Embryonic and Larval Development of Reciprocal Crosses between Clarias gariepinus (Burchell, 1822) and Clarias jaensis (Boulenger, 1909) in West Cameroon

Establishing intraspecific breeding and hybridization programs and determining genetic variability are two important issues for aquaculture. However, interspecific hybridization to improve growth and feeding efficiency is limited. For this purpose, the embryonic and larval development of reciprocal crosses of Clarias gariepinus (Burchell, 1822) and Clarias jaensis (Boulenger, 1909) were studied under laboratory conditions. The fertilization rate varied from 63.33% to 92%, while the hatching rate ranged from 55.68% to 76% with the highest value in hybrids ♀Cg × ♂Cj. Crosses between ♀Cj × ♂Cj, ♀Cg × ♂Cj and ♀Cj × ♂Cg had embryonic stages similar to those of the pure sib ♀Cg x ♂Cg. All crosses, however, had different timing for the various embryological stages. Hatching occurred at 32 h 15 min and 38 h for ♀Cj × ♂Cj and ♀Cj × ♂Cg, and 23 h and 23 h 30 min, respectively, for ♀Cg × ♂Cg and ♀Cg × ♂Cj. However, both crosses produced viable larvae until the first external feeding. The external morphological features of the larvae were completely formed by the 10th day after hatching. The body forms of the crosses at this time were indistinguishable from the pure sib. This study thus laid the groundwork for further comparative studies on hybrid performance and characterization.

Screening of Environmental Bacterial Strains for Wild Aedes Mosquito Larval Biocontrol

The effectiveness of current control measures against Aedes mosquitoes remains low, resulting in persistent epidemics in urban areas. The emergence of resistant mosquito populations to chemical insecticides highlights the need for novel, environmentally friendly, cost-effective control strategies. This study explored the potential of environmental bacterial isolates to biocontrol wild Aedes larvae. Initially, we collected bacterial samples from infectious masses of Aedes fluviatilis larvae. The isolated bacteria were identified using biochemical, enzymatic, and molecular methods, including 16S rRNA sequencing and MALDI-TOF. Previously, Aeromonas hydrophila and Bacillus thuringiensis isolated from these infectious masses showed limited Aedes larval inhibition. Consequently, we screened additional environmental isolates from the bacteriotheque. Six isolates previously identified were tested: Chromobacterium violaceum, Enterobacter cloacae, Bacillus cereus, Bacillus sphaericus, and two strains of Bacillus thuringiensis israelensis. Among these strains, B. thuringiensis and C. violaceum exhibited significant inhibitory activities against wild Aedes larvae. Bacillus thuringiensis cultures grown under daylight conditions showed a slight ability to inhibit Aedes larvae. The potential of B. thuringiensis and C. violaceum strains studied, along with optimized culture growth conditions, will be further investigated to develop bioinsecticide products to provide safer and more sustainable alternatives for controlling larvae of Aedes mosquitoes.

Larval Descriptions of Three Species of Epipaschiinae(Lepidoptera: Pyralidae) from China

The last-instar larval external morphologies of Orthaga achatina Butler, Macalla sp. and Locastra muscosalis （Walker） of Epipaschiinae are described and illustrated. All specimens examined are deposited in the Collection of College of Life Sciences, China Jiliang University, China. Biological information such as living habit also is included.

Last-instar Larval Descriptions of Three Species of Pyraustinae (Lepidoptera: Pyralidae) from Korea

The last-stage larval external morphologies of Pleuroptya rulalis （Scopoli）, Pleuroptya harutai （Inoue） and Botyodes diniasalis （Walker） of Pyraustinae are described and illustrated. All specimens are deposited in the Insect Collection of Department of Forest Resources Protection, Kangwon National University, Korea.

Last-instar Larval Descriptions of Three Species of Zygaenidae (Lepidoptera) from Korea

The last-instar larval external morphologies of Illiberis tenuis (Butler), Chalcosia remota (Walker) and Pryeria sinica Moore of Zygaenidae are described and illustrated. All the specimens are deposited in the Insect Collection of Department of Forest Resources Protection, Kangwon National University, Korea.

Larval Description of Three Species of Ennominae (Lepidoptera: Geometridae) in Korea

This study was made to describe the morphological features of larvae of Pachyligia dolosa Butle r, Cystidia stratonice (Stoll) and Planociampa antipala Prout of Ennomin ae.

Factors Affecting the Ovilarval Density of Aedes Spp. Mosquitoes in Selected Rice Fields of Mu^oz, Nueva Ecija

Variables among the macroclimate, microclimate and rice canopy categories and three other different farming systems were evaluated on their effects to the egg and larval density of Aedes spp. mosquitoes known as transmitters of animal and human diseases. No statistical difference in egg density （#eggs/mL） among farming systems （P = 0.345） were observed. However, there was significant difference in larval density （#1arvae/mL） among farming systems （P 〈 0.001） particularly between organic and conventional farms and between organic and mixed farms at （P 〈 0.05）. Among the variables in the macroclimate category, wind velocity and ambient temperature significantly influenced larval density in conventional farms. Among the variables in the microclimate category, water temperature significantly contributed to larval density in both the mixed and conventional farms whereas water turbidity, in conventional farms. Among the variables in the rice canopy category, the number of tillers per plant was a significant contributor to larval density in all farm types. No variable among the environmental exposure categories affected the larval density in organic farms.

LABORATORY OBSERVATION ON SPAWNING,FECUNDITY AND LARVAL DEVELOPMENT OF AMPHIOXUS (BRANCHIOSTOMA BELCHERI TSINGTAUNESE)

Although amphioxus is widespread in temperate and tropical seas,its population is diminishing be-cause of environmental pollution.To keep the population of this evolutionarily important animal fromdiminishing,study on its reproduction and development is necessary.The main findings in this study onthe spawning and fecundity of the amphioxus reared in laboratory and its larval development are as fol-lows.1.Water temperature markedly affected the spawning.It spawned only when water temperature reached 21℃.2.Spawning of the amphioxus in laboratory was markedly extended.Initially,the amphioxus spawned at about 7:00 PM,but spawning time was postponed as spawning days went on.3.The number of eggs produced by a female ranged from 1400 to 12800,average of 5800.This al-so represents the fecundity of the amphioxus because it shedded all eggs within the ovary at a time.4.During the first few months of life of the amphioxus,its growth rate changed seasonally.Thegrowth rate in summer and fall was greater than that

A larval specific OBP able to bind the major female sex pheromone component in Spodoptera exigua(Hübner)

Odorant binding proteins （OBPs） in insects are postulated to solubilize and transport the hydrophobic odorants across the hydrophilic antennal lymph to the olfactory receptors （ORs） located on the dendrite membrane of the sensory neurons. OBPs in adult insects have been intensively reported, but those in larvae are rarely addressed. In our study, a full-length OBP cDNA, namely SexiOBP13, was cloned by RT-PCR and RACE strategy from the heads of Spodoptera exigua larvae. The quantitative real-time PCR （qPCR） measurement indicated that SexiOBP13 was highly expressed in larval head, but very low in other parts of larva and was not detected in any tissues of adult. The binding affinities of SexiOBP13 to plant volatiles and female sex pheromone components were measured by competitive binding assays. Interestingly, SexiOBP13 displayed a high binding affinity （Ki=3.82 IJmol L-1） to Z9,E12-14：Ac, the major sex pheromone component of S. exigua, while low affinities to the tested host plant volatiles （Ki〉27 μmol L-l）. The behavioral tests further confirmed that Z9,E12-14：Ac was indeed active to elicit the behavioral activity of the third instar larvae of S. exigua. Taken together, our results suggest that SexiOBP13 may play a role in reception of female sex pheromone in S. exigua larvae. The ecological significance of the larvae preference to the adult female sex pheromone was discussed.

Effects of probiotic on microfloral structure of live feed used in larval breeding of turbot Scophthalmus maximus

The effects of an exogenous probiotic( Bacillus amyloliquefaciens) on microbial community structure of B ranchionus plicatils and A rtemia sinica were evaluated in this study during turbot( Scophthalmus maximus) larval breeding. The analysis and comparison of the microfloral composition of live feed with probiotic was conducted using the Illumina HiSeq PE250. The abundance of microbial species and diversity of microflora in live feed with B. amyloliquefaciens were higher than those in the control. The microfloral composition was similar among the three replicate experimental groups of B. plicatils compared with the control after enrichment. L actococcus, Pseudoalteromonas, and Alteromonas were always dominant. Additionally, some other bacterial species became dominant during the enrichment process. The microbial community during nutrient enrichment of A. sinica was rather similar among the three control replicates. Relative abundance of Cobetia sp., the most dominant species, was 54%–65.2%. Similarity in the microbial community was still high after adding B. amyloliquefaciens. Furthermore, P seudoalteromonas and Alteromonas replaced Cobetia as the dominant species, and the abundance of Cobetia decreased to 4.3%–25.3%. Mean common ratios at the operational taxonomic unit level were 50%–60% between the two B. plicatils and A. sinica treatments. Therefore, the microbial community structure changed after adding B. amyloliquefaciens during nutrient enrichment of B. plicatils or A. sinica and tended to stabilize. Additionally, the abundance of V ibrio in any kind of live feed was not significantly dif ferent from that in the control. These results will help improve the microflora of B. plicatils and A. sinica and can be used to understand the multiple-level transfer role of probiotic species among probiotic products, microflora of live feed, and fish larvae.

Characterization of Bacterial Communities Associating with Larval Development of Yesso Scallop(Patinopecten yessoensisis Jay, 1857) by High-Throughput Sequencing

Bacterial community presumably plays an essential role in inhibiting pathogen colonization and maintaining the health of scallop larvae, but limiting data are available for Yesso scallop （Patinopecten yessoensisis Jay, 1857） larval development stages. The aim of this study was to characterize and compare the bacterial communities associating with Yesso scallop larval development at fertilized egg S l, trochophora S2, D-shaped larvae S3, umbo larvae S4, and juvenile scallop S5 stages by Illumina high-throughput sequencing. Genomic DNA was extracted from the larvae and their associating baetera, and a gene segment covering V3-V4 region of 16S rRNA gene was amplified and sequenced using an Illumina Miseq sequencer. Overall, 106760 qualified sequences with an average length of 449 bp were obtained. Sequences were compared with those retrieved from 16S rRNA gene databases, and 4 phyla, 7 classes, 15 orders, 21 families, 31 genera were identified. Proteobacteria was predominant phylum, accounting for more than 99%, at all 5 larval development stages. At genus level, Pseudomonas was dominant at stages S1 （80.60%）, S2 （87.77%） and S5 （68.71%）, followed by Photobacterium （17.06%） and Aeromonas （1.64%） at stage S1, Serratia （6.94%）, Stenotrophomonas （3.08%） and Acinetobacter （1.2%） at stage S2, Shewanella （25.95%） and Pseudoalteromonas （4.57%） at stage S5. Moreover, genus Pseudoal- teromonas became dominant at stages S3 （44.85%） and S4 （56.02%）, followed by Photobacterium （29.82%）, Pseudomonas （11.86%）, Aliivibrio （8.60%） and Shewanella （3.39%） at stage S3, Pseudomonas （18.16%）, Aliivibrio （14.29%）, Shewanella （4.11%）, Psychro- monas （4.04%） and Psychrobacter （1.81%） at stage S4. From the results, we concluded that the bacterial community changed sig- nificantly at different development stages of Yesso Scallop larvae.

2D-QSAR Using MLR and 3D-QSAR Using CoMSIA Studies on the Toxicity of Aromatic Hydrocarbons on Larval Sinonvaculina Constricta

Aromatic hydrocarbons,one of the persistent organic pollutants（POPs）,has been usually found in mussels,accumulated for their hard mobility and activities in harbours and estuaries.In this study,based on the 96 hr-LC50 of 12 aromatic hydrocarbons with larval sinonvaculina constricta,three-dimensional quantitative structure-activity relationship（3D-QSAR） technique：comparative molecular similarity indices analysis（CoMSIA） and 2D-QSAR technique：multiple linear regression（MLR） were described to obtain more detailed insight into the structure-activity relationships between the molecular structure and bio-activity.The results show the MLR model based on density functional theory（DFT） calculation carried out at the B3LYP/6-311＊＊ level with Gaussian 03 program yielded a very good correlation with a coefficient squared R2 of 0.716 and a cross-validated Q2 of 0.874.The dipole moment and enthalpy,as the thermodynamic parameters,were two important factors influencing pLC50.Correspondingly,CoMSIA based on the partial least-squares（PLS） methodology with steric,electrostatic,hydrophobic,H-bond donor and acceptor fields contributing simultaneously were employed and the values of R2 and the cross validation with leave-One-Out（LOO） Q2LOO were 0.585 and 0.990,respectively,which reveals the structure features,such as the electronegative substituent（nitro-group）,hydrophobic groups（the benzene ring） and H-bond（nitro-group）,related to the toxicity.The results of 2D-QSAR employing MLR model and 3D-QSAR employing CoMSIA model provide the useful information for predicting the toxicity of other aromatic hydrocarbons by comparing the molecular structures of similar compounds.

Characterization of larval instars of artemisia weevil,Adosomus sp.

The artemisia weevil, Adosomus sp., has become an important wormwood （Artemisa ordosoca and A. sphaerocephala） pest in recent years in Ningxia Province, China. The number of larval instars should be determined before further studies on its life history, biology and integrate management of pest （IMP）. In this study, we measured the length and width of head capsule, based on frequency histograms and Dyar＇s law, from which we concluded that the larvae ofAdosomus sp. have four instars. Of the two variables measured, the width of head capsule provided the best division of instars. The average width of head capsule of the 1st instar larvae was 1.348±0.152 mm, the 2nd 2.109±0.199 mm, the 3rd 3.563±0.492 mm and the 4th 5.974±0.581 mm.

Dynamic metabolite alterations of Portunus trituberculatus during larval development

A mass mortality often occurs from molting to the megalopa stage during the larval development of the swimming crab Portunus trituberculatus. Larvae with insuffcient nutrient accumulation during the zoeal stages are probably unable to develop into juvenile swimming crabs. However, the nutritional information such as the primary metabolites is scarce for P. trituberculatus larvae. The aim of this work is to obtain an insight into the metabolite traits of P. trituberculatus at early developmental stages. 1 H nuclear magnetic resonance spectroscopy coupled with multivariate data analysis was used to determine how the metabolite pro?les shift during larval development in P. trituberculatus. Our results show that the trend of total metabolites exhibited a rise from zoea 1 to zoea 3, followed by a drop from zoea 4 to megalopa and recovery during the ?rst juvenile stage. A large-scale depletion of total metabolites in the zoea 4 and megalopa stages suggests a deep depression of metabolic activity, which may be linked to the mass mortality from molting to the megalopa stage. These ?ndings provided essential metabolic information about the larval development of P. trituberculatus and important clues for understanding the nutritional requirements of P. trituberculatus in early developmental stages.

Environmental characteristics of anopheline mosquito larval habitats in a malaria endemic area in Iran

Objective:To determine the effects of environmental parameters of lanal habitats on distribution and abundance of anopheline mosquitoes in Rudan county of Iran.Methods:This cross-sectional study was conducted during the mosquito breeding season from February 2010 to October 2011. The anopheline larvae were collected using the standard dipping method,the specimens were identified using a morphological-based key.Simultaneously with larvay collection,environmental parameters of the larval habitats including water current and turbidity,sunlight situation,and substrate type of habitats were recorded.Water samples were taken from breeding sites during lanal collection.Before collection of samples,the water temperature was measured.The water samples were analysed for turbidity,conductivity,total alkalinity,total dissolved solid.pH and ions including chloride,sulphate,calcium,and magnesium.Statistical correlation analysis and ANOVA test were used to analyze the association between environmental parameters and larval mosquito abundance.Results:In total 2 973 lanae of the genus Anopheles were collected from 25 larval habitats and identified using morphological characters.They comprised of six species: An.dthali(53.21%),An.stephensi(24.22%),An.culicifacies(14.06%),An.superpictus(4.07%),An. turkhudi(3.30%),and An.apoci(1.14%).The most abundant species was An.dthali which were collected from all of the study areas.Larvae of two malaria vectors.An.dthali and An.stephensi, co-existed and collected in a wide range of habitats with different physico-chemical parameters. The most common larval habitats were man-made sites such as sand mining pools with clean and still water.The anopheline mosquitoes also preferred permanent habitats in sunlight with sandy substrates.The results indicated that there was a significant relationship between mean physicochemical parameters such as water temperature,conductivity,total alkalinity,sulphate,chloride, and mosquito distribution and abundance.Conclusions:The results of this study showed a correlation between certain environmental parameters and mosquito lanae abundance,and these parameters should be considered in planning and implementing larval control programs.

COMPARATIVE STUDIES ON THE LARVAL DEVELOPMENT OF THE PENAEID SHRIMPS,PENAEUS CHINENSIS,P.MERGUIENSIS AND P.PENICILLATUS

The morphology of larval and 1st postlarval stages of Penaeus penicillatus are described.Results from comparative studies on larval development of P.penicillatus,P.merguiensis and P.chinensis are as fol-lows: These three species could not be identified during their naupliar stages. In the 1st protozoea,the antennule L1/L2 value is 1.7—2.0 in P.merguiensis,but lessthan 1.7 in P.chinensis and P.penicillatus;in the 2nd protozoea,the supra-orbital spine in P.chinensis isnot bifurcated,while those of P.merguiensis and P.penicillatus are bifurcated;in the 3rd protozoea,thereis a minute(or no)dorso-median spine on the posterior margin of the 1st and 2nd abdominal somite in P.chinensis,but they are prominent in P.merguiensis and P.penicillatus.In the mysis and 1st postlarvalstages,P.chinensis differs from P.merguiensis and P.penicillatus in having 9(8 in the other 2 species)longsetae on the exopod of pereopods 1—3;additionally,one dorsal tooth appears on the rostrum of P.chinensis in the 2nd mysis and that

Larval descriptions for four species in the genus Pleuroptya (Lepidoptera: Crambidae: Spilomelinae) from China, with notes on biology

The mature larvae of four species in the genus Pleuroptya： P. chlorophanta （Butler）, P. balteata （Fabricius）, P. quadrimaculalis （Kollar ＆ Redtenbacher） and B sabinusalis （Walker） are described and illustrated. Biological notes based on larvae are provided.

Larval habitats of mosquito fauna in Osogbo metropolis,Southwestern Nigeria

Objective:To determine the larval habitats of mosquito fauna and possible impact of land use/land cover changes on the epidemiology of mosquito-bome diseases in Osogbo metropolis,Southwestern,Nigeria.Methods:All accessible larval habitats were surveyed between May and September,2011in Osogbo metropolis while Land Use/Land cover of the city was analyzed using 2 Lansat Multispectral Scanner satellite imagery of SPOT 1986 and T.ANDSAT TM 2009.Results:A total of six species namely,Aedes aegypti,Aedes albopictus,Aedes vittatus,Anopheles gambiae complex,Culex quinquefascialus and Erelmapodite chrysogaster were encountered during the study.The occurrence and contribution of disused tyres was significantly higher(P<0.05)than the other habitats encountered,while there were no significant differences in the contribution of gutters/run-offs.septic tanks/drums,ground pools/open drains and discarded containers lo the breeding of mosquitoes(P>0.05).The accessible land use/land covered of the study area between 1986 and 2009 showed that the wet land coverage and settlement area increased from 0.19 lo 9.09 hectare and 1.00 to 2.01 hectare respectively while the forest area decreased from 60.18 to 50.14 hectare.Conclusion:The contribution of the habitats coupled with the increasing rale of flooded environment which could provide ample breeding sites for mosquitoes call for sustained environmental sanitation and management in Osogbo metropolis.

Larval stages of digenetic trematodes in Melanopsis praemorsa snails from freshwater bodies in Palestine

Objective:To detect the species of larval trematodes(cercariae) in Melanopsis praemorsa snails from 5 different fresh water bodies in Palestine.Methods:A total of 1 880 Melanopsis praemona snails were collected from different fresh water bodies in Palestine from October,2008 to November,2010.Cercariae in Melanopsis praemona snails were obtained by lighting and crushing methods.The behavior of cercariae was observed using a dissecting microscope.Results:Three different species of larval trematodes were identified from Melanopsis praemona snails collected only from Al-Bathan fresh water body,while snails from other water bodies were not infected. These species were microcercous cercaria,xiphidiocercaria and brevifurcate lophocercous cercaria.These cercariae called Cercaria melanopsi palestinia 1,Cercaria melanopsi palestinia H and Cercaria melanopsi palestinia III have not been described before from this snail in Palestine. The infection rate of Melanopsis praemona collected from Al-Bathan fresh water body was 5.7%, while the overall infection rate of snails collected from all fresh water bodies was 4.3%.Details are presented on the morphology and behavior of the cercariae as well as their development within the snail.Conclusions:These results have been recorded for the first time and these cercariae may be of medical and veterinary importance.

An integrative study of larval organogenesis of American shad Alosa sapidissima in histological aspects

We describe organogenesis at a histological level in American shad( Alosa sapidissima) larvae from 0 until 45 days after hatching(DAH). Larval development was divided into four stages based on the feeding mode,external morphological features,and structural changes in the organs: stage 1(0–2 DAH),stage 2(3–5 DAH),stage 3(6–26 DAH) and stage 4(27–45 DAH). At early stage 2(3 DAH),American shad larvae developed the initial digestive and absorptive tissues,including the mouth and anal opening,buccopharyngeal cavity,oesophagus,incipient stomach,anterior and posterior intestine,differentiated hepatocytes,and exocrine pancreas. The digestive and absorptive capacity developed further in stages 2 to 3,at which time the pharyngeal teeth,taste buds,gut mucosa folds,differentiated stomach,and gastric glands could be observed. Four defined compartments were discernible in the heart at 4 DAH. From 3 to 13 DAH,the excretory systems started to develop,accompanied by urinary bladder opening,the appearance and development of primordial pronephros,and the proliferation and convolution of renal tubules. Primordial gills were detected at 2 DAH,the pseudobranch was visible at 6 DAH,and the filaments and lamellae proliferated rapidly during stage 3. The primordial swim bladder was first observed at 2 DAH and started to inflate at 9 DAH; from then on,it expanded constantly. The spleen was first observed at 8 DAH and the thymus was evident at 12 DAH. From stage 4 onwards,most organs essentially manifested an increase in size,number,and complexity of tissue structure.