Crop-emptying Rate Research Articles

Crop-emptying rate and nectar resource allocation in a nectivorous pollinator

In nectivorous pollinators, timing and pattern of allocation of consumed nectar affects fitness traits and foraging behavior. Differences in male and female behaviors can influence these allocation strategies. These physiological patterns are not well studied in Lepidoptera, despite them being important pollinators. In this study we investigate crop-emptying rate and nectar allocation in Manduca sexta (Sphingidae), and how sex and flight influence these physiological patterns. After a single feeding event, moths were dissected at fixed time intervals to measure crop volume and analyze sugar allocation to flight muscle and fat body. Then we compared sedentary and flown moths to test how activity may alter these patterns. Sedentary males and females emptied their crops six hours after a feeding event. Both males and females preferentially allocated these consumed sugars to fat body over flight muscle. Moths began to allocate to the fat body during crop-emptying and retained these nutrients long-term (four and a half days after a feeding event). Males allocated consumed sugar to flight muscles sooner and retained these allocated nutrients in the flight muscle longer than did females. Flight initiated increased crop-emptying in females, but had no effect on males. Flight did not significantly affect allocation to flight muscle or fat body in either sex. This study showed that there are inherent differences in male and female nectar sugar allocation strategies, but that male and female differences in crop-emptying rate are context dependent on flight activity. These differences in physiology may be linked to distinct ways males and females maximize their own fitness.

Effect of lithium chloride on food intake, cloacal temperature, voluntary activity, and crop-emptying rate in chicks

Infections frequently accompany with non-specific symptoms such as anorexia and hyperthermia. In addition, there may be unpleasant sensations such as visceral discomfort during infection. Lipopolysaccharide (LPS), a Gram-negative bacteria cell wall component, is known to induce the unpleasant sensation of conditioned taste aversion in mammals. However, the relationship between unpleasant sensations and changes in behavior and physiological conditions has not been investigated extensively in birds. Lithium chloride (LiCl) is a compound that induces unpleasant sensations, including visceral discomfort, although its effects on behavior and physiological conditions have also not been investigated extensively in birds. Thus, the present study was aimed to investigate the effect of an intraperitoneal (IP) injection of LiCl on conditioned visual aversion, food intake, cloacal temperature, voluntary activity, crop-emptying rate, and blood constituents in chicks (Gallus gallus). We also examined the effect of IP injections of LPS and zymosan, a cell wall component of fungus, on conditioned visual aversion formation. First, IP injection of LiCl was confirmed to induce conditioned visual aversion in chicks. An IP injection of LiCl significantly decreased food intake, voluntary activity, and crop-emptying rate but did not affect the temperature. In addition, the injection of LiCl significantly increased plasma corticosterone concentration, indicating that LiCl serves as a stressor in chicks. Finally, IP injections of LPS and zymosan were found to induce conditioned visual aversion in chicks. Collectively, these results suggest that LiCl induces conditioned aversion, anorexia, hypoactivity, and inhibition of crop-emptying in chicks. In addition, LPS and zymosan would induce unpleasant sensations in chicks.

Effect of zymosan on feed passage in the digestive tract in chicks

ABSTRACT 1. The purpose of the present study was to examine whether zymosan, which is a component of fungi, affects feed passage through the digestive tract in chicks (Gallus gallus). 2. Intraperitoneal (IP) injection of 2.5 mg zymosan significantly reduced the crop-emptying rate and this effect was similar to that of 100 µg lipopolysaccharide (LPS). Zymosan affected phenol red transit from the proventriculus. 3. Zymosan significantly affected the gene expression of interleukin-1β (IL-1β), IL-6, IL-8 and histidine decarboxylase in various regions of the digestive tract. 4. The present study suggested that zymosan retarded feed passage through the digestive tract in chick and interleukins and histamine may be participating in this process.

Effects of toll-like receptor-7 agonists on feeding behaviour, voluntary activity, cloacal temperature and crop emptying in chicks

ABSTRACT 1. The purpose of the present study was to determine if an intraperitoneal injection of two toll-like receptor-7 (TLR7) agonists, imiquimod and resiquimod, affect feed intake, voluntary activity, cloacal temperature, crop-emptying rate, plasma corticosterone (CORT) and glucose concentrations, and splenic gene expression of cytokines in chicks (Gallus gallus). 2. Although intraperitoneal injection of 100 µg imiquimod significantly increased splenic gene expression of interleukin-1β (IL-1β), IL-6, IL-8, and interferon-γ (IFN-γ), it did not affect feed intake, voluntary activity, cloacal temperature, crop-emptying rate or plasma constituents. 3. Intraperitoneal injection of 100 µg resiquimod significantly decreased feed intake, voluntary activity, cloacal temperature, crop-emptying rate and increased plasma corticosterone concentrations. 4. Intraperitoneal injection of resiquimod significantly increased splenic gene expression of IL-1β, IL-6, IL-8, IFN-γ, and tumour necrosis factor-like cytokine 1A. 5. The results showed that activation of TLR7 is associated with anorexia, hypoactivity, hypothermia, disturbance of feed passage in the digestive tract and the response to stress in chicks.

Compound 48/80 reduces the crop-emptying rate, likely through a histamine-associated pathway in chicks

Infectious conditions are associated with reduced food passage through the digestive tract in both mammals and chicks; however, the precise mechanism mediating this response in chicks remains unclear. The purpose of the present study was to determine if mast cells, a blood cell type which plays an important role in the immune system, might affect food passage through the digestive tract in chicks. Specifically, we performed intraperitoneal (IP) injections of compound 48/80, an inducer of mast cell degranulation, and measured crop emptying. The IP injection of compound 48/80 significantly reduced the crop-emptying rate, but it did not affect the proventriculus to small intestine transit rate or the number of defecations. We also found that IP-injected histamine, which is secreted by mast cells, also reduced the crop-emptying rate. In addition, IP injection of 2-pyridylethylamine (histamine H1 receptor agonist), but not dimaprit, (R)-(−)-α-methylhistamine, and VUF8430 (histamine H2, H3, and H4 receptor agonists, respectively), reduced the crop-emptying rate, implying that histamine reduces the crop emptying rate via the histamine H1 receptor. Finally, we found that IP injection of compound 48/80 reduced mRNA expression of histidine decarboxylase, a rate-limiting enzyme for histamine synthesis, in the esophagus and proventriculus at 1 h and the proventriculus and duodenum at 3 h after the injection. In sum, the present study suggests that the degranulation of mast cells causes a reduction in the crop-emptying rate, possibly via the histamine pathway in chicks.

Physiological response to central and peripheral injection of prostaglandin D2 in chicks

Prostaglandin D2 (PGD2) is associated with a diverse array of functions in mammals including regulation of appetite, body temperature, sleep, and immune responses. Although much is known about the effects of PGD2 in mammals, there is a lack of information about its effects in birds. Therefore, the purpose of the present study was to determine if intracerebroventricular (ICV) and intraperitoneal (IP) injections of PGD2 affect feeding, voluntary movement, crop-emptying rate, corticosterone release, and cloacal temperature in chicks (Gallus gallus). ICV injection of PGD2 was associated with a reduction in food intake, a reduction in voluntary movement, an increase in the time spent sitting, a decline in crop emptying rate, and also short-term hypothermia. Central injection of PGD2 also decreased the plasma glucose concentration in chicks while it tended to increase the plasma corticosterone concentration. On the other hand, except for crop emptying, such physiological changes are not observed after IP injection of PGD2. In sum, the present study suggests that PGD2 induces anorexia, change in behavior, decline in crop empting rate, hypoglycemia and hypothermia, but most of these effects are exerted via central nervous system in chicks.

Effect of central and peripheral injection of prostaglandin E2 and F2α on feeding and the crop-emptying rate in chicks

Prostaglandins (PGs) have been shown to cause several physiological changes in mammals including anorexia, awakening and sleeping, change in digestive function, and activation of the hypothalamus-pituitary-adrenal gland (HPA) axis. However, there is a paucity of information about the effect of PGs on physiological parameters in birds. The purpose of the present study was to clarify whether intracerebroventricular (ICV) and intraperitoneal (IP) injections of prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) affect feeding, voluntary movement, crop-emptying rate, and corticosterone release in chicks (Gallus gallus). ICV injection of either PGE2 or PGF2α (2 and 4μg) significantly decreased food intake in chicks. The anorexigenic effect was also observed after IP injection of the PGs. Voluntary movement was significantly suppressed by ICV injection of PGE2 or PGF2α, although the time-course change was different between the two. In contrast, IP injection of the PGs had no or less effect on voluntary movement. Both ICV and IP injection of PGE2 significantly retarded the crop-emptying rate, whereas PGF2α significantly lowered the crop-emptying rate only after IP injection. The plasma corticosterone concentration significantly increased after ICV and IP injection of PGE2, whereas PGF2α had no effect. These results suggest that central and peripheral PGs are involved in the regulation of appetite, voluntary movement, food passage in the digestive tract, and activation of the HPA axis in chicks, although the effects depend on the site of action and type of PGs.

Lipopolysaccharide reduces food passage rate from the crop by a prostaglandin-independent mechanism in chickens

ABSTRACT1. We examined the effect of lipopolysaccharide (LPS), a component of Gram-negative bacteria, on food passage in the digestive tract of chickens (Gallus gallus) in order to clarify whether bacterial infection affects food passage in birds.2. Food passage in the crop was significantly reduced by intraperitoneal (IP) injection of LPS while it did not affect the number of defecations, suggesting that LPS may affect food passage only in the upper digestive tract.3. Similar to LPS, prostaglandin E2 (PGE2), one of the mediators of LPS, also reduced crop-emptying rate in chickens while it had no effect on the number of defecations.4. Pretreatment with indomethacin, which is an inhibitor of cyclooxygenase (COX), a prostaglandin synthase, had no effect on LPS-induced inhibition of crop emptying.5. IP injection of LPS did not affect the mRNA expression of COX2 in the upper digestive tract of chickens.6. It is therefore likely that LPS and PGE2 reduced food passage rate in the crop by a prostaglandin-independent pathway in chickens.

Crop-Emptying Rate and the Design of Pesticide Risk Assessment Schemes in the Honey Bee and Wild Bees (Hymenoptera: Apidae)

Recent scientific literature and reports from official sanitary agencies have pointed out the deficiency of current pesticide risk assessment processes regarding sublethal effects on pollinators. Sublethal effects include troubles in learning performance, orientation skills, or mobility, with possible contribution to substantial dysfunction at population scale. However, the study of sublethal effects is currently limited by considerable knowledge gaps, particularly for the numerous pollinators other than the honey bee Apis mellifera L.--the traditional model for pesticide risk assessment in pollinators. Here, we propose to use the crop-emptying time as a rule of thumb to guide the design of oral exposure experiments in the honey bee and wild bees. The administration of contaminated sucrose solutions is typically followed by a fasting time lapse to allow complete assimilation before the behavioral tests. The fasting duration should at least encompass the crop-emptying time, because no absorption takes place in the crop. We assessed crop-emptying rate in fasted bees and how it relates 1) with sucrose solution concentration in the honey bee and 2) with body mass in wild bees. Fasting duration required for complete crop emptying in honey bees fed 20 microl of a 50% sucrose solution was nearly 2 h. Actual fasting durations are usually shorter in toxicological studies, suggesting incomplete crop emptying, and therefore partial assimilation of experimental solutions that could imply underestimation of sublethal effects. We also found faster crop-emptying rates in large wild bees compared with smaller wild bees, and suggest operative rules to adapt sublethal assessment schemes accordingly.

Comparison of brain urocortin-3 and corticotrophin-releasing factor for physiological responses in chicks

Corticotrophin-releasing hormone (CRH) plays an important role in response to stress, and exerts a physiological effect via its receptor, CRH receptor type-1 (CRH-R1) and CRH receptor type-2 (CRH-R2) with high affinity to CRH-R1 in mammals. Urocortin-3 (UCN-3), a CRH family peptide, is an endogenous ligand for CRH-R2 in mammals. The physiological roles of UCN-3 and CRH-R2 have been investigated in mammals, although their roles still need to be clarified in chicks (Gallus gallus). Few studies have been performed comparing the physiological responses of CRH and UCN-3 in chicks. Therefore the present study was conducted to investigate the effect of intracerebroventricular (ICV) injection of UCN-3 on food intake, rectal temperature, crop-emptying rate and behaviors in chicks, and to compare these physiological responses with the effects resulting from CRH injection. The ICV injection of 20 and 80pmol UCN-3 decreased food intake, increased rectal temperature and decreased crop-emptying rate and the results were similar to those achieved with CRH. The injection of both UCN-3 and CRH increased spontaneous activity but the behavioral patterns were different: CRH increased the number of vocalizations while UCN-3 increased the number of jumps, wing-flaps and scratching behaviors. These results suggest that UCN-3 regulates food intake, body temperature, and gastric emptying via the CRH-R2 in the brain of chicks, and these effects were similar to those induced by CRH.

Differential thresholds of neuromedins B-, C-, and bombesin-induced anorexia and crop-emptying rate in chicks

Neuromedin B (NMB) and neuromedin C (NMC) are homologs of bombesin and are distributed throughout both the brain and gastrointestinal tract. The physiological roles of these bombesin-like peptides in chicks ( Gallus gallus) have not been documented. Therefore, the purpose of the present study was to measure the effects of these bombesin-like peptides on food intake, crop-emptying rate and body temperature in chicks, and then to compare these effects with those of bombesin. Intracerebroventricular (ICV, 5 nmol) and intraperitoneal (IP, 300 nmol/kg) injections of NMB, NMC, and bombesin significantly decreased food deprivation-induced food intake. When ICV injected (5 nmol), all three peptides significantly reduced crop-emptying rate. IP injection of NMC and bombesin (300 nmol/kg) also reduced crop-emptying rate while NMB did not. The magnitude of food intake suppression and crop-emptying rate reduction were greater for bombesin than NMB and NMC. ICV and IP injections of NMB, NMC and bombesin did not affect cloacal temperature. In sum, the present study suggests that central and peripheral NMB and NMC are associated with reduced food intake and crop-emptying of chicks, but these effects are weaker than those of bombesin.

The role of the corpus allatum in the control of vitellogenesis and fat body hypertrophy in Phormia regina (Meigen)

Allatectomy (CA −) experiments revealed that the corpus allatum (CA), and thus juvenile hormone (JH), play several important roles in the control of vitellogenesis in liver-fed Phormia regina. CA −, within 4 h of adult emergence, decreased the rate of vitellogenin (Vg) production, lowered the hemolymph Vg level and resulted in arrested ovarian development. CA − at different times showed that there is a critical period (i.e. about 12 h after a protein meal), prior to which the CA is required for complete vitellogenesis. When two doses of 10.0, 5.0 or 2.5 μg of methoprene (JH analogue) were applied, vitellogenesis was nearly completely, partially or not restored in CA −, liver-fed flies, respectively. In the absence of the CA, a liver meal resulted in fat body hypertrophy and greatly reduced hemolymph Vg levels. Methoprene treatment restored Vg biosynthesis and prevented fat body hypertrophy only if the treatment was administered within 48 h after liver feeding. CA − greatly reduced the rate of crop emptying (thus, protein utilization), but had no effect on protein ingestion. The CA is also needed to attain normal ecdysteroid levels in the hemolymph. The present results support the notion that the CA (JH) can affect vitellogenesis at various levels in liver-fed P. regina. It appears that, within 12 h after a protein meal, JH primes the previtellogenic fat body to prepare for Vg biosynthesis, and primes the ovaries to produce ecdysteroids. JH also regulates normal dietary protein utilization.

Medium-Chain Triacylglycerols Enhance Release of Cholecystokinin in Chicks

Whether medium-chain triacylglycerols (MCT) affect the plasma concentration of cholecystokinin (CCK) and crop-emptying rate in chicks was investigated after 0, 30, 60, 90, 120 or 180 min of diet intubation. Triacylglycerol sources used were corn oil [containing long-chain triacylglycerols (LCT)], glyceryl tricaprate and glyceryl tricaprylate at a level of 200 g/kg diet. Plasma CCK concentration was significantly enhanced in chicks given the two MCT treatments, but not in those given the LCT treatment, after 30 min feeding relative to the initial level. At all time points, chicks fed the diet containing LCT had significantly lower plasma CCK concentrations than those fed MCT, and chicks fed glyceryl tricaprate had higher concentrations than those fed glyceryl tricaprylate. Dietary MCT sources significantly delayed diet passage from the crop compared with dietary LCT. These results indicate that MCT are more potent stimulators of CCK secretion in chicks than LCT.

The role of the frontal ganglion and corpora cardiaca/corpora allata complex in post‐feeding weight loss in adult Heliothis zea

Abstract A post‐feeding diuretic response has been observed in adult Heliothis zea (Boddie) (Lepidoptera: Noctuidae). 2‐day‐old starved adults which were allowed to feed to repletion on a 10% (w/v) sucrose solution lost 49.1% (females) and 85.8% (males) of the weight of the ingested meal during the first hour following feeding. Ligation between head and thorax or frontal ganglionectomy, when performed immediately following feeding, each resulted in a significant and permanent reduction in this normal weight‐loss. Injection of homogenates of the corpora cardiaca/corpora allata (CC/CA) complex into non‐ligated insects immediately after feeding also reduced significantly the post‐feeding weight‐loss, but this inhibition was transient and disappeared after 1 h. Dissection and weighing of the crop from either ligated, frontal ganglionectomized, or CC/CA‐injected insects confirmed the crop as the predominant site of fluid retention in each case. We suggest that a soluble antidiuretic factor from the CC/CA acts in conjunction with the frontal ganglion to control the rate of crop emptying and subsequent diuresis by regulating the volume of ingested fluid that is passed into the haemolymph from the crop/midgut.

Response of laying hens to asymmetrical interrupted lighting regimens: Physiological aspects

1. There were no significant differences in the mean time of oviposition, distribution of ovipositions over the 24 h or proportion of eggs laid in the modal 8 h when conventionally-lit hens were compared with hens which received interrupted lighting with the same apparent daylength. 2. Intermittently-lit hens performed 25% less feeding activity than conventionally-lit hens, but without a significant reduction in mean food intake. There were genetic differences in response of feeding rate to interrupted lighting. 3. Intermittently-illuminated hens consumed about 20% of their food during the scotoperiods which interrupted the apparent day of a 1.5L:0.5D:10(0.5L:0.5D):4L:8D regimen, although there was significant genetic variation from 10 to 22%. None of the genotypes ate during the 8-h night. 4. Across 4 genotypes neither crop weight nor rate of crop emptying was affected by the lighting treatments, although a heavier mean crop weight under interrupted lighting approached significance in one breed (P less than 0.10). 5. Interrupted lighting did not cause any ocular disorders.

Regulation of food passage in the intestine of the honeybee ( Apis mellifera L.)

Crop-emptying rate and passage of sugar solution through the midgut to the rectum were investigated in foragers in summer and in winter bees. Passage from the crop to midgut depends on the molarity and volume of the food, activity of the bees and on season. Increase in haemolymph osmolarity is discussed as a factor regulating crop-emptying rate. Glucose penetrates the midgut wall and raises the haemolymph sugar level rapidly. Only small amounts of ingested liquid reach the rectum after passing through the midgut.

The relationship between crop size and egg production in Rhodnius prolixus

Earlier work showed that the number of eggs produced by a virgin female is smaller than that produced by a mated female. The current paper shows that this results not from a difference in rates of egg production, but from the operation of the same linear rate for different times. Denervating the corpus allatum in virgin females extends the time over which the same rate of egg production operates, thus indicating that the inhibition of egg production in virgin females results from a nervous inhibition of the corpus allatum. The initial rate of emptying of the crop is also approximately linear in both virgin and mated females. Later, crop emptying slows in virgins and remains linear in mated females. When these relationships are disturbed by plugging the anus of females before feeding, the rate of crop emptying in virgins more closely resembles that in mated females, and the difference in egg production between mated and virgin females disappears. These results are put into the context of a hypothesis which predicts that the degree of distension of the crop is an important determinant of the length of time that the corpus allatum remains active.

Crop filling and crop emptying by the stable fly Stomoxys calcitrans L.

In Stomoxys the immediate destination of sugar or blood is the midgut, and not the crop. The filling of the crop with blood appears to involve several factors, including age, ambient temperature, temperature of the blood meal, disturbance of the fly, and interrupted feedings. In all experiments the sex of the fly had no effect on crop filling. The age of the fly did not influence crop filling when flies fed by piercing the skin. The crop empties of blood in 10–15 min. Rate of crop emptying of sugar solutions depended upon the molarity of solutions consumed.

A MODEL OF CARBOHYDRATE NUTRITION IN THE BLOWFLYPHORMIA REGINA(DIPTERA: CALLIPHORIDAE)

AbstractAn experimental component analysis approach is used to define the physiological interactions of carbohydrate nutrition and the manner in which it regulates the crop-emptying rate. The basic components of the crop-emptying rate are frequency of valve opening and the volume of the slug of fluid which passes through the valve. This volume is solely a function of crop volume, but the frequency of opening is a complex function determined by the crop volume, and by gut activity and blood osmotic pressure, both of which are related to nutritional parameters. To guide the formulation of the relationship, a model of the mechanism of valve function is proposed, based in the phenomenon of muscle creep.The osmotic pressure is estimated by calculating the change in blood trehalose level estimated from observed rates of disappearance of sugar from the crop. Sugar emptying from the crop diffuses from the midgut to the blood, where it is partitioned between trehalose and glycogen according to established biochemical relationships. The model developed fits a wide variety of published data on crop-emptying rates of flies fed different volumes and concentrations of sugar, and may be applied to active, inactive, and flying insects.

SYNCHRONIZATION OF FUNCTION IN THE FOREGUT OF THE BLOWFLYPHORMIA REGINA(DIPTERA: CALLIPHORIDAE) DURING THE CROP-EMPTYING PROCESS

AbstractThe sequential mode of operation of the various valves and pumps in the foregut of the blowflyPhormia reginaMeigen is described for the crop-emptying process. The results of the study are discussed in relation to the results of Gelperin, who showed that the rate of crop emptying was determined by the crop volume and the blood solute concentration. A mechanism by which synchronization of function may be achieved, based on the results of Nagai, and Thomson and Holling, is proposed, i.e. synchronization depends on the activity of stretch-sensitive muscle fibres.