Absence Of Brood Research Articles

Differential expression of vitellogenin in the brain of Solenopsis invicta workers based on social and nutritional context

AbstractVitellogenin (Vg) has been recognized as a co‐opted gene involved in social colonies where it is associated with reproduction in the queen and task transitions in workers. The Solenopsis invicta genome harbours four Vg genes, Vg1, Vg2, Vg3 and Vg4, and this study explored the regional expression of these genes in the brain and head of the worker caste in different subcaste and social contexts. Transcriptomic analyses of the worker brain while in the presence or absence of brood revealed differential expression of genes involved with social behaviours. Among these, we found higher expression of Vg2 and Vg3 in the brains of workers in the absence of brood. The influence of brood on expression of Vg between worker castes was also investigated. RT‐qPCR revealed higher expression of Vg in the head of workers in the absence of brood. Further studies demonstrated that Vg was also differentially expressed in the heads of workers conducting specific tasks and differing between subcastes. Nurses maintained higher Vg expression than foragers. We conclude worker Vg expression may be linked to the brood and/or nutritional state. Vg expression changes when workers are deprived of protein suggesting it is regulated by nutritional signalling and the presence of brood.

Technological methods of limiting the reproductive activity of queen bees in conditions of honey collection

The study of the biological characteristics of the development of bee colonies, the ethology of bees, the influence of the various factors on their life activities contributes to the development and implementation of new highly efective technologies of keeping and reproduction. Of particular interest is the study of the stimulating efect of diferent numbers of brood of diferent ages in the nest of a bee colony on the trophic connections of honey bees with the biological diversity of entomophilous plants, the change in physiological characteristics of diferent generations of bees in modern changing natural and climatic conditions of unstable ecotypes. This paper presents the data of experimental studies on the influence on the biological potential of bee colonies of various technological methods of regulating the reproductive activity of queen bees. The work aims to study the technological methods of regulating the reproductive activity of queen bees. The following research methods were used: zootechnical (selection of groups of analogues, signs of bee purebredness, brood accounting), analytical (analysis of literature data and research results) and statistical. Biometric data processing was carried out on a PC using MS Excel software with built-in statistical functions. Results. As a result of the study, it was found that bee families, where the reproductive activity of queen bees was limited by the use of an isolation cage, had the highest productivity indicators. It has been proved that prolonged (15 days or more) restriction of the reproductive activity of queen bees negatively afects the strength of bee colonies and their preparation for a prolonged state of hypobiosis. Conclusions. It was found that there is a complex relationship between brood rearing by bee colonies and their productivity. The absence of brood has led to an increase in the supply of nectar only for 12-15 days. Currently, due to the lack of replenishment with young bees, bee colonies have lost their strength and weakened. It has been proven that the most efective technological method of regulating the reproductive activity of queen bees in hull hives is the use of dividing grids and the mandatory presence of brood of diferent ages. For the efective use of honey collection, it is important not only to increase the maximum number of bees before the start of the main honey collection, but also to limit the feeding of a large number of larvae in time when they are no longer needed. During a short-term honey collection, it is necessary to limit the reproductive activity of the queen bee, and during the long one, it should be limited only in the second half of honey collection. Key words: bee colony, Ukrainian steppe breed, isolation, brood, reproductive activity, honey collection, honey productivity.

Time-course RNASeq of Camponotus floridanus forager and nurse ant brains indicate links between plasticity in the biological clock and behavioral division of labor

BackgroundCircadian clocks allow organisms to anticipate daily fluctuations in their environment by driving rhythms in physiology and behavior. Inter-organismal differences in daily rhythms, called chronotypes, exist and can shift with age. In ants, age, caste-related behavior and chronotype appear to be linked. Brood-tending nurse ants are usually younger individuals and show “around-the-clock” activity. With age or in the absence of brood, nurses transition into foraging ants that show daily rhythms in activity. Ants can adaptively shift between these behavioral castes and caste-associated chronotypes depending on social context. We investigated how changes in daily gene expression could be contributing to such behavioral plasticity in Camponotus floridanus carpenter ants by combining time-course behavioral assays and RNA-Sequencing of forager and nurse brains.ResultsWe found that nurse brains have three times fewer 24 h oscillating genes than foragers. However, several hundred genes that oscillated every 24 h in forager brains showed robust 8 h oscillations in nurses, including the core clock genes Period and Shaggy. These differentially rhythmic genes consisted of several components of the circadian entrainment and output pathway, including genes said to be involved in regulating insect locomotory behavior. We also found that Vitellogenin, known to regulate division of labor in social insects, showed robust 24 h oscillations in nurse brains but not in foragers. Finally, we found significant overlap between genes differentially expressed between the two ant castes and genes that show ultradian rhythms in daily expression.ConclusionThis study provides a first look at the chronobiological differences in gene expression between forager and nurse ant brains. This endeavor allowed us to identify a putative molecular mechanism underlying plastic timekeeping: several components of the ant circadian clock and its output can seemingly oscillate at different harmonics of the circadian rhythm. We propose that such chronobiological plasticity has evolved to allow for distinct regulatory networks that underlie behavioral castes, while supporting swift caste transitions in response to colony demands. Behavioral division of labor is common among social insects. The links between chronobiological and behavioral plasticity that we found in C. floridanus, thus, likely represent a more general phenomenon that warrants further investigation.

Modelling the impact of Apivar treatment on a Varroa mite population and the influence of resistance.

Varroa destructor is a parasite of honeybees. It causes biological damage leading to the colony collapse in the absence of treatment. In recent years, acaricide resistance has emerged in Varroa mites, leading to a decrease in treatment efficacy. We modelled the action of Apivar (amitraz) treatment, using three input parameters: treatment duration, treatment period, and daily mortality due to the treatment. The output parameters were cumulative mite mortality during treatment, the residual number of Varroa mites, and treatment efficacy, expressed as a percentage. The model was validated by monitoring efficacy in the field, in 36 treated hives. According to the model, treatment in the absence of brood is optimal. For a long period without egg laying during the winter, an initial infestation of 100 mites and a start date for treatment of August 7, a minimal treatment efficacy of 98.8% is required for stabilization of the mite population for year to year. More effective treatment is associated with lower cumulative numbers of dead Varroa mites over the entire treatment period. Thus, the total number of dead mites observed during the monitoring of field efficacy provides information about more than just the initial level of colony infestation. The proportion of resistant mites can be modelized by a decrease of daily mortality rate influencing treatment efficacy. Management of the initial Varroa mite infestation of the colony by the beekeeper can compensate for the decrease in treatment efficacy for resistance thresholds of up to 40% of resistant mites. Treatment efficacy depends on several parameters, including initial level of infestation, treatment period and the presence of acaricide resistance. Amitraz resistance may lead to treatment failure, even if the beekeeper is able to keep initial infestation rates low. © 2021 Society of Chemical Industry.

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.

Воздействие регуляторов развития насекомых на рыжих тараканов двух рас и рыжих домовых муравьёв

When eating poisoned baits based on 0.1–1.0 % pyriproxyfen, within 6 weeks killed up to 50 % of German cockroaches of the S-NIID strain, and 12 % of cockroaches of the OBN strain. The resulting oothecae turned out to be defective and the second generation of cockroaches did not hatch. Morphological changes consisted were in the deformation of the wings (rudimentary, curved, twisted) and in the inability of the larvae to transform into adults. In experiments with an alternative food, similar results were obtained, females formed more oothecae, but the emergence of new generation larvae was not recorded. The consumption of pyriproxyfen-based baits by Pharaoh ant led to the elimination of colonies. A significant decrease in brood number was recorded at 3–6 weeks, and complete death of brood was observed at 6–8 weeks in all treated colonies. The absence of brood can be explained by both mortality as a result of developmental disorders and the cessation of egg laying by queens. Keywords: insect growth regulators, German cockroach, Pharaoh ant, pyriproxifen, hydroprene.

Bumblebees adjust protein and lipid collection rules to the presence of brood.

Animals have evolved foraging strategies to acquire blends of nutrients that maximize fitness traits. In social insects, nutrient regulation is complicated by the fact that few individuals, the foragers, must address the divergent nutritional needs of all colony members simultaneously, including other workers, the reproductives, and the brood. Here we used 3D nutritional geometry design to examine how bumblebee workers regulate their collection of 3 major macronutrients in the presence and absence of brood. We provided small colonies artificial nectars (liquid diets) and pollens (solid diets) varying in their compositions of proteins, lipids, and carbohydrates during 2 weeks. Colonies given a choice between nutritionally complementary diets self-selected foods to reach a target ratio of 71% proteins, 6% carbohydrates, and 23% lipids, irrespective of the presence of brood. When confined to a single nutritionally imbalanced solid diet, colonies without brood regulated lipid collection and over-collected protein relative to this target ratio, whereas colonies with brood regulated both lipid and protein collection. This brood effect on the regulation of nutrient collection by workers suggests that protein levels are critical for larval development. Our results highlight the importance of considering bee nutrition as a multidimensional phenomenon to better assess the effects of environmental impoverishment and malnutrition on population declines.

Social regulation of ageing by young workers in the honey bee, Apis mellifera

Organisms' lifespans are modulated by both genetic and environmental factors. The lifespan of eusocial insects is determined by features of the division of labor, which itself is influenced by social regulatory mechanisms. In the honey bee, Apis mellifera, the presence of brood and of old workers carrying out foraging tasks are important social drivers of ageing, but the influence of young adult workers is unknown, as it has not been experimentally teased apart from that of brood. In this study, we test the role of young workers in the ageing of their nestmates. We measured the impact of different social contexts characterized by the absence of brood and/or young adults on the lifespan of worker nestmates in field colonies. To acquire insight into the physiological processes occurring under these contexts, we analyzed the expression of genes known to affect honey bee ageing. The data showed that young workers significantly reduced the lifespan of nestmate workers, similar to the effect of brood on its own. Differential expression of vitellogenin, major royal jelly protein-1, and methylase transferase, but not methyl farneosate epoxidase genes suggests that young workers and brood influence ageing of adult nestmate workers via different physiological pathways. We identify young workers as an essential part of the social regulation of ageing in honey bee colonies.

Phosphorus 30 CH to control Varroa population in Apis mellifera colonies

IntroductionVarroa destructor is considered to be the main cause of European honeybee (Apis mellifera ssp. Linnaeus 1758) colony losses. The use of homeopathic products in veterinary practices has consistently increased in the last 50 years, but limited data are available on the application of homeopathic treatments to honeybees.The aims of this study were to investigate the acaricide efficacy and tolerability for honeybees treated for 35days with the homeopathic product Phosphorus 30 CH. MethodsThe clinical trial was carried out during the summer of 2012 in Central Italy. Twenty-four honeybee colonies were evenly divided into two different groups: one treated with Phosphorus 30 CH (12 colonies) and one left untreated (12 colonies). The mite mortality rate of the remedy was evaluated by counting the number of fallen mites on the sticky boards placed on the bottom tray of the hives every 3days. Oxalic acid administration in an absence of brood was used to estimate the number of surviving mites. To assess the honeybee tolerability to the treatment, immediately before and after the Phosphorus 30 CH administration, an evaluation of the adult honeybee population was performed. ResultsThe results revealed that no efficacy differences (p-value=0.079, U=23; EV=45; Variance (U)=150), nor differences in hive strengths (p-value=0.118; U=25.5; EV=45; Variance (U)=147.76) were observed in the treated group compared to the untreated group. ConclusionOur results are consistent with other studies conducted using homeopathic remedies to control varroa mites in Apis mellifera colonies. Further studies are needed to compare our data with different treatment durations, different administration methods and potency of the remedy.

The red imported fire ant (Solenopsis invicta Buren) kept Y not F: predicted sNPY endogenous ligands deorphanize the short NPF (sNPF) receptor.

Neuropeptides and their receptors play vital roles in controlling the physiology and behavior of animals. Short neuropeptide F (sNPF) signaling regulates several physiological processes in insects such as feeding, locomotion, circadian rhythm and reproduction, among others. Previously, the red imported fire ant (Solenopsis invicta) sNPF receptor (S. invicta sNPFR), a G protein-coupled receptor, was immunolocalized in queen and worker brain and queen ovaries. Differential distribution patterns of S. invicta sNPFR protein in fire ant worker brain were associated both with worker subcastes and with presence or absence of brood in the colony. However, the cognate ligand for this sNPFR has not been characterized and attempts to deorphanize the receptor with sNPF peptides from other insect species which ended in the canonical sequence LRLRFamide, failed. Receptor deorphanization is an important step to understand the neuropeptide receptor downstream signaling cascade. We cloned the full length cDNA of the putative S. invicta sNPF prepropeptide and identified the putative “sNPF” ligand within its sequence. The peptide ends with an amidated Tyr residue whereas in other insect species sNPFs have an amidated Phe or Trp residue at the C-terminus. We stably expressed the HA-tagged S. invicta sNPFR in CHO-K1 cells. Two S. invicta sNPFs differing at their N-terminus were synthesized that equally activated the sNPFR, SLRSALAAGHLRYa (EC50 = 3.2 nM) and SALAAGHLRYa (EC50 = 8.6 nM). Both peptides decreased the intracellular cAMP concentration, indicating signaling through the Gαi-subunit. The receptor was not activated by sNPF peptides from other insect species, honey bee long NPF (NPY) or mammalian PYY. Further, a synthesized peptide otherwise identical to the fire ant sequence but in which the C-terminal amidated amino acid residue ‘Y’ was switched to ‘F’, failed to activate the sNPFR. This discovery will now allow us to investigate the function of sNPY and its cognate receptor in fire ant biology.

Social interactions and their connection to aggression and ovarian development in orphaned worker bumblebees (Bombus impatiens)

This study examines the social dynamics of reproductive conflict. Orphaned worker bumblebees (Bombus impatiens) with comparatively high or low levels of social activity were paired to determine whether aggression and reproduction could be traced to earlier social interactions. The workers were paired according to their levels of social activity (a socially active+another socially active worker, socially active+socially inactive, and two socially inactive workers). The presence or absence of brood was also manipulated. The absence of brood increased both aggression and ovarian development, suggesting that aggression and reproduction are associated or that there is a third variable that affects both. Socially active pairs were significantly more aggressive: here, social activity can be taken as an early indicator of aggression. No such effect, however, was obtained on ovarian development as the socially active pairs did not differ on their degree of ovarian development compared to the others. Within the socially active+socially inactive pairs, the socially active worker did not have more developed ovaries and was not more aggressive than her socially inactive partner. Results highlight that environmental conditions (the absence of brood) can predict ovarian development and although social activity can be observed prior to aggression, differences in aggression do not translate into differences in ovarian development under these conditions.

On the relationship between aggression and reproduction in pairs of orphaned worker bumblebees (Bombus impatiens)

This study characterized aggression and reproduction within pairs of orphaned bumblebee sisters (Bombus impatiens (Cresson, 1863)). Twenty-one pairs were filmed in the laboratory over 5–10 days. Frequencies of aggression and egg-laying were obtained for each bee, and the presence or absence of brood was manipulated. Aggression and egg-laying were more likely to co-occur in pairs placed without brood compared to pairs placed with brood. A significant positive correlation was found between members of a pair in the rates of aggression. In addition, a strong positive correlation was found in their rates of egg-laying: bees that had more sons also tended to have more nephews. The results show that under conditions of unrestricted food availability, behavioural interactions are compatible with continued reproduction by both orphaned workers. Though aggression may limit reproduction, it seems either to be an ineffective means of obtaining a reproductive monopoly in some situations and/or to be a set of behaviours invested with other possible functions.

The effects of young brood on the foraging behavior of two strains of honey bees (Apis mellifera)

Honey bee foragers specialize on collecting pollen and nectar. Pollen foraging behavior is modulated by at least two stimuli within the nest: the presence of brood pheromone and young larvae and the quantity of stored pollen. Genetic variation in pollen foraging behavior has been demonstrated repeatedly. We used selected high and low pollen-hoarding strains of bees that differ dramatically in the quantity of pollen collected to determine if the observed differences in foraging could be explained by differential responses to brood stimuli. Workers from the high and low pollen-hoarding strains and wild-type bees were co-fostered in colonies with either brood or no brood. As expected based on previous studies, returning high pollen-hoarding foragers collected heavier pollen loads and lighter nectar loads than low pollen-hoarding bees. Effects of brood treatment were also observed; bees exposed to brood collected heavier pollen loads and initiated foraging earlier than those from broodless colonies. More specifically, brood treatment resulted in increased pollen foraging in high pollen-hoarding bees but did not affect pollen foraging in low pollen-hoarding bees, suggesting that high pollen-hoarding bees are more sensitive to the presence of brood. However, response to brood stimuli does not sufficiently explain the differences in foraging behavior between the strains since these differences persisted even in the absence of brood.

Self-organized asymmetries in ant foraging: a functional response to food type and colony needs

The dominant paradigm to explain asymmetries in the spatial distribution of foraging animals is that they track the spatial heterogeneity of their environment. However, in social insects, endogenous spatial asymmetries can emerge within a uniform environment as an outcome from the self-organizing process of trail recruitment. We studied how self-organized asymmetries contribute to the exploitation of different food sources (carbohydrate or proteins) in colonies of the aphid-tending ant Lasius niger varying in their nutritional needs (presence or absence of brood). Colonies with brood fed on sucrose sources exhibit a higher mobilization of foragers than the other experimental groups. Foraging patterns differ greatly according to food type: colonies strongly focus their activity on only one droplet of sucrose, whereas they show a rather homogeneous distribution of foragers between proteinaceous sources. In addition, the presence of brood in the colony enhances the asymmetry of collective foraging for both types of food. These spatial differences in self-organized foraging patterns allow efficient exploitation of natural resources and play a role in the competitive strategy of this widespread palearctic ant. Copyright 2002.

The capacity of a Myrmica ant nest to support a predacious species of Maculinea butterfly

Caterpillars of Maculinea arion are obligate predators of the brood of Myrmica sabuleti ants. In the aboratory, caterpillars eat the largest available ant larvae, although eggs, small larvae and prepupae are also palatable. This is an efficient way to predate. It ensures that newly-adopted caterpillars consume the final part of the first cohort of ant brood in a nest, before this pupates in early autumn and becomes unavailable as prey. At the same time, the fixed number of larvae in the second cohort is left to grow larger before being killed in late autumn and spring. Caterpillars also improve their feeding efficiency by hibernating for longer than ants in spring, losing just 6% of their weight while the biomass of ant larvae increases by 27%. Final instar caterpillars acquire more than 99% of their ultimate biomass in Myrmica nests, growing from 1.3 mg to an estimated 173 mg. A close correlation was found between the weights of caterpillars throughout autumn and the number of large ant larvae they had eaten. This was used to calculate the number of larvae eaten in spring, allowing both for the loss of caterpillar weight during winter and the increase in the size of their prey in spring. It is estimated that 230 of the largest available larvae, and a minimum nest size of 354 M. sabuleti workers, is needed to support one butterfly. Few wild M. sabuleti nests are this large: on one site, it was estimated that 85% of nests were too small to produce a butterfly, and only 5% could support two or more. This prediction was confirmed by the mortalities of 376 caterpillars in 151 wild M. sabuleti nests there. Mortalities were particularly high in nests that adopted more than two caterpillars, apparently due to scramble competition and starvation in autumn. Survival was higher than predicted in wild nests that adopted one caterpillar. These caterpillars seldom exhaust their food before spring, when there is intense competition among Myrmica for nest sites. Ants often desert their nests in the absence of brood, leaving the caterpillar behind. Vacant nests are frequently repopulated by a neighbouring colony, carrying in a fresh supply of brood. Maculinea arion caterpillars have an exceptional ability to withstand starvation, and sometimes survive to parasitize more than one Myrmica colony. Despite these adaptations, predation is an inefficient way to exploit the resources of a Myrmica nest. By contrast, Maculinea rebeli feeds mainly at a lower trophic level, on the regurgitations of worker ants. Published data show that Myrmica nests can support 6 times more caterpillars of Maculinea rebeli than of M. arion in the laboratory. This is confirmed by field data.

Pollen Hoarding and Use by High and Low Pollen-Hoarding Honeybees During the Course of Brood Rearing

SummaryHoneybees (Apis mellifera) from a line which had been selected for high pollen-hoarding behaviour (HPH) hoarded more pollen than bees from a low pollen-hoarding line (LPH) when they were kept in observation colonies with known amounts of brood. These differences were not found when brood was in the egg stage and pollen stores were small, but were large and significant when brood was in the larval stage and pollen stores were more abundant. Differences in amounts of stored pollen that were established between the lines during the larval stage were maintained after brood cells were capped, but amounts of pollen stored did not change significantly. HPH bees also hoarded more pollen in the absence of brood. The two lines used similar amounts of pollen and reared similar amounts of brood. Mortality of the LPH bees was higher and varied significantly more than that of the HPH bees. It is suggested that bees which hoard a large amount of pollen are either less inhibited from collecting pollen by the presence of stored pollen or more stimulated to collect pollen by its absence.

Activation of the Hypopharyngeal Glands of Honeybees in Winter

SummaryAlthough the hypopharyngeal glands of overwintering worker honeybees (Apis mellifera) are hypertrophied, glands isolated from such bees were found to display low rates of protein synthesis in vitro. In the presence of brood, protein synthesis was activated to a maximum within 3 days; in the absence of brood, however, neither pollen consumption nor juvenile hormone treatment of workers stimulated protein synthesis. When the colony was transferred to a flight room, workers' hypopharyngeal glands remained activated for several weeks while the first brood was being reared. Later, only newly emerged bees were involved in rearing brood.

Studies on Hiving Package Bees 4. Effects on Loss and Drifting of Bees of the Method of Hiving, Time of Day, Apiary Layout, and the Presence or Absence of Brood

SummaryHiving package bees into hives containing worker brood, or into hives arranged in the apiary in a U layout, did not significantly reduce subsequent loss of bees. More bees were lost, and more drifted, when packages were hived during the day than in late evening. But hiving packages on the top of frames instead of inside the hive did not increase the subsequent loss of bees.