Larval Death Research Articles

Effectiveness of Papaya Seed Solution and Avocado Seed As Larvicide of Mosquitoes Aedes sp.

Mosquito Aedes sp. is a species of mosquito in tropical and subtropical regions that are vectors for transmitting the dengue virus to man through the bite; with that, there is a need for existence, effort prevention, and a control-friendly alternative environment using larvicide vegetables that are solution seed fruit papaya (Carica papaya L.) and seeds fruit avocado (Persea americana). The study aims to determine the effectiveness of seed fruit papaya (Carica papaya L.) and seed fruit avocado (Persea americana) on the larval mortality of Aedes sp. Type study This is a post-test-only group design. The population is the third instar larva of Aedes sp. The sample used 1,200 larvae of Aedes sp. on each solution of seed fruit papaya and seed fruit avocado, with variations of 6 doses that are 0%, 2%, 4%, 6%, 8%, and 10%. Concentration variation of mosquito larvicide from papaya seeds (Carica papaya L.) and avocado seeds (Persea americana), with the highest concentration of 10% resulting in the death of mosquito larvae as high as 72% and 88%, respectively. The effective concentration at Lc50 found is 6% for papaya seed solution (Carica papaya L.) and 4% for avocado seed solution (Persea americana).

ԿԱՂԱՄԲԻ ՑԵՑԻ ԹՐԹՈՒՐՆԵՐԻ ԴԵՄ ՊԱՅՔԱՐԻ ՄԻՋՈՑԱՌՈՒՄՆԵՐԻ ՄՇԱԿՈՒՄ ԱՐՄԱՎԻՐԻ ՄԱՐԶԻ ՊԱՅՄԱՆՆԵՐՈՒՄ

Scientific research was conducted from 2020 to 2022 under laboratory conditions and on cabbage plantations (plot and industrial). It has been confirmed that cabbage plantations in the Lukashin community of the Armavir region had a high population of cabbage moth caterpillars. Local bacterial cultural liquids of Bacillus thuringiensis species tested separately and in combination with sublethal doses of insecticides showed high biological effectiveness against phytophagous caterpillars of ages I III, which does not differ significantly from the reference indicator: commercial bacterial preparation Lepidocide. According to the results of laboratory examination of the bodies of the deceased larvae, it was found out that the decomposing body tissues of the pest larvae were filled with insecticidal sporocrystalline components, which confirmed that the death of the phytophagous larvae is the result of the effect of the tested insecticides. When struggling against cabbage moth caterpillars, it is proposed to use bacterial culture fluids alone with a lethal dose of 300 million spores/ml and in combinations with their sublethal quantity (titer of 150 million spores/ml) with the chemical insecticide calypso (0.033 % suspension).

Effect of Temperature Fluctuation on the Indian Major Carp Labeo rohita and Cirrhinus mrigala Larvae under a Controlled Environment

Major carp i.e., Rohu (Labeo rohita) and Mrigala (Cirrhinus mrigala) are economically very important and commonly cultured in Indian subcontinent. In Pakistan aquatic organisms especially, freshwater species are facing many environmental problems such as variation in weather pattern. Temperature fluctuation is pervasive and most common environmental factor that is very distressing for major carps. The larvae of Labeo rohita and Cirrhinus mrigala were treated with different temperatures 10, 15, 20, 25, 30, 33 and 35 °C following 28 °C acclimation temperature. Thermal variation rate was recorded 2 °C/day. Death rate of both species larvae was observed. In temperature group 10 °C, 15% and 64% mortality of Labeo rohita was observed while, in Cirrhinus mrigala 16% and 66% mortality was recorded at 14 and 10 °C respectively. When larvae of both species were exposed to 10-20 °C, significantly (P < 0.05) maximum death rate was observed at this temperature as compared to other experimental groups. Cumulative death rate of Labeo rohita and Cirrhinus mrigala were recorded 84, 43, 22, 16, 1, 2, 3% and 86, 45, 23, 17, 1, 2, 4% in 10, 15, 20, 25, 30, 33, 35 °C temperature groups, respectively. All larvae of both species died within 2 days at temperature group 10 °C and continued to die at temperature groups 15 °C and 20 °C up to 11 days. Both species larval mortality persisted in temperature groups at 25 °C up to 18 days. Simple regression analysis was applied for thermal range (T < 28 °C and T > 28 °C), variation in death per fall and elevation of ∆T = 1 °C was measured in the log-linear regression model framework. When water temperature dropped from acclimation temperature 28 °C, the accumulative death of larvae for 1 °C decrease of temperature from acclimation one, significantly (P < 0.05) was calculated in both species. When water temperature elevated from 28 °C, less steep beta coefficient was observed in Labeo rohita and Cirrhinus mrigala. 1 °C elevation of water temperature from acclimation temperature 28 °C, the accumulative death in Labeo rohita and Cirrhinus mrigala were (P > 0.05) obtained

PERBANDINGAN EFEKTIVITAS EKSTRAK DAUN KERSEN (Mutingia calabura) DAN DAUN AKASIA (Acacia mangium) SEBAGAI LARVASIDA TERHADAP JENTIK NYAMUK Aedes aegypti (L.) DI WILAYAH BANJARMASIN

Dengue fever (dengue) is a dangerous and even deadly disease caused by the Aedes aegypti mosquito as the vector of the disease. One way to prevent dengue fever (dengue) is the use of larvicides to inhibit and kill Aedes aegypti larvae. In this case, it is necessary to use one part of the plant, namely Kersen leaves (Mutingia calabura) and Acacia leaves (Acacia mangium). This study aims to compare the effectiveness of the effect of the bioactive compounds contained in extracts of Kersen leaves (Mutingia calabura) and Acacia leaves (Acacia mangium) as larvicides. The plant extraction method is simplicia. The prepared leaf samples were washed thoroughly and dried for ± 2 weeks in a closed state from the sun. The dried leaf samples were then mashed with a dry blender to obtain powder (dry weight), then macerated with ethanol solvent with a concentration of 0.1%, 0.5% and 1%. Based on the results of the research conducted, there was a significant effect of giving cherry leaf extract and acacia leaves from each concentration tested after 24 hours of treatment, with the highest number of larvae deaths at a concentration of 1%. However, in this case there was no significant difference between the administration of the two extracts as Aedes aegypti larvicide

Metabolic reprogramming of Helicoverpa armigera larvae by HearNPV facilitates viral replication and host immune suppression.

Baculoviruses are highly evolved parasites that genetically reprogram the developing phenotype of their host insect to produce a vessel for virus replication and dispersal. Here we show that larvae of Helicoverpa armigera infected with HearNPV accumulate glucose in the midgut, which reduces food consumption and alters the dynamics of pathways governing metabolism and immunity. We used transcriptomics to demonstrate the role of the insulin signalling pathway in regulating the HearNPV infection process. Dietary restriction decreased mortality of infected larvae and reduced viral replication prior to death, whereas dietary supplementation with glucose produced the opposite effects. The expression of most tricarboxylic acid cycle (TCA) and energy metabolism-related genes was reduced in infected larvae, whereas the expression of immunity-, glycolysis- and insulin-related genes was enhanced. Treatment of infected larvae with insulin increased their survival, reduced viral replication and inhibited climbing behaviour compared to a control treatment with DMSO, whereas RNAi suppression of the insulin receptor gene produced the opposite effects. Inhibition of glycolysis with dichloroacetate (DCA) promoted viral replication and accelerated larval death, but inhibition of the TCA cycle with 2-deoxyglucose (2-DG) did not, although both diminished climbing behaviour. This work demonstrates that successful baculovirus infections hinge on metabolic reprogramming of the host and concurrent suppression of immune responses in the larval midgut, with the insulin signalling pathway mediating a trade-off between glucose metabolism and virus resistance.

THE EFFECT OF MASCULUS IMMERSION AGAINST THE DEATH OF MOSQUITO FLACERS

The transition from the dry season to the rainy season causes mosquito larvae in stagnant water. Researchers are looking for natural larvicidal solutions that are safe and effective with male papaya flowers (masculus). The aim of the study was to determine the effect of masculus immersion water on the death of mosquito larvae in water reservoirs. The location is in Curup Tengah District. Quasi experimental type, Chi-square analysis, calculating odds ratio, Chi square test. Almost all (94.4%) there were 34 dead larvae and a small portion (5.5%) there were 2 live larvae, from 36 Aedes aegypti larvae in 50 ml of masculine immersion water, 1 minute. The results of Chi-square analysis showed that P value = 0.04 < ? 0.05, there was a significant effect between masculine immersion water and Aedes aegypti larvae mortality. Where the value of p value = 0.043, has the effect of masculus immersion water, at odds ratio = 4.10 times. Overall (100%) there were 36 dead larvae and a small portion (0%) there were 0 live larvae, out of 36 Aedes aegypti larvae in the bath 100 ml of masculus soaking water, time under 1 minute. The results of the Chi-square analysis showed that the P value = 0.04 <?0.05, there was a significant effect between the masculine immersion water and the mortality of Aedes aegypti larvae. Where the p value = 0.040, has the effect of masculus soaking water, at odds ratio = 4.00 times. In order for the community to be active in eradicating Aedes aegypti larvae, activities get used to making masculine soaking, pouring it into a water reservoir

A nano-delivery system expands the insecticidal target of thiamethoxam to include a devastating pest, the fall armyworm.

Nano-delivery systems have been applied to deliver various synthetic/botanical pesticides to increase the efficiency of pesticide use and reduce the volumes of pesticides applied. Previous studies have supported the hypothesis that the nanocarriers can help expand the insecticidal target of pesticides to include non-target pests. However, the potential mechanism underlying this interesting phenomenon remains unclear. Herein, a widely applied star polycation (SPc) nanocarrier was synthesized to construct a thiamethoxam (TMX) nano-delivery system. The SPc-based delivery system could promote the translocation of exogenous substances across the membrane of Sf9 cells, increase the cytotoxicity of TMX against Sf9 cells by nearly 20%, and expand the insecticidal target of TMX to include Spodoptera frugiperda (the fall armyworm), with a 27.5% mortality increase at a concentration of 0.25mg/mL. Moreover, the RNA-seq analysis demonstrated that the SPc could upregulate various transport-related genes, such as Rab, SORT1, CYTH, and PIKfyve, for the enhanced cellular uptake of TMX. Furthermore, enhanced cell death in larvae treated with the TMX-SPc complex was observed through changes in the expression levels of death-related genes, such as Casp7, BIRC5, MSK1, and PGAM5. The SPc-based nano-delivery system improved the cellular uptake of TMX and expanded its insecticidal target by adjusting the expression levels of death-related genes. The current study mainly identified the transport and cell death genes related to nanocarrier-based insecticidal target expansion, which is beneficial for understanding the bioactivity enhancement of the nano-delivery system.

Thyroid hormone-induced cell death in sea urchin metamorphic development.

Thyroid hormones (THs) are important regulators of development, metabolism and homeostasis in metazoans. Specifically, they have been shown to regulate the metamorphic transitions of vertebrates and invertebrates alike. Indirectly developing sea urchin larvae accelerate the formation of juvenile structures in response to thyroxine (T4) treatment, while reducing their larval arm length. The mechanisms underlying larval arm reduction are unknown and we hypothesized that programmed cell death (PCD) is linked to this process. To test this hypothesis, we measured larval arm retraction in response to different THs (T4, T3, rT3, Tetrac) and assessed cell death in larvae using three different methods (TUNEL, YO-PRO-1 and caspase-3 activity) in the sea urchin Strongylocentrotus purpuratus. We also compared the extent of PCD in response to TH treatment before and after the invagination of the larval ectoderm, which marks the initiation of juvenile development in larval sea urchin species. We found that T4 treatment results in the strongest reduction of larval arms but detected a significant increase of PCD in response to T4, T3 and Tetrac in post-ingression but not pre-ingression larvae. As post-ingression larvae have initiated metamorphic development and therefore allocate resources to both larval and the juvenile structures, these results provide evidence that THs regulate larval development differentially via PCD. PCD in combination with cell proliferation likely has a key function in sea urchin development.

TOXICITY OF DERRIS ELIPTICA BENTH. ON MORTALITY OF AEDES AEGYPTI LINN LARVAE

The death of the three Aedes aegypti Linn larvae that were placed inside has been the subject of a study on the toxicity test of Derris elliptica (Benth). This study's objectives were to ascertain the effect of tuba root extract on the quantity of larval instars of three Aedes aegypti Linn, as well as to ascertain the concentration of tubal root extract that affected as larvaside by measuring Lethal Concentration (LC50). Experiment-based research is the type used. With seven concentrations and three replications over the course of 24 hrs, the research was carried out in partnership using a Randomized Complete Random Design (RAL) design. The probit analysis yields the LC50 result. The findings demonstrated that Derris eliptica extract, with an LC50 value of 125.99 ppm, had an impact on the death of instar larvae of three Ae. aegypti Linn.

UJI EFEKTIVITAS EKSTRAK DAUN KEMANGI (Ocimum sanctum) SEBAGAI LARVASIDA ALAMI TERHADAP KEMATIAN LARVA NYAMUK AEDES AEGYPTI

Ocimum sanctum, known as daun kemangi (Ocimum sanctum)in Indonesia is a plat that is common as fresh vegetables. In addition, Ocimum sanctum also can be used as medicine, vegetable pesticides, making essential oils, vegetables, and refreshing drinks. This study aimed to determine the effectiveness of Ocimum sanctum Extract on the death of Aedes aegypti larvae. This study used the experimental laboratory method. The sample population was Aedes aegypti, with as many as 300 nymphs with a “posttest-only control design.” The concentration of extract Ocimum sanctum used was 1,5%, 2%, 2,5%, dan 3%. Each treatment contained 25 larvae and was observed in 24 hours. The study shows us that an Ocimum sanctum extract concentration of 1,5% was able to kill 36% of larvae, attention of 2% can be able to kill 52%, a concentration of 2,5% was able to kill 68% of larvae, dan concentration of 3% was able to kill 76%. The based engagement was most effective for killing Aedes aegypti larvae at a concentration of 3%.

Chemical Control of Mosquitoes and the Pesticide Treadmill: A Case for Photosensitive Insecticides as Larvicides.

Insecticides reduce the spread of mosquito-borne disease. Over the past century, mosquito control has mostly relied on neurotoxic chemicals-such as pyrethroids, neonicotinoids, chlorinated hydrocarbons, carbamates and organophosphates-that target adults. However, their persistent use has selected for insecticide resistance. This has led to the application of progressively higher amounts of insecticides-known as the pesticide treadmill-and negative consequences for ecosystems. Comparatively less attention has been paid to larvae, even though larval death eliminates a mosquito's potential to transmit disease and reproduce. Larvae have been targeted by source reduction, biological control, growth regulators and neurotoxins, but hurdles remain. Here, we review methods of mosquito control and argue that photoactive molecules that target larvae-called photosensitive insecticides or PSIs-are an environmentally friendly addition to our mosquitocidal arsenal. PSIs are ingested by larvae and produce reactive oxygen species (ROS) when activated by light. ROS then damage macromolecules resulting in larval death. PSIs are degraded by light, eliminating environmental accumulation. Moreover, PSIs only harm small translucent organisms, and their broad mechanism of action that relies on oxidative damage means that resistance is less likely to evolve. Therefore, PSIs are a promising alternative for controlling mosquitoes in an environmentally sustainable manner.

Uji Efektivitas Larvasida Ekstrak Daun Pegagan (Centella asiatica L. Urban) Terhadap Larva Culex quinquefasciatus

Culex quinquefasciatus is a vector of filariasis (elephantiasis) and Japanese encephalitis. Filariasis is still an unresolved disease in Indonesia. The use of temephos as a chemical larvicide repeatedly causes environmental pollution and is difficult to decompose, so the World Health Organization recommends looking for alternative effects. Gotu kola leaf extract contains metabolic substances such as steroids,saponins, flavonoids, phenolics that can be used as larvicides. This study aimed to determine the effectiveness of the larvicide extract of pegagan (Centella asiatica L. Urban) on the mortality of Culex quinquefasciatus larvae. This study used an experimental research design with a posttest only control group design using 4 concentration groups and 2 control groups, consisting of 4 repetitions in each, namely concentrations of 125 ppm, 250 ppm, 500 ppm, 1000 ppm, abate positive control and aquadest negative control. with the mean larval mortality was 31%, 65%, 81%, 98% which was observed for 48 hours. The number of larval deaths was analyzed using the Kruskall-Wallis test and logit analysis. The results of the analysis showed that pegagan leaf extract had an effect on the mortality of Culex quinquefasciatus larvae with a significant value (p < 0.05), then the results of logit regression analysis showed the LC50 value of 206.71 ppm. The conclusion of this study was that the leaf extract of pegagan (Centella asiatica L. Urban) was effective against the mortality of Culex quinquefasciatus larvae.

Uji Efektivitas Larvasida Ekstrak Daun Pegagan (Centella asiatica L. Urban) Terhadap Larva Culex quinquefasciatus

Culex quinquefasciatus is a vector of filariasis (elephantiasis) and Japanese encephalitis. Filariasis is still an unresolved disease in Indonesia. The use of temephos as a chemical larvicide repeatedly causes environmental pollution and is difficult to decompose, so the World Health Organization recommends looking for alternative effects. Gotu kola leaf extract contains metabolic substances such as steroids,saponins, flavonoids, phenolics that can be used as larvicides. This study aimed to determine the effectiveness of the larvicide extract of pegagan (Centella asiatica L. Urban) on the mortality of Culex quinquefasciatus larvae. This study used an experimental research design with a posttest only control group design using 4 concentration groups and 2 control groups, consisting of 4 repetitions in each, namely concentrations of 125 ppm, 250 ppm, 500 ppm, 1000 ppm, abate positive control and aquadest negative control. with the mean larval mortality was 31%, 65%, 81%, 98% which was observed for 48 hours. The number of larval deaths was analyzed using the Kruskall-Wallis test and logit analysis. The results of the analysis showed that pegagan leaf extract had an effect on the mortality of Culex quinquefasciatus larvae with a significant value (p < 0.05), then the results of logit regression analysis showed the LC50 value of 206.71 ppm. The conclusion of this study was that the leaf extract of pegagan (Centella asiatica L. Urban) was effective against the mortality of Culex quinquefasciatus larvae.

Study of Pathogenesis Using Fluorescent Strain of Cordyceps farinosa Revealed Infection of Thitarodes armoricanus Larvae via Digestive Tract.

Cordyceps farinosa is often utilized as a biocontrol agent because of its wide host range, strong lethality, and safety for mammals. Artificial rearing of Thitarodes armoricanus larvae is a prerequisite for the artificial cultivation of Chinese cordyceps, and C. farinosa is the most lethal pathogenic fungus during the rearing process. However, the infection process of C. farinosa is still unclear. In this study, we cloned the promoter of the C. farinosa glyceraldehyde 3-phosphate dehydrogenase gene, constructed the EGFP expression cassette, and integrated it into the C. farinosa genome via Agrobacterium transformation. We obtained a fluorescent strain for better observation of the infection process. Using two different inoculation methods of the fluorescent strain, we observed the traditional infection process through the body surface as well as through the digestive tract via feeding. Both infection modes can lead to larval death and mummification. Our findings demonstrated that during the artificial rearing of T. armoricanus, preventing C. farinosa pollution should be an important part of the disinfection of the rearing environment.

STUDI IN VITRO EKSTRAK DAUN TEMBAKAU (Nicotiana tabacum) DAN DAUN BINAHONG HIJAU (Anredera cordifolia steenis) SEBAGAI INSEKTISIDA ALAMI UNTUK MYIASIS PADA RUMINANSIA

The purpose of this study was to determine the effectiveness of the combination of tobacco leaf extract (Nicotiana tabacum) and green binahong leaf (Anredera cordifolia steenis) against myiasis. The study used the in vitro method for testing, while the leaf extract was obtained using the immersion method. This research was conducted using a completely randomized design (CRD) with a one-way pattern (One Way ANNOVA) with 6 treatments and 4 replications. The test uses fresh beef samples that have been rotten for 6 days at room temperature. The fresh weight of each meat sample was 100 grams. The treatments were P0 (control: only water), P1 (100% tobacco), P2 (100% green binahong), P3 (50% tobacco: 50% green binahong), P4 (70% tobacco: 30 green binahong) and P5 (30% tobacco: 70% green binahong). The results observed in the study included the time (seconds) required for larvae to come out of the meat after spraying on each treatment, the death of myiasis larvae at 5, 10, 15, and 25 minutes. The results showed that treatment P4 got the best results. compared with other treatments with a significant difference at the level of p <0.05. Key words: Tobacco leaves, Binahong leaves, Myiasis, Animal health.

EVALUASI UJI EFEKTIVITAS EKSTRAK KAYU MANIS (Cinnamomum burmanni) SEBAGAI LARVASIDA TERHADAP KEMATIAN JENTIK NYAMUK (Aedes aegypti)

Alternative larvicides against Aedes aegypti larvae and safe for the environment, one of which is cinnamon oil which has been shown to have a larvicidal effect on larvae. Cinnamon contains flavonoid compounds which are strongly suspected to have a larvicidal effect. It can be said that this research is to determine the effectiveness of extracts from cinnamon as a larvicide against the death of Aedes aegypti mosquito larvae. And for the extraction method used in this study using the maceration method. For a concentration of 2% it can kill a total of 32 (53%) larvae, and for a concentration of 4% it can kill 43 (72%) total lava, and a concentration of 6% can kill 53 (88%) larvae, and for a positive control, namely abate (temephos). ) has the best larvicidal effect with an average % larval mortality of 100% within 1 hour. Cinnamon extract test treatments with a concentration of 2% (2ml/100ml) experienced larval death 32 (43%), and for a concentration of 4% (4ml/100ml) experienced larvae mortality 43 (53%). and for a concentration of 6%, 53 (88%) larvae died. And for temephos, it was able to kill a total of all larvae, while for negative control it did not die. The most effective concentration of cinnamon extract in killing larvae was 6%, the higher the concentration, the higher the larval mortality value.

Using Rhizhopora apiculata Extract for Mosquito Larvae Control

Temephos is the most commonly used synthetic larvicide to control vectors of several diseases. Currently in some areas there has been resistance of larvae to temephos, so natural larvicides are needed as an alternative. Rhizophora apiculata contains flavonoid compounds that are respiratory toxins to some larvae. This research was conducted in March - Juny 2022, to determine the inhibitory of mangrove extract against mosquito larvae in brackish water. Samples were collected from the Bakar Bakau Dumai, Riau Indonesia. The experiment was setted in a single factor experimental design. Mangrove leaves are finely ground and kneaded while mixed with water and deposited for 6 minutes and filtered. This extract solution was mixed with brackish water to obtain a test medium of 500 l with a concentration of 6 (a1), 9 (a2) and 12% (a3), positive control or 1 g of abate powder (a4) and negative control or brackish water (a0). A total of 20 mosquito larvae were put into the media and their mortality was observed at 0, 15, 30, 45 and 60 minutes after introduction. The mortality of larvae were then analyzed using probit analysis to obtain LC50 (Lethal Concentration 50) and LT50 (Lethal Time 50) values. R. apiculata extract is toxic to mosquito larvae, where larval death has been seen since 15 minutes and continues until 60 minutes after introduction. At the 60th minute the mortality rate is as follows; a1 (60 %), a2 (80 %), a3 (100 %), a4 (100 %), and a0 a1 ( %). Based on the results of the above probit values ​​in the LC50 and LT50 tests on R. apiculata leaves, the LC50 value is 9,732 while the LT50 value is estimated at 21,217.

Chronic toxic effects of isoflucypram on reproduction and intestinal energy metabolism in zebrafish (Danio rerio)

The intestine is a vital organ involved in chemical and nutrient uptake and biotransformation. Intestinal dysfunction can impair energy and material supply for reproduction. Isoflucypram, a new succinate dehydrogenase inhibitor fungicide, is highly toxic to aquatic systems. However, the chronic toxic effects of isoflucypram on intestinal differentiation in aquatic organisms remain unknown. In this study, zebrafish (F0, 4-month-old) were exposed to 0, 0.008, or 0.08 μM isoflucypram for 120 days. After 90 days of exposure, F0 generations of adult zebrafish were paired, and the corresponding F1 generation embryos were obtained and observed. After 120 days of exposure, the gut of F0 generation zebrafish was collected, and intestinal histopathology and mitochondrial morphology were analyzed. Exposure to 0.08 μM isoflucypram resulted in significant death, hatching delay, and malformation (blood clot clustering, pericardial edema, and microphthalmia) of F1 embryos and larvae. Exposure to isoflucypram caused irregular and swollen villi in the zebrafish gut, accompanied by alterations in the intestinal mitochondrial ultrastructure. In addition, the differentially expressed genes involved in mitochondrial energy metabolism were significantly enriched. Overall, our data suggest that chronic exposure to isoflucypram is associated with reproductive and intestinal dysfunction in adult zebrafish.

Trace Determination of Grouper Nervous Necrosis Virus in Contaminated Larvae and Pond Water Samples Using Label-Free Fiber Optic Nanoplasmonic Biosensor.

We developed a fast (<20 min), label-free fiber optic particle plasmon resonance (FOPPR) immunosensing method to detect nervous necrosis virus (NNV), which often infects high-value economic aquatic species, such as grouper. Using spiked NNV particles in a phosphate buffer as samples, the standard calibration curve obtained was linear (R2 = 0.99) and the limit of detection (LOD) achieved was 2.75 × 104 TCID50/mL, which is superior to that obtained using enzyme-linked immunosorbent assay (ELISA). By using an enhancement method called fiber optic nanogold-linked immunosorbent assay (FONLISA), the LOD can be further improved to <1 TCID50/mL, which is comparable to that found by the conventional qPCR method. Employing the larvae homogenate samples of NNV-infected grouper, the results obtained by the FOPPR biosensor agree with those obtained by the quantitative polymerase chain reaction (qPCR) method. We also examined pond water samples from an infected container in an indoor aquaculture facility. The lowest detectable level of NNV coat protein was found to be 0.17 μg/mL, which is one order lower than the LOD reported by ELISA. Therefore, we demonstrated the potential of the FOPPR biosensor as an outbreak surveillance tool, which is able to give warning indication even when the trend of larvae death toll increment is still not clear.

Breeding and conservation of Luciola cruciata Motschulsky, 1854 (Coleoptera: Lampyridae) larvae in forests near chemical factories

The number of fireflies in Japan has decreased with the development of cities and industries. As a first step toward the regeneration of an environment for fireflies, we report an attempt to breed aquatic firefly larvae. Focusing on the operational stability of equipment used, we use a safety evaluation method like that employed in petrochemical plants. The death of larvae is a major risk in the operational safety of firefly larvae breeding. The larval death scenario is analyzed and clarified using fault tree analysis, demonstrating that reducing operational mistakes in monitoring water flow and temperature conditions contribute most to the reduction of the probability of larval death. An experiment simulating water supply stoppage to estimate the permissible time for a response once the water temperature rose is reported. A firefly larval breeding system equipped with an alarm function for prompting emergency responses is constructed. Fireflies, including mature larvae, are successfully bred and the effectiveness of this system is demonstrated by comparing it with a conventional system. The superiority of the breeding system of this study is indicated by a twofold increase in the yield of mature larvae and the lower expenses related to this strategy.