Megalopa Research Articles

Helicoverpa zea-Associated Gut Bacteria as Drivers in Shaping Plant Anti-herbivore Defense in Tomato.

Insect-associated bacteria can mediate the intersection of insect and plant immunity. In this study, we aimed to evaluate the effects of single isolates or communities of gut-associated bacteria of Helicoverpa zea larvae on herbivore-induced defenses in tomato. We first identified bacterial isolates from the regurgitant of field-collected H. zea larvae by using a culture-dependent method and 16S rRNA gene sequencing. We identified 11 isolates belonging to the families Enterobacteriaceae, Streptococcaceae, Yersiniaceae, Erwiniaceae, and unclassified Enterobacterales. Seven different bacterial isolates, namely Enterobacteriaceae-1, Lactococcus sp., Klebsiella sp. 1, Klebsiella sp. 3, Enterobacterales, Enterobacteriaceae-2, and Pantoea sp., were selected based on their phylogenetic relationships to test their impacts on insect-induced plant defenses. We found that the laboratory population of H. zea larvae inoculated with individual isolates did not induce plant anti-herbivore defenses, whereas larvae inoculated with a bacterial community (combination of the 7 bacterial isolates) triggered increased polyphenol oxidase (PPO) activity in tomato, leading to retarded larval development. Additionally, field-collected H. zea larvae with an unaltered bacterial community in their gut stimulated higher plant defenses than the larvae with a reduced gut microbial community. In summary, our findings highlight the importance of the gut microbial community in mediating interactions between herbivores and their host plants.

Dietary effects of intensively reared zoeae of Portunus trituberculatus on survival and growth of paralarvae of the East Asian common octopus Octopus sinensis

Zoea larvae of decapod crustaceans are considered to be the best prey organisms for culturing paralarvae of merobenthic octopuses. Because paralarvae consume many zoeae until settling as juveniles, a reliable method is required to rear a large number of zoeae at a high stocking density while maintaining their nutrition at a level to meet the demands of octopus paralarvae. However, when rearing zoeae, “sinking-death syndrome” (where many zoeae are deposited on the bottom of the rearing tanks) results in high mortality. In Experiment 1, to reduce larval deposition and lower the mortality, an upwelling system was installed and tested for its effectiveness in rearing a high stocking density of Portunus trituberculatus zoeae at low mortality. The effect of different supply densities of Artemia on growth and morphology of zoeae was also investigated to evaluate the nutrient sufficiency of zoeae under intensive rearing conditions. In Experiment 2, Octopus sinensis paralarvae were reared for 15 d, supplied with either early-stage zoeae or late-stage (long-term reared) zoeae, to examine the dietary effect of intensively reared zoeae on paralarval survival and growth. In Experiment 1, the proportion of zoeae sinking to the bottom was significantly reduced by using the upwelling system, and the survival rate of zoeae was higher in tanks with an upwelling system at a high stocking density of zoeae (500 individuals L−1) compared to those without. Larger body size and faster morphogenesis of larvae were obtained at the final (fourth) zoeal stage when zoeae were supplied with Artemia at high density compared with those supplied at low density. Composition of docosahexaenoic acid (DHA) in intensively-reared final-stage zoeae (10 d old) was maintained at a similar level to that in first-stage zoeae (1 d old) by supplying a high density of Artemia enriched with DHA. In Experiment 2, a higher survival rate and heavier body weight of paralarvae were obtained in the group supplied mainly with late-stage zoeae compared to that with early-stage zoeae. Because the supply of zoeae was adjusted to the same dry weight for both groups, it is concluded that supplying large-sized zoeae increases the efficiency of prey capture and nutrient absorption by the paralarvae. These results suggest that a combination of the use of an upwelling system and a high-density supply of enriched Artemia is effective for intensive rearing of zoeae, achieving reduced facility costs and more efficient production of high-quality prey for rearing octopus paralarvae.

Morphological Description of Megalopal Stages of Three Portunid Species (Decapoda, 2 Brachyura, Portunidae) from Indus Deltaic Area (northern-Arabian Sea)

The larvae of crustaceans, including those of brachyuran crabs, are a significant part of zooplanktonic communities constituting an ecologically important fraction of the pelagic communities. The present study describes taxonomic studies on three megalop stages of Portunus pelagicus (Linnaeus, 1758), Charybdis feriatus (Linnaeus, 1758) and Carcinus maenas (Linnaeus, 1758) belonging to family Portunidae collected from Indus deltaic creek system. Zooplankton samples were collected from three locations: Shahbandar 24°15’48.083’N, 67°90’15’333’E, Ketibandar 24°9’16.06’N, 67°27’7.64’E and Korangi creek 24°48’18.80’’N, 67°12’30.31’E during April to October 2018. No data available on taxonomic studies of portunid megalops upto species level from Paksitan, hence this is a first attempt to examine and to describe taxonomic features of megalops collected in the zooplankton samples. This study will contribute to the scientific knowledge on megalops taxonomy and identification as well as be useful for future research by taxonomists and biologists.

The transcriptome of Litopenaeus vannamei in zoea larvae and adults infected by Vibrio parahaemolyticus

IntroductionThe rapid development of the Litopenaeus vannamei industry largely depends on the acquisition of high-quality larvae. Shrimp larval development is a unique metamorphic process that results in mortality due to disease vulnerability. Currently, studies on innate immunity in shrimp are mainly focused on the adult stage, but little has been done on innate immunity in larvae.MethodsIn this study, utilizing a high-throughput Illumina sequencing approach, we compare the transcriptome of L. vannamei Zoea larvae and adults infected by Vibrio parahaemolyticus.ResultsA total of 487,887,650 high quality reads were obtained, assembled, and aggregated into 23,802 genes, among which 3315 were identified as differentially expressed genes. Then GO term enrichment analysis, KEGG pathway enrichment analysis and functional gene analysis were performed. We found that pathways that are involved in the innate immune response, such as mTOR signaling pathway, MAPK signaling pathway, and Notch signaling pathway, were more enriched in the Zoea stage compared to the adult stage, suggesting that innate immunity against Vibrio vulnificus may exist during the Zoea larvae stage.Discussionwere more enriched in the Zoea stage compared to the adult stage, suggesting that innate immunity against Vibrio vulnificus may exist during the Zoea larvae stage. These findings will provide useful information for the study of innate immunity in shrimp larvae.

Genes expression in Penaeus monodon of Bangladesh; challenged with AHPND-causing Vibrio parahaemolyticus

Vibrio parahaemolyticus, the causative agent of Acute hepatopancreatic necrosis disease (AHPND), was discovered in 2013 as a unique isolate that produces toxins and kills penaeid shrimps in devasting nature in Bangladesh and causes severe economic losses. This research aimed to understand the expressions of immune genes in different stages of the host species, Penaeus monodon, against virulence and toxin genes upon being challenged with V. parahaemolyticus. Healthy post-larvae (PL) samples were collected from southwestern of Bangladesh from July 2021 to August 2022. The tryptic soy agar with 1.5% sodium chloride (NaCl) was used to inoculate the cells of V. parahaemolyticus, and the tryptic soy broth (TSB) with 1.5% NaCl was used to transfer the colonies. The spectrophotometry measured bacteria density. PCR, qPCR, SDS-PAGE, and Western blot measured gene expression and survivability after the immersion challenge. The 1 × 105CFU/mL of V. parahaemolyticus was used for 144 h.p.i (hours post-infection) challenge to six stages of post-larvae (PL) of P. monodon (PL20, PL25, PL30, PL35, PL40, and PL45), PL30 and PL35 showed 100% mortality by day 72 (h.p.i.) after exposure that indicated most vulnerable to V. parahaemolyticus. The expression of immune and toxic genes was confirmed by qPCR. The immune genes toll-like receptors (TLR), prophenoloxidase (ProPO), lysozyme (lyso), and penaeidin (PEN) of PL20 and PL25 of P. monodon were expressed robustly up-trends. PL30 and PL35 showed the lowest gene expression at the end of 72 (h.p.i.). At the end of the 144 (h.p.i.) exposure, the immune genes TLR, ProPO, lyso, and PEN expressed highest in PL45 than other post-larvae stages of P. monodon. The toxic genes (pirA, ToxR, ToxA, ToxB, tlh, tdh, and trh) in PL30 and PL35 of P. monodon after exposure of V. parahaemolyticus were expressed highest at the end of the 72 (h.p.i.). The lowest toxic genes expressions were revealed in PL20 and PL45 at the end of the 144 (h.p.i.). The SDS-PAGE analysis of proteins from the bacterium revealed identical protein profiles with toxic genes, and those toxins were further confirmed by Western blot. The 20 kDa, 78 kDa (ToxR), 20 kDa, 25 kDa (ToxA), 25 kDa (ToxB), 20 kDa, 27 kDa, 75 kDa (tdh), and 20 kDa, 27 kDa, 75 kDa, and 78 kDa (trh) proteins were strong responses in Western blot, indicating the crucial involvement of these immune-related genes in the defense and recovery of the first-line defense mechanisms during V. parahaemolyticus infection to shrimp. The all-toxic genes showed a unique homology and those derived from the common ancestor compared with V. parahaemolyticus (NCBI accession no. AP014859.1). All clades were derived with different traits with very low genetic distance, where the overall mean distance was 3.18 and showed a very uniform and homogenous pattern among the lineages. The V. parahaemolyticus infection process in different PL stages in P. monodon revealed novel insights into the immune responses. The responses may lead to the subsequent production of a DNA vaccine, enhancing shrimp health management to minimize the economic losses due to AHPND experiencing an outbreak of early mortality syndrome (EMS) toward sustainable production P. monodon (shrimp).

Decomposition and insect succession of pig cadavers in tents versus outdoors – A preliminary study

The pattern of insect succession and the species composition on cadavers can be influenced by several parameters, one of which is concealment. It has been previously shown for cadavers inside containers (e.g. suitcases or vehicles) or various indoor situations, that concealment can lead to a delayed arrival, altered species composition and decreased number of taxa present at the cadaver. As no data is yet available for the specific environment of tents on these processes, we placed five pig cadavers inside closed two-person tents during the summer of 2021 in a mixed forest in Germany. Five control cadavers were freely accessible for insects. To minimize disturbances, tents were only opened every fifth day over a period of 25 days for estimating the temperature profiles, insect diversity and quantification of the cadavers’ decomposition using the total body score (TBS).The temperature inside the tents was only slightly elevated compared to the ambient temperature during the study. Although the tents prevented direct access of adult flies and beetles, the cadavers were colonized because the flies oviposited on the zippers and fly screens of the inner tents. However, the resulting infestation of the cadavers by fly larvae was reduced and delayed, compared to the exposed cadavers. The dominant fly species on both the tent and exposed cadavers was the blow fly Lucilia caesar. Open cadavers showed the expected decomposition patterns with large larval masses. 25 days after placement, only bones and hair remained from the exposed pigs (TBS = 32), while most of the tissue of the cadavers inside the tents was still present (TBS = 22.5) and post feeding larvae were not able to leave the tents. Regarding the attraction of beetles to both treatments, open cadavers were predominately colonized by the silphid Oiceoptoma thoracicum, while the silphid Necrodes littoralis was the most dominant species in the pitfall traps surrounding the tents. Considering the prolonged pre-appearance interval of fly larvae colonizing the cadavers inside tents, the entomological evidence of forensic cases dealing with concealed bodies should be handled with caution, since the post mortem interval might be significantly underestimated.

Reproductive performance of captive-reared Indian white shrimp, Penaeus indicus, broodstocks over two generations

Closing the complex life cycle of closed thelycum shrimp in captivity is one of the fundamental challenges in breeding programs. In the present study, we investigated the sexual maturity, broodstock development, and spawning performance of two generations of captive-reared Indian white shrimp, Penaeus indicus, over 36 months originated from a single stock of wild brooders. The post larvae (GN-1) produced from wild P. indicus (G0) and P.L. (GN-2) produced from captive-reared (GN-1) broodstocks were nursery (1000 PL m-3) and grow-out (12 shrimp m-2) reared, and subsequently raised in broodstock ponds (1 shrimp m-2). The annual salinity and photoperiod in broodstock ponds varied between 20 to 36 ppt, and 11.2 -12.5 L and 11.5-12.8 D hours, respectively. The light intensity varied between 91 ± 6 lux at dusk to 75,358 ± 1719 lux at noon. The size at first impregnation or mating was 16.45 ± 1.7 g (132 DOC) and 17.62 ± 1.9 g (90 DOC), respectively, in GN-1 and GN-2 females. By 220 DOC, 25% of the GN-1 females initiated gonad development, whereas 55% of the GN-2 females recorded developing ovaries or were in stage II at 150 DOC. The broodstock attained an average final body weight of 38.85 ± 1.5 g (GN-1) and 42.65 ± 1.8 g (GN-2) by 360 DOC. The highest (p<0.01) eggs per gram body weight (5137 ± 303 eggs g-1) and hatchability, H (83 ± 0.7%), was recorded in wild broodstocks (G0) followed by GN-2 (1,715 ± 162 eggs g-1; H: 69 ± 2%) and GN-1 (1,476 ± 151 eggs g-1; H: 75 ± 1%). However, captive-reared broodstock had better survival (89-92%) than wild broodstocks (71 ± 0.8%). Further, indoor maturation trial (21 days) using ablated broodstocks (GN-1) revealed 79% of the impregnated broodstocks undergo molting, resulting in the loss of sperm pack and subsequent reduction in mating efficacy to 29%. The average sperm count and percentage of normal sperm also recorded (p<0.05) reduction during the maturation cycle. The data generated in the present investigation can form the baseline information for developing the breeding strategy for the genetic improvement of Indian white shrimp in India.

Variation of dietary protein/lipid levels used in postlarvae of freshwater prawn Macrobrachium rosenbergii cultured in a biofloc system

A 70-day experimental trial was performed to evaluate the contribution of biofloc to the nutrition of Macrobrachium rosenbergii 15 days old postlarvae (PL) (average 82.00 ± 19.71 mg) fed different crude protein (P) and lipids (L) levels in zero-water exchange culture tanks. Six biofloc treatments (BFT) as experimental diets with 15, 20, or 25% P levels and 5 or 8% L levels were managed: BFT-15/5; BFT-15/8; BFT-20/5; BFT-20/8; BFT-25/5; BFT-25/8, and a clear-water control without biofloc fed with 25% P and 8% L (CW-25/8). The experiment was done in triplicate in 21-60 L plastic tanks containing 10 prawns tank-1. At the end of the experiment, survival of prawns was above 66%, with no significant differences among experimental groups (P > 0.05). The best growth performance was observed in the experimental prawns maintained in BFT-20/5, BFT-20/8, BF-25/5, and BFT-25/8 compared to the control (P < 0.001). The feed conversion rate of the prawns in BFT-20/5 was significantly lower than that in control (P < 0.001); the best P efficiency ratio and productive P value were observed in all BFT compared to control prawns (P < 0.001). Results showed that it is feasible to use low concentrations of P (20%) and L (5%) in diets to grow giant freshwater prawn PL in a biofloc system. Results also demonstrated that biofloc contributes to the P and L requirements of cultured freshwater prawn PL, as indicated by improved feed utilization, P retention, and growth performance.

Immersion Effect of Estradiol-17β on Cannibalism of Asian Redtail Catfish (<I>Hemibagrus nemurus</I>) Post Larvae

Highlight Research The dose, duration of immersion, and time interval of immersion of the estradiol-17β affect the rate of cannibalism and increase the seed survival of Asian redtail catfish in low treatment in this research. Over optimum treatment increased the incidence of cannibalism at Asian redtail catfish and decrease growth performance. Treatment of estradiol-17β, give the ability of Asian redtail catfish to live on high density The treatment of estradiol-17β, has an effect on concentration plasma of body testosterone and cortisol Abstract The cannibalistic behavior of Asian redtail catfish greatly hampers the supply of these fish seeds, invoking the need to be controlled. Estradiol is one of the hormones that has been known to reduce cannibalistic behavior on fish. This study aimed to evaluate the effect of estradiol-17β immersion on the incidence of cannibalism in the rearing of post larvae of Asian redtail catfish. Post larvae was treated with a combination of doses of estradiol hormone 0, 1, and 2 ppm and immersion time of two and four hours with immersion intervals of three and six days with a completely randomized design. Each treatment had a fish density of 10 fish L-1, with mean size individual length of 6.73 ± 0.73 mm (three days of age after hatched), with four replications. Fish were fed with tubifex up until satiation point and reared for 30 days. The results showed that the administration of the estradiol-17β through immersion with a dose of 1 ppm for two hours and interval of six days was able to reduce the level of cannibalism and increase the survivability. A further increase in dose, immersion time, and interval had the opposite effect. Estradiol-17β immersion with certain dose, duration, and interval affected the rate of cannibalism, growth rate, and survival. Estradiol-17β immersion at a dose of 1 ppm for two hours and six days interval was the best to reduce the level of cannibalism and normal mortality in post larvae of Asian redtail catfish.

DNA barcoding of crustacean larvae with two new records of Caridina gracilipes and Ptychognathus altimanus in the Western Region of Segara Anakan lagoon in Indonesia

Abstract. Winarni ET, Simanjuntak SBI, Nuryanto A. 2023. DNA barcoding of crustacean larvae with two new records of Caridina gracilipes and Ptychognathus altimanus in the Western Region of Segara Anakan lagoon in Indonesia. Biodiversitas 24: 341-348. Several studies have been carried out on crustacean larvae diversity, but they focused on the eastern and central regions of the Segara Anakan lagoon/estuary, Cilacap District, Central Java Province, Indonesia. Furthermore, one study has explored crustaceans in the western region but focused on adult individuals and used morphological characteristics. Currently, there is no internet data on the crustacean larvae diversity from the estuary's western region, and there is a high possibility that some species are unidentified. This study aims to describe crustacean larvae diversity in the western region of the Segara Anakan lagoon in Indonesia by using DNA barcoding. Sequence divergence of 3% to databases in GenBank and BOLDsystems was used as a genetic threshold for species border. A total of 14 morphotypes were barcoded, but only nine were successful, of which three were identified as bacteria and six as crustaceans. Based on the predetermined genetic threshold, all crustacean morphotypes can be identified at the species level, and six species were obtained. Meanwhile, a previous study on the adult individual only identified specimens at the genus level, and only one genus was similar to these obtained results. A total of 5 out of 6 species were new records to the western region Cilacap, while 2, namely Caridina gracilipes and Ptychognathus altimanus, are newly recorded in the Segara Anakan lagoon. These results contribute significantly to the information on crustacea larvae diversity, which is essential for sustainable management.

Fluorene is Highly Toxic to Zoea Larvae of the Red-Clawed Crab Chiromantes haematocheir

Fluorene is Highly Toxic to Zoea Larvae of the Red-Clawed Crab Chiromantes haematocheir

Phenotypic variability in the shield morphology of wild- vs. lab-reared eumalacostracan larvae

Morphological identification of planktic crustacean larvae is required in many scientific contexts, such as ecology or taxonomy. Due to a still low availability of genetic sequences for many ingroups of Eumalacostraca, this task is still more feasible by morphological methods. Our understanding of eumalacostracan larval morphology is challenged by phenotypic variability. We investigated four eumalacostracan ingroups: Galatheidae, Hippoidea, Raninidae and Stomatopoda. Representatives of all four groups develop through spine-bearing planktic larval stages. Incorporating dorsal and lateral shield outlines into three-dimensional shape analysis of the shields, we compare specimens from the wild with laboratory-reared specimens. Using graphical and statistical analysis methods, we find that at least the lateral morphology of the shields of Hippoidea and Raninidae seems to be too strongly dependent on phylogeny to show phenotypic variability with our current sample size, but Hippoidea do show phenotypic variability in their dorsal shield morphology. In Galatheidae and Stomatopoda, a clear difference in shield morphology can be found between wild-caught and laboratory-reared specimens. This difference likely represents phenotypic variability. The exact environmental signals causing this phenotypic variability are still unknown, but some candidates are discussed.

Histopathological Investigation of the Giant Prawn Macrobrachium rosenbergii in the Extensive Culture Ponds of Nellore Region, Andhra Pradesh, India

The present study was carried out in Muthukur area of Nellore region of Andhra Pradesh located at 14.29 19 latitude and 80.10383 longitude), India since this area is actively engaged with aquaculture activities of fish and prawn farming. A recent data indicated that 280 to 984 kg per hectare per crop achieved in Macrobrachium rosenbergii under extensive system in a culture period of 180 to 210 with stocking density of 3 to 5 juveniles per square meter. Since the scampi Macrobrachium rosenbergii was the candidate as well as prominent species in that region, histopathological study was carried out to the see quality of the prawn for the present study. During the investigation of shrimp disease in the culture pond, the prawn Macrobrachium rosenbergii were found to die due to swollen head disease having enlargement of cephalothoracic region containing gill, heart and hepatopancreas, etc. Another kind of symptom of black spots were noticed on the dorsal portion of anterior exoskeleton in the cephalothorax region. Enlargement of pigmentary with black spots formed in the periphery of dorsal side of exoskeleton might be due to the presence of suspected white spot syndrome virus. This kind of disease was found to attack commonly in Macrobrachium rosenbergii in most of the culture ponds. Apart from the study of shrimp disease in culture ponds, attempts were also made to identify the disease in the post larvae of Macrobrachium rosenbergii in the hatchery in and around Nellore region. Mass mortality was found to occur in the post larval stages due to a kind of white muscle disease. It has led to great loss of economy not only to the entrepreneurs involved in the hatchery at Nellore region but also to the country as well. WSSV was characterised by prominent eosinophilic to pale basophilic intra nuclear inclusion bodies in hypertrophied nuclei of most commonly in the epithelial cells and connective tissue cells of the above target tissues. Result of the study showed that multiple infection is quite common in the prawn to be cultured once the water quality has become deteriorated and It is suggested that although it is a extensive culture system, water management and supplement of feeds are prerequisite to maintain the pond.

Potential inert diets to supplement Artemia in larviculture of the giant Africa river prawn Macrobrachium vollenhovenii (Herklots, 1857) (Crustacea: Palaemonidae)

The protocol of culture of Macrobrachium vollenhovenii the main indigenous candidate for freshwater prawn culture in Africa is still under study. Though just few information exists, the transition of larvae from stage V to stage VI has been reported as the critical rearing period in larviculture. This study was to evaluate the efficiency of two locally diets to supplement Artemia in the feeding scheme from stage V to post larvae in the larviculture of this species. The two experimental diets were differentiated by the main source of protein: fish silage (Diet 1) and shrimp meat (Diet 2). One batch of larvae was cultured till stage V. The experiment itself was conducted in triplicate with three treatments: feeding Artemia exclusively (TA, control); fed partial replacement of Artemia with inert diet 1 (T1) or fed partial replacement of Artemia with diet 2 (T2). Larval development in T2 was significantly faster than TA and T1. Survival rate was significantly higher in T2 (12.64±1.2%) than TA (6.57±0.29%) and T1 (6.77±0.17%). The total length of larvae in T2 was significantly higher than TA and T1. Though the highest survival obtained in this study is still low, it’s however higher than those reported in other studies with this species. Also, the importance of finding alternatives to Artemia and cheaper diets remains very important.

APLIKASI PAKAN ALAMI DAN BUATAN PADA PEMELIHARAAN LARVA UDANG VANNAME (Litopenaeus vannamei) DI HATCHERY PT. SURI TANI PEMUKA UNIT HATCHERY NEGARA, BALI

This study aims to determine the application of live and artificial feed in the rearing of vanname shrimp larvae (Litopenaeus vannamei). The work consists of preparation of rearing media, nauplii stocking, feed management and monitoring of larval rearing. A total of 2,000,000 nauplii were used and reared in concrete tanks with a water volume capacity of 14 tons equipped with a filtration system and water changes carried out by flowtrough and circulation. The feed used consisted of livel feed including Chaetoceros muelleri, Thalassiosira sp and Artemia sp. and also artificial feed (commercial feed). The results showed that the application of live and artificial feed during larval rearing was positively correlated with larval stadia development and larval survival rate. Larval development in each stadia, including zoea, mysis and post larvae, showed normal development. The total larval population at each stadia decreased with a final mortality value of 40%. Nevertheless, the survival rate until the end of the PL-10 rearing period was observed to be 60% and this condition was in optimal condition

Plankton Community Structure and Biomass in the Eastern Middle Caspian Sea

Despite the role of planktonic organisms in the fishery value of the Caspian Sea and in addition to the increase in the plankton population in the Caspian Sea, there are few detailed studies regarding the determination of the planktonic organisms in the Caspian Sea. In the present investigation, we aimed to study the cell abundance and diversity of the phyto- and zooplankton in the eastern part of the Middle Caspian Sea in the spring of 2016. The composition of phytoplankton consisted of 50 species belonging to 4 systematic groups which were registered in the eastern part of the Middle Caspian: Cyanophyta (7), Bacillariophyta (24), Dinoflagellata (13), and Chlorophyta (6). Zooplankton were represented by 9 taxa: Cladocera—6, Copepod—1, and other groups—2. The most important phytoplankton species were Rhizosolenia calcar-avis, Anabaena bergii, Exuviaella cordata, and Binuclearia lauterbornii. The 0–50 m layer in the eastern Middle Caspian was the most productive, where the biomass varied from 98 mg/m3 to 109 mg/m3, consisting largely of diatoms. The cladoceran Evadne anonyx typica, the copepod Acartia tonsa, and the larvae of barnacle crustaceans (Cirripedia) were widely distributed in this layer. Zooplankton abundance decreased markedly with the depth. The maximum zooplankton concentrations were confined to depths down to 200 m.

Helicoverpa zea (Lepidoptera: Noctuidae) In-Season and Overwintering Pupation Response to Soil Type.

Heliothinae soil pupation is understudied despite the key role this life stage plays in their development. Many Heliothinae are important agricultural pests and understanding the interplay of environment and pupation is important to optimize pest management tactics oriented toward pupae. We studied the impact of three soil types (coarse sand, high organic muck, and fine-textured clay) on Helicoverpa zea (Boddie) in-season and overwintering pupal survivorship, diapause, depth, and weight in at two locations (North and South Carolina). We introduced wild-collected (in-season) and laboratory-reared (over the winter) infestations of H. zea larvae to each of the three soils and later excavated pupae. In-season and over the winter pupal survivorship was lower in fine-textured clay soils than in coarse sand or high organic muck. In addition, pupal depth and weight, in-season and over the winter, varied significantly by soil type. In general, depth was the shallowest, and pupae weight was lower when recovered from fine-textured clay soils. Finally, diapausing characteristics varied significantly by location and year, likely impacted by differing environmental conditions. Our results suggest that fine-textured clay soils negatively impact Heliothinae pupation and may be suppressing populations in areas with these soil types.

A study on the feeding of shrimp larvae of Macrobrachium nipponense on algae in vitro

Experiments were carried out for the propagation and rearing of Macrobrachium nipponense and its feeding on algae, with the aim of determining the density, survival, and growth of larvae in vitro. Hatched larvae of zoae were reared at a density of 50 zoea/L with algae mixture: Chlorella vulgaris, Scenedesmus sp., Pediastrium sp., Microctinium sp., Navicula sp., Ulothrix sp., Cyclotella sp., Daitoma sp. at three concentrations of 0.5=A, 1.0=B, 1.5=C x 10⁵ cell/ml, and the survival % rates of zoea larvae were 45.00±5.00, 53.33±7.64, 50.00±5.00 respectively. Then, three densities: 25=A, 50=B, 75=C zoea/L were tested by feeding them with the best concentration of 1.0×10⁵ cell/ml for 10 days, with the result being survival % rates were 50.00±5.00, 51.67±7.64, 31.67±7.64, respectively. After that, stage post-larvae were reared at a density of (50=A,100=B, 150=C) Pl/pond and fed with a concentration of 1.0 x 10⁵ cell/ml of the algae mixture for 28 days, which resulted in survival % rates of 48.33±7.64, 40.00±5.00, 33.33±7.64, and this stage, weight was 50.67±2.08, 50.00±2.00, 40.33±2.52mg respectively. The results of the analysis of survival rates for different densities of zoea larvae found significant differences (P < 0.05) between density C and density of both A and B, of which there were no significant differences (P > 0.05) between them. There were no significant differences (p > 0.05) in the survival rates of zoea in different concentrations of the selected algae. Also, there were no significant differences (p > 0.05) in the survival rates and weight rate of post-larvae when fed on algae (B).

Potential of Fermented Commercial Feed to Replace Silk Worms on Post larvae of Asian Redtail Catfish (Hemibagrus nemurus)

Asian redtail catfish (Hemibagrus nemurus) is an economically fish on Malay community. On its breeding requires silk worms as natural food that has the best for growth and survival in the post larvae phase. On the other hand, the availability of silk worms is very dependent on natural conditions. During the rainy season, the availability of silk worms becomes very rare, and this becomes a separate problem for general fish breeders. Based on this, the aimed of this research was to determine how the effect of alternative feeds, in the form of fermented commercial feeds, on the growth performance and survival rate of Asian redtail catfish post larvae. This study used a completely randomized design with 3 treatments and 3 replications, namely rare of Asian redtail catfish post larvae with silkworm feed (A), fermented commercial feed (B), non-fermented commercial feed (C), the size of post larvae used was 11.00 ± 0.00 mm, with a stocking density of 4 fish/L. The best results from this study were found in treatment A, which resulted in absolute weight growth of 0.77 ± 0.00 g, absolute length growth of 23.33 ± 0.36 mm, but the highest survival rate was obtained in treatment B (81.33 ± 4.51%), although not significantly different from treatment A. Based on the observation of feed structure, fermented commercial feed was structurally softer. The behavior of the feed response, treatment B was not different from treatment A, while the behavior of the feeding pattern showed that fermented feed (B) was better than non-fermented commercial feed (C). The results of the proximate test, the fermented feed decreased in protein, fat and crude fiber content, while the ash content increased slightly.

EFFECT OF PROBIOTIC AND SUPPLEMENTED FEED ON GROWTH, SURVIVAL AND DISEASE RESISTANCE OF WHITE SHRIMP LITOPENAEUS VANNAMEI POSTLARVAE

The present investigation was focused on the effect of Bacillus megaterium enriched to the Artemia nauplii and sprayed on the supplemented feed was fed to the white shrimp Litopenaeus vannamei postlarvae (PL) to obtain high survival and growth. Artemia nauplii enriched with different levels of B. megaterium (5×107, 5×109 and 5×1011 cfu /mL) fed to postlarvae for a period of 30 days. Similarly, supplemented feed with probiotic of different levels fed to PL for a time period of 15 days. Postlarvae fed with 5×109 cfu cells (E2) of B. megaterium enriched Artemia nauplii and supplemented feed produce better survival and growth when compared to that of other concentrations and control group. The specific growth rate was found to be maximum in postlarvae fed with B. megaterium enriched Artemia and supplemented feed when compared to the control group. The biochemical constituents, such as protein, lipid and carbohydrate contents were considerably more in PL fed with both feeds, particularly at 5×109 cfu cells. In the challenging study, results showed a higher survival rate in postlarvae fed with enhanced Artemia nauplii and supplemented feed of E2. Therefore, it is evident that 5×109 cfu cells of B. megaterium can be considered as an appropriate concentration for the growth and survival of L. vannamei postlarvae.