Frustrative nonreward: Detailed c-Fos expression patterns in the amygdala after consummatory successive negative contrast.

The amygdala has been implicated in frustrative nonreward induced by unexpected reward downshifts, using paradigms like consummatory successive negative contrast (cSNC). However, existing evidence comes from experiments involving the central and basolateral nuclei on a broad level. Moreover, whether the amygdala's involvement in reward downshift requires a cSNC effect (i.e., greater suppression in downshifted animals than in unshifted controls) or just consummatory suppression without a cSNC effect, remains unclear. Three groups were exposed to (1) a large reward disparity leading to a cSNC effect (32-to-2% sucrose), (2) a small reward disparity involving consummatory suppression in the absence of a cSNC effect (8-to-2% sucrose), and (3) an unshifted control (2% sucrose). Brains obtained after the first reward downshift session were processed for c-Fos expression, a protein often used as a marker for neural activation. c-Fos-positive cells were counted in the anterior, medial, and posterior portions (A/P axis) of ten regions of the rat basolateral, central, and medial amygdala. c-Fos expression was higher in 32-to-2% sucrose downshift animals than in the other two groups in four regions: the anterior and the medial lateral basal amygdala, the medial capsular central amygdala, and the anterior anterio-ventral medial amygdala. None of the areas exhibited differential c-Fos expression between the 8-to-2% sucrose downshift and the unshifted conditions. Thus, amygdala activation requires exposure to a substantial reward disparity. This approach has identified, for the first time, specific amygdala areas relevant to understand the cSNC effect, suggesting follow-up experiments aimed at testing the function of these regions in reward downshift.

Mice lacking proSAAS display alterations in emotion, consummatory behavior and circadian entrainment.

ProSAAS is a neuroendocrine protein that is cleaved by neuropeptide-processing enzymes into more than a dozen products including the bigLEN and PEN peptides, which bind and activate the receptors GPR171 and GPR83, respectively. Previous studies have suggested that proSAAS-derived peptides are involved in physiological functions that include body weight regulation, circadian rhythms and anxiety-like behavior. In the present study, we find that proSAAS knockout mice display robust anxiety-like behaviors in the open field, light-dark emergence and elevated zero maze tests. These mutant mice also show a reduction in cued fear and an impairment in fear-potentiated startle, indicating an important role for proSAAS-derived peptides in emotional behaviors. ProSAAS knockout mice exhibit reduced water consumption and urine production relative to wild-type controls. No differences in food consumption and overall energy expenditure were observed between the genotypes. However, the respiratory exchange ratio was elevated in the mutants during the light portion of the light-dark cycle, indicating decreased fat metabolism during this period. While proSAAS knockout mice show normal circadian patterns of activity, even upon long-term exposure to constant darkness, they were unable to shift their circadian clock upon exposure to a light pulse. Taken together, these results show that proSAAS-derived peptides modulate a wide range of behaviors including emotion, metabolism and the regulation of the circadian clock.

Dissociating wanting and anticipated liking from consummatory liking in smokers with different levels of nicotine dependence.

INTRODUCTION: Incentive Sensitisation theory suggests wanting and liking are dissociable concepts, with wanting, but not liking typically increasing with repeated drug use. Wanting is associated with anticipation of reward, whereas liking relates to pleasure derived from consummatory behaviour. However, numerous studies have conceptualised liking as an anticipatory cognition. This study explores whether levels of nicotine dependence differentially effect wanting and liking responses to smoking-related cues, and whether anticipated and consummatory liking are equivalent, and dissociable from wanting. METHOD: Heavy (HS, mean = 16 cigarettes/day) and light non-daily (LS, mean = 2 cigarettes/day) smokers completed wanting and anticipated liking questionnaires pre-, immediately post-exposure to smoking-related and neutral cues and at session-end. Consummatory liking was measured post-session, immediately after smoking. RESULTS: Wanting and anticipated liking responses were comparable. Smoking-related cues increased wanting and anticipated liking compared to neutral cues. This effect was maintained until session-end. No baseline differences were seen between HS and LS on wanting or anticipated liking, however after cue exposure, and at session-end, HS reported greater drug wanting and anticipated liking than LS. Conversely, HS and LS did not differ on consummatory liking. Analyses confirmed the relationship between wanting and anticipated liking was significantly stronger than wanting and consummatory liking or anticipated and consummatory liking. CONCLUSIONS: Wanting and anticipated liking appear to be overlapping constructs assessing expectations of reward, that are dissociable from consummatory liking. Furthermore, heavier smoking increases drug wanting, but not smoking pleasure. Future attempts to dissociate these concepts should ensure liking is measured during/immediately after consumption.

Site-specific effects of aromatase inhibition on the activation of male sexual behavior in male Japanese quail (Coturnix japonica).

Aromatization within the medial preoptic nucleus (POM) is essential for the expression of male copulatory behavior in Japanese quail. However, several nuclei within the social behavior network (SBN) also express aromatase. Whether aromatase in these loci participates in the behavioral activation is not known. Castrated male Japanese quail were implanted with 2 subcutaneous Silastic capsules filled with crystalline testosterone and with bilateral stereotaxic implants filled with the aromatase inhibitor Vorozole targeting the POM, the bed nucleus of the stria terminalis (BST) or the ventromedial nucleus of the hypothalamus (VMN). Control animals were implanted with testosterone and empty bilateral stereotaxic implants. Starting 2 days after the surgery, subjects were tested for the expression of consummatory sexual behavior (CSB) every other day for a total of 10 tests. They were also tested once for appetitive sexual behavior (ASB) as measured by the rhythmic cloacal sphincter movements displayed in response to the visual presentation of a female. CSB was drastically reduced when the Vorozole implants were localized in the POM, but not in the BST nor in the VMN. Birds with implants in the BST took longer to show CSB in the first 6 tests than controls, suggesting a role of the BST in the acquisition of the full copulatory ability. ASB was not significantly affected by aromatase blockade in any region. These data confirm the key role played by the POM in the control of male sexual behavior and suggest a minor role for aromatization in the BST or VMN.

Whole-transcriptome analysis of atrophic ovaries in broody chickens reveals regulatory pathways associated with proliferation and apoptosis.

Broodiness in laying hens results in atrophy of the ovary and consequently decreases productivity. However, the regulatory mechanisms that drive ovary development remain elusive. Thus, we collected atrophic ovaries (AO) from 380-day-old broody chickens (BC) and normal ovaries (NO) from even-aged egg-laying hens (EH) for RNA sequencing. We identified 3,480 protein-coding transcripts that were differentially expressed (DE), including 1,719 that were down-regulated and 1,761 that were up-regulated in AO. There were 959 lncRNA transcripts that were DE, including 56 that were down-regulated and 903 that were up-regulated. Among the116 miRNAs that were DE, 79 were down-regulated and 37 were up-regulated in AO. Numerous DE protein-coding transcripts and target genes for miRNAs/lncRNAs were significantly enriched in reproductive processes, cell proliferation, and apoptosis pathways. A miRNA-intersection gene-pathway network was constructed by considering target relationships and correlation of the expression levels between ovary development-related genes and miRNAs. We also constructed a competing endogenous RNA (ceRNA) network by integrating competing relationships between protein-coding genes and lncRNA transcripts, and identified several lncRNA transcripts predicted to regulate the CASP6, CYP1B1, GADD45, MMP2, and SMAS2 genes. In conclusion, we discovered protein-coding genes, miRNAs, and lncRNA transcripts that are candidate regulators of ovary development in broody chickens.

Effects of contingent and noncontingent nicotine on lever pressing for liquids and consumption in water-deprived rats.

Nicotine has been proposed to be a primary reinforcer and a reinforcement enhancer. To date, no studies have examined whether nicotine enhances consummatory behaviors or only operant responding (appetitive behaviors). Experiments were designed to test whether contingent and noncontingent nicotine enhance lever pressing for and consumption of fluids in water-deprived rats. Animals were water-deprived throughout all experiments. They were trained to press two levers under a variable interval (VI-20, 1-35s). Their lever pressing and water consumption were measured after noncontingent subcutaneous (s.c.) injection of nicotine (1mg/kg), and in 3 choice conditions (water and quinine solution (18µg/ml); water and nicotine (32µg/ml) solution; quinine (18µg/ml) and nicotine (32µg/ml) solutions) where nicotine was thus delivered contingently upon lever pressing. The effects of nicotine (1mg/kg; s.c.) on the consumption of water in a time-limited free access (1h) paradigm were assessed. Nicotine significantly increased lever pressing and the number of earned reinforcements on both levers in the two choice conditions and when administered s.c. compared to all groups that did not receive nicotine. However, under no condition did animals consume more fluids than baseline. Under the time-limited free access condition nicotine reduced water consumption. Although our findings do not support a reinforcing effect for nicotine, they are consistent with the incentive-amplification hypothesis. Its relevance for human smoking is yet unclear.

Central ghrelin increases food foraging/hoarding that is blocked by GHSR antagonism and attenuates hypothalamic paraventricular nucleus neuronal activation.

The stomach-derived "hunger hormone" ghrelin increases in the circulation in direct response to time since the last meal, increasing preprandially and falling immediately following food consumption. We found previously that peripheral injection of ghrelin potently stimulates food foraging (FF), food hoarding (FH), and food intake (FI) in Siberian hamsters. It remains, however, largely unknown if central ghrelin stimulation is necessary/sufficient to increase these behaviors regardless of peripheral stimulation of the ghrelin receptor [growth hormone secretagogue receptor (GHSR)]. We injected three doses (0.01, 0.1, and 1.0 µg) of ghrelin into the third ventricle (3V) of Siberian hamsters and measured changes in FF, FH, and FI. To test the effects of 3V ghrelin receptor blockade, we used the potent GHSR antagonist JMV2959 to block these behaviors in response to food deprivation or a peripheral ghrelin challenge. Finally, we examined neuronal activation in the arcuate nucleus and paraventricular hypothalamic nucleus in response to peripheral ghrelin administration and 3V GHSR antagonism. Third ventricular ghrelin injection significantly increased FI through 24 h and FH through day 4. Pretreatment with 3V JMV2959 successfully blocked peripheral ghrelin-induced increases in FF, FH, and FI at all time points and food deprivation-induced increases in FF, FH, and FI up to 4 h. c-Fos immunoreactivity was significantly reduced in the paraventricular hypothalamic nucleus, but not in the arcuate nucleus, following pretreatment with intraperitoneal JMV2959 and ghrelin. Collectively, these data suggest that central GHSR activation is both necessary and sufficient to increase appetitive and consummatory behaviors in Siberian hamsters.

Involvement of Neuropeptide Orexin B in Basolateral Amygdala Mediated Consummatory Behaviour in Male Wistar Albino Rats.

UNLABELLED: The basolateral amygdala has been implicated in the regulation of food intake besides the hypothalamic centres. In the present study, we hypothesized that the Orexin B, a polypeptide identified in the lateral hypothalamic region, may be involved in the modification of the functions the of amygdaloid centres. We therefore studied the effect of infusion of Orexin B and its antagonist (TCS-OX2-29) into Basolateral amygdala to study the feeding behaviour. MATERIALS AND METHODS: Adult male Wistar albino rats were selected and grouped into control, sham operated control and experimental groups (n = 6 each) Orexin was infused in two doses (3 nmol/µl, 30 nmol/ µl) and TCS-OX2-29 (10 µg/µl) was infused in another group. Sequential Food intake and water intake were measured at 1, 2, 4, 6, 12 hours and intake for the day was also recorded in all groups and the results (mean ± SEM) were statistically analyzed by Kruskal Wali's test and p < 0.05 was considered significant. RESULTS: The food intake and water intake were significantly increased (p < 0.01) in the high dose group though the increase in the low dose treated animals was less. Injection of Orexin B antagonist decreased the food and water intake significantly. DISCUSSION AND CONCLUSION: The results suggest that Orexin plays a role in the modulation of feeding behaviour. In the lower doses it did not show significant effect. At higher doses, the effect was marked. The role of orexin in ingestive behaviour is further confirmed by the action of antagonist infusion, which resulted decrease in the feeding activities.

Brain expression of pCREB in rats exposed to consummatory successive negative contrast.

A 32-to-4% sucrose devaluation leads to suppression of consummatory behavior relative to unshifted 4% sucrose controls. This is accompanied by an emotional response inducing memory consolidation. Expression levels of phosphorylated cyclic adenosine monophosphate response element-binding protein (pCREB, a marker of synaptic plasticity) were higher after the first devaluation session than after the second in prelimbic cortex, anterior cingulate cortex, and dorso-medial striatum. The central nucleus of the amygdala showed a tendency to differential pCREB expression. This evidence contributes to identifying the brain circuit for one form of traumatic memory involving reward loss.

Role of bed nucleus of the stria terminalis corticotrophin-releasing factor receptors in frustration stress-induced binge-like palatable food consumption in female rats with a history of food restriction.

We developed recently a binge-eating model in which female rats with a history of intermittent food restriction show binge-like palatable food consumption after 15 min exposure to the sight of the palatable food. This "frustration stress" manipulation also activates the hypothalamic-pituitary-adrenal stress axis. Here, we determined the role of the stress neurohormone corticotropin-releasing factor (CRF) in stress-induced binge eating in our model. We also assessed the role of CRF receptors in the bed nucleus of the stria terminalis (BNST), a brain region implicated in stress responses and stress-induced drug seeking, in stress-induced binge eating. We used four groups that were first exposed or not exposed to repeated intermittent cycles of regular chow food restriction during which they were also given intermittent access to high-caloric palatable food. On the test day, we either exposed or did not expose the rats to the sight of the palatable food for 15 min (frustration stress) before assessing food consumption for 2 h. We found that systemic injections of the CRF1 receptor antagonist R121919 (2,5-dimethyl-3-(6-dimethyl-4-methylpyridin-3-yl)-7 dipropylamino pyrazolo[1,5-a]pyrimidine) (10-20 mg/kg) and BNST (25-50 ng/side) or ventricular (1000 ng) injections of the nonselective CRF receptor antagonist D-Phe-CRF(12-41) decreased frustration stress-induced binge eating in rats with a history of food restriction. Frustration stress also increased Fos (a neuronal activity marker) expression in ventral and dorsal BNST. Results demonstrate a critical role of CRF receptors in BNST in stress-induced binge eating in our rat model. CRF1 receptor antagonists may represent a novel pharmacological treatment for bingeing-related eating disorders.

Fos expression in monoaminergic cell groups in response to sociosexual interactions in male and female Japanese quail.

Monoaminergic neurotransmitters regulate different components of sexual behaviors, but how the different monoaminergic cell groups selectively regulate these behaviors is not well understood. We examined the potential contribution of these different cell groups in the control of different aspects of sexual behaviors in male and female quail. We used double-label immunohistochemistry, labeling the protein product of the immediate early gene, Fos, along with tyrosine hydroxylase (TH) or tryptophan hydroxylase (TPH), markers for catecholaminergic or indolaminergic cells, respectively. Rhythmic Cloacal Sphincter Movements (RCSM) were recorded as a measure of male appetitive sexual behavior. Consummatory sexual behaviors were evaluated based on the species-typical copulation sequence. Enhanced Fos expression in the medial preoptic nucleus and bed nucleus of the stria terminalis was observed in association with both physical and visual contact to the opposite sex for males, but not for females. Fos induction associated with physical contact was observed in the ventral tegmental area and anterior periaqueductal gray in both sexes. In males only, the number of Fos-immunoreactive (ir) cells increased in the visual contact condition in these 2 dopaminergic cell groups, however no significant effect was observed for double-labeled TH-Fos-ir cells. In addition, consummatory but not appetitive sexual behavior increased Fos expression in TPH-ir cells in the raphe pallidus of males. This increase following physical but not visual contact agrees with the notion that activation of the serotoninergic system is implicated in the development of sexual satiation but not activated by simply viewing a female, in contrast to the dopaminergic system.

Effect of Orexin-A infusion in to the Nucleus Accumbens on consummatory behaviour and alcohol preference in male Wistar rats.

BACKGROUND: Effect of administration of Orexin-A into nucleus accumbens (NAcc) in relation to the regulation of feeding behavior and alcohol consumption at specific time intervals is relatively unknown. MATERIALS AND METHODS: In this study, Male Wistar albino rats (n = 54) weighing about 250 ± 10 grams were implanted bilaterally with guide cannula (22 gauze) to target NAcc by stereotaxic surgery. Saline (0.9%) for control and Orexin-A for experimental groups (100 pmol or 250 pmol) were infused by Harvard picoplus pump. Food, water and alcohol (10%) consumption were measured at 1, 2, 4 and 24 hours to evaluate the effect of Orexin-A in fasted rats (24 hours). Preference study was carried out by two bottle choice test. RESULTS: Orexin-A infusion into NAcc showed significant increase in food at 1 hr in all groups compared to controls (p < 0.05) and alcohol (p < 0.02) intake. The changes were dose dependent. There was no noticeable preference or alcohol. CONCLUSIONS FOR: These findings showed that Orexin-A in NAcc could be involved in feeding and drinking but not alcohol preference. The results highlight the effect of Orexin A infusion into NAcc in consummatory behaviour besides other hypothalamic and mesolimbic centres.

Overexpression of neuropeptide Y in the dorsomedial hypothalamus increases trial initiation but does not significantly alter concentration-dependent licking to sucrose in a brief-access taste test.

Evidence in the literature raises the possibility that alterations in neuropeptide Y (NPY) in the dorsomedial hypothalamus (DMH) may contribute to hyperphagia leading to body weight gain. Previously, we have shown that compared to AAVGFP controls, adeno-associated virus (AAV)-mediated overexpression of NPY in the DMH of lean rats resulted in significantly higher body weight gain that was attributed to increased food intake, and this was further exacerbated by a high-fat diet. Here, we tested AAVNPY and AAVGFP control rats in a brief-access taste procedure (10-s trials, 30-min sessions) to an array of sucrose concentrations under ad libitum and partial food and water access conditions. The test allows for some segregation of the behavioral components by providing a measure of trial initiation (appetitive) and unconditioned licks at each concentration (consummatory). Consistent with previous findings suggesting that NPY has a primary effect on appetitive function, overexpression of DMH NPY did not significantly alter concentration-dependent licking response to sucrose but when tested in a non-restricted food and water schedule, AAVNPY rats initiated significantly more sucrose trials compared to AAVGFP controls in a brief-access taste test.

Neurobiology of consummatory behavior: mechanisms underlying overeating and drug use.

Consummatory behavior is driven by both caloric and emotional need, and a wide variety of animal models have been useful in research on the systems that drive consumption of food and drugs. Models have included selective breeding for a specific trait, manipulation of gene expression, forced or voluntary exposure to a substance, and identification of biomarkers that predict which animals are prone to overconsuming specific substances. This research has elucidated numerous brain areas and neurochemicals that drive consummatory behavior. Although energy homeostasis is primarily mediated by the hypothalamus, reinforcement is more strongly mediated by nuclei outside the hypothalamus, in mesocorticolimbic regions. Orexigenic neurochemicals that control food intake can provide a general signal for promoting caloric intake or a more specific signal for stimulating consumption of a particular macronutrient, fat, carbohydrate, or protein. The neurochemicals involved in controlling fat ingestion--galanin, enkephalin, orexin, melanin-concentrating hormone, and the endocannabinoids--show positive feedback with this macronutrient, as these peptides both increase fat intake and are further stimulated by its intake. This positive association offers some explanation for why foods high in fat are so often overconsumed. Consumption of ethanol, a drug of abuse that also contains calories, is similarly driven by the neurochemical systems involved in fat intake, according to evidence that closely relates fat and ethanol consumption. Further understanding of the systems involved in consummatory behavior will enable the development of effective therapies for the treatment of both overeating and drug abuse.

Food restriction dissociates sexual motivation, sexual performance, and the rewarding consequences of copulation in female Syrian hamsters.

Animals can switch their behavioral priorities from ingestive to sex behaviors to optimize reproductive success in environments where energy fluctuates. We hypothesized that energy availability differentially affects the appetitive (motivation), consummatory (performance), and learned (rewarding) components of behavior. In Experiment 1, appetitive and consummatory aspects of sex behavior were dissociated in the majority of female Syrian hamsters restricted to 75% of their ad libitum food intake for between 8 and 11 days. Food restriction significantly inhibited vaginal scent marking, decreased the preference for spending time with male hamsters vs. spending time with food, and increased food hoarding with no significant effect on consummatory behaviors such as the incidence of lordosis or food intake. In Experiments 2 and 3, we attempted to use a similar level of food restriction to dissociate sexual appetite from sexual reward. In hamsters, formation of a conditioned place preference (CPP) for copulatory reward is reflected in increased nucleus accumbens (NAc) neural activation, measured as immunocytochemical staining for c-Fos, the protein product of the immediate-early gene, c-fos. In Experiment 2, neural activation increased 1h after copulation in the NAc, and did not differ significantly between 10-day food-restricted and ad libitum-fed females in any brain area examined. In Experiment 3, females were either food-restricted or fed ad libitum over 8-30 days of conditioning with copulatory stimuli. Food-restricted females showed significantly fewer appetitive behaviors, but no difference in formation of a CPP compared to females fed ad libitum. Together these data are consistent with the idea that mild levels of food restriction that inhibit appetitive behaviors fail to attenuate consummatory behaviors and the rewarding consequences of copulation. Thus, appetitive sex behaviors are, at least partially, neuroanatomically and behaviorally distinct from both consummatory behaviors and copulatory reward.

Resistance to Chalkbrood Disease in Apis mellifera L. (Hymenoptera: Apidae) Colonies with Different Hygienic Behaviour

Chalkbrood disease affects the larvae of honeybees Apis mellifera L. and is caused by the fungus Ascosphaera apis. Infected larvae die when they are stretched in the cap cell and suffer a gradual hardening that ends in a very hard structure (mummie). Several studies have demonstrated that colonies that express an efficient hygienic behaviour (uncapping of cell and subsequent removal of dead brood) exhibit a higher resistance to the disease. However, it remains unclear whether the advantage of hygienic colonies over less hygienic ones lies in the ability to remove mummies or in the early detection of infected larvae and its cannibalization before they harden. To elucidate this aspect, the hygienic behaviour of 24 colonies, which were subsequently provided with pollen cakes containig A. apis, was evaluated. The number of mummies and the number of partially cannibalized and whole larvae in uncapped cells were recorded. The most hygienic colonies controlled the disease better. These colonies also had a higher tendency to uncap cells that contained infected larvae and cannibalize them. The presence of A. apis in partially cannibalized and whole larvae in uncapped cells indicate that the advantage of hygienic colonies over less hygienic ones lies in the early detection of infected larvae death and their quick removal from the cell before they become mummies.

Appetitive and consummatory sexual and agonistic behaviour elicits FOS expression in aromatase and vasotocin neurones within the preoptic area and bed nucleus of the stria terminalis of male domestic chickens.

Some components of male sexual and agonistic behaviours are considered to be regulated by the same neurocircuitry in the medial preoptic nucleus (POM) and the medial portion of bed nucleus of the stria terminalis (BSTM). To better understand this neurocircuitry, numbers of aromatase- (ARO) or arginine vasotocin- (AVT) immunoreactive (ir) neurones expressing immediate early gene protein FOS were compared in the POM and BSTM of male chickens following sexual or agonistic behaviours. Observations were made on males showing: (i) appetitive (courtship) and consummatory (copulation) sexual behaviours; (ii) only appetitive sexual behaviour, or (iii) displaying agonistic behaviour toward other males. Control males were placed on their own in the observation pen, or only handled. In the POM, appetitive sexual behaviour increased ARO+FOS colocalisation, whereas agonistic behaviour decreased the number of visible ARO-ir cells. In the dorsolateral subdivision of BSTM (BSTM1), appetitive sexual behaviour also increased ARO+FOS colocalisation, although the numbers of visible ARO-ir and AVT-ir cells were not altered by sexual or agonistic behaviours. In the ventromedial BSTM (BSTM2), appetitive sexual behaviour increased ARO+FOS and AVT+FOS colocalisation, and all behaviours decreased the number of visible ARO-ir cells, particularly in males expressing consummatory sexual behaviour. Positive correlations were found between numbers of cells with ARO+FOS and AVT+FOS colocalisation in both subdivisions of the BSTM. Waltzing frequency was positively correlated with ARO+FOS colocalisation in the lateral POM, and in both subdivisions of the BSTM in males expressing sexual behaviour. Waltzing frequency in males expressing agonistic behaviour was negatively correlated with the total number of visible ARO-ir cells in the lateral POM and BSTM2. These observations suggest a key role for ARO and AVT neurones in BSTM2 in the expression of appetitive sexual behaviour, and differential roles for ARO cells in the POM and BSTM in the regulation of components of sexual and agonistic behaviours.

Efeito da qualidade da água no ciclo de vida e na atração para oviposição de Aedes aegypti (L.) (Diptera: Culicidae) / The effect of water quality in the life cycle and in the attraction for the egg oviposition of Aedes aegypti (L.) (Diptera: Culicidae)

The present research aimed at evaluating the influence of the water quality in the life cycle and attraction of Aedes aegypti (L.) females to oviposit using different sources of water (raw sewage, effluent of UASB reactor, effluent of polishing lagoon, effluent of anaerobic filter, rain water and de-chlorinated water). The immature development time and survivorship were evaluated on a daily basis in two distinct feeding systems (with and without food). The quality of the water was shown to affect the egg and larval stages, but not the pupal or the adult. In the absence of food, no development was observed in rain water and de-chlorinated water. Immature development was faster in water sources from raw sewage, although with the lowest survivorship (37.3 percent). Free-choice tests indicated that females preferred to lay most of their eggs on water collected from the effluent of a UASB reactor, achieving the highest oviposition activity index (OAI) of 0.57. In non-choice tests, females laid larger batches of eggs in water collected from anaerobic filters (204.8 eggs), with the lowest number of eggs being laid on de-chlorinated water (37.3 eggs). It can be concluded that A. aegypti does not demonstrate any particular preference to lay eggs on clean water. This has serious implications for developing strategies to manage populations of this important vector in urban areas as it was shown to lay eggs and successfully develop on several different sources of water.

Differential regulation of female sexual behaviour by dopamine agonists in the medial preoptic area.

The medial preoptic area (mPOA) is a brain region critical in the control of male sexual behaviour, and the neurotransmitter dopamine (DA) plays an important role within it. However, both the roles of DA and the mPOA in female sexual behaviour are not fully understood, with few studies producing consistent data. The present study examined the function of DA within the mPOA on the full cascade of female sexual behaviour. Ovariectomized female rats were bilaterally cannulated into the mPOA and partially hormonally primed with estradiol benzoate (EB). Different doses of a nonselective DA receptor agonist, and selective DA D1 and D2 receptor agonists (apomorphine, SKF 38393 and quinpirole, respectively) were infused bilaterally to the mPOA. Copulatory behaviour was then immediately tested over a period of 30 min in a bilevel chamber with a sexually experienced male. Precopulatory behaviours were increased in females following infusions of a low dose (0.25µg) of apomorphine and both a low (0.05µg) and a high dose (0.2µg) of quinpirole. However, hops and/or darts were decreased following infusion of a low dose (0.05µg) of SKF 38393. These results suggest that the ratio of DA D1/D2 activity within the mPOA of female rats is critical for the expression of precopulatory behaviours, and may work with other brain areas responsible for stimulating lordosis to control the timing of female sexual behaviour.

Circadian foraging rhythms of bumblebees monitored by radio-frequency identification.

Circadian clocks enable organisms to anticipate changes of environmental conditions. In social insects, the colony as a superorganism has a foraging rhythm aligned to the diurnal patterns of resource availability. Within this colony rhythm, the diurnal patterns of individuals are embedded, and various tasks within the colony are performed at different times by different individuals to best serve the colony as a whole. Recent studies have shown that social cues influence the traits of the circadian clock in social insects, but keeping track of the activity of individual workers is not an easy task. Here the authors use fully automatic radio-frequency identification (RFID) to analyze the circadian rhythms of bumblebee foragers (Bombus terrestris) in the normal social context of their nest. They monitored their foraging patterns under different light conditions in the laboratory, including light:dark cycles (LD) as well as constant darkness (DD) and constant light conditions (LL). Their results show that the majority of bumblebee foragers exhibit robust circadian rhythms in LD under laboratory conditions, while they show free-running rhythms both in DD and LL, with free-running periods being significantly shorter in LL conditions. The authors also found that bumblebee workers show an increased level of arrhythmic activity ("death dance") in the hours or days before their death.