Sesarmidae. Another distinctive character for this species is the zoeal setation of the maxilla endopod (2+2) in which most of the sesarmids have setation (2+3) except for Sesarma tetragonum (Fabricius, 1798). Other comparisons with previous larval studies of the genus Armases Abele, 1992 are briefly discussed.
Acesso aberto (Open Access)
Dieta de Micoureus demerarae (Thomas) (Mammalia, Didelphidae) associada às florestas contíguas de mangue e terra firme em Bragança, Pará, Brasil
(2006-12) FERNANDES, Marcus Emanuel Barroncas; ANDRADE, Fernanda Atanaena Gonçalves de; SILVA JÚNIOR, José de Sousa e
The diet of Micoureus demerarae (Thomas, 1905) was studied in mangrove and terra firme stands by using stomachal and faecal samples. The number of captured individuals was inversely proportional to availability of fruits and insects, being Coleoptera and Hemiptera the most consumed arthropod orders and Passifloraceae and Arecaceae the most ingested fruits. Thus, either fruits variability or their high yield during the dry season seem to explain the increase of captured animals in the terra firme stands, where they originally come from. The food items suggest that this species has an omnivorous diet, independently of the seasonality or distribution of available resources.
Acesso aberto (Open Access)
Influência da biomassa inicial sobre o crescimento e a produtividade de peixes em sistema de policultivo
(2006-12) NUNES, Zélia Maria Pimentel; LAZZARO, Xavier; PERET, Alberto Carvalho
The analysed species composition, fish growth, and productivity of four polycultures (P75, P78, P87, and P207) with the objective to improve the small reservoir (0.1–5 ha) fishery management and productivity in the Brazilian semiarid region were conducted a experiment. To mimic reservoir conditions, we used 120 and 5,000m2 ponds and evaporation and infiltration water loss was replaced. In addition, manure and fertilizers were used only moderately. The initial biomass of Nile tilapia Oreochromis niloticus, 'tambaqui' Colossoma macropomum, 'curimatã pacu' Prochilodus argenteus, common carp Cyprinus carpio, and 'tucunaré' Cichla ocellaris ranged from 75 to 207kg ha–1. The fish showed low growth rates (<0.01g g–1 d–1) after 75 days of culture (P78 and P87). Tambaqui, tilapia, and curimatã growth decreased after 53 days (P75). In moderate biomass, tambaqui grew less than carp and curimatã did (P207). Tilapia productivity reached 720kg ha–1yr–1 (P78) and fell to 220kg ha–1yr–1 because of the reproductive process (P75 and P207). The carp productivity of 1,600kg.ha–1yr–1 was higher than those of the other fish (P87). The 75kg.ha–1 biomass level (60:30:4:3:3% of tilapia, tambaqui, carp, curimatã, and tucunaré, respectively) optimized fish growth and productivity. The use of monosexed tilapia and tambaqui feed supplementation was indispensable for the success of polyculture.
Acesso aberto (Open Access)
Population analysis of Scomberomorus cavalla (Cuvier, 1829) (Perciformes, Scombridae) from the Northern and Northeastern coast of Brazil
(2007) SANTA BRÍGIDA, Erikson Luiz; CUNHA, Divino Bruno da; RÊGO, Péricles Sena do; SAMPAIO, Maria Iracilda da Cunha; SCHNEIDER, Horacio; SOUZA, Marcelo Nazareno Vallinoto de
Scomberomorus cavalla is a pelagic fish species widely distributed on the Atlantic west coast, and a noticeable decrease in its capture level in the USA and Gulf of Mexico is occurring, compared to the levels reached by the species in the past. Likewise, in some areas of Brazil, there has been indication of over-harvesting. However, there are no molecular studies focusing on the management of such an important item. Thus, in the present study, 380 nucleotide base pairs of the mitochondrial DNA D-Loop region of samples from Macapá, Bragança, and Fortaleza were sequenced. Phylogenetic and population analyses revealed that there is only one panmitic population, and low levels of genetic variability were verified. These results, as well as the noticed over-harvesting of S. cavalla, represent very important data to determine the management of such stock in order to prevent a collapse or the risk of future extinction.
Acesso aberto (Open Access)
Experimental infection in Notodiaptomus sp. (Crustacea: Calanoida) with larvae of Camallanus sp. (Nematoda: Camallanidae)
(2007-04) MARTINS, Maurício Laterça; GHIRALDELLI, Luciana; GARCIA, Fabiana; ONAKA, Eduardo Makoto; FUJIMOTO, Rodrigo Yudi
This trial registered the experimental infection viability with nematode larvae Camallanus sp. in Notodiaptomus sp., a crustacean, which can be an intermediate host. Adult females of nematode were dissected from the intestines of Xiphophorus maculatus (Osteichthyes: Poeciliidae), at a fish farm in the State of São Paulo. Females were slightly compressed for larvae release, collected with Pasteur pipette and separated on Petri dishes with 9ml filtered water at 28.1ºC, from zooplankton culture. Treatments consisted of Petri dishes with 60 and 105 copepods, in which 120, 150 and 210 larvae of nematode were added in four replications. Twenty-four and 36h after exposition to the larvae, the copepods were fixed in 70% alcohol to record the amount of fixed larvae. Twenty four hours after exposition, 60 copepods group with 120 larvae showed significantly higher prevalence (46.5%) when compared to 105 copepods and 120 larvae (33.2%). Thus, these answers suggested that 120 larvae were enough for a successful infectivity. Experimental infection was available and so, it was used as a pattern to life cycle studies of camallanid nematodes and hosts susceptibility tests.