Groups Of Larvae Research Articles

Historical invasion rates vary among insect trophic groups.

Globalization has spread thousands of invasive insect species into new world regions,1,2,3 causing severe losses in ecosystem services. Previous work proposed that plant invasions facilitate insect invasions through the creation of niches for non-native herbivores.3,4,5,6 Despite the impact of insect invasions, a comprehensive understanding is lacking on how invasion success varies among insect feeding groups. We therefore compiled the predominant larval trophic groups (herbivores, predators, parasites, detritivores, and brood-carers) for 5,839 non-native insect species in nine world regions to compare (1) proportions of species in each group between non-native species and the world's fauna, (2) how invasion success for each trophic group has changed over the last three centuries, and (3) how historical herbivore invasions are related to plant invasions over time and parasite invasions are related to herbivores. We find that herbivores represent a significantly larger proportion (52.4%) among non-native insects compared with the world fauna (38.4%), whereas proportions of non-native detritivores (including fungivores), predators, and brood-carers are significantly lower; parasite proportions do not significantly differ. Predators and detritivores dominated among invasions in the 18th century but subsequently diminished, likely due to changing invasion pathways, whereas proportions of herbivores, parasites, and brood-carers increased over time. We found herbivore invasions to lag 80 years behind plant invasions, whereas parasitoids appear to co-invade with their herbivore hosts. The dominance of herbivores among non-native insects and their strong cross-correlation with plant invasions further strengthens the hypothesis that plant invasions drive the global rise in numbers of non-native insects.

Microbial influence on the larval survival of Japanese eel Anguilla japonica: Antibiotic-mediated alterations and biomarker isolation.

In rearing systems for the Japanese eel Anguilla japonica, although it is assumed that microorganisms influence larval survival and mortality, particularly during the early stages of growth, the effects of bacterial communities on larval survival have yet to be sufficiently determined. In this study, we compared the bacterial communities associated with larval survival at three stages of eel growth. To artificially alter bacterial communities and assess larval survival, eel larvae were treated with 11 types of antibiotic, and larval survival and bacterial characteristics were compared between the antibiotic-treated and antibiotic-free control groups. Throughout the three growth stages, eels treated with four antibiotics (polymyxin B, tetracycline, novobiocin, and erythromycin) had survival rates higher than those in the control groups. The bacterial communities of surviving larvae in the control and antibiotic groups and dead larvae in the control groups were subsequently analyzed using 16S rRNA gene amplicon sequencing. PERMANOVA analysis indicated that these three larval groups were characterized by significantly different bacterial communities. We identified 14 biomarker amplicon sequence variants (ASVs) of bacterial genera such as Oceanobacter, Alcanivorax, Marinobacter, Roseibium, and Sneathiella that were enriched in surviving larvae in the antibiotic treatment groups. In contrast, all four biomarker ASVs enriched in dead larvae of the control groups were from bacteria in the genus Vibrio. Moreover, 52 bacterial strains corresponding to nine biomarkers were isolated using a culture method. To the best of our knowledge, this is the first study to evaluate the bacterial communities associated with the survival and mortality of larvae in during the early stages of Japanese eel growth and to isolate biomarker bacterial strains. These findings will provide valuable insights for enhancing larval survival in the eel larval rearing systems from a microbiological perspective.

Spatiotemporal and Trade-Off Dynamics in Prey–Predator Model with Domed Functional Response and Fear Effect

In the ecological scenario, predators often risk their lives pursuing dangerous prey, potentially reducing their chances of survival due to injuries. Prey, on the other hand, try to strike a balance between reproduction rates and safety. In our study, we introduce a two-dimensional prey–predator model inspired by Tostowaryk’s work, specifically focusing on the domed-shaped functional response observed in interactions between pentatomid predators and neo-diprionid sawfly larvae. To account for the varying effectiveness of larval group defense, we incorporate a new component into the response equation. Our investigation delves into predator trade-off dynamics by adjusting the predator’s mortality rate to reflect losses incurred during encounters with dangerous prey and prey’s trade-off between safety and reproduction rate incorporating this domed-shaped functional response. Our model demonstrates bistability and undergoes various bifurcations, including transcritical, saddle-node, Hopf, Bogdanov–Takens, and Homoclinic bifurcations. Critical parameters impact both predator and prey populations, potentially leading to predator extinction if losses due to dangerous prey encounters become excessive, highlighting the risks predators face for their survival. Furthermore, the efficacy of group defense mechanisms can further endanger predators. Expanding our analysis to a spatially extended model under different perturbations, we explore Turing instability to explain the relationship between diffusion and encounter parameters through both stationary and dynamic pattern formation. Sensitivity to initial conditions uncovers spatiotemporal chaos. These findings provide valuable insights into comprehending the intricate dynamics of prey–predator interactions within ecological systems.

Evolution of larval gregariousness is associated with host plant specialisation, but not host morphology, in Heliconiini butterflies.

Insect herbivores, such as lepidopteran larvae, often have close evolutionary relationships with their host plants, with which they may be locked in an evolutionary arms race. Larval grouping behaviour may be one behavioural adaptation that improves host plant feeding, but aggregation also comes with costs, such as higher competition and limited resource access. Here, we use the Heliconiini butterfly tribe to explore the impact of host plant traits on the evolution of larval gregariousness. Heliconiini almost exclusively utilise species from the Passifloraceae as larval host plants. Passifloraceae display incredible diversity in leaf shape and a range of anti-herbivore defences, suggesting they are responding to, and influencing, the evolution of Heliconiini larvae. By analysing larval social behaviour as both a binary (solitary or gregarious) and categorical (increasing larval group size) trait, we revisit the multiple origins of larval gregariousness across Heliconiini. We investigate whether host habitat, leaf defences and leaf size are important drivers of, or constraints on, larval gregariousness. Whereas our data do not reveal links between larval gregariousness and the host plant traits included in this study, we do find an interaction between host plant specialisation and larval behaviour, revealing gregarious larvae to be more likely to feed on a narrower range of host plant species than solitary larvae. We also find evidence that this increased specialisation typically precedes the evolutionary transition to gregarious behaviour. The comparatively greater host specialisation of gregarious larvae suggests that there are specific morphological and/or ecological features of their host plants that favour this behaviour.

In silico identification and expression analyses of catalases in Tenebrio molitor

AbstractAgricultural intensification has led to significant increases in production, but the overuse of pesticides and associated hazards pose threats to biodiversity and ecological functions. Catalase (CAT), a key antioxidant enzyme, plays a crucial role in alleviating oxidative stress by directly interacting with toxins. In this study, we identified three CAT isoforms in Tenebrio molitor (TmCAT‐iso1, TmCAT‐iso2 and TmCAT‐iso3). These CATs possess a CAT domain, tetramer interface sites and a heme‐binding pocket. We examined the expression of Tm catalases across all developmental stages and in specific tissues using quantitative real time polymerase chain reaction (qRT‐PCR) experiments. Our findings demonstrate that TmCAT‐iso1 and TmCAT‐iso3 exhibit peak expression in young and late larval stages, respectively, whereas TmCAT‐iso2 shows peak expression during the egg and pre‐pupal stages. Tissue distribution analysis revealed the high expression of TmCAT‐iso1 and TmCAT‐iso2 in larval hemocytes, whereas TmCAT‐iso3 is predominantly expressed in larval Malpighian tubules. Furthermore, injection with chlorantraniliprole significantly elevated mRNA expression levels of TmCAT‐iso1, TmCAT‐iso2, and TmCAT‐iso3 in larval groups, compared with control groups. Our study highlights the distinct developmental stages and tissues where TmCATs are expressed. We also elucidated the effects of pesticide application on the expression of each TmCAT, revealing the physiological characteristics of CATs in response to these pesticides, which are dose‐ and time‐dependent in T. molitor.

Does Size Matter? Small and Large Larvae of Pikeperch (Sander lucioperca) in a Comparative Gene Expression Analysis

Size differences are common in the aquaculture of fishes. In the larviculture of cannibalistic species such as pikeperch, they majorly influence mortality rates and consequently provoke losses in the aquaculture industry. With this study, we aim to reveal molecular differences between small and large pikeperch of the same age using a set of 20 genes associated with essential developmental processes. Hereby, we applied a general study design to early and late larval pikeperch before the onset of piscivory to explore the causes of growth differences in these developmental groups. The analysis of the expression levels showed developmental but not size-related differences in PGC1A, TGFB1, MYOD1, MRF4, and the collagens COL1A1 and COL1A2. Furthermore, increased head lengths were found in larger late larvae compared to their smaller conspecifics. While no uniquely size-related expression differences were found, the expression patterns of PGC1A in combination with TGFB1 as regulators of the citric acid cycle indicate a possible influence of mitochondrial energy metabolism. Furthermore, expression differences of MYOD1 and MRF4 point out possible temporal advantages of myogenetic processes in the larger late larval group and hypothesise growth advantages of the larger late larvae resulting from various influences, which provide a promising target for future research.

Collagen10a1 GEN EXPRESSION AND BONE MINERALIZATION IN THE col10a1:nlGFP TRANSGENTIC MEDAKA FISH LARVAE

Objective: To assess the expression level of the osteoblast-specific collagen10a1 gene and the degree of bone mineralization during the early larval stages of col10a1:nlGFP transgenic medaka fish to identify a specific developmental time window suitable for conducting bone anabolic effect evaluations of bioactive substances. Methods: Homozygous and hemizygous col10a1:nlGFP fish larval groups at 7, 9, 10, 11, and 14 days post fertilization (dpf) were used in the study (n=…/group). The fish were subjected to live staining with alizarin red S (ARS) dye to visualize their mineralized bone structures. Fluorescent images were captured using a fluorescent stereoscope to document both the GFP and ARS signals in the fish. The density of the GFP signal was utilized to assess the expression level of the collagen10a1 gene in osteoblasts, while the density of the ARS signal was used to evaluate the extent of bone mineralization. ImageJ software was employed for this analysis. Results: The intensity of GFP signal exhibited an upward trend as the fish grew from 7 to 9 dpf, followed by a gradual decline from 9 to 14 dpf. Along with that, the intensity of ARS signal increased as the fish grew from 7 to 10 dpf, followed by a gradual decrease from 10 to 14 dpf. These findings indicate that the optimal developmental window for conducting tests on the fish with bioactive compounds, utilizing a stereo fluorescence microscope, is between 7 and 9 dpf.

Multi-species probiotics enhance survival, growth, intestinal microbiota and disease resistance of rohu (Labeo rohita) larvae

Multi-strain probiotics provide the most dependable approaches to improve health, immune response, and disease resistance in farmed fishes. In the present study, we examined the effects of multi-species probiotics on the survival, growth, immune response, and disease resistance of rohu (Labeo rohita) larvae. Newly hatched larvae from the day of first feeding (average weight of 0.003 ​g) were reared with multi-species probiotics having a combination of Bacillus subtilis (109 colony forming units (cfu)/mL) and Lactobacillus spp. (Lactobacillus plantarum, Lactobacillus buchneri - 1011 ​cfu/mL) in water containing doses of 0 (control-C), 0.5 ​mL/L (treatment 1-T1), and 1.0 ​mL/L (treatment 2-T2) in triplicates for 90 days. After the experiment, a challenge test was performed to assess the fish's resistance to pathogenic Aeromonas veronii. Significantly higher survival was recorded in larvae of treated groups (87% in T2 and 79% in T1) compared to the control (62%). Significantly higher growth performance (weight gain and specific growth rate—SGR) was shown by the probiotic-treated larval groups compared to the control. Probiotic supplementation resulted in significantly higher counts of total viable colony (TVC) and lactic acid bacteria (LAB) in the intestine. Some immunological parameters (mucosal fold fattening, goblet cell abundance, expansion of lamina propria and enterocytes) of the gut were significantly better in probiotic-treated fish. The liver of treated fish showed irregular shape nuclei turning into regular shape and reducing spaces between the hepatic cells. Probiotic-treated fish had the highest post-challenge survival rate (90%) against A. veronii infection. The erythrocytes of challenged fish treated with probiotics had significantly lower frequencies of various nuclear and cellular abnormalities. These findings suggest that multi-species probiotic supplements could improve the survival, growth, health status, and immune response of rohu in the early stages of its development.

Live-food enriched with Chlorella vulgaris as a potential supplemental diet to enhance performance and immune response of Tor tambroides larvae (Bleeker 1854)

Tor tambroides is one of the Tor species identified in Southeast Asia with a promising aquaculture potential in Malaysia, fetching market price of up to USD 53 per kilogram. It is a slow grower that takes more than two years to reach marketable body weight (∼800 g) in captivity. This study was designed to establish the C. vulgaris enriched Artemia sp. and Moina sp. in enhancing the growth performance of T. tambroides larvae. The larvae were divided into five treatments, control (C) (commercial feed); unenriched Moina (UM); enriched Moina (EM); unenriched Artemia (UA); enriched Artemia (EA). The concentration of C. vulgaris used during enrichment was 1 × 107 algal cells/mL. On 14 to 29 days after hatching (DAH), the larvae were co-fed with the commercial feeds and each treatment four times daily. The highest body weight gained were observed in the larval group fed with EA (18.56 ± 1.02 mg), followed by UA (15.89 ± 2.08 mg) and were statistically different as compared to the UM (6.89 ± 0.51) and EM (6.11 ± 1.09) and C (3.56 ± 1.20) (p < 0.05). The final total length was also the highest in larvae fed with EA (17.8 ± 0.04 mm), followed by UA (17.2 ± 0.0 mm), EM (16.4 ± 0.02 mm), UM (16.0 ± 0.02 mm) and the lowest in C (15.4 ± 0.02 mm). The larvae fed with EA also displayed a significant increase in specific growth rate (4.66%), followed by UA (4.13%) and were statistically different to UM (2.10%), EM (1.88%) and C (1.14%) (p < 0.05). The relative growth rate of the larvae was the highest in EA (92.27%) and lowest in C (17.68%) (p < 0.05). The survival rate of the larvae was the highest in UM and EM with 89.4%, followed by EA (89.13%), UA (88.51%) and C (84.7%). The EA had high and positive upregulation of growth hormone genes (0.16 ± 0.13), myostatin gene (0.11 ± 0.10), MHCC1a gene (0.48 ± 0.12) and CC3 gene (0.28 ± 0.14) and were statistically different as compared to the control group. The enriched Artemia had enhancing effect on the growth performance and expression of the immune and growth genes of the larvae, potentially due to its nutritional contents and better ingestion by the larvae. The study suggests C. vulgaris enriched Artemia can be used in the hatcheries to improve the growth and survival of T. tambroides larvae, shorten its rearing period and increases its yield.

Feeding Spodoptera exigua larvae with gut-derived Escherichia sp. increases larval juvenile hormone levels inhibiting cannibalism

Feed quality influences insect cannibalistic behavior and gut microbial communities. In the present study, Spodoptera exigua larvae were fed six different artificial diets, and one of these diets (Diet 3) delayed larval cannibalistic behavior and reduced the cannibalism ratio after ingestion. Diet 3-fed larvae had the highest gut bacterial load (1.396 ± 0.556 × 1014 bacteria/mg gut), whereas Diet 2-fed larvae had the lowest gut bacterial load (3.076 ± 1.368 × 1012 bacteria/mg gut). The gut bacterial composition and diversity of different diet-fed S. exigua larvae varied according to the 16S rRNA gene sequence analysis. Enterobacteriaceae was specific to the Diet 3-fed larval gut. Fifteen culturable bacterial isolates were obtained from the midgut of Diet 3-fed larvae. Of these, ten belonged to Escherichia sp. After administration with Diet 1- or 2-fed S. exigua larvae, two bacterial isolates (SePC-12 and -37) delayed cannibalistic behavior in both tested larval groups. Diet 2-fed larvae had the lowest Juvenile hormone (JH) concentration and were more aggressive against intraspecific predation. However, SePC-12 loading increased the JH hormone levels in Diet 2-fed larvae and inhibited their cannibalism. Bacteria in the larval midgut are involved in the stabilization of JH levels, thereby regulating host larval cannibalistic behavior.

Dietary supplementation of Terminalia arjuna bark extract improved growth, biochemical parameters and innate immunity in Heteropneustes fossilis larvae

Achieving healthy aquatic environment has been elusive with the process of intensification due to irrational use of chemicals. Plant extracts are hence candidate of choice as an alternative in aquaculture. Moreover, the poor larval survival of Heteropneustes fossilis (singhi) needs urgent research attention, which can be effectively addressed by boosting immunity, particularly by enhancing nonspecific immunity in the larvae. Hence, the study investigates the effects of dietary supplementation of Terminalia arjuna (TA) methanolic bark extract on growth, immune biomarkers and biochemical status in the stinging catfish, Heteropneustes fossilis larvae. 180 numbers of fish larvae (15 days post hatch; 22 ± 2.6 mm mean length and 43 ± 3.5 mg mean weight) were equally distributed in to four groups and fed with 0 % (control), 0.1 %, 0.25 % and 0.5 % of TA supplemented feed. Growth attributes, non-specific immune and biochemical parameters were analysed after 40 days of feeding. Results demonstrated that, larval group fed with 0.25 % TA extract had significantly (P < 0.05) improved final body weight, weight gain percent, daily weight gain and SGR compared to other treatment groups. Supplementation with 0.25 % TA extract significantly (P < 0.05) elevated respiratory burst activity (RBA), myeloperoxidase activity (MPO), lysozyme and biochemical parameters including alkaline phosphatase (ALP) activity, total protein, albumin as well as SOD level. However, 0.5 % TA dietary group revealed reduced growth and compromised immunity in the larva. Moreover, 0.25 % level significantly (P < 0.05) reduced hepato-cellular enzymes like ALT and AST activities and glucose as compared to control. However, the increase in extract level up to 0.5 % in the diet exhibited stress, which is evident from undermined growth and immunity. The present study suggests that the dietary TA bark extract inclusion level up to 0.25 % is safe limit and can modulate immunity, antioxidant and growth performance in stinging catfish, H. fossilis larvae.

Novel insights regarding the safety and efficacy of pyrethroid-coated nanoparticles against Hyalomma ticks

Nanoparticles have been shown to inhibit major life cycle stages of ticks, indicative of the promising application of nanomaterials against hard ticks. The study thus probed into one of the alternative options to curtail Hyalomma by employing nanocomposites consisting of pyrethroids (cypermethrin and deltamethrin) coated nanoparticles of iron oxides and iron sulfides keeping alongside the evaluation of their toxicity through plant and mammalian cell lines. The nanoparticles used in this study were roughly spherical in morphology and exhibited various size dimensions upon characterization using SEM, EDX, and FTIR. The application of nanomaterials on female ovipositioning tick showed a decline up to 15% (females ovipositioned) in deltamethrin-coated FeO NPs, whereas this decline was up to 18% in Cyp-FeS NPs and up to 5% in Cyp-FeO NPs. Similarly, the larval hatching was also impacted, leading to a hatching percentage of 5% and only 1% by application of Cyp-FeS NPs and Cyp-FeO NPs, respectively. Similarly, the larval groups had LC90 of 4.1 and 4.73 mg/L for the Cyp-FeO NPs and Cyp-FeS NPs groups. The delta-FeO NPs and delta-FeS NPs demonstrated a promising effect against adult ticks, showing LC50= 3.5 mg/L, LC90= 6.7 mg/L and LC50= 3.8 mg/L, LC90= 7.9 mg/L, respectively. MTT assay revealed that the pyrethroids coupled with iron oxide nanoparticles showed the least cytotoxicity even at the highest concentration (10–1 µL) among other nanomaterials. The study thus concluded a safer spectrum of non-target effects of pyrethroids-coated nanomaterials in addition to their significant anti-tick activity.

Quantification of lipid droplets in hatchery reared veliger larvae of the green-lipped mussel, Perna canaliculus

Domestication efforts and selective breeding in bivalve aquaculture would greatly benefit from reliable screening biomarkers in the early life stages of development (e.g., larvae). In this study the lipids remaining at the completion of embryo development in selectively-bred/hatchery reared green-lipped mussel, Perna canaliculus, were targeted and quantified using two approaches: confocal laser scanning microscopy and image analysis (CLSM/IA) on Oil Red-O stained larva (i.e., lipid droplet number and volume distribution), and Iatroscan thin layer chromatography/flame ionization detection (TLC/FID) (i.e., energetic and structural lipid classes content). Four groups of newly formed pre-feeding veliger larvae, produced from two genetically distinct families (FA, FB) that completed embryo development at either low (L, 17 °C) or high (H, 21 °C) temperatures, were evaluated. The FB produced offspring better equipped to deal with higher temperatures during embryonic development, with greater survival, higher normal development, and larger larvae than FA when developing at 21 °C. In terms of lipids content, CLSM/IA showed that each individual larva had overall between 83 and 157 lipid droplets (ranging in volume from 2.5 to 294 μm3). The TLC/FID estimation of mean total lipid content ranged from 4.1 to 6.9 ƞg larva−1 (29–39% structural lipid and 62–69% energetic lipid). Both lipid quantification methods were successful in detecting differences among larval groups with different genetic backgrounds, as well as providing insight into the ability to cope with changes in the growing environment when relying on maternal energy sources (triacylglycerol-TAG identified as the main source of energy for early development). Stronger differences between the two families were identified using CLSM/IA than with TLC/FID (i.e., with FA having overall more and larger lipid droplets). However, TLC/FID was able to distinguish FA larvae reared at high temperatures from the other groups (due to lower levels of TAG, 46% of total lipids, versus 52–56% in the other groups), therefore being more sensitive to the pooled population response compared to the individual lipid droplet quantification in CLSM/IA. The application of these tools, when fully developed, could be extended to controlled commercial operations to diagnose and predict larval performance, enabling more directed early screening and informing production and breeding decisions.

Analyzing Gut Microbial Community in Varroa destructor-Infested Western Honeybee (Apis mellifera).

The western honeybee Apis mellifera L., a vital crop pollinator and producer of honey and royal jelly, faces numerous threats including diseases, chemicals, and mite infestations, causing widespread concern. While extensive research has explored the link between gut microbiota and their hosts. However, the impact of Varroa destructor infestation remains understudied. In this study, we employed massive parallel amplicon sequencing assays to examine the diversity and structure of gut microbial communities in adult bee groups, comparing healthy (NG) and Varroa-infested (VG) samples. Additionally, we analyzed Varroa-infested hives to assess the whole body of larvae. Our results indicated a notable prevalence of the genus Bombella in larvae and the genera Gillamella, unidentified Lactobacillaceae, and Snodgrassella in adult bees. However, no statistically significant difference was observed between NG and VG. Furthermore, our PICRUSt analysis demonstrated distinct KEGG classification patterns between larval and adult bee groups, with larvae displaying a higher abundance of genes involved in cofactor and vitamin production. Notably, despite the complex nature of the honeybee bacterial community, methanogens were found to be present in low abundance in the honeybee microbiota.

Evidence of isotopic maternal transmission influence on bluefin tuna (Thunnus thynnus) larval growth

Pre-flexion stages of Atlantic bluefin tuna (Thunnus thynnus) larvae were collected in 2014 during the peak of spawning in the two main spawning areas: Gulf of Mexico (GOM) and Mediterranean Sea (MED). We examined daily growth, otolith biometry, and stable isotopes and found that the GOM grew at a faster rate, had larger otoliths, wider daily increments, and significantly lower values of δ15N when compared to the MED. In addition, an intra-population comparative analysis between slow- and fast-growing individuals (deficient vs. optimal growth groups, respectively) showed that optimal growth groups had significantly lower δ15N within each spawning area, implying a direct relationship between growth potential, development, and maternal transmission of isotopic signatures. A third pre-flexion larval group that was aquaculture-reared also exhibited the same pattern to the wild larval groups. In addition, for the first time, we estimated the maternal trophic niches using models developed with field-captured pre-flexion larvae. The estimated maternal trophic niches for the GOM were narrower than the MED, implying differences in the maternal trophodynamics from each nursery area. Overall, the inter-population (GOM vs. MED) and intra-population growth groups (deficient vs. optimal) grew faster and had narrower maternal niches. This study shows the advantages that larval SIA research can aid in the understanding of the trophodynamics of their breeders by examining the trophic relationship of a spawning stock jointly with the development of growth potential in offspring within the same breeding season.

Application of Cypermethrin-Coated ZnS and ZnO Nanoparticles against Rhipicephalus Ticks.

Rhipicephalus ticks are described as important ticks impacting the costs of livestock rearing and by-products sale. The prevalence and response of ticks towards cypermethrin sprays indicate the need to implement the rational use of acaricides. In our previous studies, ZnO nanoparticles were shown to inhibit the major life-cycle stages of Hyalomma ticks, indicative of promising application of nanomaterials against the hard ticks. The current study was designed to probe into one of alternative options to curtail Rhipicephalus ticks by employing cypermethrin-coated nanoparticles of ZnO (C-ZnO NPs) and ZnS (C-ZnS NPs). The nanocomposites showed a roughly spherical type of morphology and various size dimensions upon characterization using SEM and EDX. Female ovipositioning was declined up to only 48% in ZnS and up to 32% in ZnO NPs even after 28 days in vitro. Similarly, the larval hatching was also impacted, leading to a hatching percentage of 21% and 15% by application of C-ZnS NPs and C-ZnO NPs, respectively. The LC90 in female adult groups were 3.94 mg/L and 4.27 mg/L for the C-ZnO NPs and C-ZnS NPs groups, respectively. Similarly, the larval groups had LC90 of 8.63 and 8.95 mg/L for the C-ZnO NPs and C-ZnS NPs groups. The study is a proof of the concept for incorporating effective and safe nanocomposites as acaricides. The studies on the efficacy and spectrum of non-target effects of nanomaterial-based acaricides can further refine the research on finding novel alternatives for tick control.

Oxytocin protective effects on zebrafish larvae models of autism-like spectrum disorder.

Autism is a complicated neurodevelopmental disorder characterized by social interaction deficiencies, hyperactivity, anxiety, communication disorders, and a limited range of interests. The zebrafish (Danio rerio) is a social vertebrate used as a biomedical research model to understand social behavior mechanisms. After spawning, the eggs were exposed to sodium valproate for 48 hr, after which the eggs were divided into eight groups. Except for the positive and control groups, there were six treatment groups based on oxytocin concentration (25, 50, and 100 μM) and time point (24 and 48 hr). Treatment was performed on days 6 and 7, examined by labeling oxytocin with fluorescein-5-isothiocyanate (FITC) and imaging with confocal microscopy and the expression levels of potential genes associated with the qPCR technique. Behavioral studies, including light-dark background preference test, shoaling behavior, mirror test, and social preference, were performed on 10, 11, 12, and 13 days post fertilization (dpf), respectively. The results showed that the most significant effect of oxytocin was at the concentration of 50 μM and the time point of 48 hr. Increased expression of shank3a, shank3b, and oxytocin receptor genes was also significant at this oxytocin concentration. Light-dark background preference results showed that oxytocin in the concentration of 50 µM significantly increased the number of crosses between dark and light areas compared with valproic acid (positive group). Also, oxytocin showed an increase in the frequency and time of contact between the two larvae. We showed a decrease in the distance in the larval group and an increase in time spent at a distance of one centimeter from the mirror. Our findings showed that the increased gene expression of shank3a, shank3b, and oxytocin receptors improved autistic behavior. Based on this study some indications showed that oxytocin administration in the larval stage could significantly improve the autism-like spectrum.

Predation efficiency of the carnivorous aquatic plant Utricularia australis against Asian tiger mosquito Aedes albopictus larvae: Implications for biological control

The Asian tiger mosquito, Aedes albopictus, one of the world’s worst invasive animal species and competent vector of many arboviruses, poses a serious threat to human health. An effective and environmentally friendly control strategy is required to mitigate the negative impacts of this pest. The aquatic carnivorous plants of the Utricularia genus, known as bladderworts, feed on invertebrates using their modified leaves as traps (bladders) and could be considered for biological control. The southern bladderwort, U. australis, was used in a no-choice experiment to test its predation ability against Ae. albopictus larvae. Larvae were divided in two size groups: 1st–2nd and 3rd–4th larval instars. Twenty Ae. albopictus larvae were placed inside 1 l plastic cups with a 30 cm long segment of the plant and left for a 7-day period. Twelve segments of U. australis were used, six for each larval size group, counting the number of bladders of each segment at the beginning of the experiment. The 7-day process was repeated five times for each segment/cup over a two-month period. The number of captured larvae and emerged adults was recorded daily. A total of 84 captured larvae were chosen to measure larval length, percentage of larval body trapped within the bladder, bladder perimeter and bladder area, in order to evaluate the ability of the bladders in capturing larvae, by complete or partial suction of the body, depending on the relative sizes of larvae and bladders. Results indicated that U. australis is an effective predator of Ae. albopictus larvae, with a higher efficiency against the 1st–2nd instar group (72%) compared to the 3rd–4th group (39%). The number of captured larvae depended on the number of bladders on each segment and instar group. The percentage of trapped larval body depended on the relationship between bladder size and larval length. Although the bladders effectively captured small larvae by complete suction of the body, they also killed 3rd–4th instar larvae by trapping a small portion of the body within the lumen. The plant segments continuously captured mosquito larvae, with an efficiency that did not decrease during the 2-month period. The use of U. australis as a biocontrol agent against Ae. albopictus larvae could be favoured by its ecological plasticity, broad distribution, its ability to thrive in small containers and the good overlap of the two species regarding phenology and habitat preferences.

The effect of Artemia nauplii (Artemia franciscana) enriched with different commercial products on the growth performance of the larvae of freshwater angelfish, Pterophyllum scalare (Lichtenstein, 1823)

The present study was planned to determine an optimum live-feeding protocol for angelfish larvae (Pterophyllum scalare). Larvae with an initial weight of 0.10 mg, a length of 4.5 mm, and a depth of 1 mm were reared on three different feeding regimens for 30 days. All experimental larval groups were fed Artemia nauplii from the end of the yolk-sac resorption. The control treatment (Group I) was maintained on Artemia nauplii on days 14-28, and on Artemia nauplii + dry feed on days 29 and 30. Group II was reared with Artemia nauplii enriched with Algamac 3050 on days 14-28 and with dry feed + Artemia nauplii enriched with Algamac 3050 on days 29 and 30, whereas Group III was fed with Artemia nauplii enriched with Red Pepper on days 14-28, and with dry food + Artemia nauplii enriched with Red Pepper on days 29 and 30. The highest weight (37.8±0.51 mg) and length (15.8±0.35 mm) were determined in Group II with significant differences from the control group (p&lt;0.05). However, enrichment treatments were comparable in terms of growth performance (p&gt;0.05). The survival rate of the larvae in the treatments varied between 70-75% without significant differences (p&gt;0.05). Overall, the study results suggest that a feeding protocol for angelfish larvae with the administration of Artemia nauplii during the first two weeks after hatching and then enriched Artemia with Algamac 3050 over the following 14-28 days followed by a gradual weaning onto dry feed.

Evolution of the larvicidal effects of secondary metabolites produced by Bacillus subtilis (Ehrenberg, 1835) Cohn, 1872 wild type UTB1 and mutant M419 against Plutella xylostella (L., 1758) (Lep.: Plutellidae)

The effects of Bacillus subtilis, wild type bacterium UTB1 and mutant M419, on two larval instar groups of the diamondback moth, Plutella xylostella L. (Lep.: Plutellidae) until three days after treatment have been investigated. Larval mortality rate increased with increasing the concentration and over the days after treatment. Increasing the larval instar resulted in elevating the LC50 value for both types of biosurfactants. In terms of lethality, there was no significant difference between the two bacteria in the final mortality rate after three days.