Effect of Temperature on the Embryogenesis of Three Geographically Distinct Populations of Meloidogyne incognita Is Driven by Intrinsic Thermal Acclimation Reaction.

Research interest in the mechanisms enabling plant-parasitic nematodes to adjust their physiological performance and cope with changing temperatures has intensified in light of global warming. Here, we show that geographically distinct populations of the root-knot nematode Meloidogyne incognita, which is prevalent in the three main pepper-growing regions in Israel-Carmel Valley (Carmel), Jordan Valley (JV), and Arava Rift (Arava)-possess persistent differences in their thermal acclimation capacity, which affect pre- and postembryonic development. The optimal temperature for embryonic growth completion was 25°C for the Carmel population; 25 and 30°C for the JV population; and 30°C for the Arava population. Cumulative hatching percentages showed variations among populations; relative to hatching at 25°C, the Carmel population experienced hatching reduction at the higher studied temperatures 30 and 33°C, while the JV and Arava populations exhibited an increase in hatching at 30 and 33°C, respectively. Juvenile survival indicates that at the lowest temperature (20°C), the Carmel population gained the highest survival rates throughout the experimental duration, while at the same duration at 33°C, the Arava population gained the highest survival rate. Infective juveniles of the Carmel population demonstrated increased penetration of tomato roots at 25°C compared to the JV and Arava populations. Inversely, at 33°C, increased penetration was observed for the Arava compared to the Carmel and JV populations. Altogether, the Arava population's performance at 33°C might incur distinct fitness costs, resulting in consistent attenuation compared to the Carmel population at 25°C. Precisely defining a population's thermal acclimation response might provide essential information for models that predict the impact of future climate change on these populations.

Triploid brown trout, Salmo trutta, develop functional gonads with age and are able to interbreed with diploid counterparts.

The study investigated if gonad maturation in triploid brown trout, Salmo trutta, was entirely suppressed or only delayed, and if triploids could interbreed with diploid counterparts. Ten percent of the total number of 3-year-old triploid S. trutta, 15% of 4-year-old fish, and 17% of 5-year-old fish produced semen. Three and 4 years old triploid fish did not produce eggs, but 15% of the 5-year-old fish did so. The quantity and sperm motility of triploid semen did not differ from diploids, but the sperm concentration was significantly lower. When diploid eggs were fertilized with triploid semen (3n × 2n crosses), the percentage of eyed stage embryos, of hatched larvae, and of normal-shaped larvae did not differ from the diploid controls. Circa 90% of 3n × 2n crosses had a ploidy level of 2.4n. In the remaining percentage of 3n × 2n crosses, the ploidy level was ≥2n and <2.4n. In sperm competition experiments where diploid eggs were fertilized with a mixture of diploid and triploid semen, 52% of the originating larvae had a ploidy level of 2n, 43% of 2.4n, and 5% of the fish were not exactly classified. From the start of feeding to an age of 248 days, the mortality rate of 3n × 2n interploid crosses and of 2n × 2n controls was similar. The growth of interploid crosses was significantly higher than that of controls. In triploid mature females, the egg mass per kilogram of body weight was significantly lower than in diploids. The mass of the non-hardened eggs and the percentile weight increase during hardening did not differ from diploid eggs. When triploid eggs were fertilized with diploid semen (2n × 3n crosses), the development rate to normal hatched larvae was less than 10%. All originating larvae had a ploidy level of 3n. From the start of feeding to an age of 248 days, 2n × 3n crosses had a higher mortality rate (15%) than diploid controls (<5%). Growth of this type of interploid crosses was reduced in comparison to controls. Therefore, triploids introduced into natural waters for recreational fisheries or escaping from farms may interbreed with diploid counterparts. This not only alters the genotypes of local populations but also changes the ploidy levels.

Effect of dietary vitamin E supplement on the reproductive performance and gene expression profiling in Ompok bimaculatus during breeding period.

This study aimed to evaluate the effect of vitamin E on the reproductive responses and the expression of reproductive genes in butter catfish (Ompok bimaculatus). Diets with different levels of vitamin E supplementation (0, 100, and 150 mg/kg) were provided to groups of fish for 60 days. After rearing for 60 days fish were induced with synthetic hormone, that is, Ovatide to study the breeding performance. Ovatide was administrated intramuscularly at the rate of 0.5 and 0.25 mL/kg of body weight for females and males, respectively, in all the treatments. Breeding performance result shows that supplements of vitamin E positively influenced the GSI%, fertilization rate, fecundity, and hatching rate. To understand the relationship between vitamin E and the breeding performance of the fish at the molecular level, a gene expression study was conducted. This study employed real-time PCR for the selected genes critical for reproductive function. In the brain, testis, and ovary dietary vitamin E supplementation of 100 mg/kg significantly enhanced the mRNA transcription of FSHR, Brdt, ESR1, 17beta2, and LHR. Hence, it can be said that 100 mg/kg of vitamin E supplementation in the diet during the reproductive period of O. bimaculatus could improve breeding performance and the mRNA expression of reproductive hormone receptor genes in both males and females of O. bimaculatus.

The investigation of post-thaw chilled storage and the applicability of large-scale cryopreservation in chub (Squalius cephalus) sperm.

Chub (reophillic cyprinids) is one of the most sensitive bioindicator fish of environmental changes following anthropogenic activities. The improvement of different biotechnological procedures could help support its conservation and strengthen the natural populations. The aim of this study was to compare the effects of two different hormonal agents (carp pituitary extract and Ovopel™) on various motility parameters (pMOT-%, DAP-µm, VCL µm s-1, VSL-µm s-1, LIN-%, ALH-µm, BCF-Hz) of fresh and cryopreserved/thawed sperm (stored at 4 °C for 6 h). Additionally, we sought to develop a novel, large-scale cryopreservation method for chub sperm, assessing freezing methods (Styrofoam box and a controlled-rate freezer) and different containers (0.5, 5 mL straw and 4 mL cryotube) for sperm cryopreservation. The results of this study indicated no difference between the carp pituitary extract and Ovopel treated groups in either the fresh or frozen/thawed sperm (at 0, 3, 6, hour post thawing, P = 0.4351). In contrast, the quality of the thawed chub sperm was negatively affected after 3 h chilled storage in both hormonal treatments (P = 0.0036, P < 0.0001). When assessing the motility parameters of the sperm between the 5 mL straw and 4 mL cryotube groups cryopreserved in a Styrofoam Box, no difference was observed (P = 0.103). Additionally, sperm loaded in 4 mL cryotubes showed no difference in motility when cryopreserved with either the Styrofoam box or controlled-rate freezer methods (P = 0.109). A similar hatching rate was observed in sperm preserved using the Styrofoam box (35 ± 7 %) and controlled rate freezer (25 ± 9 %) methods (P = 0.300). In a second fertilization trial, hatching rate was similar between control (72 ± 19 %) and cryopreserved (4 mL cryotube and Styrofoam box, 61 ± 5 %) groups. (P = 0.257). Based on our findings and its standard features (less species specific, precise dose calculation), Ovopel can be a good candidate for the stimulation of spermiation in chub sperm prior to cryopreservation. Furthermore, our study presents a novel and applicable method for the large-scale cryopreservation of chub sperm.

Expression and functional analysis of transformer-2 in Phytoseiulus persimilis and other genes potentially participating in reproductive regulation.

Transformer-2 (tra-2) is an important sex-determining gene in insects. It also plays a role in the reproduction of phytoseiid mites. We performed bioinformatic analyses for the tra-2 ortholog in Phytoseiulus persimilis (termed Pptra-2), measured its expression at different stages and quantitatively identified its function in reproduction. This gene encodes 288 amino acids with a conserved RRM domain. The peak of its expression was observed in adult females, especially ca. 5 days after mating. In addition, expression is also higher in eggs than in other stages and adult males. When Pptra-2 was silenced through RNA interference with oral delivery of dsRNA, 56% of the females had their egg hatching rates decreased in the first 5 days, from ca. 100% to ca. 20%, and maintained at low levels during the rest of the oviposition period. To detect other genes functionally related to Pptra-2, transcriptome analyses were performed on day 5 after mating. We compared mRNA expressions among interfered females with significantly reduced egg hatching rate, interfered females without significant hatching rate and CK. In total 403 differential genes were identified, of which 42 functional genes involved in the regulation of female reproduction and embryonic development were screened and discussed.

Cytotoxicity of lycopene-mediated silver nanoparticles in the embryonic development of zebrafish-An animal study.

Nano-silver (AgNP) has biological properties which are significant for consumer products, food technology, and medical applications (e.g., wound care products, implantable medical devices, in diagnosis, drug delivery, and imaging). Thus, the use of nano-silver is becoming more and more widespread in medicine. However, the effect of these AgNPs on zebrafish remains unclear. Whereas, lycopene, a fat-soluble carotenoid acts as a potent antioxidant has proved its major role in treating many oral health problems such as lichen planus, and periodontitis. Usage of these lycopene AgNPs would yield better results in wound healing. In this study, we investigated the cytotoxic effects of AgNPs on fibroblasts cells of humans. To investigate the toxic effects of the lycopene-mediated AgNPs on the zebrafish (Danio rerio) and to examine these effects on the embryonic development of the fetus of this species. In this study, zebrafish embryos were treated with AgNPs 0.5, 1, 2, 3, 4 or 5 L nanoparticles/ml for 24 to 96 h post fertilization. Our results showed that with the increasing concentration of nanoparticles, there was a very mild toxic effect. Less toxic effects were observed with 1µl. Our results show that exposure to silver nanoparticles is less toxic to embryonic zebrafish at lower concentrations. The results will contribute to the current understanding of the potential biotoxic effects of nanoparticles and will aid in the safety assessment and synthesis of silver oxide nanoparticles.

Synergistic effect of water temperature and dissolved oxygen concentration on rates of fertilization, hatching and deformity of hybrid yellow catfish (Tachysurus fulvidraco♀×Pseudobagrus vachellii♂).

In the process of selecting and developing freshwater aquaculture species, yellow catfish (Tachysurus fulvidraco) have received widespread attention from Chinese farmers, fishery scientists and technologists. Achieving full artificial breeding of yellow catfish would help improve the quantity and quality of fingerlings supplied for large-scale production of this species. Temperature (T) and dissolved oxygen (DO) are the most important abiotic factors affecting the breeding efficiency of aquatic organisms. In this study, the synergistic effects of T and DO on fertilization rate (FR, %), hatching rate (HR, %) and deformity rate (DR, %) of hybrid yellow catfish (T. fulvidraco♀ × Pseudobagrus vachellii♂) were studied by central composite design (CCD) and response surface methodology. A quadratic regression model for the effects of T and DO on FR, HR and DR was established, and the combination of T and DO was optimized. The first and second order effects of T and DO on FR and HR were significant under the conditions of this experiment (P < 0.05). The first and second order effects of T on DR were significant (P < 0.05) but there was no significant effect of DO on DR (P > 0.05). T and DO had significant interaction effects on FR (P < 0.05). High T and high DO environments reduced FR and HR of yellow catfish eggs and increased DR of the newly hatched larvae. The optimal combination of T and DO was 26.0 °C and 8.3 mgL-1, respectively. Maximum FR and HR coincided with minimal DR whose predicted values were 87.2%, 89.1% and 2.7%, respectively, with reliability of 0.979. Maintaining T and DO in the best combination will help to improve breeding efficiency and ensure production of the highest quantity and quality of fingerlings.

RNAi mediated knockdown of RpL11, RpS2, and tra-2 led to reduced reproduction of Phytoseiulus persimilis.

Phytoseiulus persimilis is one of the most important biological control agents of spider mites. Multiple studies have been conducted on factors affecting its reproduction, but limited research on related molecular mechanisms has been carried out. In this study, RNA interference of three genes, ribosomal protein L11 (RpL11), ribosomal protein S2 (RpS2), and transformer-2 (tra-2), to newly emerged females were performed through oral delivery of double-stranded RNA, and knockdown of target genes was verified using qRT-PCR analysis. When RpL11 or RpS2 was interfered, 42 and 30% P. persimilis individuals either laid no egg or had no egg hatched, whereas the remaining females had their oviposition duration reduced by 31.8 and 49.9%, fecundity reduced by 48.1 and 67.8%, and egg hatching rate reduced by 20.4 and 22.4%, respectively. In addition, offspring sex ratios were significantly male biased especially at low fecundities. When tra-2 was interfered, no significant difference in fecundity was detected, but egg hatching rate reduced by 30.6%. This study verified the possibility of RNA interference in Phytoseiidae through oral delivery, and indicated that RpL11 and RpS2 are involved in egg formation, whereas tra-2 is involved in embryo development in P. persimilis. Phytoseiid mites have different sex determination pathways compared to insects. The present study provides data and evidence at molecular biological level for future research on reproduction and sex determination of phytoseiid mites.

Lethal and sublethal endpoints observed for Artemia exposed to two reference toxicants and an ecotoxicological concern organic compound.

Swimming speed alteration and mortality assays with the marine crustacean Artemia franciscana were carried out. EC50 and LC50 values after 24-48h exposures were calculated for two reference toxicants, copper sulphate pentahydrate (CuSO4·5H2O) and Sodium Dodecyl Sulphate (SDS), and an ecotoxicological concern organic compound, Diethylene Glycol (DEG). Different end-points have been evaluated, in order to point out their sensitivity levels. The swimming speed alteration (SSA) was compared to mortality values and also to the hatching rate inhibition (literature data). SSA resulted to be more sensitive than the mortality and with a sensitivity comparable to (or even higher than) the hatching rate endpoint.

Cryotolerance of Day 2 or Day 6 in vitro produced ovine embryos after vitrification by Cryotop or Spatula methods.

This study was conducted to evaluate the cryotolerance of in vitro produced ovine embryos submitted to vitrification at different developmental stages using two methods of minimum volume and rapid cooling rate. Embryos were vitrified at early stage (2 to 8-cells) on Day 2 or at advanced stage (morulae and blastocysts) on Day 6 after in vitro fertilization. Vitrification procedure consisted of the Cryotop (Day 2, n=165; Day 6, n=174) or the Spatula method (Day 2, n=165; Day 6, n=175). Non vitrified embryos were maintained in in vitro culture as a control group (n=408). Embryo survival was determined at 3h and 24h after warming, development and hatching rates were evaluated on Day 6 and Day 8 after fertilization, and total cell number was determined on expanded blastocysts. Embryo survival at 24h after warming increased as the developmental stage progressed (P<0.05) and was not affected by the vitrification method. The ability for hatching of survived embryos was not affected by the stage of the embryos at vitrification or by the vitrification method. Thus, the proportion of hatching from vitrified embryos was determined by the survival rate and was lower for Day 2 than Day 6 vitrified embryos. The percentage of blastocysts on Day 8 was lower for the embryos vitrified on Day 2 than Day 6 (P<0.05), and was lower for both days of vitrification than for non-vitrified embryos (P<0.05). No interaction of embryo stage by vitrification method was found (P=NS) and no significant difference was found in the blastocyst cell number among vitrified and non-vitrified embryos. In conclusion, both methods using minimum volume and ultra-rapid cooling rate allow acceptable survival and development rates in Day 2 and Day 6 in vitro produced embryos in sheep. Even though early stage embryos showed lower cryotolerance, those embryos that survive the vitrification-warming process show high development and hatching rates, similar to vitrification of morulae or blastocysts.

Thermal stress in Arctic charr Salvelinus alpinus broodstock: a 28 year case study.

Temperature and egg viability data from an Arctic charr Salvelinus alpinus hatchery covering a period of 28 years were analysed. During the study period, there was a significant increase in the mean water temperature in May, July, August and September of c. 2° C. Independent of year, the egg viability showed a negative correlation with the mean monthly temperatures in July, August and September as well as with the temperature difference between October and November. The negative effect of high summer temperatures was further supported by a comparison of egg viability from replicate broodstock reared at two sites differing mainly in summer water temperature. The eggs from the colder site were, on average, significantly larger (4·4 mm compared with 4·0 mm) and had higher hatching rates (57% compared with 37%). These results suggest that unfavourable temperature conditions during the summer and autumn can explain much of the excessive egg mortality experienced at the main facility used for the Swedish S. alpinus breeding programme. The main effect was supra-optimal temperatures during the period July to September, but there also appears to have been an effect from the temperature regime before and during spawning (October to November) that was unrelated to the summer temperatures. These findings emphasize the importance of site selection and sustainable management of aquaculture hatcheries in the light of the ongoing climate change.

Occurrence and pattern of legacy and emerging per- and Poly-FluoroAlkyl substances (PFAS) in eggs of loggerhead turtle Caretta caretta from western Mediterranean.

Per-and Poly-FluoroAlkyl Substances (PFAS) are a class of persistent, toxic, and mobile and chemicals both from industrial sources and from the use and disposal of Consumers products containing PFAS, whose concentration in marine food webs could pose a toxicological risk for biota and humans. In 2021, unhatched eggs were sampled from 41 loggerhead turtle Caretta caretta nests from the Italian shores of the Campania Region (Southern Italy). Whole eggs were analysed for the presence of 66 legacy and emerging PFAS with Liquid Chromatography coupled to Hybrid High Resolution Mass Spectrometry. A median Σ66 Per- and Poly-FluoroAlkyl Substances value of 3.34 ng/g egg fresh weight was found; perfluoroctane sulfonate (PFOS) represented the most contributing congener (47%), followed by perfluoro-n-undecanoic acid, perfluoro-n-tridecanoic acid, perfluoro-n-decanoic acid, perfluoro-n-decanoic acid, and perfluoro-n-tetradecanoic acid, respectively. Such compounds showed a log-norm distribution, suggesting found concentrations could represent the baseline levels in the considered sampling area. Emerging ChloroPolyFluoroPolyEthers Carboxylic Acids (ClPFECAs) were found in 20 out of 41 samples in the range 0.01-1.59 ng/g. Four samples had 20-100 fold higher concentration compared to that of other samples, suggesting the presence of hot spot areas possibly related to presence of fluoropolymer-based marine litter turtles may ingest. The analysis of two paired eggs/liver samples recovered from stranded animals revealed PFAS concentration in the same order of magnitude, supporting the role of vitellogenin in their selective transfer to yolk. Significant (P = 0.0155) Kendall negative correlation coefficient of -0.2705 among PFOS content in eggs and the recorded hatching success prompts for further investigation on associated exposure assessment and related eco-toxicity risk. This work reports for the first time PFAS presence in georeferenced loggerhead turtle eggs of the Mediterranean Sea and results represent a starting point to study PFAS time-trends in this vulnerable species.

Broodstock development, induced spawning and larval rearing of the bilih, Mystacoleucus padangensis (Bleeker, 1852), a vulnerable species, and its potential as a new aquaculture candidate.

Background: Mystacoleucus padangensis living in Lake Singkarak, Indonesia, has high potential market demand but is threatened by overfishing and has not been successfully cultured. This study describes the first broodstock development, induced breeding, and larval rearing of M. padangensis. Methods: A total of 1,000 female and 1,000 male broodfish were collected from the wild and reared in two concrete ponds (128 m 2) at the Centre for Biodiversity Conservation, P.T. Semen Padang, Indonesia. The broodfish were fed commercial feed to satiation at 09:00 and 17:00 h. The females (average weight 7.56 ± 0.85 g) and males (4.86 ± 1.20 g) were selected at a ratio of 1:4 (female:male), and gonad maturation was induced with a single dose of GnRH analogue (Ovaprim) of 0.1 ml/fish. At 16 h after hormone injection, eggs were collected individually into a plastic vessel. Spermatozoa were collected with sterile syringes. Eggs were fertilized using the "dry" method, and 0.5 ml samples (equal to 100 eggs) were taken. The eggs were incubated in a plastic strainer with a water volume of 1.57 litres and placed in a tarpaulin pond with a volume of 150.72 litres. Results: The overall hatching rate was 78.93 ± 4.13%. The newly hatched larvae were 3900.81 µm long, with a yolk sac of 82881.480 µm 2. The mouth opened at 72 days post hatching (DPH) with a gape measuring approximately 61.880 µm. The protocol of larval feeding started with artificial feed, followed by Artemia nauplii up to 30 DPH. Weaning of larvae started at 4 DPH. Larvae started metamorphosis by 15 DPH and ended by 22 DPH when the larvae reached 7430.27 µm. Larval rearing resulted in an average survival rate of 28.4 ± 3.04%. Conclusions: Its successful spawning induction and high larval hatching and survival rates make M. padangensis an excellent aquaculture candidate.

Carotenoids and retinoids in the gonad of brood-stock pikeperch: accumulation during vitellogenesis and influence on egg quality in farmed pikeperch Sander lucioperca.

Carotenoids are determinants of reproductive fitness and egg quality. Here we studied the accumulation of astaxanthin (AX), canthaxanthin (CA) zeaxanthin (ZX), lutein (LU), retinol (RX) and dehydroretinol (DR) during vitellogenesis comparing previtellogenic and vitellogenic pikeperch (Sander lucioperca) eggs (n = 5 each), as well as selected tissues (liver, fat and muscles) in first süawning females (1176-1450 g). Futhermore, we compared egg batches with high (88-99% hatching rate, n = 5) or low (40-67% hatching rate, n= 5) egg quality. Vitellogenic follicles revealed higher concentrations of DR, RX, ZX and LU compared to previtellogenic follicles. Neither CA nor AX was detectable. In parallel, DR and RX were mobilized in the liver. In adipose and muscle tissue, comparing previtellogenic and vitellogenic females, no significant differences in carotenoid/retinoid content were observed. In high quality egg batches, both DR and RX were increased. LU was lower in high quality than in low quality eggs. In a conclusion, the amount of retinoids seems suboptimal in low quality egg batches and increased DR and RX are desirable in pikeperch. Since hypervitaminosis of retinoids can be problematic though, supplementation of the food with carotenoids, which can serve as precursors for retinoids, has to be carried out carefully.

Hydroxyapatite-binding Silver/Titanium Dioxide as a Potential Control Compound Against Mosquito Vectors, Aedes aegypti (Diptera: Culicidae) and Anopheles dirus (Diptera: Culicidae).

Controlling mosquitoes is vital for counteracting the rising number of mosquito-borne illnesses. Vector control requires the implementation of various measures; however, current methods lack complete effectiveness, and new control agents or substances are urgently needed. Therefore, this study developed a nonwoven fabric sheet coated with hydroxyapatite-binding silver/titanium dioxide compound (hydroxyapatite-binding silver/titanium dioxide sheet [HATS])and evaluated its effectiveness on all stages of laboratory Aedes aegypti (Linnaeus); Diptera: Culicidae and Anopheles dirus (Peyton & Harrison); Diptera: Culicidae. We reared larvae with HATS and control sheets and assessed their mortality, emergence, and hatching rates. The submersion rates of engorged female mosquitoes in submerged HATS and control sheets were also compared. The HATS strongly affected mosquito development, resulting in high mortality rates (mean ± SE) of 99.66 ± 0.58% (L1-L2) and 91.11 ± 9.20% (L3-L4) for Ae. aegypti and 100% of both stages for An. dirus. In contrast, mosquitoes raised in the control sheet showed relatively high survival rates of 92.33 ± 3.21% (L1-L2) and 95.67 ± 0.58% (L3-L4) for Ae. aegypti and 86.07 ± 3.53% (L1-L2) and 92.01 ± 8.67% (L3-L4) for An. dirus. Submersion of engorged females was found in the HATS oviposition cup, leading to a decreased number of eggs and a low hatching rate compared to that of the control. Overall, HATS may be a useful new control method for Ae. aegypti and An. dirus.

Hierarchical shift of the Aedes albopictus microbiota caused by antimicrobiota vaccine increases fecundity and egg-hatching rate in female mosquitoes.

Recent studies show that mosquito-microbiota interactions affects vector competence and fitness. We investigated if host antibodies modifying microbiota impact mosquito physiology. We focused on three prevalent bacteria (Acinetobacter, Pantoea, and Chryseobacterium), originally isolated from the Asian tiger mosquito Aedes albopictus. Our goal was to assess the impact of host antibodies on mosquito microbiota and life traits. Female mosquitoes were fed with blood from rabbits immunized with each bacterium or a mock vaccine. We compared various factors, including feeding behavior, survival rates, and reproductive success of the mosquitoes. Interestingly, mosquitoes fed with blood from a Chryseobacterium-immunized rabbit showed a significant increase in fecundity and egg-hatching rate. This outcome correlated with a decrease in the abundance of Chryseobacterium within the mosquito microbiota. While no significant changes were observed in the alpha and beta diversity indexes between the groups, our network analyses revealed an important finding. The antimicrobiota vaccines had a considerable impact on the bacterial community assembly. They reduced network robustness, and altered the hierarchical organization of nodes in the networks. Our findings provide the basis for the rational design of antimicrobiota vaccines to reduce mosquito fitness and potentially induce infection-refractory states in the microbiota to block pathogen transmission.

Effects of Eggshell Thickness, Calcium Content, and Number of Pores in Erosion Craters on Hatching Rate of Chinese Alligator Eggs.

The Chinese alligator (Alligator sinensis), found only in a small region in southeastern Anhui Province, is listed as critically endangered (CR) by the International Union for Conservation of Nature (IUCN) due to its current declining population trend. Any abnormalities in the physical properties of an egg can decrease the hatching rate. In particular, eggshells play an essential role in embryo development, motivating us to analyze the microstructures of the eggshells of Chinese alligators. In this study, we categorized the eggshells into two groups, based on the hatching rates, and analyzed the relationship between the eggshell parameters (eggshell thickness, calcium content, and number of pores in erosion craters) and the hatching rate, as well as the relationships between the eggshell parameters. We found that the shells of the eggs with high hatching rates were thicker than those of the eggs with low hatching rates. There were also fewer erosion-crater pores on the surfaces of the eggs with high hatching rates than on the surfaces of the eggs with low hatching rates. Moreover, the shell Ca content was significantly higher in the eggs with high hatching rates than in the eggs with low hatching rates. Cluster modeling indicated that the highest hatching rate occurred when the eggshell thickness was 200-380 µm and there were 1-12 pores. These results suggest that eggs with adequate Ca contents, thicker shells, and less air permeability are more likely to hatch. Furthermore, our findings can inform future studies, which will be vital for the survival of the critically endangered Chinese alligator species.

Reproduction of Black Soldier Fly (Diptera: Stratiomyidae) Under Different Adult Densities and Light Regimes.

The black soldier fly (BSF) Hermetia illucens (L.) (Diptera: Stratiomyidae) has been recognized as a promising insect species for sustainable management of organic waste and by-products. Indoor breeding of BSF with artificial lighting has been proved successful, but efforts are still needed to optimize BSF reproductive output. Increasing adult density seems an option to exploit space, whereas decreasing artificial lighting duration may reduce unnecessary power consumption. This study aimed at investigating the effects of adult density (10, 25, and 50 pairs per 30 × 30 × 30 cm cage; i.e., 370, 926, and 1,852 pairs/m3), light regime (8:16, 12:12, and 16:8 [L:D] h), and their possible interactions, on some BSF life history traits relevant to reproduction. The results show that the overall BSF reproductive output increased with increasing adult density but was not affected by light regimes per se. With the highest BSF adult density tested, an average of more than 20,000 neonate larvae were produced from a cage within 10 d. At this density, increasing photoperiod increased neonate production, but also decreased the number of neonates per watt used for artificial illumination. The temporal oviposition patterns, mean individual female reproductive output, mating success, egg hatching rate, and insect survival rate were not affected by adult density or light regime as simple effects. However, the interaction between adult density and light regime was significant for the first oviposition peak, mean individual female reproductive output, and insect survival rate. The possible mechanisms behind our results are discussed.

Temperature, season, and latitude influence development-related phenotypes of Philippine Aedes aegypti (Linnaeus): Implications for dengue control amidst global warming.

BACKGROUND: Dengue is endemic in the Philippines. Aedes aegypti is the primary vector. This study aimed to determine the hatching behavior and viability of Ae. aegypti first-generation (F1) eggs when exposed to temperature and photoperiod regimes under laboratory conditions. METHODS: Parental eggs were collected from selected highland and lowland sites in the Philippine big islands (Luzon, Visayas, and Mindanao) during the wet (2017-2018) and dry (2018) seasons. F1 egg cohorts were exposed separately in environmental chambers at 18, 25, and 38 °C with respective photoperiods for 6 weeks. Phenotypes (percent pharate larvae [PPL], hatch rates [HRs], and reproductive outputs [ROs]) were determined. RESULTS: Results of multivariate analyses of variance (MANOVA) between seasons showed significant main effects of temperature, season, and big island on all phenotypes across all sites. Significant interaction effects between seasons on all phenotypes across sites were shown between or among (1) season and big island, (2) season and temperature, (3) big island and temperature, (4) season, big island, and temperature, (5) big island, altitude, and temperature, and (6) season, big island, altitude, and temperature. Factors associated with the big islands might include their ecology, available breeding sites, and day lengths due to latitudinal differences, although they were not measured in the field. MANOVA results within each season on all phenotypes across sites showed (1) significant main effects of big island and temperature, and (2) significant interaction effects between big island and temperature within the wet season and (3) between temperature and photoperiod within the dry season. PPL were highest at 18 °C and were formed even at 38 °C in both seasons. Pharate larvae might play an adaptive role in global warming, expanded distribution to highlands, and preponderance to transmit human diseases. HRs in both seasons were highest at 25 °C and lowest at 38 °C. ROs were highest at 25 °C in the wet season and at 18 °C in the dry season. CONCLUSIONS: Temperature and latitude of Philippine big islands influenced the development-related phenotypes of Ae. aegypti in both seasons. The two seasons influenced the phenotypes and their interaction effects with big island and/or temperature and/or altitude. Recommendations include year-round enhanced 4S control strategies for mosquito vectors and water pipeline installation in rural highlands.

Reproduction of Limnatis paluda (Tennent 1859) in laboratory conditions.

The reproductive functions of Limnatis paluda were studied in laboratory conditions including imposing of two thermal conditions (T1: 18 ± 2 °C and T2: 26 ± 2 °C) and with there being placement of three bedding substrates (tile, moss, and stone) in the containers specimens were confined. Furthermore, values for reproductive variables of cocoons and hatchlings were recorded. With the T2 treatment, gravid adults had cocoon depositions, whereas those when there was imposing of the T1 treatment did not have cocoon depositions. There was cocoon deposition only on the moss bedding, and it is presumed that moss could provide a robust and stable nursing microenvironment for developing embryos. Frequency (%) of cocoon depositions did not vary during the months of the deposition period. Hatching occurred after 26 ± 2 days when there was imposing of the T2 treatment. There was no correlation between the values for size of the ovigerous cocoons and number of offspring. There was a negative correlation between number and mean weight of hatchlings. There was a difference in cocoon weight for the different months and fluctuation in mortality and hatching rate which is assumed to be related to differences in feeding behaviors.