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1.
Lynnath E. Beckley 《African Zoology》2013,48(3):187-192
The larval development of the southern African endemic sparid Spondyliosoma emarginatum is described and illustrated from specimens collected in Algoa Bay and the Swartkops, Sundays and Swartvlei estuaries of the Cape Province. S. emarginatum has demersal eggs. Preflexion larvae are moderately elongate (BD = 18–23% BL) with body depth increasing to 31 % BL in postflexion stages. The head is rounded and the snout blunt but becomes more elongate in postflexion stages. There are short spines on the preoperculum. Flexion occurs at about 6 mm BL and postflexion larvae are characterized by distinct medio-lateral pigmentation. Osteological development is described from a series of cleared and stained specimens. All fins have the adult complement of spines and rays by 12 mm BL. The larvae of S. emarginatum are compared with those of the European S. canthurus and other southern African sparids. 相似文献
2.
Jessica Fry Juan Pérez Casanova Lynn Lush Andy Walsh Cyr Couturier 《Journal of aquatic animal health》2015,27(1):57-64
The direct exposure of fish eggs to ozonated water has generated interest as a means of ensuring pathogen-free eggs without the use of harsh chemicals. However, there are numerous knowledge gaps, including safe contact times, exposure levels, and potential long-term effects on aquaculture species in both freshwater and seawater. The effect of different ozone (O3) doses (0.5–1.0, 1.5–2.0, and 2.5–3.0 mg of O3/L for 90 s) on recently fertilized eggs of Atlantic Cod Gadus morhua and eyed eggs of Atlantic Salmon Salmo salar and Rainbow Trout Oncorhynchus mykiss was evaluated in comparison with the effects of two commercial disinfectants: Perosan (0.004 mg/L) and Ovadine (100 mg/L). The impact of ozone application was evaluated based on hatching success, larval nucleic acid concentration, larval growth, and survival. Overall, results indicated that ozonation of Atlantic Cod eggs at a dose less than 3.0 mg/L for 90 s produced no negative effect on the larvae up to 30 d posthatch. Furthermore, ozonation of Atlantic Salmon and Rainbow Trout eggs generated no negative effect on the larvae, based on monitoring until 85% yolk sac re-absorption (16 d posthatch).
Received May 6, 2014; accepted October 24, 2014 相似文献
3.
The embryonic development of artificially spawned southern mullet, Liza richardsonii, eggs and the development of the larvae to 46 days are described and illustrated using drawings and photographs. The floating eggs hatched in sea water at 18–24°C after 46–60 h. Newly stripped eggs usually had more than one oil droplet (up to 16) which merged during development. Free embryos averaged 2,36 mm at hatching and had distinct yellow pigment. 相似文献
4.
Jakov DULČIĆ Branimir BAŽDARIĆ Leon GRUBIŠIĆ Pero TUTMAN Branko DRAGIČEVIĆ 《Integrative zoology》2009,4(3):272-276
Although information about embryonic and larval development of garpike, Belone belone (Linnaeus, 1761), is present in the published literature, the bulk of research concerns garpike from the northeastern Atlantic Ocean and the Baltic Sea. The present work describes the embryonic and larval development of garpike, Belone belone, from the Adriatic Sea, and methods used for incubation of fertilized eggs in aquarium conditions. Because garpike is, as suggested by some authors, divided into subspecies, we conclude that some differences in embryonic development could also be expected. In the present study, eggs were fertilized using the dry fertilization method and were incubated in a tank equipped with aeration and constant sea water flow. Salinity and content of dissolved oxygen were constant, and the temperature varied between 19.4 and 22.3°C. Eggs were spherical, measuring 3071.9 ± 75.73 μm in diameter. Yolk sacs were homogeneous and did not contain oil globules. The first larvae hatched 329 h and 47 min after fertilization. Absorption of the yolk sac occurred 17 h – 48 h after hatching and the total length of newly hatched larvae was 9.78 mm. The peculiarities observed in the embryonic and early larval development are evidence of an exceptional plasticity and adaptive potential, which could be considered as helpful features in extending the natural range of occurrence of this species. 相似文献
5.
Abstract AIMS: To measure the development of Teladorsagia (=Ostertagia) circumcincta and Trichostrongylus colubriformis eggs to third-stage infective larvae (L3) at different times of the year. Also, to measure the spatial distribution of L3 across herbage, soil and faeces, in order to assess whether spatial issues could be important in larval dynamics on pasture. METHODS: Field plots were contaminated with sheep faeces containing approximately 20,000 eggs of each of T. circumcincta and T. colubriformis on five separate occasions, viz 01 December 1996 (summer), 18 March 1998 (autumn), 17 June 1998 (winter), 15 October 1998 (spring), and 23 July 1999 (winter). Replicate plots (n=10) were harvested at intervals for up to 12 months after deposition of faeces, and the number and distribution of L3 were measured. Larvae were sampled from faeces (where these remained), herbage, and three soil zones to a depth of 145 mm. RESULTS: There were large differences between contamination dates in the percentage of eggs that developed to L3. For both species the highest percentage development was for eggs deposited in December (7.8% and 25.9% for T. circumcincta and T. colubriformis, respectively) and the lowest for June (0.4% and 0.03% T. circumcincta and T. colubriformis, respectively). Development in winter was often delayed, and this was always associated with a low yield of larvae, probably due to compounding mortalities associated with long periods of exposure to low temperatures. The relative distribution of L3 present on herbage, in faeces or in the soil varied between sampling times. However, overall the most L3 were recovered from soil (74% and 66% for T.circumcincta and T. colubriformis, respectively, averaged over all samples), and the lowest recoveries were from the herbage. CONCLUSIONS: Although the data are limited, the results indicated that the highest percentage of eggs developed to infective larvae in summer and only minimal development occurred in winter. The data do not support the view that substantial contamination of pastures with sheep parasites occurs over winter. Large numbers of larvae were recovered from soil, which indicates that, assuming they can subsequently migrate onto herbage, soil is a potentially important reservoir ofinfective larvae in New Zealand. Therefore, the spatial distribution of L3 on pasture may affect both the dynamics and transmission of parasite populations. Further work on both these issues is warranted. 相似文献
6.
At 18 °C the eggs of the kelp-fly, Fucellia capensis, hatch in 24 – 32 h and the larval and pupal stages last 10 – 12 and 9 – 14 days respectively. The growth curve is discontinuous, with declining relative growth rates in successive larval instars. Food consumption is relatively independent of size, at 0,25 mg dry kelp mg-1 wet larva day-1. Respiration rate is related to larval mass by the equation: Respiration rate (μl O2 h-1) = 2,75 (wet mass larva)0,66. In terms of energy an individual larva consumes 245,5 J over its lifespan, grows to the equivalent of 43,9 J and respires 51,6 J, indicating an assimilation efficiency of 30% and a gross growth efficiency of 17%. Kelp-fly larvae are probably less significant consumers of drift kelp than amphipods or isopods, but they promote the decay of wrack beds and are favoured as food by sea-shore birds. 相似文献
7.
The larval development ol the southern African endemic clupeid Gilchristella aestuaria is described and illustrated from specimens collected in the Swartvlei and Sundays estuarine systems of the Cape Province. Free embryos have no visible gut, unpigmented eyes and bodies, and are dependent on the yolk sac contents for nutrition. This stage lasts until about 4 mm body length (BL) when the eyes become pigmented and a gut becomes visible. Between 4 mm and 7 mm BL melanophores on the ventral aspect of the body form, and the dorsal and caudal lin anlagen develop. Between 7 mm and 8 mm BL the swimbladder lorms, flexion occurs and the anal fin anlage develops. By the 10 mm BL stage most of the skeletal elements have begun to differentiate, with the vertebral centra already showing signs of ossification. General ossification commences between 12 mm and 13 mm BL. All unpaired fins have the adult complement of rays by 15 mm BL. Scalation starts between 16 mm and 17 mm BL and is complete by 20 mm BL. Body depth increases gradually, from about 5% of BL in the early larval stages to >14% of BL in the juveniles. The pre-anal length decreases from about 87% of BL in the larvae to approximately 69% of BL in the juveniles. Head length increases from approximately 11% of BL in the larvae to 24-29% of BL in the juveniles. The larval snoui is initially 2% of BL, increasing to 7% of BL in the juvenile stages owing to the development of jaw elements. 相似文献
8.
R. Pereyra Lago 《African Zoology》2013,48(3):200-212
Sesarma catenata larvae were raised in the laboratory and the development stages described in detail. Larval development comprises four zoea and one megalopa stage. Morphological features of the first zoea and megalopa stages of Sesarma catenata are compared with those of other Sesarminae species described in the literature. The genera Sesarma, Metasesarma, and Bresedium appear to be closely related taxa within the subfamily. The diagnostic value of some features of larval morphology is briefly discussed. 相似文献
9.
TS Waghorn DP Reynecke A-MB Oliver CM Miller A Vlassoff JP Koolaard 《New Zealand veterinary journal》2013,61(6):279-286
Abstract AIM: To describe the seasonal pattern of development of third-stage infective larvae (L3) from eggs of Teladorsagia (=Ostertagia) circumcincta, Trichostrongylus colubriformis and Haemonchus contortus on pasture in the North Island of New Zealand. METHODS: Sheep faeces containing known numbers of eggs of all three nematode species were deposited on, or buried in, pasture plots at three sites, viz coastal Manawatu, Upper Hutt Valley, and East Cape hill country. Development was measured by recovering L3 from faeces, herbage and soil 28–31 days after deposition on 13–18 occasions, between January 2005 and July 2006. Analysis of the number of larvae recovered used a mixed model including number of eggs deposited, weight of faeces recovered (an assumed indicator of earthworm activity), site, contamination date, and position of deposited faeces, i.e. on the surface or buried. RESULTS: There was a significant effect of contamination date on development of all three species, with maximum numbers ofL3 developing between late spring (November) and early autumn (March), and minimum numbers in June and July. There were large differences between species, with H. contortus exhibiting a long period (April to October) where development was close to zero, whereas T. circumcincta developed to some extent all year round. Development of T. colubriformis was intermediate between the other two species. Burying faeces containing nematode eggs increased the number of L3 recovered compared with surface deposition (p≤0.001), although there were a small number of exceptions involving only T. colubriformis. The weight of faeces recovered at harvest, which was assumed to be an indication of earthworm activity, was correlated with the number of L3 recovered for all species (p<0.001). In a separate analysis, earthworms were assumed tohave been active if <5 g faeces remained at harvest. Where this occurred, the number of L3 of T. colubriformis and T.circumcincta recovered was reduced by 56% and 58%, respectively (p<0.001). CONCLUSIONS: A marked seasonal pattern of development was observed for all three species, with the most larvae developing in spring-early autumn and the least in winter. This seasonal pattern was most pronounced in H. contortus and least obvious in T. circumcincta. Burying faeces containing eggs generally resulted in more L3 being recovered, whilst the apparent activity of earthworms resulted in fewer larvae being recovered. 相似文献
10.
11.
《African Zoology》2013,48(2):240-251
This paper describes the morphology and ecology of the larvae and early juveniles of two common gobiids in warm temperate South African estuaries. The early developmental stages of Glossogobius callidus and Redigobius dewaali were collected during plankton surveys in seven permanently open and five intermittently open estuaries along southeastern South Africa. Larval G. callidus have a characteristic ventral row of pigment that extends from the cleithral symphysis along the ventral midline of the tail to the end of the caudal peduncle; notochord flexion takes place at the yolk-sac stage, between 3 and 4 mm BL. Larval R. dewaali are characterized by having two very large stellate melanophores on the ventral surface of the trunk and tail, and internal pigment between the snout and hindgut; notochord flexion takes place between 4 and 6 mm. Body lengths at settlement for G. callidus and R. dewaali are 13 mm and 16 mm, respectively. G. callidus and R. dewaali dominate the larval gobiid catch in warm temperate estuaries. Estuary type and freshwater input played a defining role in the occurrence of larvae of these, often sympatric, species in temperate estuaries. Larval G. callidus occurred in both permanently open and intermittently open estuaries, and were most abundant in mesohaline regions over the spring/summer period. By contrast, larval R. dewaali occurred exclusively in permanently open estuaries and were more prevalent in the fresh and oligohaline regions in autumn. Larvae of both species were more prevalent in freshwater-rich estuaries. Densities of G. callidus and R. dewaali peaked at 101 and 3829 larvae per 100 m3respectively. The usefulness of using the early stages of these gobiids as indicators of estuarine health based on their specific and often prolific estuarine occurrence is discussed. 相似文献
12.
Lynnath E. Beckley 《African Zoology》2013,48(3):199-200
The larval stages of the red mangrove crab Sesarma meinerti de Man were reared in the laboratory. Larval development consists of five zoeal stages and one megalopa. Zoeal development lasts an average of 25 days at 25°C. The external morphology of larvae is described in detail and their relationship with larvae of congeneric species is briefly discussed. 相似文献
13.
The current control of parasitic nematodes in small ruminants relies on the use of chemical anthelminthics, but the development
of resistance and the problem of drug residues require research into alternatives. Acetone extract and solvent–solvent fractions
of Vernonia amygdalina Del. (Compositae) were evaluated in vitro for potential anti-parasitic effects against the eggs and larvae of Haemonchus contortus. Significant effects were obtained with the extract and fractions but differences were observed depending on the parasitic
stage. The acetone extract and fractions inhibited egg hatching and inhibited larval development and killed larvae of H. contortus in a concentration-dependent manner. Best-fit 50% lethal concentration (LC50) values were 957.0, 76.0, 524.0, 309.0 and 224.0 μg/ml for the acetone extract, and the butanol, hexane, chloroform and 35%
water in methanol fractions, respectively, when tested against nematode eggs. Best-fit LC50 values for the larval viability test were 508.2, 485.5, 569.3, 348.9 and 196.6 μg/ml for the acetone extract, and the butanol,
hexane, chloroform and 35% water in methanol fractions, respectively. The butanol fraction was most active against nematode
eggs while the 35% water in methanol fraction was the most active on nematode larvae, although differences in activity between
fractions were not significant (p > 0.05). Overall, these in vitro results suggest that V. amygdalina, traditionally used by small farmers in Western Africa, does possess anti-parasitic properties. 相似文献
14.
A-MB Oliver DM Leathwick TS Waghorn CM Miller DS Atkinson 《New Zealand veterinary journal》2013,61(6):383-387
Abstract AIM: To determine whether the fungicide, carbendazim, as applied to pastures for controlling facial eczema (FE), would inhibit development of the free-living stages of the gastrointestinal nematode parasite Trichostrongylus colubriformis. METHODS: Two studies were conducted, using sheep faeces containing eggs of T. colubriformis. In the first, the faeces were either exposed or not to an application of carbendazim sprayed at the recommended rate for FE control. After spraying, dishes containing the faeces were incubated at 20°C for 14 days, and the resulting third-stage infective larvae (L3) extracted by baermannisation and counted. In addition, naturally infested pasture was also sprayed, and the number of L3 present 7 days later was assessed by cutting herbage samples and extracting larvae by soaking in water and baermannisation. In the second, the faeces were incubated at 20°C for 0, 3 or 7 days before being exposed to no, one or two applications of carbendazim. After further incubation for 14, 11 or 7 days, L3 were similarly extracted by baermannisation and counted. RESULTS: In the first study, there was a 74% reduction in the number of T. colubriformis larvae recovered from faeces exposed to carbendazim compared with faeces not exposed, but there was no reduction in the number of L3 recovered from herbage. In the second study, faeces incubated for 0 or 3 days prior to exposure to a single application of carbendazim yielded 98% or 89% fewer larvae, respectively, than faeces not exposed. Faeces incubated for 7 days prior to exposure yielded similar numbers of larvae to faeces not exposed. CONCLUSION: Treatment of pastures with carbendazim for FE control is likely to result in reduced development of the larvae of T. colubriformis, and by inference those of other species, where the application coincides with the presence of freshly deposited faeces containing eggs and developing larvae. However, no effect of treatment on L3 was indicated. The significance of this for on-farm nematode parasite control remains to be determined, as does any potential for strategic applications of carbendazim to pasture aimed at reducing numbers of parasite larvae on pasture. The latter should not be contemplated without due consideration of the implications for the development of anthelmintic resistance. 相似文献
15.
Emanuele Brianti Salvatore Giannetto Donato Traversa Sharon R. Chirgwin Krishna Shakya Thomas R. Klei 《Veterinary parasitology》2009,163(4):348-356
A mixed population of equine cyathostomin (Nematoda, Strongyloidea) infective third stage larvae (L3) was cultured in vitro using a cell-free medium. Some L3 were cultured immediately after Baermann collection from fecal cultures, while others were kept in water at 4 °C for 7 days before initiating the in vitro cultures. Cultures were examined daily for viability. At days 2, 7, 14 and 21 larvae were collected for identification of developmental stage and morphological changes, using both light and scanning electron microscopy. Larvae were classified as early L3 (EL3), developing L3 (DL3), late L3 (LL3) and fourth stage larvae (L4) on the basis of morphological features. Viability remained high throughout the entire study period in cultures of both non-refrigerated (84.7%) and refrigerated (77.4%) larvae. However, viability of the non-refrigerated was significantly greater from 7 through 21 days of culture. Significant differences were also observed in the percentage of DL3 between the non-refrigerated and refrigerated larval cultures by day 7. The highest percentage of DL3 larvae (22.5%) was reached at the end of study in those larvae that were not previously refrigerated. The data suggests that prior refrigeration decreases viability and slows L3 development. At day 21 LL3 larvae were only a small percentage of the DL3: 6.9 and 5% in non-refrigerated and refrigerated cultures, respectively. Few of these larvae freed themselves from the L3 cuticle and moulted to L4 stage. Characteristics of individual species in vitro developmental patterns were determined by the molecular identification of individual larvae in pools of larvae randomly collected at days 0 and 21. Seven species (Coronocyclus coronatus, Cylicostephanus goldi, Cylicostephanus longibursatus, Cyathostomum catinatum, Cylicocyclus nassatus, Cylicocyclus ashworthi, Petrovinema poculatum) were identified in the day 0 pool. The greatest tendency to develop in vitro was shown by the genus Cylicostephanus with the species C. goldi and C. longibursatus that developed to the LL3-L4 stages. C. nassatus, C. ashworthi and C. coronatus did not progress in their development beyond the EL3 stage, while no apparent signs of development were registered for C. catinatum. 相似文献
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17.
Agyei AD 《Tropical animal health and production》2003,35(3):207-217
The types of gastrointestinal parasites (Eimeria and helminths) encountered by 70 lambs and the seasonal pattern of both Eimeria and strongylate infections in these lambs in the derived Coastal Savanna were followed for three years. Eimeria oocysts and helminth eggs were detected in the faeces of lambs at the same time, indicating the concurrence of both Eimeria and helminth infections. Eimeria oocysts were first seen in the lambs 20 days after birth (DAB) and the level of oocyst output increased by the fourth week. Eimeria species identified in the lambs were E. parva, E. pallida, E. faurei, E. ahsata, E. bakuensis, E. intricata, E. granulosa, E. ovinoidalis and, occasionally, E. marsica. E. ovinoidalis, the most pathogenic species, dominated the oocyst output during the early part of the life of the lambs. Strongyloides papillosus eggs appeared at 46 DAB, preceding strongylate nematode eggs, which were seen at 57 DAB and those of Moniezia at 69 DAB. The pattern of Eimeria oocyst output paralleled that of the worm egg output, and high oocyst and strongylate worm egg counts corresponded with the period of high rainfall during the study period. Although oocyst and worm egg output fluctuated, high Eimeria oocyst counts were seen again in the lambs when they were 1 and 2 years old. Haemonchus species formed 71% of the infective larvae revealed by larval culture. 相似文献
18.
1. Successful invasion by nematode parasites is associated with several factors including egg hatching at the right time in their hosts. To determine a simple and appropriate medium for culture and egg hatching of the highly pathogenic species of the Acuariidae family, Cheilospirura hamulosa were cultured in three different media. In addition the viability of C. hamulosa eggs was determined after storage in frozen infected gizzards.2. Eggs removed from the uteri of the female worms in infected gizzards were pooled and washed in distilled water and screened under a stereo dissecting microscope. Eggs were counted and cultured in three different media, nutrient agar, normal saline 0.9% and Bearman, at room temperature. Additionally, 10 infected gizzards were kept at ?20°C for 2 and 8 months.3. After 4–5 d there had been no growth in the nutrient agar medium, whereas 11% of the cultured eggs in the Bearman medium contained larvae 2–3 d after culturing. In 0.9% normal saline medium the two polar knobs appeared on the two poles of the eggs at 2 d post cultivation, and 74% of the eggs contained a larva on the third day. Mature larvae gradually exited from the eggs.4. Eggs collected from female worms in gizzards frozen at ?20°C were cultured in the same three culture media at room temperature. Larvae were visible in the eggs after 2–3 d in the Bearman and 0.9% normal saline media and hatched thereafter.5. The 0.9% normal saline medium is recommended for egg hatching and cultivation of C. hamulosa due for simplicity, efficacy and cost effectiveness. Moreover, freezing of the infected gizzards at ?20°C is proposed for long-term storage of the eggs. 相似文献
19.
J. Owen D. Slocombe PhD DVM DICTA Mary C. Lake RVT 《Journal of Equine Veterinary Science》2007,27(10):439-445
A clinical trial was conducted with 2- to 3-year-old ponies to determine the effectiveness against strongyles of 2.64 mg pyrantel tartrate/kg body weight administered in the daily ration throughout a pasture season in Canada. Ten ponies were given the anthelmintic, and 10 were not treated and served as controls. Each group of ponies was on a separate pasture. The mean strongyle eggs/g of feces for each group, before treatment and turnout to pasture, was greater than 2,200. Thereafter, the mean eggs/g feces for the untreated group remained high (1,405−2,294) and those for the treated group decreased markedly to, and remained at, very low levels (0.2−16.8). Strongyle larval counts for the pasture with the untreated ponies rose to 26,790 larvae/kg dry herbage in August, whereas that for the treated group was 610 larvae/kg dry herbage. At the end of the season, two ponies from each group were isolated for 6 weeks and necropsied. The mean number of strongyles in the untreated and treated ponies was 69,288 and 8,452.5, respectively. In the untreated ponies, 21 species of strongyles were found, and approximately 84% of them were from eight species of cyathostomes. In the treated ponies, 14 species of strongyles were found, and approximately 77% were from one species, Cylicostephanus minutus (52.0%), and immature cythostomes (25%). Adverse reactions were not observed in any of the treated ponies. Pyrantel tartrate was highly effective in significantly reducing the strongyle egg and pasture larval counts and the transmission of strongyles during a pasture season. 相似文献
20.
The survival period for larvae of Boophilus annulatus (Say), Boophilus microplus (Canestrini) and hybridized Boophilus ticks was determined by exposure to various combinations of temperature (20, 25, 30 and 35°C) and relative humidity (32, 63, 75, 84 and 97% RH) in the laboratory. Results indicated that within a given temperature and RH regime, there was no difference (P > 0.05) in larval survival among the three species tested, indicating that these ticks respond similarly over a wide range of temperature and RH combinations. Larval survival in all three species was longest (P < 0.05) at 20°C and either 84 or 97% RH. With each increase in temperature at the 84 and 97% RH treatment levels, there was a corresponding significant (P < 0.05) decrease in larval survival. When the temperature reached 35°C at all humidities or when the RH was 63% or less at all temperatures, the mean larval survival period was 43 days or less in all cases and little difference (P > 0.05) was observed among the treatment regimes included. Results suggest that at a RH of 75% and more, the temperature is the determining factor in larval survival, whereas at a RH of 63% and less the RH is the determining factor in larval survival, regardless of temperature. 相似文献