Brood Care Research Articles

The brain atlas of a subsocial bee reflects that of eusocial Hymenoptera.

The evolutionary transition from solitary life to group-living in a society with cooperative brood care, reproductive division of labor and morphological castes is associated with increased cognitive demands for task-specialization. Associated with these demands, the brains of eusocial Hymenoptera divide transcriptomic signatures associated with foraging and reproduction to different populations of cells and also show diverse astrocyte and Kenyon cell types compared with solitary non-hymenopteran insects. The neural architecture of subsocial bees, which represent evolutionary antecedent states to eusocial Hymenoptera, could then show how widely this eusocial brain is conserved across aculeate Hymenoptera. Using single-nucleus transcriptomics, we have created an atlas of neuron and glial cell types from the brain of a subsocial insect, the small carpenter bee (Ceratina calcarata). The proportion of C. calcarata neurons related to the metabolism of classes of neurotransmitters is similar to that of other insects, whereas astrocyte and Kenyon cell types show highly similar gene expression patterns to those of eusocial Hymenoptera. In the winter, the transcriptomic signature across the brain reflected diapause. When the bee was active in the summer, however, genes upregulated in neurons reflected foraging, while the gene expression signature of glia associated with reproductive functions. Like eusocial Hymenoptera, we conclude that neural components for foraging and reproduction in C. calcarata are compartmentalized to different parts of its brain. Cellular examination of the brains of other solitary and subsocial insects can show the extent of neurobiological conservation across levels of social complexity.

Investigating the role of non-helpers in group living thrips.

Behavioural variation among individuals is a hallmark of cooperative societies, which commonly contain breeders and non-breeders, helpers and non-helpers. In some cases, labour is divided with non-breeders "helping." Conversely, in some societies, subordinate non-breeders may not help. These individuals may be (i) an insurance workforce ensuring continuity of help for breeders when other helpers are lost, (ii) conserving energy while waiting to breed themselves or (iii) simply of too poor physiological quality either to help or breed. In the Australian Outback, Acacia thrips Dunatothrips aneurae (Thysanoptera) glue Acacia phyllodes into "domiciles" using silk-like secretions, either alone or cooperatively. Domicile maintenance is important for humidity, so repair can be interpreted as helping. I found that not all females helped to repair damage; some repaired partially or not at all ("non-helpers"). At the same time, some co-foundresses are non- or partially reproductive ("non-breeders"), and their role is currently unknown. I first tested the possibility that helping and breeding are divided, with non-helping females breeding, and non-breeders helping. In a lab experiment, I rejected this idea. Experimentally damaged domiciles were typically repaired by reproductive females, and less so by non- or partially reproductive individuals. To test whether non-helpers are an insurance workforce, I successively removed repairing females and found that non-helping females from the same domicile did not increase effort as a result, rejecting this hypothesis. Then I tested whether non-helpers were conserving energy waiting to breed. In a field experiment, I removed all other females, allowing either a helpful female or a non-helper to "inherit" her domicile. Isolated like this, non-helpers laid very few eggs compared to helpers or naturally occurring single foundresses, despite similar ovarian development. My findings show that labour was not divided: reproduction and helping covaried positively, probably depending on individual variation in female quality and intra-domicile competition. Non-helping females were neither an insurance workforce nor conserving energy waiting to breed. They are likely simply of poor quality, freeloading by benefiting from domicile maintenance by others. I hypothesize they are tolerated because of selection for indiscriminate communal brood care in the form of domicile repair.

Vibrations from the crypt: Investigating the possibility of vibrational communication in burying beetles

AbstractCommunication is fundamental in the animal kingdom, essential to interactions such as mating, defense, and parental care. Vibrational communication has often been overlooked in the past, but in recent decades, it has become clear that insects use substrate vibrations as a communication signal. In burying beetles of the genus Nicrophorus, which are known for their biparental brood care, both parents stridulate. Spending a considerable period of their lives underground, it is very likely the beetles utilize vibrations as part of their communication system. As playback experiments are challenging with this species, this study looked at the physical propagation of the signal of Nicrophorus vespilloides Herbst (Coleoptera: Siliphidae) through three soil types, as well as behavior, to see whether vibrational communication is possible. The aims were to determine: (1) whether the soils used in the laboratory compare to soil from the field, (2) whether the distance of propagation is enough for the range the beetles cover during brood care, (3) whether the two sexes show a difference in stridulation likelihood, (4) whether propagation of defensive signals differs from brood care signals, and (5) whether we can determine a behavior during stridulations that shows a clear and useable reaction to the signal. We manipulated beetles to induce stridulation and then used laser Doppler vibrometers to record the signals using three substrates and various distances, alongside behavioral observations. We showed that the three substrates tested, peat, coconut coir, and forest soil, displayed differences in terms of vibrational propagation, and that burying beetle stridulation signals can be transmitted up to about 25 cm in the soil. We also showed that the location where the animals stridulate exerts a significant influence on the total duration and number of stridulations. Overall, vibrational communication is in principle conceivable in this species, as the signals are transmitted far enough in the natural substrate to allow complex communication, opening possibilities for vibrational communication during this biparental brood care.

Kangaroo mother care improves cardiorespiratory physiology in preterm infants: an observational study

ObjectivesTo evaluate whether kangaroo mother care (KMC) in preterm infants on non-invasive respiratory support improves indices of cardiorespiratory wellbeing.Study designProspective quasi-experimental observational study.SettingTertiary perinatal neonatal unit.Patients50 very preterm infants being...

Juveniles of a biparental cichlid fish compensate lack of parental protection by improved shoaling performance

Parental brood care greatly affects offspring’s fitness, but the specific effects of care on the collective behaviour of independent offspring are less well understood. It has been suggested that the loss of care induces increased sibling cooperation to compensate parental contributions. However, the empirical evidence is ambiguous. Here, we examined how the loss of early parental care affects the collective behaviour, i.e. shoaling performance of independent juveniles in a genetically heterogeneous lab-population of the biparental cichlid fish Pelvicachromis pulcher. Applying a split-clutch design, we reared in- and outbred offspring with or without parents. In the experiment, we examined shoal density (inter-individual distance) in relation to body size of the shoaling fish. Dense shoaling reduces predation risk and small fish may benefit strongest because they are particularly vulnerable to predation by gape-limited predators. Juveniles reared without parents formed denser shoals and they adjusted shoaling behaviour depending on own body size compared to juveniles reared with parents; especially smaller fish formed dense shoals. Inbreeding did not significantly affect shoaling performance. This indicates that juveniles compensate missing parental care by adjusting their shoaling behaviour depending on own vulnerability. Our study contributes to the understanding of the co-evolution of brood care and sibling cooperation.

The contribution of the Middle Triassic fossil assemblage of Monte San Giorgio to insect evolution

The Triassic represents a critical period for understanding the turnover of insect fauna from the Paleozoic to the Mesozoic following the end-Permian mass extinctions (EPME); however, fossil deposits from the Early-Middle Triassic are scarce. The exceptionally preserved 239 million-year-old fossil insect fauna recorded at Monte San Giorgio (Switzerland), including 248 fossils representing 15 major insect clades is presented here. Besides the exceptional features, including their small size and excellent preservation, the fossils have importance in the evolutionary history of the group. The taxonomic and ecological diversity recovered, including both freshwater (dragonflies and caddisflies) and terrestrial taxa (true bugs and wasps), demonstrates that complex environments sustained a paleocommunity dominated by monurans (thought not to have survived the EPME), midges, and beetles. Interestingly, a blattodean-like fossil bearing an external ootheca was also found, important for understanding Paleozoic roachoids to extant cockroaches’ transition and the evolution of maternal brood care. Moreover, the youngest and first complete specimen of †Permithonidae and the oldest sawfly fossils were discovered. Finally, round-shaped bodies, compatible with seminal capsules or lycophyte spores, were found on the abdomens of several midge-like individuals. If these are spores, non-seed-bearing plants could have been the first entomophilous plants rather than gymnosperms, as recently supposed. Altogether, these fossils contribute substantially to understanding insect evolution and Paleozoic-Mesozoic faunal turnover.

Evolution of obligate asexuality in termites with mixed‐sex societies

AbstractMales are a ubiquitous feature of animals and play crucial roles beyond the contribution of gametes in some species (e.g., paternal care for offspring and nuptial gifts for females). In termites, colonies commonly consist of both male and female reproductives, workers, and soldiers (i.e., mixed‐sex societies), where males and females both play critical roles beyond reproduction (e.g., brood care, foraging, nest construction and maintenance, and colony defense). Male‐specific roles may also exist in termite colonies. While obligate asexuality had not been observed in any termite population until recently, all‐female asexual populations of the termite Glyptotermes nakajimai were reported in 2018. This was the first and only known case of evolutionary transition from mixed‐sex to all‐female asexual societies in animals. Here, asexual reproduction in termites is first reviewed, followed by a discussion of how and why G. nakajimai evolved obligate asexuality. The study of the evolution of obligate asexuality in termites with mixed‐sex societies is important because it may enhance our understanding of the significance of males in animal societies and populations.

Population profile of haemocytes in the subcastes of the leaf‐cutter ant Atta sexdens (Hymenoptera: Formicidae) unveiled by flow cytometry

AbstractThe leaf‐cutter ant Atta sexdens is crucial in ecological balance and economic activities, due to its contribution to the aeration and accumulation of organic matter in the soil, but it may also be an agricultural pest when it defoliates plants for the fungus growth used as a food source. This leaf‐cutter ant exhibits a polymorphic worker caste system with distinct activities in the colony. These functions are performed by workers classified into subcastes, including gardeners, which are responsible for the fungus and brood care; cleaners (waste removers), which remove wastes; foragers, which collect and transport plant parts to the nest; and soldiers, which are responsible for colony defence and the support of foraging activities. In our previous work, we showed that A. sexdens has five types of circulating haemocytes in the haemolymph, which play a vital role in immune defence. Herein, we further investigated the population profile of circulating haemocytes in the haemolymph of different worker subcastes of A. sexdens using flow cytometry. Each subcaste exhibited a single population of haemocytes in the haemolymph. However, a detailed 3D dispersion analysis uncovered five distinct haemocyte subpopulations, two of which presented higher quantities. The soldier displayed haemocytes with high fluorescence intensity, compared with the gardener, waste remover, and forager, along with increased complexity, compared with the gardener subcaste. These results suggest that these cells may be granulocytes and plasmatocytes, which are known for their role in insect immune defence.

Differential Neuroanatomical, Neurochemical, and Behavioral Impacts of Early-Age Isolation in a Eusocial Insect

Introduction: Social experience early in life appears to be necessary for the development of species-typical behavior. Although isolation during critical periods of maturation has been shown to impact behavior by altering gene expression and brain development in invertebrates and vertebrates, workers of some ant species appear resilient to social deprivation and other neurobiological challenges that occur during senescence or due to loss of sensory input. It is unclear if and to what degree neuroanatomy, neurochemistry, and behavior will show deficiencies if social experience in the early adult life of worker ants is compromised. Methods: We reared newly eclosed adult workers of Camponotus floridanus under conditions of social isolation for 2–53 days, quantified brain compartment volumes, recorded biogenic amine levels in individual brains, and evaluated movement and behavioral performance to compare the neuroanatomy, neurochemistry, brood-care behavior, and foraging (predatory behavior) of isolated workers with that of workers experiencing natural social contact after adult eclosion. Results: We found that the volume of the antennal lobe, which processes olfactory inputs, was significantly reduced in workers isolated for an average of 40 days, whereas the size of the mushroom bodies, centers of higher-order sensory processing, increased after eclosion and was not significantly different from controls. Titers of the neuromodulators serotonin, dopamine, and octopamine remained stable and were not significantly different in isolation treatments and controls. Brood care, predation, and overall movement were reduced in workers lacking social contact early in life. Conclusion: These results suggest that the behavioral development of isolated workers of C. floridanus is specifically impacted by a reduction in the size of the antennal lobe. Task performance and locomotor ability therefore appear to be sensitive to a loss of social contact through a reduction of olfactory processing ability rather than change in the size of the mushroom bodies, which serve important functions in learning and memory, or the central complex, which controls movement.

Honey bee colony behavior and ontogeny are adversely affected when exposed to a pesticide-contaminated environment.

Honey bees exhibit age polyethism and thus have a predictable sequence of behaviors they express through developmental time. Numerous laboratory studies show exposure to pesticides may impair critical honey bee behaviors (brood care, foraging, egg-laying, etc.) that adversely affect colony productivity and survival. There are fewer studies that examine the impacts of pesticides in natural field settings, especially given the challenges of implementing treatment groups and controlling variables. This study helps address the need for impact studies on pollinators under field conditions to assess the consequences of chemical overuse and dependency in agricultural and urban landscapes. To assess the impact of systemic pesticides in a natural field setting on worker bee behavioral development, observation hives were established to monitor changes in behaviors of similarly aged workers and sister queens within 2 experimental groups: (i) colonies located near point-source systemic pesticide pollution (pesticide contaminated treatment), and (ii) colonies embedded within a typical Midwestern US agricultural environment (control). In this study, worker bees in the contaminated environment exhibited important and biologically significant behavioral differences and accelerated onset of hive tasks (i.e., precocious behavioral development) compared to similarly aged bees at the control site. Queen locomotion was largely unaffected; however, the egg-laying rate was reduced in queens at the contaminated (treated) site. These results show that environmental pesticide exposure can disrupt colony function and adversely affect worker bee behavioral maturation, leading to reduced worker longevity and decreased colony efficiency.

Body Size, Cerebral Blood Flow, Ambient Temperature, and Relative Brain Temperatures in Newborn Infants under Incubator Care.

Subtle changes in body temperature affect the outcomes of ill newborns. However, the temperature profile of neonatal brains remains largely unknown. In open-cot care, increased cerebral perfusion is correlated with higher superficial brain temperatures. This study investigated the dependence of brain temperature (relative to rectal temperature) on ambient temperature, body size, cerebral perfusion, and metabolism in infants receiving incubator care. Rectal, scalp, and brain temperatures, superior vena cava flow, and brain oxygenation were assessed using echocardiography, thermo-compensatory temperature monitoring, and near-infrared spectroscopy in 60 newborns. These infants had a mean postconceptional age of 36.9 (2.2) weeks and weighed 2348 (609) g at the time of evaluation. The ambient temperature was maintained at 30.0 (1.0) °C. A higher rectal temperature was associated with greater postconceptional age (p = 0.002), body weight (p < 0.001), and head circumference (p < 0.001). Relative scalp, superficial brain, and deep brain temperatures were associated with smaller head circumference (p < 0.001, p = 0.030, and p = 0.015, respectively) and superior vena cava flow (p = 0.002, p = 0.003, and p = 0.003, respectively). In infants receiving incubator care, larger head sizes and increased brain perfusion were associated with lower relative scalp and brain temperatures. When considered alongside previous reports, cerebral perfusion may contribute to maintaining stable cerebral tissue temperature against ambient temperature changes.

The costs of overwintering in paper wasps (Polistes dominula and Polistes gallicus): the use of energy stores

Overwintering insects are facing energetic challenges because of food shortage, low temperature, and desiccation stress. Paper wasps of the genus Polistes overwinter as mated adults (gynes) in hibernacula protecting them from predation, snow, and rain but barely from low environmental temperature. In different climates, they face differing overwintering temperature regimes, and therefore they may differ in their energy use. We investigated how much of energy resources built up until autumn is used during diapause dormancy in natural hibernacula by measuring lipid, glycogen, and free carbohydrate content in autumn and early spring in Polistes dominula from temperate European (Austrian) and warm Mediterranean (Italian) climate and Polistes gallicus from Mediterranean climate. Winter energy consumption amounted to ~ 339 and ~ 310 J per wasp in the Austrian and Italian Polistes dominula populations. The smaller Italian Polistes gallicus consumed ~ 247 J. This amounts to 2.62, 2.35, and 1.79 J per day. Of this, the energy demand was mainly fuelled by lipids (84%, 93%, and 90%, respectively), but glycogen stores contributed also considerably (16%, 6%, and 9%). Free carbohydrates decreased only by 0.7%, 1%, and 0.8%. While fat stores seem still sufficient in spring, the wasps depleted most of their carbohydrates. The energy reserves of 396, 400, and 147 J per wasp remaining in spring in the three populations seem sufficient to fuel rest or simple brood care activities for a whole summer but restrict foraging flights to a few hours (~ 3.5–6 h). Results suggest that energy supply might become challenging in expected future climate scenarios.

Mechanisms for polyandry evolution in a complex social bee

Polyandry in social Hymenoptera is associated with reduced within-colony relatedness and increased colony-level ecologic fitness. One explanation for this sees increasing within-nest genetic diversity as a mechanism for improving group task efficiency and colony competitiveness. A queen on her mating flight captures nearly 90% of her breeding population’s allele potential by her tenth effective mating (me ~ 10 males). Under this population allele capture (PAC) model, colony fitness gains track mating number in an asymptotic manner, leveling out after about the tenth mating. A supporting theory we call the genotype composition (GC) model sees genetic novelty at mating levels higher than the me ~ 10 asymptote, the hyperpolyandry zone, resulting from unique genotype compositions whose number are potentially infinite. Colony fitness gains under the GC model will track mating number in a linear manner. We set up field colonies with Apis mellifera queens each instrumentally mated with 1, 2, 4, 8, 16, or 32 males, creating a polyandry gradient bracketing the qualitative divide of me ~ 10, measured tokens of colony level fitness, and collected observation hive data. Our results lead us to conclude that (1) ancestral colony traits fundamental to eusociality (cooperative brood care) respond to mating level changes at or below me ~ 10 in a manner consistent with the PAC model, whereas (2) more derived specialized colony phenotypes (resistance to the non-native parasite Varroa destructor) continue improving with increasing me in a manner consistent with the GC model. By either model, (3) the mechanism for increasing colony fitness is an increase in worker task specialisms and task efficiency.Significance statementPolyandry is a female’s practice of mating with many males, storing their sperm, and using it to produce genetically diverse offspring. In complex social bees, a queen captures nearly 90% of her breeding population’s diversity potential by her tenth mating; however, queens in nature routinely mate with many more than ten males. We tested two models that, together, explain how social bee colonies ecologically benefit from queen mating numbers ranging from 2 to potential infinity. A population allele capture (PAC) model focuses on colony fitness gains at mating numbers at or below 10, and we provide evidence that it was at these polyandry levels that significant gains were made in an ancestral eusocial trait, cooperative brood care. A genotype composition (GC) model focuses on colony fitness gains at higher mating numbers, and we believe these gains are centered around more recently evolved ecologic specialisms such as parasite resistance.

"Comparison of a Novel Incubator with Standard Incubator Care: A Randomised Multi-Centre, Cross-Over Study"

"Comparison of a Novel Incubator with Standard Incubator Care: A Randomised Multi-Centre, Cross-Over Study"

Processes For The Transformation Of Fruit And Vegetable Residues For The Production Of Edible Mushrooms

The cultivation of edible mushrooms from fruit and vegetable residues presents itself as a promising solution for the sustainable utilization of these wastes and the production of nutritious food. Fruit and vegetable residues include crop residues, leaves, branches and unsold products, which contain a wide range of nutrients and bioactive compounds. These are used as substrate for the cultivation of edible mushrooms. Edible mushrooms, such as mushrooms, shiitake and pleurotus, are appreciated worldwide for their taste, texture and nutritional properties. They contain protein, fiber, vitamins, minerals and bioactive compounds with antioxidant, anti-cancer and anti-diabetic properties. In addition, the global market for edible mushrooms is experiencing significant growth due to their wide range of applications in the food, pharmaceutical and cosmetic industries. The method of cultivating edible mushrooms from fruit and vegetable waste involves the selection of suitable waste, its preparation by sterilization, addition of nutritional enrichment agents and inoculation of the desired mushroom. After a period of incubation and proper care, the mushrooms can be harvested and used in various food preparations. The cultivation of edible mushrooms by solid fermentation has great advantages, as it is the most efficient way of converting vegetable waste into high-value human food.

Extended parental care in the mass provisioning silk wasp, Microstigmus rosae

Abstract Insurance-based mechanisms, where surviving group-members can complete parental care after the death of a nestmate, are key to the origin of cooperative group formation in insects. Selection for group living via these models is proposed to be dependent on the life expectancy of adult carers relative to the duration of offspring dependency on parental care. Progressive provisioning, where adults feed offspring gradually as they grow, is thought to extend this period of dependency and is therefore suggested to be an important factor promoting the evolution of sociality. In contrast, mass-provisioning species provide offspring with all the food they need to reach maturity at the beginning of their development. Since offspring are then nutritionally independent, the applicability of insurance models is less clear. In this paper we experimentally demonstrate that adult presence on the nest, even after the end of provisioning, is critical for brood survival in the mass provisioning silk wasp Microstigmus rosae. After 10 days, experimentally orphaned nests contained 65% fewer healthy offspring than controls. Adult females were also recorded performing post-provisioning parental care behaviours including nest maintenance and repair, putative hygienic brood care and aggressive nest defence against both ants and parasitoid wasps. By demonstrating the potential applicability of insurance advantages our results highlight how, even in mass provisioners, insurance-based mechanisms may be part of what favours group living. Significance statement Extended parental care is an important precursor to the evolution of eusociality. In this context, group living can serve as a form of “life insurance”, ensuring that dependent offspring receive the care they need to reach maturity should the mother die. Such mechanisms are especially important to our understanding of social evolution as they are able to account for the origins of cooperative group formation, not just its maintenance. However, for mass-provisioning species, where all food items are provided upfront, the significance of insurance advantages remains unclear. In this study, we experimentally demonstrate that adult attendance is critical for brood survival in the mass provisioning wasp, Microstigmus rosae. Our results reveal the applicability of insurance advantages to M. rosae with important implications for our understanding of the potential adaptive value of group living in mass provisioning species.

The effect of Israeli acute paralysis virus infection on honey bee brood care behavior

To protect themselves from communicable diseases, social insects utilize social immunity—behavioral, physiological, and organizational means to combat disease transmission and severity. Within a honey bee colony, larvae are visited thousands of times by nurse bees, representing a prime environment for pathogen transmission. We investigated a potential social immune response to Israeli acute paralysis virus (IAPV) infection in brood care, testing the hypotheses that bees will respond with behaviors that result in reduced brood care, or that infection results in elevated brood care as a virus-driven mechanism to increase transmission. We tested for group-level effects by comparing three different social environments in which 0%, 50%, or 100% of nurse bees were experimentally infected with IAPV. We investigated individual-level effects by comparing exposed bees to unexposed bees within the mixed-exposure treatment group. We found no evidence for a social immune response at the group level; however, individually, exposed bees interacted with the larva more frequently than their unexposed nestmates. While this could increase virus transmission from adults to larvae, it could also represent a hygienic response to increase grooming when an infection is detected. Together, our findings underline the complexity of disease dynamics in complex social animal systems.

Effect of Solenopsis invicta virus 3 on brood mortality and egg hatch in Solenopsis invicta

Solenopsis invicta virus 3 (SINV-3) has been shown to cause significant mortality among all stages of its host, Solenopsis invicta. One impact of the virus is alteration of worker ant foraging behavior, which results in colony starvation and collapse over time. Additionally, it has been hypothesized that SINV-3 infection of S. invicta may disrupt worker ant brood care behavior. To investigate this possibility, various combinations of SINV-3-infected and -uninfected adult (worker) and immature (brood) stages were placed together and monitored using the response variables, mortality, egg hatch, and virus load. While significant differences in percent cumulative S. invicta worker ant mortality among six combinations of SINV-3-infected and -uninfected stages were observed, no significant differences in percent cumulative mortality of S. invicta larvae or pupae were observed. No significant differences in egg hatch were observed among SINV-3-uninfected, SINV-3-infected (colony-treated and queen-treated), and starved colonies. Eggs hatched normally in 10–12 days for all treatments indicating that egg care by worker ants was unaffected by SINV-3 infection status. The study further clarifies SINV-3 pathogenesis in its host, S. invicta. Larval mortality in SINV-3-infected colonies does not appear to be caused by worker ant neglect. S. invicta brood under the care of SINV-3-infected worker ants did not exhibit higher mortality rates compared with those tended by SINV-3-uninfected worker ants.

Age-dependent hypopharyngeal gland size and protein content of stingless bee workers, Tetragonula pagdeni.

Eusocial insects, such as stingless bees (Meliponini), depend on division of labour, overlapping generations, and collaborative brood care to ensure the functionality and success of their colony. Female workers transition through a range of age-specific tasks during their lifespan (i.e., age-polyethism) and play a central role in the success of a colony. These age-specific tasks (e.g., brood care or foraging) often closely coincide with key physiological changes necessary to ensure optimal performance. However, our understanding of how nutrition, age, and polyethism may affect the development of such physiological traits in stingless bees remains limited. Here we show that pollen consumption and age-polyethism govern hypopharyngeal gland (HPG) acini size and protein content in Tetragonula pagdeni. By conducting a controlled laboratory experiment we monitored the effect of pollen consumption on worker bee survival as well as assessed how a pollen diet and age affected their HPG acini width and protein content. Further, we sampled nurses and foragers from field colonies to measure the effect of age-polyethism on HPG acini width. We found that pollen consumption enhanced survival and led to increased HPG acini width and protein content and that HPG acini were as expected largest in nurse bees. Our findings highlight the beneficial effects of an adequate diet for physiological development and health in stingless bees and reveal that age-polyethism is the key factor governing HPG size in worker bees. As HPGs are imperative for collaborative brood care-an essential component of eusociality-the data provide a foundation for future studies to investigate the impact of potential environmental stressors on a critical physiological trait in stingless bees which may serve as a proxy to understand the effects at the colony level.

Identifying the genes involved in the egg-carrying ovigerous hair development of the female blue crab Callinectes sapidus: transcriptomic and genomic expression analyses

BackgroundCrustacean female sex hormone (CFSH) controls gradually developing adult female-specific morphological features essential for mating and brood care. Specifically, ovigerous hairs are developed during the prepuberty molt cycle of the blue crab Callinectes sapidus that are essential for carrying the eggs until they finish development. Reduced CFSH transcripts by CFSH-dsRNA injections result in fewer and shorter ovigerous hairs than the control. This study aimed to identify the specific genes responsible for ovigerous hair formation using transcriptomic, genomic and expression analyses of the ovigerous setae at three stages: prepuberty at early (OE) and late premolt (OL), and adult (AO) stages.ResultsThe de novo Trinity assembly on filtered sequence reads produced 96,684 Trinity genes and 124,128 transcripts with an N50 of 1,615 bp. About 27.3% of the assembled Trinity genes are annotated to the public protein sequence databases (i.e., NR, Swiss-Prot, COG, KEGG, and GO databases). The OE vs. OL, OL vs. AO, and OE vs. AO comparisons resulted in 6,547, 7,793, and 7,481 differentially expressed genes, respectively, at a log2-fold difference. Specifically, the genes involved in the Wnt signaling and cell cycle pathways are positively associated with ovigerous hair development. Moreover, the transcripts of ten cuticle protein genes containing chitin-binding domains are most significantly changed by transcriptomic analysis and RT-qPCR assays, which shows a molt-stage specific, down-up-down mode across the OE-OL-AO stages. Furthermore, the expression of the cuticle genes with the chitin-binding domain, Rebers and Riddiford domain (RR)-1 appears at early premolt, followed by RR-2 at late premolt stage. Mapping these 10 cuticle protein sequences to the C. sapidus genome reveals that two scaffolds with a 549.5Kb region and 35 with a 1.19 Mb region harbor 21 RR1 and 20 RR2 cuticle protein genes, respectively. With these findings, a putative mode of CFSH action in decapod crustaceans is proposed.ConclusionsThe present study describes a first step in understanding the mechanism underlying ovigerous hair formation in C. sapidus at the molecular level. Overall, demonstrating the first transcriptome analysis of crustacean ovigerous setae, our results may facilitate future studies into the decapod female reproduction belonging to the suborder Pleocyemata.