Larval Diet Research Articles

Early-Life Dietary Restriction and Diet Type Affect Juvenile Brain Morphology in Spadefoot Toads (Spea bombifrons)

Across a breadth of animal taxa, early-life environmental variation has been demonstrated to have lasting effects on later-life traits, including brain morphology. Here, we use Plains Spadefoot Toads (Spea bombifrons) to evaluate how larval diet type and amount influence later-stage, juvenile brain size and the relative sizes of brain regions. We specifically investigate whether developmental plasticity in brain morphology mirrors previously documented interspecific variation with relation to nutritional restriction and carnivory. Our findings demonstrate, contrary to expectation, that exposure to dietary restriction during the larval stage causes an increase in relative juvenile brain size. However, consistent with our predictions, consuming a prey-based shrimp diet during the larval stage results in relatively larger juvenile telencephalons, an intraspecific response that parallels an interspecific pattern in frogs where more-carnivorous species possess relatively larger telencephalons. Our results demonstrate that early-life dietary restriction and early-life diet type can generate changes in juvenile brain size and morphology in ways that may influence later-life behaviors and fitness. Further, our study suggests that intraspecific and environmentally induced changes in brain morphology can mirror interspecific divergence in brain morphology, supporting a role for developmental plasticity in promoting evolutionary change.

Influence of Dietary Protein Content on the Nutritional Composition of Mealworm Larvae (Tenebrio molitor L.)

The use of insects as livestock feed is becoming increasingly accepted because they provide an important source of protein. The purpose of this study was to investigate the chemical composition of mealworm larvae (Tenebrio molitor L.) reared on a range of diets that differed in nutritional composition. Focus was placed on the influence of dietary protein content on larval protein and amino acid composition. For the experimental diets, wheat bran was chosen as the control substrate. The following types of flour-pea protein, rice protein, sweet lupine, and cassava, as well as potato flakes, were mixed with wheat bran and used as the experimental diets. An analysis of the moisture, protein, and fat content was then carried out for all diets and larvae. Furthermore, the amino acid profile was determined. It was shown that supplementing the feed with pea and rice protein was most suitable in terms of high protein yield in larvae (70.9-74.1% dry weight) with low fat content (20.3-22.8% dry weight). The total amino acid content was highest in larvae that were fed with a mixture of cassava flour and wheat bran (51.7 ± 0.5% dry weight), as well as the highest content of essential amino acids (30.4 ± 0.2% dry weight). Moreover, a weak correlation between larval protein content and diet was identified, yet a stronger influence of dietary fats and carbohydrates on larval composition was found. This research could result in improved formulations of artificial diets for Tenebrio molitor larvae in the future.

Honey bee larval culture in vitro: gut emptying determines the transition from larva to prepupa and recombinant AccApidaecin improves antibacterial activity.

In vitro rearing of honey bee larvae is ideal for bioassay studies; no honey bee stable cell lines are available. Inconsistency of internal development staging of reared larvae and a susceptibility to contamination are common problems encountered. Standardized protocols on rearing larvae in vitro to make the larvae growth and development more similar to that of natural colonies are necessary to ensure the accuracy of experimental results and promote honey bee research as a model organism. Here, we concluded that when larval fasting weight was >160 mg, the time point of gut emptying can be defined as the critical point separating the larval and prepupal stages. In this way, we can conduct precise studies on the prepupal stage, such as organ remodeling during metamorphosis. Simultaneously, we further verified that recombinant AccApidaecin in genetic engineered bacteria added to the larval diet upregulated antibacterial peptide gene expression, and did not stimulate the stress response in larvae, nor did it affect the pupation rate or eclosion rate. This demonstrated that feeding recombinant AccApidaecin can enhance the individual antibacterial ability at the molecular level.

Metals and metal isotopes incorporation in insect wings: Implications for geolocation and pollution exposure

Anthropogenic activities are exposing insects to elevated levels of toxic metals and are altering the bioavailability of essential metals. Metals and metal isotopes have also become promising tools for the geolocation of migratory insects. Understanding the pathways of metal incorporation in insect tissues is thus important for assessing the role of metals in insect physiology and ecology and for the development of metals and metal isotopes as geolocation tools. We conducted a diet-switching experiment on monarch butterflies [Danaus plexippus (L.)] with controlled larval and adult diets to evaluate the sources of 23 metals and metalloids, strontium isotopes, and lead isotopes to insect wing tissues over a period of 8 weeks. Concentrations of Ca, Co, Mo, and Sb differed between the sexes or with body mass. Ni and Zn bioaccumulated in the insect wing tissues over time, likely from the adult diet, while increases in Al, Cr, Cd, Cu, Fe, and Pb were, at least partially, from external sources (i.e., dust aerosols). Bioaccumulation of Pb in the monarch wings was confirmed by Pb isotopes to mainly be sourced from external anthropogenic sources, revealing the potential of Pb isotopes to become an indicator and tracer of metal pollution exposure along migratory paths. Concentrations of Ba, Cs, Mg, Na, Rb, Sr, Ti, Tl, and U appeared to be unaffected by intrinsic factors or additions of metals from adult dietary or external sources, and their potential for geolocation should be further explored. Strontium isotope ratios remained indicative of the larval diet, at least in males, supporting its potential as a geolocation tool. However, the difference in strontium isotope ratios between sexes, as well as the possibility of external contamination by wetting, requires further investigation. Our results demonstrate the complexity of metal incorporation processes in insects and the value of studying metals to develop new tools to quantify pollution exposure, metal toxicity, micronutrient uptake, and insect mobility.

Development of a waste brewery yeast larval diet for rearing Bactrocera zonata for use in SIT

Development of a waste brewery yeast larval diet for rearing Bactrocera zonata for use in SIT

Temporal stability of δ2H in insect tissues: Implications for isotope-based geographic assignments

Hydrogen isotope geolocation of insects is based on the assumption that the chitin in the wings of adult migratory insects preserves the hydrogen isotope composition (δ2H) of the larval stages without influence of adult diet. Here, we test this assumption by conducting laboratory feeding experiments for monarch butterflies (Danaus plexippus) including: (1) a starvation treatment where adults were not fed and (2) an enriched treatment where adults were fed a diet isotopically enriched in deuterium (~ +78‰) compared to the larval diet. The δ2H values of adult wings were measured at different time steps along the 24-day experiment. We also investigated intra-wing differences in δ2H values caused by wing pigmentation, absence of wing scales, and presence of major wing veins. We conclude that, although the magnitude of the changes in δ2H values are small (~6‰), wing δ2H values vary based on adult diet and insect age, particularly early after eclosion (i.e., 1–4 days). We found that wing shade, wing pigmentation, and the presence of wing scales do not alter wing δ2H values. However, wing samples containing veins had systematically higher δ2H values (~9‰), suggesting that adult diet influences the hemolymph that circulates in the wing veins. We hypothesise that there is a stronger influence of adult diet on the isotope signal of wings during early adult life relative to later life because of increased metabolic and physiologic activity in young insect wings. We argue that the influence of the isotopic contribution of adult diet is generally small and is likely minimal if the wings are carefully sampled to avoid veins. However, we also demonstrated that wings are not inert tissues, and that adult feeding contributes to some of the intra-population δ2H variance. We conclude that δ2H geolocation using insect wings remains valid, but that adult feeding, butterfly age and wing vein sampling generate an inherent uncertainty limiting the precision of geolocation.

Gene expression responses of Bactrocera tryoni larvae feeding on different ripening stages of tomato fruit

AbstractThe Queensland fruit fly, Bactrocera tryoni, is an economically important pest insect of horticultural crops in Australia, damaging a wide variety of fruits and vegetables. To study the B. tryoni–fruit interaction, we conducted a transcriptomic investigation of B. tryoni larvae feeding on three ripening stages of tomato fruit, which had been previously shown to influence larval performance. Fruit fly larval survival in immature tomato fruit is very poor, which we hypothesized to be due to the effect of tomato fruit toxins which are mostly expressed in green fruit. We found 2709 transcripts differentially expressed in larvae feeding on the three ripening stages. The transcript expression pattern was most divergent between larvae feeding in immature fruit compared with fully ripe fruit, with intermediate expression in larvae feeding in colour‐break fruit. Gene Set Enrichment Analysis showed that larvae fed in immature fruit had a higher number of depleted GO terms in comparison with larvae fed on fully ripe fruit, particularly GO terms associated with larval development, metabolism and basic cellular functions. Enriched GO terms in larvae fed on fully ripe fruit showed the opposite pattern, with a greater number of enriched terms related to larval growth and detoxification processes. We concluded that poor larval survival in immature‐green fruit is likely because the substrate offers a very poor diet for larvae, which limits normal developmental functions. By contrast, in colour‐break and fully ripe fruit the substrate allows normal development, including the expression of metabolically costly detoxification mechanisms.

An Entomopalynological Analysis of Larval Provisions of Xylocopa iris (Christ, 1791) (Hymenoptera: Apidae) in Turkey

Bees are indispensable living components of ecosystems because of the pollination services they offer. In this respect, it is important to determine the extent of host plant specialization by evaluating their pollen diet, information that can easily be gathered by analyzing the pollen content of their nests. Here we examined two Xylocopa (Copoxyla) iris (Christ, 1791) nests from different provinces in Turkey to identify the relationship between the surrounding vegetation and the possible pollinator or forager X. iris, a species for which there is limited available pollen preference data. We investigated the larval provisions and pollen content of these nests and compared pollen content with the pollen of the surrounding vegetation. In addition, we inspected the nest architecture and nesting biology and reviewed extant information about the distribution of this species in Turkey. Our investigation found that both nests were unbranched with 7-8 cells, each containing seven individuals at different stages of development. Pollen analysis revealed that plants of the families Fabaceae and Lamiaceae were most preferred by X. iris. These findings suggest that even though the nectar and pollen foraging behavior of this species is known to be polylectic, their larval diet choices might be much more specialized.

Using combinations of microalgae to condition European flat oyster (Ostrea edulis) broodstock and feed the larvae: Effects on reproduction, larval production and development

Hatchery production of European flat oyster (Ostrea edulis) is erratic and is dependent upon broodstock conditioning and larval rearing conditions, including nutrition at both steps. In this study, the combined effects of broodstock and larval diets upon larval growth, survival, competence and metamorphosis and fatty acid and sterol compositions were studied. Four-year-old broodstock were conditioned in 700-L flow-through tanks (50 oysters per tank) at 19 °C and subjected to three dietary conditions in duplicate during 19 weeks. Two mixed diets were supplied continuously at an equivalent of 2 billion cells per day per oyster: Rhodomonas salina + Chaetoceros neogracile (Rs + C) or R. salina + Thalassiosira weissflogii (Rs + Tw), and the third condition was unfed. Samples of microalgae, released larvae (day 0), and larvae at day 9 were collected, and fatty acids (FAs) in neutral (NL) and polar lipids (PL) and sterols were analysed. Larval collection was continuous to estimate numbers of larvae released, which was dependent upon broodstock diet. Oysters fed Rs + C doubled the number of larvae compared to those receiving Rs + Tw - 47.8 compared to 23.1 million larvae, respectively. FAs in NL and PL, as well as sterol composition of released larvae, differed significantly depending upon broodstock diet. Larvae were reared in 5-L cylinders in a flow-through system at 22 °C. Larvae were subsequently fed different single and mixed microalgal diets in triplicate, incorporating Tisochrysis lutea (T), C. neogracile (C), and Diacronema lutheri (D), at a constant concentration of 1500 μm3 μL−1 at the outlet of the rearing tank. Larval growth responded to both broodstock and larval diets; whereas, larval survival, competence, and settlement were influenced by both factors and their interactions. Broodstock receiving Rs + C produced larvae that grew faster (5.6–10.8 μm day−1) than larvae from the other broodstock dietary regimes (4.6–9.6 μm day−1). Larvae from fed broodstock (Rs + C or Rs + Tw) receiving the bi-specific diet T + C exhibited the highest growth rate (9.5–10.8 μm day−1); whereas, those fed the single diet D. lutheri exhibited low growth and competence (4.6–6.1 μm day−1; 4%) on day 9. Fed larvae originating from broodstock fed Rs + C exhibited better survival (92–97%) than those released by broodstock fed Rs + Tw (70–93%). Except for those supplied with T, fed larvae exhibited higher settlement when originating from broodstock receiving Rs + C. On day 9, FA and sterol compositions of larvae reflected the biochemical content of the larval diets. Overall, the best results were observed in larvae fed T + C originating from broodstock fed Rs + C.

Feeding Asian honeybee queens with European honeybee royal jelly alters body color and expression of related coding and non-coding RNAs.

Background and aims: The Asian honeybee (Apis cerana) and the European honeybee (Apis mellifera) are reproductively isolated. Previous studies reported that exchanging the larval food between the two species, known as nutritional crossbreeding, resulted in obvious changes in morphology, physiology and behavior. This study explored the molecular mechanisms underlying the honeybee nutritional crossbreeding. Methods: This study used full nutritional crossbreeding technology to rear A. cerana queens by feeding them with an A. mellifera royal jelly-based diet in an incubator. The body color and the expression of certain genes, microRNA, lncRNA, and circRNA among nutritional crossbred A. cerana queens (NQ), and control A. cerana queens (CQ) were compared. The biological functions of two target genes, TPH1 and KMO, were verified using RNA interference. Results: Our results showed that the NQ's body color turned yellow compared to the black control queens. Whole transcriptome sequencing results showed that a total of 1484, 311, 92, and 169 DEGs, DElncRNAs, DEmiRNAs, and DEcircRNAs, respectively, were identified in NQ and CQ, in which seven DEGs were enriched for three key pathways (tryptophan, tyrosine, and dopamine) involved in melanin synthesis. Interestingly, eight DElncRNAs and three DEmiRNAs were enriched into the key pathways regulating the above key DEGs. No circRNAs were enriched into these key pathways. Knocking down two key genes (KMO and TPH1) resulted in altered body color, suggesting that feeding NQ's an RNAi-based diet significantly downregulated the expression of TPH1 and KMO in 4-day-old larvae, which confirmed the function of key DEGs in the regulation of honeybee body color. Conclusion: These findings reveal that the larval diets from A. mellifera could change the body color of A. cerana, perhaps by altering the expression of non-coding RNAs and related key genes. This study serves as a model of epigenetic regulation in insect body color induced by environmental factors.

Effect of Dietary Lipid Sources and Their Combinations on Growth and Fatty Acid Composition of Milkfish (Chanos chanos) Larvae

Background: The success of larval rearing is greatly influenced by first feeding regimes and the nutritional quality of weaning diets, with dietary lipids being recognized as one of the most important nutritional factors that affect larval growth and survival. Reports are scanty on milkfish larval nutrition and growth and survival unlike other marine species. Methods: In this investigation during 2020, five larval diets were prepared with 40 g kg-1 of entirely fish oil (F4), corn oil (C4) or fish oil and corn oil in 3:1 (F3C1), 2:2 (F2C2) and 1:3 (F1C3) ratios. Each diet was fed to triplicate groups of milkfish larvae (45 mg) in a flow-through rearing system for 42 days. Result: A growth indices were highest in the F3C1 group, followed by F2C2, F4 and other dietary treatments. The whole-body fatty acid profile was found to change significantly with increasing fish oil replacement with corn oil, i.e., the n-3 polyunsaturated and saturated fatty acid proportions decreased linearly, while the n-6 polyunsaturated fatty acids content increased. Overall, this study reveals that growth and survival of milkfish is dependent on dietary lipid source or combinations that meet the essential fatty acid requirements during the early life stages.

The size of larval rearing container modulates the effects of diet amount and larval density on larval development in Aedes aegypti.

Mass-rearing of mosquitoes under laboratory conditions is an important part of several new control techniques that rely on the release of males to control mosquito populations. While previous work has investigated the effect of larval density and diet amount on colony productivity, the role of the size of the container in which larval development takes place has been relatively ignored. We investigated the role of container size in shaping life history and how this varied with density and food availability in Aedes aegypti, an important disease vector and target of mass-rearing operations. For each treatment combination, immature development time and survival and adult body size and fecundity were measured, and then combined into a measure of productivity. We additionally investigated how larval aggregation behaviour varied with container size. Container size had important effects on life history traits and overall productivity. In particular, increasing container size intensified density and diet effects on immature development time. Productivity was also impacted by container size when larvae were reared at high densities (1.4 larva/ml). In these treatments, the productivity metric of large containers was estimated to be significantly lower than medium or small containers. Regardless of container size, larvae were more likely to be observed at the outer edges of containers, even when this led to extremely high localized densities. We discuss how container size and larval aggregation responses may alter the balance of energy input and output to shape development and productivity.

A Novel Approach in the Development of Larval Largemouth Bass Micropterus salmoides Diets Using Largemouth Bass Muscle Hydrolysates as the Protein Source.

This study's objectives were to determine the effect of Largemouth Bass (LMB) muscle hydrolysates obtained using same-species digestive enzymes and the degree of LMB muscle hydrolysis when included in the first feeds of growth performance and survival, skeletal development, intestinal peptide uptake, and muscle-free amino acid composition of larval LMB. LMB muscle was mixed with digestive enzymes from adult LMB, and hydrolyzed for 1.5, 3, and 6 h, respectively. Five diets were produced, the intact diet containing non-hydrolyzed muscle and four diets with 37% muscle hydrolysate inclusion. Those diets were characterized by their level of each hydrolysate (presented as a ratio of 1.5, 3, and 6 Ts hydrolysates): 1:1:1, 1:3:6, 1:3:1, 6:3:1 for diets A, B, C, and D, respectively. To account for gut development, one group of larval LMB was fed a weekly series of diets B, C, and D to provide an increasing molecular weight profile throughout development. This group was compared against others that received either; (1) diets D, C, and B; (2) diet A; or (3) intact diet. The initial inclusion of the hydrolysates significantly improved the total length of the larval LMB; however, neither the hydrolysate inclusion nor the series of dietary molecular weight profiles improved the overall growth of larval LMB. The inclusion of hydrolysates significantly decreased the occurrence of skeletal deformities. The degree of hydrolysis did not have a significant effect on the parameters measured, except for intestinal peptide uptake, which was increased in the group that received the most hydrolyzed diet at the final time of sampling. The lack of overall growth improvement suggests that while the hydrolysates improve the initial growth performance, further research is necessary to determine the optimal molecular weight profile, hydrolysate inclusion level, and physical properties of feeds for larval LMB.

8-HQA adjusts the number and diversity of bacteria in the gut microbiome of Spodoptera littoralis.

Quinolinic carboxylic acids are known for their metal ion chelating properties in insects, plants and bacteria. The larval stages of the lepidopteran pest, Spodoptera littoralis, produce 8-hydroxyquinoline-2-carboxylic acid (8-HQA) in high concentrations from tryptophan in the diet. At the same time, the larval midgut is known to harbor a bacterial population. The motivation behind the work was to investigate whether 8-HQA is controlling the bacterial community in the gut by regulating the concentration of metal ions. Knocking out the gene for kynurenine 3-monooxygenase (KMO) in the insect using CRISPR/Cas9 eliminated production of 8-HQA and significantly increased bacterial numbers and diversity in the larval midgut. Adding 8-HQA to the diet of knockout larvae caused a dose-dependent reduction of bacterial numbers with minimal effects on diversity. Enterococcus mundtii dominates the community in all treatments, probably due to its highly efficient iron uptake system and production of the colicin, mundticin. Thus host factors and bacterial properties interact to determine patterns of diversity and abundance in the insect midgut.

Black Soldier Fly (Hermetia illucens), a source of antimicrobial peptides

In the modern world, multi-drug antibiotic resistance is an increasingly serious problem which poses a serious threat to both plants, animals and humans. The unreasonable use of antibiotics has led to the spread and increase in the number of infectious diseases that existing antibiotics may not be able to cope with. Thus, there is a need for the development of new classes of antibiotics that do not induce resistance. It is necessary to find agents with new mechanisms of action for the development of such antimicrobial compounds. Antimicrobial peptides are excellent candidates for this role. Penetrating through the membranes, they affect the target protein without high specificity, which in turn reduces the probability of induced resistance to a minimum [13]. Scientists have identified about 57 active peptides belonging to various groups of antimicrobial peptides, including defensins, cecropins, attacins and lysozyme. Defensins form the largest group of antimicrobial peptides in insects. As a rule, a defensin-like peptide contains from 34 to 43 amino acids. Antimicrobial peptides obtained from Hermetia illucens can become a good alternative to antibiotics for the prevention and treatment of infectious diseases, as they differ in their antimicrobial properties and are less likely to induce resistance [8]. The lipid composition as well as the amino acid composition can be changed by different larvae diets. Larvae fat contains oleic, palmitic, lauric, myristic, stearic and palmitolic acids, which are saturated and unsaturated fatty acids, and have an intense effect against bacteria.

Evaluating the stomach content of Wild Scalloped Spiny Lobster (Panulirus homarus)

Abstract. Amin M, Fitria A, Mukti AT, Manguntungi AB, Amrullah S, Alim S, Martin MB. 2022. Evaluating the stomach content of Wild Scalloped Spiny Lobster (Panulirus homarus). Biodiversitas 23: 6397-6403. The high demand for spiny lobster seeds has placed intense pressure on the lobsters’ wild stock in Indonesia. To address this issue, a hatchery was developed to produce scalloped spiny lobster larvae. However, the dietary requirements after the yolk sac has been depleted have proven to be a significant challenge. Thus, the present study aimed to identify the potential live diet of scalloped spiny lobster larvae by identifying the stomach contents of lobster larvae captured in the wild. Fifteen scalloped spiny lobsters at the post-larval stage were collected from three fishing grounds: Gerupuk Bay (Lombok Island), Tawang Bay (East Java), and Prigi Bay (East Java), Indonesia. The stomach of each scalloped spiny lobster was dissected under a dissecting microscope and its contents were observed under a binocular microscope for plankton identification and abundance. The stomach contents of scalloped spiny lobster resulted in five identified plankton species collected from Prigi Bay [Tintinnopsis sp. (37.5%), Grammatophora sp. (25%), Synedra sp. (18.8%), Phormidium sp. (4.3%), and Rhizisolenia sp. (4.3%)]; six plankton species collected from Tawang Bay [Ochromonas sp. (32.3%), Synedra sp. (20.6%), Tintinnopsis sp. (14.7%), Uronema sp. (14.7%), Coscinodiscuss sp. (2.9%), and Planktoniella sp. (2.9%)]; and six plankton species collected from Gerupuk Bay [Synedra sp. (33.3%), Chlorococcum sp. (33.0%), Phormidium sp. (13.3%), Gymnidinium sp. (6.6%), unidentified Cirripedia (3.3%), Rhizosolenia sp. (3.0%)]. Of these plankton, Synedra sp. and Rhizolenia sp. were the most common representatives in the stomach of all lobster samples. Thus, assessing these two plankton genera is highly recommended for future studies.

Silymarin, Silybum marianum, Supplemented Weaning Diet Boosted Survival, Growth, Antioxidant Status, and Fatty Acids Profile of Seabass, Dicentrarchus labrax

Abstract To sustain normal development, high survival, and rapid growth, marine fish larvae require a diet rich in polyunsaturated fatty acids, which could decrease the risk of reactive oxygen species accumulations. Consequently, a 60-day feeding experiment was conducted to determine the effect of silymarin (SM) supplementation in weaning diets on the growth performance, survival, antioxidant enzyme activities, and fatty acids profile of European seabass (Dicentrarchus labrax) larvae. Four isonitrogenous and isolipidic diets were investigated using SM at levels of 0, 200, 400, and 600 mg kg−1 (SM0.00, SM200, SM400, and SM600, respectively). The findings showed that, in a dose-dependent manner, increasing dietary levels of SM enhanced survival, growth, and feed utilization. In the SM600 group, the weight gain, survival, and feed conversion ratio (FCR) improved by 123.21, 11.66, and 38.72%, respectively, compared to the control group. The dose-response analysis demonstrated a strong positive correlation (R2=0.96) between SM levels and weight increase, and a strong negative correlation (R2=0.88) between SM levels and FCR. The antioxidant enzyme activities of larvae given SM-enriched diets were significantly greater than those of the control group. Compared to the control group, the CAT and SOD improved by 81.77 and 5.08% in the SM600 group. In addition, the saturated fatty acid content decreased while the unsaturated fatty acid content increased, particularly in the SM600 group. The results indicate that supplementing the micro diet of European seabass larvae during weaning with SM at a dose of 600 mg kg−1 increases growth, survival, antioxidant status, and fatty acid profiles.

Пищевые отношения между пелагическими личинками рыб и планктонными организмами в прикамчатских водах

The nutritional relations between fish larvae and zooplankton organisms in marine waters off Kamchatka Peninsula based on the ichthyoplankton samples as well as changes in the diet of fish larvae in Kamchatka waters are considered. In spring, the most suitable food organisms for small fish larvae are polychaeta larvae, Cirripedia and Calanoida nauplii, small forms of copepods, mollusks, juveniles of amphipods. In early summer larvae of Polychaeta, nauplii of Cirripedia and Calanoida, small forms of Cladocera and Copepoda are also available. The main forage organisms for larger larvae are furcilia and calyptopis of euphausiids, small larvae of Decapoda. In the second half of summer, larger forms, mainly of the same organisms, are available for late larvae of many fishes. The relationship between the distribution of marine fish larvae and zooplankton organisms is shown. A list of available food organisms for fish larvae during pelagic development has been compiled. Three main trophic groups have been proposed.

Epigenetics Mechanisms of Honeybees: Secrets of Royal Jelly.

Early diets in honeybees have effects on epigenome with consequences on their phenotype. Depending on the early larval diet, either royal jelly (RJ) or royal worker, 2 different female castes are generated from identical genomes, a long-lived queen with fully developed ovaries and a short-lived functionally sterile worker. To generate these prominent physiological and morphological differences between queen and worker, honeybees utilize epigenetic mechanisms which are controlled by nutritional input. These mechanisms include DNA methylation and histone post-translational modifications, mainly histone acetylation. In honeybee larvae, DNA methylation and histone acetylation may be differentially altered by RJ. This diet has biologically active ingredients with inhibitory effects on the de novo methyltransferase DNMT3A or the histone deacetylase 3 HDAC3 to create and maintain the epigenetic state necessary for developing larvae to generate a queen. DNMT and HDAC enzymes work together to induce the formation of a compacted chromatin structure, repressing transcription. Such dialog could be coordinated by their association with other epigenetic factors including the ubiquitin-like containing plant homeodomain (PHD) and really interesting new gene (RING) finger domains 1 (UHRF1). Through its multiple functional domains, UHRF1 acts as an epigenetic reader of both DNA methylation patterns and histone marks. The present review discusses the epigenetic regulation of honeybee's chromatin and how the early diets in honeybees can affect the DNA/histone modifying types of machinery that are necessary to stimulate the larvae to turn into either queen or worker. The review also looks at future directions in epigenetics mechanisms of honeybees, mainly the potential role of UHRF1 in these mechanisms.

Effects of Diet Composition on the Life-History Traits of Bactrocera Dorsalis (Hendel) (Diptera: Tephritidae)

Nutrient acquisition at the larval stage has significant impacts on the development, body weight, and fecundity of fruit flies. In this study, we examined the effects of diet composition on the life-history traits of the oriental fruit fly Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We reared the flies on four larval diets, namely three artificial diets, which had the main ingredients of sugar, brewer’s yeast, and preservatives; and one fruit-based diet, which had the main contents of ground guava, brewer’s yeast, and preservatives. The three artificial diets had varied yeast-to-sugar ratios (Y:S) of 5:1 in the protein-rich diet, 1.67:1 in the standard diet, and 1:3 in the sugar-rich diet. Differences in development time, pupal weight, adult weight, and fecundity of B. dorsalis were investigated. It was found that the development times of fruit flies on the protein-rich and fruit-based diets were shorter than those on the sugar-rich and standard diets. Pupae and adults in the fruit-based and standard diets were heavier than those from the protein-rich and sugar-rich diets. There was a strong effect of diet on the per-day fecundity whereby the flies in the fruit-based diet had the highest per-day fecundity, while the lowest per-day fecundity was in the sugar-rich diet. The per-day fecundity of the fruit flies on the standard and sugar-rich diets increased gradually from day 1 to day 15, while it decreased in the protein-rich and fruit-based diets.