Shorter Larval Development Research Articles

Molecular ecology of the Javanese ricefish, Oryzias javanicus (Bleeker): genetic divergence along the Indonesian Archipelago

Context Investigating the patterns of genetic diversity and population structure of the Javanese ricefish, Oryzias javanicus, is instrumental in identifying their dispersal patterns and demographics in response to ecological changes and biogeographical barriers. Aims To acquire a better understanding of the evolutionary history of Javanese ricefish. Methods We sequenced part of the mitochondrial DNA (mtDNA) control region in 335 individuals and genotyped 280 individuals for four microsatellite loci from seven Indonesian sites. Key results Both genetic diversity (h = 0.19–0.86 and DIVGene = 0.10–0.43) and nucleotide diversity (π = 0.06–0.61%) were low compared with other fish taxa. The analysis of molecular variance showed considerable genetic differences (P < 0.0001) for both genetic markers across all sampled locations. These results suggest that there has been a historical restriction on gene flow. Conclusion The observed population-structure pattern reflects a short pelagic larval development, which is closely linked to a restricted dispersal potential. This ultimately leads to isolation by distance, potentially allowing local adaptation to sites that augment any oceanographic, geographic, or biological barriers to gene flow. Implications The results presented in this study can be used to create more effective ways to protect the species in question.

Induced breeding, embryonic and larval development of Koi carp (Cyprinus carpio) in Khulna, Bangladesh

The aim of the present study was to perform induced breeding and to observe embryonic and larval development stages in different seasons for mature male and female Koi carp, Cyprinus carpio, was done by administering the synthetic hormone ovaprim, in a single dose for males and a double dose for females at 0.4-1.0 ml/kg body weight via an intramuscular injection. Spawning occurred between 5-6 hrs after the 2nd injection in summer (April) at a temperature of 26-29 oC and 17-20 0C in winter (December). Using doses of 0.4ml/kg, 0.7ml/kg and 1.0 ml/kg of ovaprim, the fertilization rate of eggs were obtained at 42.31%, 54.55% and 61.82 % in summer and 26.92%, 38.00% and 39.23 % in winter. Hatching rates were 42.78%, 44.60% and 55.00 % in the summer season and 30.22%, 31.01% and 31.67 % in the winter season with the same doses of ovaprim. The fertilized eggs were adhesive, transparent, and spherical with diameters ranging between 0.8 mm and 1.0 mm and yellowish white in color. Due to a positive response to the hormone Ovaprim, considerable fertilization and hatching rate, short embryonic period and larval development, it is possible to conduct a successful breeding program of this species commercially

Staging and normal table of postembryonic development of the clownfish (Amphiprion ocellaris).

BackgroundThe clownfish Amphiprion ocellaris is one of the rare coral reef fish species that can be reared in aquaria. With relatively short embryonic and larval development, it could be used as a model species to study the impact of global changes such as temperature rise or anthropogenic threats (eg, pollution) on the postembryonic development at molecular and endocrinological levels. Establishing a developmental table allows us to standardize sampling for the scientific community willing to conduct experiments on this species on different areas: ecology, evolution, and developmental biology.ResultsHere, we describe the postembryonic developmental stages for the clownfish A. ocellaris from hatching to juvenile stages (30 days posthatching). We quantitatively followed the postembryonic growth and described qualitative traits: head, paired and unpaired fins, notochord flexion, and pigmentation changes. The occurrence of these changes over time allowed us to define seven stages, for which we provide precise descriptions.ConclusionsOur work gives an easy system to determine A. ocellaris postembryonic stages allowing, thus, to develop this species as a model species for coral reef fishes. In light of global warming, the access to the full postembryonic development stages of coral reef fish is important to determine stressors that can affect such processes.

Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem

Physical-biological interactions in the ocean: case studies from the northern Canary Current Upwelling Ecosystem

Sex-specific compensatory growth in the larvae of the greater wax moth Galleria mellonella.

Deficiency of food resources in ontogeny is known to prolong an organism's developmental time and affect body size in adulthood. Yet life-history traits are plastic: an organism can increase its growth rate to compensate for a period of slow growth, a phenomenon known as 'compensatory growth'. We tested whether larvae of the greater wax moth Galleria mellonella can accelerate their growth after a fast of 12, 24 or 72h. We found that a subgroup of female larvae showed compensatory growth when starved for 12h. Food deficiency lasting more than 12h resulted in longer development and lower mass gain. Strength of encapsulation reactions against a foreign body inserted in haemocoel was the weakest in females that showed compensatory growth, whereas the strongest encapsulation was recorded in the males and females that fasted for 24 and 72h. More specifically, we found sex-biased immune reactions so that females had stronger encapsulation rates than males in one group that fasted for 72h. Overall, rapidly growing females had a short larval development period and the shortest adult lifespan. These results suggest that highly dynamic trade-offs between the environment, life-history traits and sex lead to plasticity in developmental strategies/growth rates in the greater wax moth.

Genetic differentiation and connectivity of morphological types of the broadcast-spawning coral Galaxea fascicularis in the Nansei Islands, Japan.

Population connectivity resulting from larval dispersal is essential for the maintenance or recovery of populations in marine ecosystems, including coral reefs. Studies of species diversity and genetic connectivity within species are essential for the conservation of corals and coral reef ecosystems. We analyzed mitochondrial DNA sequence types and microsatellite genotypes of the broadcast-spawning coral, Galaxea fascicularis, from four regions in the subtropical Nansei Islands in the northwestern Pacific Ocean. Two types (soft and hard types) of nematocyst morphology are known in G.fascicularis and are significantly correlated with the length of a mitochondrial DNA noncoding sequence (soft type: mt-L; hard type: mt-S type). Using microsatellites, significant genetic differentiation was detected between the mitochondrial DNA sequence types in all regions. We also found a third genetic cluster (mt-L+), and this unexpected type may be a cryptic species of Galaxea. High clonal diversity was detected in both mt-L and mt-S types. Significant genetic differentiation, which was found among regions within a given type (F ST=0.009-0.024, all Ps≤0.005 in mt-L; 0.009-0.032, all Ps≤0.01 in mt-S), may result from the shorter larval development than in other broadcast-spawning corals, such as the genus Acropora. Nevertheless, intraspecific genetic diversity and connectivity have been maintained, and with both sexual and asexual reproduction, this species appears to have a potential for the recovery of populations after disturbance.

Photoperiod-temperature interaction-a new form of seasonal control of growth and development in insects and in particular a Carabid Beetle, Amara communis (Coleoptera: Carabidae)

Amara communis larvae are found to develop significantly faster and have higher growth rate at short-day (12 h) as compared to long-day (22 h) photoperiods under all temperatures (16, 18, 20 and 22 degrees C) used. The coefficient of linear regression of larval development rate on temperature was significantly higher at short days than at long days. At that thermal developmental thresholds appeared similar at both photoperiods. Body weight of young beetles reared under different photoperiods was just the same. Thus, the photoperiodic effect does not simply accelerate or retard insect development, but modifies their thermal reaction norm. Under short days larval development becomes faster and more temperature dependent, which ensures the timely completion of the development at the end of summer. The analysis of data from literature allowed us to find photoperiodic modification of thermal requirements for development in 5 insect orders--Orthoptera, Heteroptera, Coleoptera, Lepidoptera, Diptera. Modification may result in significant changes in the slope of the regression line and hence in the sum of degree-days and thermal developmental threshold. Consequently, during summer under the influence of changing day-length the thermal requirements for development in many insects gradually vary, which may have adaptive significance. Thus, the photoperiodic modification of thermal reaction norm acts as a specific form of seasonal control of insect development.

Experimental evolution of sperm count in protandrous self-fertilizing hermaphrodites

Sperm count evolution is driven by sexual selection, with an added role of selection on gamete resource allocation for hermaphrodite spermatogenesis. However, self-fertilization by hermaphrodites retards sexual selection and results in the evolution of reduced investment in sperm or pollen. In contrast to reproduction limited by female gametes (Bateman's Principle), self-fertilizing Caenorhabditis elegans hermaphrodites exhibit sperm-limited reproduction. Caenorhabditis elegans hermaphrodites are thought to experience a fitness trade-off between lifetime fecundity and generation time: longer sperm production decreases the risk of self-sperm depletion, but at the same time delays the onset of selfing and thus increases egg-to-egg generation time. Theory predicts that shorter larval development will favor lower sperm counts and longer development will favor more sperm. To investigate how developmental trajectories affect the evolution of sperm production, we performed experimental evolution by directly competing alleles controlling hermaphrodite sperm count, conducted under different environmental conditions that alter development time. Results are partially consistent with theory: rapid larval development generally favored alleles encoding production of few sperm. However, we identify some previously unrecognized simplifications of the theory and its application to our experimental system. In addition, we evaluated the generality of sperm limitation in C. elegans. Although optimal growth conditions yield sperm limitation, non-optimal conditions induce oocyte limitation, suggesting that this species might conform to Bateman's Principle under many natural settings. These findings demonstrate how developmental trajectories can shape the fitness landscape for the evolution of reproduction and sperm traits, even without sexual selection.

Changes in biochemical and fatty acid composition of the razor clam Solen marginatus (Solenidae: Bivalvia) during larval development

Aquaculture studies have revealed that polyunsaturated fatty acids are critical for maintaining substantial growth, survival and reproductive rates, and high food conversion efficiencies for a wide variety of marine and freshwater organisms. The aim of this study was to investigate the gross biochemical and fatty acid composition of both neutral and polar lipid compartments of the razor clam Solen marginatus throughout embryonic and larval development. High levels of stored reserves in S. marginatus eggs allow a short larval development, lasting only 8 days. The energy required for embryogenesis was obtained from stored proteins. During larval development from D-shaped veliger until settlement, protein, lipid, and carbohydrate reserves were indistinctly stored for metamorphosis. Although total lipids increased, fatty acids in both neutral and polar lipids decreased during embryonic development. The depots allow a short larval development in which settlement is reached with lower amounts of stored neutral and polar lipids than the contents found in the oocytes. Non-methylene-interrupted dienoic fatty acid levels were similar to those of some polyunsaturated fatty acids, with increasing percentages at the onset of metamorphosis. This study indicates that S. marginatus exhibits a different pattern in the use of gross biochemical and fatty acid reserves during larval development compared to other razor clam and bivalve species, mainly due to the large size of its eggs and the short larval development stage reported in this species.

Detached aquaculture buoys in the SE Pacific: potential dispersal vehicles for associated organisms

Throughout the world's oceans a wide variety of floating plastics are found, among which buoys stand out for their high floatability and diversity and abundance of associated organ- isms. Between 2001 and 2005, we conducted 25 ship surveys in the Bay System of Coquimbo (BSC), during which we registered 34 detached buoys floating between 1 and 45 km from the coast. The objective of this study was to infer the possible origin of these buoys, identify the associated biota and characterize their biological traits. Short-term drift experiments (30 min) showed that buoys without rope responded primarily to the velocity and direction of the wind, while buoys with ropes (3 m length) followed surface currents. Using the wind velocity and direction during the 12 h before cap- ture of the detached buoys, we estimated the hypothetical trajectories of these buoys during that time period. Results indicated that most buoys originated from aquaculture facilities in the BSC. A total of 134 different species from 14 phyla was found on 18 anchored (91 species) and 22 detached (116 spe- cies) buoys sampled. Community composition was similar among buoys—54% of all species were common for anchored and detached buoys—but a higher number of rare species occurred on detached buoys. Buoys do not seem to lose but rather gain organisms after detachment. The most common functional groups on these buoys were mobile species, suspension-feeders and species with sexual reproduction, separate sexes, internal fertilization and direct or very short larval development. Fouling communities on detached buoys were mostly in advanced successional stages, comprising diverse species (including several non-indigenous species) adapted to the conditions at the sea sur- face. These results suggest that floating buoys may transport associated species over extensive distances, thereby also contributing to the spread of non-indigenous species.

Influence of Fertilization on the Colorado Potato Beetle, <I>Leptinotarsa decemlineata</I>, in Organic Potato Production

The abundance of the Colorado potato beetle, Leptinotarsa decemlineata (Say), in organically grown potato did not change significantly in response to increasing rates of dehydrated poultry manure. However, peaks of abundance of larvae were shifted forward in time in response to the high rate of organic fertilizer. Tests using excised foliage showed that the shift was not caused by differential larval mortality or longer developmental times. Time allocation to resting, walking, and feeding by adults was similar regardless of fertilizer rate. Adult foliage consumption was unaffected by organic fertilizer rates in no choice tests and significantly affected in few choice tests. A 22% longer larval development time on plants treated with low fertilizer rate than on plants with high rate was the most significant effect. Even though maximum plant height, canopy, biomass, and yield were significantly smaller in the organic than in conventional plots, the suitability of the plants was not affected except for reduced feeding by summer beetles. Summer adults spent less time feeding and consumed two to five times less foliage on organic potato than on inorganically fertilized and conventionally produced plants. The overall influence of fertilizer on Colorado potato beetle populations was limited and therefore can only play a secondary role in management strategies for organic potato. Avoidance of excessive organic fertilizer that promotes short larval development time and extension of the period over which large Colorado potato beetle larvae are present should be recommended.

Comparison of Biology and Host Plant Use of <I>Archanara geminipuncta</I>, <I>Archanara dissoluta</I>, <I>Archanara neurica</I>, and <I>Arenostola phragmitidis</I> (Lepidoptera: Noctuidae), Potential Biological Control Agents of <I>Phragmites australis</I> (Arundineae: Poaceae)

Abstract Phragmites australis (Cavanilles) Trinius ex Steudel (Arundineae: Poaceae) is an invasive plant in freshwater and brackish North American wetlands. Inability to control this grass with chemical, mechanical, or physical means resulted in initiation of a biological weed control program. As part of investigations of potential biocontrol agents attacking P. australis in Europe, we compared distribution, life history, and host plant use of four sympatric stem-boring noctuid moths in the field and in common gardens. Archanara geminipuncta (Haworth) is the most widespread and abundant species followed by Archanara dissoluta (Treitschke), Archanara neurica (Hubner), and Arenostola phragmitidis (Hubner). The two early species, Aren. phragmitidis and Arch. neurica, hatch from overwintering eggs ≈2 wk before the later species, and shorter larval development causes adults of early species to emerge 2–4 wk before Arch. geminipuncta and Arch. dissoluta. Early Aren. phragmitidis and Arch. geminipuncta instars a...

Reproductive biology of a riverine cyprinid, Labeo umbratus (Teleostei: Cyprinidae), in small South African reservoirs

The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.

Crecimiento y supervivencia de larvas de Echinometra lucunter (Echinoidea: Echinometridae) alimentadas con las microalgas Chaetoceros gracilis e Isochrysis galbana

Larval growth and survival of Echinometra lucunter (Echinoidea: Echinometridae) fed with microalgae Chaetoceros gracilis and Isochrysis galbana. Thirty sexually mature sea urchins (Echinometra lucunter; diameter 45.8 ± 17.5 mm) were collected at Macanao, Margarita Island, Venezuela (11°48’29” N / 64°13’10” W). They were injected potassium chloride (50 M) directly into the celomic cavity. After two minutes 90% spawned (17 females and 10 males), the others never spawned. Fertilization was 87.0 ± 12.6% (1:100 oocytes/sperm) at 29 ± 2oC. The fertile eggs were placed in three treatment gropsu with nine containers (18 liters; 2 eggs/ml) each, all with bottom aeration. Treatments were: Chaetoceros gracilis; Isochrysis galbana, and a mixture of both microalgae (respectively: 20 000 and 60 000 cell/ml for each microalgae, 1:1 for the mixture). Salinity, pH, temperature and larval survival were determinated daily. The study ended when the post-metamorphic phase was completed. The embryonic development time was 16.3 ± 0.2 h until the prism stage at pH 8.4 ± 0.1; 38 ± 1 psu and 28 ± 1.4°C. The two-arms larval stage was reached at 24 h: 33 min, with a total length of 190 ± 16.3 μm fed on C. gracilis, 152 ± 19.0 μm with I. galbana and 182.4 ± 14.1 μm with the mixture. The larvae next to metamorphosis reabsorbed the arms and had the characteristic shape of juvenile urchins at 12 days with 670.2 ± 22.2 μm fed on C. gracilis, 665 ± 12.1 μm fed on I. galbana and 670 ± 14.1 μm fed on the mixture. The accumulated survival to the juvenile stage was 14.7 ± 3.8% when fed on C. gracilis, higher than the other treatments (5.4 ± 1.2; 14.0 ± 2.6). E. lucunter is an excellent prospect to be commercially cultured because of its short embryonic (16 hours) and larval development time (12 days) and good survival rate when fed on monoculture (C. gracilis and I. galbana) or mixed diet (we recommend C. gracilis). Rev. Biol. Trop. 53(Suppl. 3): 337-344. Epub 2006 Jan 30.

Distribution, Adult Morphology, and Larval Development of Sacculina Sinensis (Cirripedia: Rhizocephala: Kentrogonida) in Hong Kong Coastal Waters

Abstract Sacculina sinensis (Cirripedia: Rhizocephala) is a parasitic barnacle first reported in Hong Kong by Boschma (1933) to infect the intertidal crab, Leptodius exaratus. Since then, no studies have been conducted to investigate its distribution and morphology, which are important in providing background information for further taxonomic and ecological studies. In the present study, S. sinensis has shown to have a limited distribution in Hong Kong, being confined to only four out of the nine sheltered boulder shores sampled and with a mean infestation rate of 11.3 percent. The localized distribution of S. sinensis in Hong Kong is probably due to its short larval development times (four naupliar stages and one cypris stage, completed in about six days) and hence limited larval dispersal distance. The externa of S. sinensis is ovoid in shape with two distinct shoulders, and the outer cuticle surface is spinous. From histological studies, the male receptacles are located posteriorly in the visceral mass...

Riparian gravel banks of upland and lowland rivers in Victoria (south-east Australia): arthropod community structure and life-history patterns along a longitudinal gradient

Riparian sand and gravel banks are inhabited by a fauna that is well adapted to varying river water levels and frequent inundation of the banks. Arthropods found in these habitats were studied from November 1998 to January 1999 in the upper and lower floodplains of the main rivers and tributaries in ten major catchments in the Victorian Alps. Wolf spiders (Lycosidae, 68%) and ground beetles (Carabidae, 7.8%) were the most abundant arthropods, with densities averaging 14.6 ± 1.8 (s.e.) and 2.3 ± 0.4 individuals m–2 respectively. Species composition and wolf spider densities changed substantially between upland and lowland rivers. These differences correspond with changes in altitude, shading, and gravel and gravel bank size. Comparison of our results with similar studies conducted in temperate Northern Hemisphere floodplains showed significant differences. Carabidae, not Lycosidae, are the dominant arthropod group in Northern Hemisphere floodplains. Wolf spider densities are higher in upper than lower reaches of rivers in the Victorian Alps, but do not change along rivers in the Northern Hemisphere. In contrast, carabid beetles showed similar densities between upland and lowland floodplains in Victoria, but increase in density along rivers in the Northern Hemisphere. A second, monthly sampling program on gravel banks along the Avon River (Gippsland) over a one-year period in 1996 and 1997 provided information on the life histories of eight common gravel-bank arthropods: Venatrix lapidosa, V. arenaris, two undescribed Artoria species (‘A’, ‘B’) (Lycosidae), Eudalia macleayi, Elaphropus ovensensis, Perileptus constricticeps and an unidentified Loxandrus species (‘B’) (Carabidae). Artoria sp. A and sp. B are diplochronous. Despite its smaller size, Artoria sp. B matured one month after Artoria sp. A. Lower temperatures at upland streams and rivers, the typical habitat for Artoria sp. B, may delay its development in comparison with Artoria sp. A, which is generally found further downstream. The life histories of both lycosid spiders and carabid beetles, characterised by prolonged reproductive period and short larval development, appear to have some adaptive value in regard to the disturbance-prone environment.

Glandular trichomes of Solanum berthaultii and its hybrids with potato deter oviposition and impair growth of potato tuber moth

AbstractGlandular trichomes on foliage of the wild potato species, Solanum berthaultii Hawkes, deter oviposition by the potato tuber moth (PTM), Phthorimaea operculella Zeller and negatively affect other important performance parameters. Oviposition deterring factors are localized in the glandular trichomes of S. berthaultii. When mechanically transferred to foliage of a susceptible potato cultivar, trichome contents reduced egg laying by 97%. Removal of glandular trichomes from S. berthaultii foliage using a combination of chemical and mechanical procedures increased oviposition rates ca. 210‐fold. Removal of trichomes also led to increased mobility of larvae on the leaf surface, more leaf feeding, shorter larval development and larger pupae. The resistance conferred by glandular trichomes of S. berthaultii provides an important genetic trait potentially useful for management of PTM.

Laboratory Culture of Beneficial Dung Scarabs

Cattle dung accumulation presents problems of pasture fouling, nutrient loss, intestinal parasitosis, and pest fly development. These problems have been confronted, with variable success, with the introduction of coprophagous scarabs (Coleoptera: Scarabaeidae). This work reports the results of field collections and laboratory culture of immature and adult dung scarabs. We compared several treatments of eggs and larvae in search of good methods for rearing scarabs in aseptic conditions. We collected 13 abundant species from northern and central Argentina. We obtained ≈4,500 eggs, some of which we sent to quarantine facilities in the United States, and others which we reared in our laboratory with 5 different techniques. Five common and widespread species, Ontherus sulcator (F.), Gromphas lacordairei Brulle, Dichotomius semiaeneus (Germar), Sulcophanaeus menelas (Castelnau), and Bolbites onitoides Harold, had the highest oviposition rates and were also the easiest to rear. Two methods, freeze-dried and gamma sterilized brood masses and balls, provided the best results (i.e., percentage of beetles completing development). As a rule, the species with short larval development time and wide distributions were easier to rear.

Development, Longevity and Fecundity of the False Wireworms Pterohelaeus Darlingensis and P. Alternatus (Coleoptera: Tenebrionidae). Ii. Effect of Food Type.

Pterohelaeus darlingensis Carter and P. alternatus Pasc. were reared under constant temperatures on 10 different foods in the laboratory in Australia. In P. darlingensis, wheat, barley and sorghum resulted in the shortest larval development periods, longest pupal periods and lowest pre-imaginal mortality. Egg-laying rates were highest on wheat, barley and maize and lowest on oats and soyabean. No females were produced after feeding on wheat straw, and no eggs were laid after feeding on linseed and turnip weed. Only wheat, barley, maize and sorghum (in descending order) allowed an increase in population. In P. alternatus, wheat, sorghum and barley resulted in the shortest pre-imaginal development with the least mortality. Egg-laying rates were highest on wheat, maize and sorghum and lowest on barley and oats. No eggs were laid by females fed on linseed. Wheat, sorghum, maize, sunflower, barley and soyabean allowed a positive population growth. These results are discussed in relation to control of the tenebrionids by crop rotation.

Larval development of the snapping shrimpAlpheus heterochaelisSay, reared in the laboratory

Summary Larvae of Alpheus heterochaelis from North Carolina hatch from large eggs as advanced zoeae, usually moult three times, and exhibit almost no linear growth during a short (4 days at 25°c) larval development. Stage I lasts 6 hours at most and is sometimes skipped; III lasts about twice as long as II. Individuals simultaneously exhibiting characteristics of Stage III and the postlarva were occasionally seen. The three zoeal stages and postlarva are described in detail and illustrated. Stages in embryonic and juvenile development and the hatching process are briefly described. An ‘extended’ pattern of larval development, characteristic of most alpheid species, is described in a general way, and the ‘abbreviated’ development of A. heterochaelis compared to it. At hatching, A. heterochaelis larvae bear rudimentary pereiopods and pleopods; other structures are at the same level of development in both patterns, but subsequent morphogenesis is faster in A. heterochaelis. Larval development of Synalpheus spp., some of which exhibit extreme abbreviation or direct development, is briefly described with reference to the A. heterochaelis pattern.