Brood Development Research Articles

Poison or Potion: Effects of Sunflower Phenolamides on Bumble Bees and Their Gut Parasite.

Simple SummaryBee declines have been reported worldwide, partly due to parasite spread induced by human activities. However, bees may forage on specific floral resources to face parasite infection. Such natural resources are comparable to ‘natural pharmacies’ and may be favoured in bee conservation strategies. Consumption of sunflower pollen, despite being detrimental for larval development, has been recently shown to reduce the load of a widespread bumble bee gut parasite in the common eastern bumble bee. Although the underlying mechanisms remain unknown, it has been suggested that sunflower phenolamides—a family of molecules found in most flowering plants—may be responsible for such a reduction in parasite load. Here, we tested the impacts of sunflower phenolamides on healthy and infected buff-tailed bumble bees. Expectedly, sunflower pollen had harmful consequences on bumble bee development but surprisingly, it did not alter parasite load. By contrast, sunflower phenolamides had milder effects on bumble bee development but unexpectedly increased parasite load. Phenolamide effects may stem from the physiological stress they induced or the gut microbial community alteration they may have triggered. Since biological models and experimental framework differ greatly in related studies tackling plant–bee–parasite interplays, we challenged the definition of medicinal effects and questioned the way to assess them in controlled conditions.Specific floral resources may help bees to face environmental challenges such as parasite infection, as recently shown for sunflower pollen. Whereas this pollen diet is known to be unsuitable for the larval development of bumble bees, it has been shown to reduce the load of a trypanosomatid parasite (Crithidia bombi) in the bumble bee gut. Recent studies suggested it could be due to phenolamides, a group of compounds commonly found in flowering plants. We, therefore, decided to assess separately the impacts of sunflower pollen and its phenolamides on a bumble bee and its gut parasite. We fed Crithidia-infected and -uninfected microcolonies of Bombus terrestris either with a diet of willow pollen (control), a diet of sunflower pollen (natural diet) or a diet of willow pollen supplemented with sunflower phenolamides (supplemented diet). We measured several parameters at both microcolony (i.e., food collection, parasite load, brood development and stress responses) and individual (i.e., fat body content and phenotypic variation) levels. As expected, the natural diet had detrimental effects on bumble bees but surprisingly, we did not observe any reduction in parasite load, probably because of bee species-specific outcomes. The supplemented diet also induced detrimental effects but by contrast to our a priori hypothesis, it led to an increase in parasite load in infected microcolonies. We hypothesised that it could be due to physiological distress or gut microbiota alteration induced by phenolamide bioactivities. We further challenged the definition of medicinal effects and questioned the way to assess them in controlled conditions, underlining the necessity to clearly define the experimental framework in this research field.

Octopamine drives honeybee thermogenesis.

In times of environmental change species have two options to survive: they either relocate to a new habitat or they adapt to the altered environment. Adaptation requires physiological plasticity and provides a selection benefit. In this regard, the Western honeybee (Apis mellifera) protrudes with its thermoregulatory capabilities, which enables a nearly worldwide distribution. Especially in the cold, shivering thermogenesis enables foraging as well as proper brood development and thus survival. In this study, we present octopamine signaling as a neurochemical prerequisite for honeybee thermogenesis: we were able to induce hypothermia by depleting octopamine in the flight muscles. Additionally, we could restore the ability to increase body temperature by administering octopamine. Thus, we conclude that octopamine signaling in the flight muscles is necessary for thermogenesis. Moreover, we show that these effects are mediated by β octopamine receptors. The significance of our results is highlighted by the fact the respective receptor genes underlie enormous selective pressure due to adaptation to cold climates. Finally, octopamine signaling in the service of thermogenesis might be a key strategy to survive in a changing environment.

Effect of climate on strategies of nest and body temperature regulation in paper wasps, Polistes biglumis and Polistes gallicus

Polistes paper wasps are a widespread taxon inhabiting various climates. They build nests in the open without a protective outer layer, which makes them vulnerable to changing temperatures. To better understand the options they have to react to environmental variation and climate change, we here compare the thermoregulatory behavior of Polistes biglumis from cool Alpine climate with Polistes gallicus from warm Mediterranean climate. Behavioral plasticity helps both of them to withstand environmental variation. P. biglumis builds the nests oriented toward east-south-east to gain solar heat of the morning sun. This increases the brood temperature considerably above the ambience, which speeds up brood development. P. gallicus, by contrast, mostly avoids nesting sites with direct insolation, which protects their brood from heat stress on hot days. To keep the brood temperature below 40–42 °C on warm days, the adults of the two species show differential use of their common cooling behaviors. While P. biglumis prefers fanning of cool ambient air onto the nest heated by the sun and additionally cools with water drops, P. gallicus prefers cooling with water drops because fanning of warm ambient air onto a warm nest would not cool it, and restricts fanning to nests heated by the sun.

Camera Work

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Efficient Allocation of Labor Maximizes Brood Development and Explains Why Intermediate-Sized Groups Perform Best During Colony-Founding in the Ant, Pogonomyrmex californicus

Cooperation in nature is usually between relatives, but unrelated individuals can also cooperate, requiring significant benefits to outweigh the costs of helping non-kin. Unrelated queens of the ant, Pogonomyrmex californicus, work together to found a new colony, a phenomenon known as pleometrosis. While previous studies have shown that pleometrosis improves queen survival and worker production, little is known of the behavioral interactions within nests that explain these advantages. We aimed to determine how the optimal group size for a small, simple social group is related to group productivity and the organization of work. Collecting queens from a known pleometrotic population, we established nests with either one, three, six, or nine foundresses and observed the resulting nascent colonies for 50 days. We found that queens in social founding groups survived longer and had higher productivity. While all social groups were equally successful in producing workers, intermediate-sized groups were most successful in terms of per capita production. Inactivity increased with group size. In addition, the proportion of essential colony growth tasks performed (such as foraging and brood care) was lowest in both solitary-founded groups and in groups of nine queens. As a result, intermediate sized groups outperformed both solitary queens and groups of nine in the efficiency with which they converted eggs into workers. These results emphasize the benefits of cooperation and the ways in which group size can influence fitness and the allocation of labor in social groups.

Social Apoptosis in Varroa Mite Resistant Western Honey Bees (Apis mellifera).

Honey bees are eusocial animals that exhibit both individual and social immune responses, which influence colony health. This is especially well-studied regarding the mite Varroa destructor Anderson and Trueman (Parasitiformes: Varroidae), a parasite of honey bee brood and disease vector. Varroa was introduced relatively recently to Apis mellifera L. (Hymenoptera: Apidae) and is a major driver of the catastrophic die-off of honey bee colonies in the last decade. In contrast, the original host species, Apis cerana Fabricius (Hymenoptera: Apidae) is able to survive mite infestations with little effect on colony health and survival. This resilience is due in part to a newly identified social immune response expressed by developing worker brood. Varroa infested female A. cerana brood experience delayed development and eventually die in a process called 'social apoptosis'. Here, an individual's susceptibility to Varroa results in colony level resistance. We tested for the presence of the social apoptosis trait in two Varroa resistant stocks of A. mellifera (Pol-line and Russian) with different selection histories and compared them to a known Varroa-susceptible stock (Italian). We assessed the survival and development of worker brood reared in either highly or lightly infested host colonies, then receiving one of three treatments: uninfested, experimentally inoculated with a Varroa mite, or wounded to simulate Varroa damage. We found that response to treatment was only differentiated in brood reared in lightly infested host colonies, where experimentally infested Russian honey bees had decreased survival relative to the mite-susceptible Italian stock. This is the first evidence that social apoptosis can exist in Western honey bee populations.

Early development of brood of Pangasianodon hypophthalmus using Green House Technique

Early development of brood of Pangasianodon hypophthalmus using Green House Technique

Queen Egg Laying and Egg Hatching Abilities are Hindered in Subterranean Termite Colonies When Exposed to a Chitin Synthesis Inhibitor Bait Formulation.

Subterranean termite control methods using chitin synthesis inhibitors (CSIs) aim at eliminating colonies that feed upon a bait formulation. Several benzoylurea active ingredient formulations are currently commercially available as alternative termite management strategies to liquid termiticides. Individual workers need to molt on a regular basis and CSIs interfere with such molting process, allowing sufficient time for the acquisition of a colony-wide lethal dose prior to widespread mortality. As workers progressively die, the colony eventually collapses, leaving only soldiers and primary reproductives that starve to death. One common observation is that young workers often die early owing to their relatively short molting cycle. However, the absence of brood in dying colonies raises questions about the potential fate of eggs laid by the queen. This study aims to determine if CSI baits also terminate the ability of a colony to produce a new cohort of workers by disabling the ongoing brood development. Incipient termite colonies were used to test the impact of noviflumuron on the queen's ability to lay eggs and on the eggs' ability to hatch. Our results showed that queens in colonies exposed to CSI not only initially laid less eggs than the control queens, but eggs also did not develop and were progressively cannibalized, eventually leading to colony establishment failure. This result implies that queens of mature colonies exposed to CSI would lose the ability to lay viable eggs as the colony collapses, leading to an absence of worker replacement, aiding in colony elimination.

Evaluation of total phenols content, anti-DPPH activity and the content of selected antioxidants in the honeybee drone brood homogenate

The subject of the present research is the evaluation of health-promoting properties caused by the presence of some vitamins as well as the antioxidative potential of the honeybee drone brood homogenate (DBH). The study used 139 homogenate samples obtained from various apiaries and collected over 3 years, three times during each beekeeping season. Samples differed in terms of varroa infestation, stage of brood development, location of the apiary, and the degree of environmental contamination. The content of ascorbic acid, α-tocopherol, all-trans-retinol, and coenzyme Q10 in the tested samples was determined through the application of HPLC/DAD/UV and LC/QQQ/MS methods. The antioxidant potential of samples was assessed using the Folin-Ciocalteu and DPPH methods.

Nutritional effects of supplementary diets on brood development, biological activities and honey production of Apis mellifera L.

The present research work was conducted to assess the impact of nutrient-enriched diet on the physiological activities and subsequently honey yield. Eighteen colonies of Apis mellifera L. were selected from Dera Ismail Khan region, KPK, Pakistan, during the winter and summer seasons, 2019–2020. Five pollen supplement diets were prepared and provided to screen out the palatable one to be fed as pollen alternative nutrition to bee bread. Results of diet consumption regarding mean data for consumption rate displayed that soybean flour enriched artificial diet was maximally consumed (74.34 g) by honey bees per week. Minimum consumption was observed for grinded groundnut enriched diet (64.62 g) which was relatively lesser than the other tested artificial diets. Results of area of worker brood disclosed that soybean flour fortified diet (1489.27 cm2/colony) statistically noteworthy than the other artificial diets whereas control (463.51 cm2/colony) was least effective. Highest bee strength (10.00 bee frames/colony) was noted in the bee colonies fed with soybean flour fortified diet, date paste (8.0 bee frames/colony) was the next effective one, among the tested pollen replacement diets whereas relatively least (5 bee frames/colony) was noticed in case of grinded groundnut. Highest body weight (12.41 g) of neonate bees was noted in case of soybean enriched diet while lowermost (5.31 g) was noted in control bees. Results of wax cell built up and foraging efficiency were also superior in artificial diets than respective control bees. Hence, artificial diets especially soybean-enriched pollen alternative diet can boost up the physiology of honey bee leading to increased honey yield and profit.

Presence, persistence and distribution of thymol in honeybees and beehive compartments by high resolution mass spectrometry

Thymol has been considered as an organic varroacide with less toxicity than synthetic chemicals such as amitraz, coumaphos or tau-fluvalinate. The present study evaluates the presence, persistence and distribution of thymol during a five-month sampling period; before, during and after the application of thymol treatment in field conditions. Moreover, its impact on the development of bee brood was also studied at different development stages which consist of larvae, prepupae, pupae and adult honeybee. Samples of beebread (processed pollen), honey, beeswax, adult bees, pupae, prepupae and larvae were analysed by gas chromatography coupled to time of flight mass spectrometry for an accurate identification. Adult bees were the samples with the highest concentration level of thymol during treatment application (Thymovar® strips, 30 gr of thymol per hive) by the beekeeper, however they showed 69% of thymol dissipation three months after treatment. Regarding the bee brood, concentrations of thymol decreased significantly (89-97% of disappearance) in a period of three months, though about 42 µg/kg of thymol persisted in larvae. Thymol was found to accumulate in honey and beeswax at a level of 882 μg/kg and 1305 μg/kg respectively, in the studied period. As the main issue of thymol residues in honey is related to the modification of organoleptic properties, more than toxicology, the levels found in this study indicate that the taste of honey may be affected during and up to three months after the treatment application. In addition, we did not find adverse effects on the evolution of the colonies due to the applied treatment.

Effect of probiotic supplement feed on the foraging activity of Indian honeybee (Apis cerana indica F.)

Aim: To investigate the effect of probiotic supplement feed on the foraging behaviour Indian honeybee colonies to resolve the excessive usage of antibiotics. Methodology: The effect of sugar syrup feed (Untreated hives) and sugar syrup + probiotic supplement feed @ 10 ml 100 ml-1 syrup (Treated hives) on Indian honeybees was tested. The foraging activity and foraging rate were recorded and subjected to paired t- test analysis. Results: The present observation showed a significant difference in the foraging rate between the colonies fed with sugar syrup + probiotic supplement (2.33 ± 0.11 min-1) than the colonies that received sugar syrup alone (1.35 ± 0.06 min-1). The highest foraging rate (2.80 ± 0.39 min-1) was recorded in treated hives. Interpretation: The experiment revealed that the brood development was directly proportional to brood pheromone levels, which positively affects the foragers, consequently foraging rate and honey production. Thus, the probiotic supplement feeding may influence the foraging behaviour of honeybee colonies.

Effects on Brood Development in the Carpenter Ant Camponotus vicinus Mayr after Exposure to the Yeast Associate Schwanniomycespolymorphus Kloecker.

Simple SummaryCarpenter ants are important to ecosystem services as they assist in the breakdown of course woody debris when excavating wood for nests. Feeding on a variety of carbohydrate and protein sources, they have an infrabuccal filter that limits passage of large food particles to their gut. A variety of yeasts have been found associated with the infrabuccal pocket and the nests of these ants. The yeast Schwanniomyces polymorphus is associated with the carpenter ant Camponotus vicinus. To examine a possible nutritional association between this yeast and ant, we reared small sub-colonies of defaunated and non-defaunated C. vincus brood on several artificial diets where various nutritional components were removed. Part of the testing involved exposure of brood to these diets and cells of S. polymorphus. Dietary treatments that were augmented with yeast generally had deleterious effects on brood development compared to diets without yeast. However, increased brood weight and increased number of adult ants from initial brood was observed in non-defaunated ants fed a diet where B vitamins and sterols were absent, but augmented with live yeast. The results suggest a supplemental role for this yeast in ant nutrition and development.The yeast Schwanniomyces polymorphus is associated with the infrabuccal pocket in the carpenter ant Camponotus vicinus (Hymenoptera: Formicidae), but its role in ant development is poorly defined. The potential effects of this yeast on brood development were examined on sets of larval groups and workers over a 12 week period. Worker–larval sets were fed variations of a completely artificial, holidic diet and exposed or not exposed to live S. polymorphus. Worker–larval sets in half of the experiment were defaunated using a two-step heat and chemical process. Brood development and number of adult ants produced were significantly affected by the heat/chemical defaunation process. Compared to worker–larval groups fed a basal, complete diet, all treatments resulted in no or deleterious larval development. Brood weights and number of worker ants produced from the original larval sets at initiation were significantly higher in non-defaunated ant groups fed a diet lacking both B vitamins and cholesterol and exposed to live S. polymorphus. We propose that this yeast may help ants to more efficiently assimilate nutrients when fed nutrient-deficient diets, particularly those deficient in sterols.

Biological and behavioral responses of European honey bee (Apis mellifera) colonies to perfluorooctane sulfonate exposure.

Bees provide pollination services to managed and wild ecosystems but are threatened globally due to multiple stressors, including exposure to contaminants. Perfluorooctane sulfonate (PFOS) is a widely detected and persistent contaminant that accumulates and biomagnifies in food chains. In this exposure effect study, small whole colonies of Apis mellifera (1000 bees) were exposed to PFOS using a purpose-built cage system over a 4-week period. The PFOS exposure concentrations were provided to bees in sugar syrup at concentrations detected in the environment, ranging from 0 to 1.6 mg L-1 . A range of biological and behavioral responses were monitored. Bee tissue, honey, and fecal matter were analyzed using isotope dilution combined with liquid chromatography-tandem mass spectrometry adapted for bee and honey matrix analysis. Bee mortality increased significantly with PFOS exposure at 0.8 mg L-1 or greater, and brood development ceased entirely at 0.02 mg L-1 or greater. Colony activity, temperament, hive maintenance, and defense were adversely affected in all PFOS exposure treatments compared with the control, even at the lowest PFOS exposure of 0.02mg L-1 . Perfluorooctane sulfonate was detected in bee tissue with a mean bioaccumulation factorof 0.3, and it was also identified in honey and in feces collected from the hive cages. These findings provide the first evidence that PFOS exposure adversely affects honey bee colonies and may transfer to honey. With PFOS contaminating thousands of sites worldwide, our study has implications for exposed bee populations under natural conditions, pollination services, the honey industry, and human health. Integr Environ Assess Manag 2021;17:673-683. © 2021 SETAC.

Temporal changes in volatile profiles of Varroa destructor‐infested brood may trigger hygienic behavior in Apis mellifera

AbstractVarroa destructor Anderson & Trueman (Acari: Varroidae) is one of the major contributors to the significant losses of western honey bee, Apis mellifera L. (Hymenoptera: Apidae), colonies worldwide. Hygienic behavior, in which individual workers detect, uncap, and remove unhealthy brood, is a type of social immunity that reduces pathogen and parasite loads in the colony. Previous evidence suggests that hygienic worker bees identify diseased brood through olfactory cues. The aims of the present work were (1) to study the hygienic behavior of worker bees toward V. destructor‐infested cells at different stages of brood development, (2) to explore changes in brood volatile profiles associated with the progression of mite infestation, and (3) to analyze the role of specific volatile compounds in triggering the hygienic behavior. Results showed that the removal rate of infested brood changed along its development and the progression of mite reproduction. Two compounds, ethyl hexanoate and α‐pinene, were present in volatile collections from mite‐infested pupae but absent from uninfested pupae. Field bioassays showed that these volatiles are relevant to elicit the hygienic behavior. A third compound, β‐ocimene, was present in infested and uninfested brood but its abundance pattern varied according to the infestation status throughout brood development. Specifically, for uninfested brood, the abundance of β‐ocimene showed a reduction in black‐eyed pupae, whereas for infested brood, its abundance decreased drastically in light‐pink‐eyed pupae and remained constant in black‐eyed pupae. Our results revealed that olfactory signals associated with V. destructor infestation change as the reproductive cycle of V. destructor progresses inside the cell. These changes can be mimicked to some extent by adding specific volatile compounds to the cell to induce hygienic removal. These findings shed light on the chemical basis of hygienic behavior against V. destructor and could facilitate the development of improved hygienic selection tools to breed mite‐resistant honey bee colonies.

Thermal Impacts of Apicultural Practice and Products on the Honey Bee Colony.

Hive design and apicultural processes have not been fundamentally changed since the design and commercialization of the Langstroth moveable frame hive in 1854. Colonies of Apis mellifera Linnaeus (Hymentoptera: Apidae) (the honey bee) maintain a brood nest temperature within the narrow range of 34.5-35.5°C, critical for brood development. Apis mellifera invest considerable energy to maintain hive homeostasis through behavioral modification of the hive environment. Human honey-harvesting processes and removal of the honey-filled comb (a source of thermal mass) have a detrimental impact on hive temperature that requires an increased investment of energy to rectify. This additional energy demand on the bees is a form of stress to the colony and diverts workers away from other essential tasks to that of environmental management. We investigated the thermal energy loss resulting from the removal and extraction of honey, the rate of thermal loss of an Australian standard Langstroth 10 frame hive, and the effect of honey and wax as a thermal mass in unoccupied bee hive. The results demonstrate that considerable energy expenditure would be required to rectify the hive thermal environment after honey harvesting or honeycomb frame addition. Honey provides thermal mass in the beehive, acting as a thermal buffer to external temperature change, which may mediate part of the thermal losses from the simplistic design of the Langstroth hive. Identification of these impacts in current apicultural practice and hive design allows for the improvement in the design of beehives and associated practices. These improvements may reduce stress to the bee colony, increasing colony efficiency for pollination and nectar foraging.

Social disruption: Sublethal pesticides in pollen lead to Apis mellifera queen events and brood loss

Eusocial Apis mellifera colonies depend on queen longevity and brood viability to survive, as the queen is the sole reproductive individual and the maturing brood replenishes the shorter-lived worker bees. Production of many crops rely on both pesticides and bee pollination to improve crop quantity and quality, yet sublethal impacts of this pesticide exposure is often poorly understood. We investigated the resiliency of queens and their brood after one month of sublethal exposure to field relevant doses of pesticides that mimic exposure during commercial pollination contracts. We exposed full size colonies to pollen contaminated with field-relevant doses of the fungicides (chlorothalonil and propicanizole), insecticides (chlorypyrifos and fenpropathrin) or both, noting a significant reduction in pollen consumption in colonies exposed to fungicides compared to control. While we found no difference in the total amount of pollen collected per colony, a higher proportion of pollen to non-pollen foragers was detected in all pesticide exposed colonies. After ceasing treatments, we measured brood development, discovering a significant increase in brood loss and/or cannibalism across all pesticide exposed groups. Sublethal pesticide exposure in general was linked to reduced production of replacement workers and a change in protein acquisition (pollen vs. non-pollen foraging). Fungicide exposure also resulted in increased loss of the reproductive queen.

Cold stress induces specific antioxidant responses in honey bee brood

Multiple harmful factors cause chronic sub-lethal stress in managed honey bee colonies. In weak colonies, worker bees may not efficiently maintain the optimum temperature (33–36°C) in peripheral brood development areas. A short period at 25°C induces physiological adjustments and increases the mortality in honey bee brood reared in vitro. Molecular damage due to oxidative imbalance can be one of the main causes of mortality when organisms are under stress. Here, we demonstrate that in vitro rearing honey bee brood exposed 3 days at sub-optimal temperature (25°C) does not lead to H2O2 accumulation and oxidative protein damage. Cold-stressed honey bee brood showed increased levels of both total antioxidant status (TAS) and expression of peroxiredoxins PRX1 and PRX4, but not of catalase activity. Results indicate that specific antioxidant defenses induced in honey bee brood under moderated cold stress are enough to keep H2O2 levels under control and avoid major protein damages. It is concluded that the increase of mortality in cold-stressed brood are due to multifactor’s, beyond uncontrolled oxidative injuries.

Thermoregulation dynamics in commercially reared colonies of the bumblebee Bombus terrestris

AbstractThermoregulation, that is, the active control of temperature, is key to ensure proper brood development in both wild and captive bumblebee nests. In this study, thermoregulation dynamics were assessed relative to colony age and ambient temperature using commercially reared Bombus terrestris L. (Hymenoptera, Apidae, Bombus) colonies. We observed a positive relationship between brood and nest temperatures in response to ambient temperature. Thermoregulation investment (by either brooding or fanning) was lowest at brood surface temperatures between 33 and 34 °C and ambient temperatures between 28 and 32 °C. Brood temperature was less stable and thermoregulation investment higher in younger colonies, especially at lower ambient temperatures. Furthermore, queens initiated colonies sooner and colonies developed faster when kept at an ambient temperature of 29 °C as compared to 24 °C. Our results suggest that ambient temperatures are ideally kept between 29 and 31 °C.

Impact on survivality and mortality of Apis mellifera L. brood and workers exposed to thiamethoxam treated mustard

The present study was aimed to find out the possible effect of thiamethoxam on growth, development and behaviour of Apis mellifera. The risk of thiamethoxam to broods and adult worker bees was assessed by exposing the honey bee colonies to thiamethoxam treated mustard crop under semi field (within cage) conditions. Observations regarding broods and adult worker bees mortality, brood emergence were taken at a regular interval. Detailed examination of brood development throughout the study demonstrated that thiamethoxam had a negative impact on brood development and survivability. Delayed developmental period of two to four days was observed in colonies placed on the thiamethoxam treated mustard field.