Effect of topical application of a juvenile hormone mimic on the duration of the moulting cycle in fifth instar Rhodnius

Fifth instar Rhodnius prolixus given a single topical application of synthetic juvenile hormone (JH) on one of the first 12 days after feeding showed a sigmoid relationship between day of treatment and duration of the moulting cycle. A similar relationship was observed between day of treatment and mean ‘juvenile score’ in subsequently emerging insects. The linear relationship between mean ‘juvenile score’ and duration of the moulting cycle suggests that the increased time from feeding to ecdysis for late-treated insects is a result of the morphogenetic effects of the JH treatment. Some of the partially juvenilized insects obtained by treatment after day 5 produced an odour characteristically detected only from adult insects. The possible significance of this observation is discussed.     

Ecdysis period of Rhodnius prolixus head investigated using phase contrast synchrotron microtomography

Microtomography using synchrotron sources is a useful tool in biological imaging research since the phase coherence of synchrotron beams can be exploited to obtain images with high contrast resolution. This work is part of a series of works using phase contrast synchrotron microtomography in the study of Rhodnius prolixus head, the insect vector of Chagas’ disease, responsible for about 12,000 deaths per year. The control of insect vector is the most efficient method to prevent this disease and studies have shown that the use of triflumuron, a chitin synthesis inhibitor, disrupted chitin synthesis during larval development and it’s an alternative method against insect pests.The aim of this work was to investigate the biological effects of treatments with triflumuron in the ecdysis period (the moulting of the R. prolixus cuticle) using the new imaging beamline IMX at LNLS (Brazilian Synchrotron Light Laboratory). Nymphs of R. prolixus were taken from the Laboratory of Biochemistry and Physiology of Insects, Oswaldo Cruz Foundation, Brazil. Doses of 0.05 mg of triflumuron were applied directly to the abdomen on half of the insects immediately after feeding. The insects were sacrificed 25 days after feeding (intermoulting period) and fixed with glutaraldehyde.The results obtained using phase contrast synchrotron microtomography in R. prolixus showed amazing images of the effects of triflumuron on insects in the ecdysis period, and the formation of the new cuticle on those which were not treated with triflumuron. Both formation and malformation of this insect’s cuticle have never been seen before with this technique.     

Temporal modulation and adaptive control of the behavioural response to odours in Rhodnius prolixus

It has been demonstrated in several insect species that a circadian clock makes the whole of antennal chemoreceptors more sensitive during a particular temporal window every day. This assessment raises the question about how insects exhibiting bimodal activity handle their sensitivity to odours which are relevant at different moments of the day. To shed some light on this problem, we studied in Rhodnius prolixus the daily dynamics of their responsiveness to CO₂ (host-associated cue) and aggregation cues (refuge-associated), which are relevant at dusk and dawn, respectively. We analysed: (1) whether a temporal modulation of the responsiveness to odours does exist in R. prolixus, (2) if this modulation is a general one or it is specific for each type of volatile, and (3) if it is controlled by exogenous or endogenous mechanisms. We found that the responsiveness to CO₂ only occurs at dusk and that to assembling odours is restricted to dawn. Experiments under free-running conditions revealed that only the responsiveness to CO₂ is controlled by a circadian clock, but not that to assembling signals. Thus, by combining endogenous and exogenous mechanisms, sensitivities to different odours are adjusted according to their associated behavioural context and moment of the day.     

Malaria Mosquitoes Host-Locate and Feed upon Caterpillars

Adult female mosquitoes need blood to develop their eggs and both sexes use nectar and honeydew as carbohydrate resources for flight, survival and to enhance reproduction. However, there are also a few reports in the literature of mosquitoes feeding on haemolymph of soft-bodied insects such as caterpillars. The frequency and significance of this entomophagous behavior is not well understood, but is thought to be a vestige of ancestral feeding behavior or an opportunistic behavior that has evolved over time. In our current paper we investigated the extent to which the malaria mosquito, Anopheles stephensi, is attracted to, and can successfully feed on, larvae of two common moth species, Manduca sexta and Heliothis subflexa. Using y-tube olfactometer assays we found that female An. stephensi readily flew upwind to and landed on the caterpillars of both moth species. The nature of the volatile cues used in host location remains unclear but respirometer studies suggest a possible role of CO₂. Laboratory cage assays further showed that the female mosquitoes were able to actively feed on moth larvae and gain sufficient nutritional benefit to influence survival. The extent to which such an opportunistic behavior occurs in the field has yet to be explored but our results suggest that this haemolymph feeding behavior could play a role in malaria mosquito life history and could provide a novel mechanism for horizontal transmission of pathogens and other micro-organisms between hosts.     

Phenol oxidases from Rhodnius prolixus: Temporal and tissue expression pattern and regulation by ecdysone

Rhodnius prolixus 5th instar nymphs have significant PO enzymatic activity in the anterior midgut, fat body and hemolymph. The tissue with the major amount of PO activity is the anterior midgut while those with higher specific activities are the fat body and hemolymph. In this work the temporal pattern of PO enzymatic activity in different tissues was investigated. In fat body, PO peaks occur at 7, 12 and 16 days after a blood meal. In hemolymph, PO diminishes until day 7, and then recovers by day 14. In the anterior midgut tissue, PO peaks on day 9 and just before ecdysis; a similar pattern was observed in the anterior midgut contents. Some of these activities are dependent on the release of ecdysone, as feeding blood meal containing azadirachtin suppresses them and ecdysone treatment counteracts this effect. These results suggest that during the development of the 5th instar, the insect has natural regulating cycles of basal PO expression and activation, which could be related to the occurrence of natural infections. The differences in temporal patterns of activity and the effects of azadirachtin and ecdysone in each organ suggest that, at least in R. prolixus, different tissues are expressing different PO genes.     

Influence of the intestinal anticoagulant in the feeding performance of triatomine bugs (Hemiptera; Reduviidae)

Triatomines are haematophagous insects in all post-embryonic life stages. They are vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Their vectorial ability is influenced by their feeding performance, which varies greatly amongst species. Recent work showed that inhibition of the coagulation process in the anterior midgut (crop) environment considerably influences the blood meal size. In this work, we performed a comparative study of the level of anticoagulant activity in the saliva and crop contents of three triatomine species - Triatoma infestans, Triatoma brasiliensis and Rhodnius prolixus - and correlated this with their feeding performance on live hosts. Moreover, the feeding parameters on a large diameter vessel influenced by the crop anticoagulants were evaluated in detail. The anticoagulant activity was significantly higher in the crop contents than in salivary glands, varying from 1.6-fold higher for R. prolixus to 70-fold higher for T. brasiliensis. Amongst the species, T. brasiliensis had the lowest crop anticoagulant activity, the lowest concentration of thrombin inhibitor, and took the longest to feed. Triatoma brasiliensis nymphs that had their intestinal anticoagulant (brasiliensin) knocked down by RNA interference had the lowest capacity to maintain cibarial pump frequency at higher levels throughout the feeding process and consequently a lower ingestion rate (mg/min), even when fed under favourable conditions (large diameter vessel). However, the feeding difficulty for brasiliensin knockdown T. brasiliensis nymphs was reversed by treating the host mice with heparin (a potent systemic anticoagulant) before blood feeding. The results indicate that crop anticoagulant activity influences modulation of the blood-pumping frequency to the intestine and significantly affects the feeding efficiency of triatomine spp. on live hosts.     

Preface

The vector of Chagas' disease, Rhodnius prolixus, feeds exclusively on blood. The blood meals are slowly digested, and these insects wait some weeks before the next meal. During the life of an insect, energy‐requiring processes such as moulting, adult gonadal and reproductive growth, vitellogenesis, muscular activity, and fasting, lead to increased metabolism. Carbohydrates are a major source of energy and their mobilization is important. We determined the amounts of glycogen, trehalose, and glucose present in the fat body and/or hemolymph of adult males of R. prolixus and recorded the processes of accumulation and mobilization of these carbohydrates. We also tested our hypothesis that these processes are under endocrine control. The amount of glycogen in the fat body progressively increased until the fourth day after feeding (from 9.3±2.2 to 77. 3±7.5 µg/fat body), then declined to values around 36.3±4.9 µg/fat body on the fifteenth day after the blood meal. Glycogen synthesis was eliminated in decapitated insects and head‐transplanted insects synthesized glycogen. The amount of trehalose in the fat body increased until the sixth day after feeding (from 16. 6±1.7 to 40. 6±5.3 nmol/fat body), decreased abruptly, and stabilized between days 7 and 15 at values ranging around 15–19 nmol/fat body. Decapitated insects did not synthesize trehalose after feeding, and this effect was reversed in head‐transplanted insects. The concentration of trehalose in the hemolymph increased after the blood meal until the third day (from 0.07±0.01 to 0.75±0.05 mM) and at the fourth day it decreased until the ninth day (0.21±0.01 mM), when it increased again until the fourteenth day (0.79±0.06 mM) after the blood meal, and then declined again. In decapitated insects, trehalose concentrations did not increase soon after the blood meal and at the third day it was very low, but on the fourteenth day it was close to the control values. The concentration of glucose in the hemolymph of untreated insects remained low and constant (0.18±0.01 mM) during the 15 days after feeding, but in decapitated insects it progressively increased until the fifteenth day (2.00±0.10 mM). We recorded the highest trehalase activity in midgut, which was maximal at the eighth day after feeding (2,830±320 nmol of glucose/organ/h). We infer that in Rhodnius prolixus, the metabolism of glycogen, glucose, and trehalose are controlled by factors from the brain, according to physiological demands at different days after the blood meal. © 2009 Wiley Periodicals, Inc.     

Biostable insect kinin analogs reduce blood meal and disrupt ecdysis in the blood-gorging Chagas’ disease vector,Rhodnius prolixus

Rhodnius prolixus is a blood-gorging hemipteran that takes blood meals that are approximately 10 times its body weight. This blood meal is crucial for growth and development and is needed to ensure a successful molt into the next instar. Kinins are a multifunctional family of neuropeptides which have been shown to play a role in the control of feeding in a variety of insects. In this study, two biostable Aib-containing kinin analogs were tested to see if they interfere with blood-feeding and subsequent development into the next instar. One of the analogs, 1729 (Ac-R[Aib]FF[Aib]WGa), had no effect on the size of the blood meal or on the subsequent molting of the insect into the next instar. This analog also did not interfere with either short-term or long-term diuresis. The second analog, 1728 ([Aib]FF[Aib]WGa), appeared to be an antifeedant. Insects feeding on blood containing this analog (15 μM) only consumed 60% of the blood meal taken by insects fed on blood without analog. Insects feeding on blood containing 1728 had a slower rate of rapid diuresis (diuresis in the first 3–5 h after feeding) leading to less urine being excreted by 5 days post feeding. The consequence of these effects was that insects fed on 1728 did not molt. This data indicates that the biostable Aib-containing analog 1728 disrupts normal growth and development in the blood-feeding insect, R. prolixus.     

Sn-protoporphyrin inhibits both heme degradation and hemozoin formation in Rhodnius prolixus midgut

Hematophagy is a feeding habit that involves the ingestion of huge amounts of heme. The hematophagous hemipteran Rhodnius prolixus evolved many genetic resources to protect cells against heme toxicity. The primary barrier against the deleterious effects of heme is the aggregation of heme into hemozoin in the midgut lumen. Hemozoin formation is followed by the enzymatic degradation of heme by means of a unique pathway whose end product is dicysteinyl-biliverdin IX-γ (Rhodnius prolixus biliverdin, RpBv). These mechanisms are complemented by a heme-binding protein (RHBP) in the hemolymph that attenuates the pro-oxidant effects of heme. In this work, we show that when insects are fed with blood enriched with a heme analog, Sn-protoporphyrin (SnPP-IX), both hemozoin synthesis and RpBv production are inhibited in a dose-dependent manner. These effects are accompanied by increased oxidative damage to the midgut epithelium and inhibition of oviposition, indicating that hemozoin formation and heme degradation are protective mechanisms that work together and contributed to the adaptation of this insect to successfully feed on vertebrate blood.     

Feeding in Rhodnius prolixus: Increasing sensitivity to ATP during prolonged food deprivation

The percentages of third instar larvae of Rhodnius prolixus that would gorge on 4 × 10⁻⁶M ATP in 0·15 M NaCl were determined at various times from 15 to 140 days after a normal blood meal. As the time interval increased so did the proportion of insects that gorged, indicating an increasing sensitivity to the gorging stimulant. The relationship between sensitivity to ATP and the time elapsed since the previous blood meal is linear, sensitivity increasing by about 20 per cent of its value at day 15 every 10 days. This changing sensitivity may be related to a continuous metabolic activity such as depletion of food reserves; it does not appear to be affected by desiccation, and continues after all detectable remains of the last blood meal have been absorbed from the gut during the period 40 to 140 days after feeding.     

A post-ecdysial plasticization of the abdominal cuticle in Rhodnius

The ecdysis and emergence of fifth instar larvae of Rhodnius prolixus have been closely observed. At the time of ecdysis the cuticle of the head, legs, and wingpads is soft and readily deformed. it does not become sufficiently rigid for normal use until about 90 min later. The cuticle of the abdomen is however hard and inextensible at the time of ecdysis. From about 60 min onward this cuticle undergoes a plasticization; it is maximally extensible at about 180 min, thereafter becoming inextensible again. Unlike the plasticization of the abdominal cuticle which occurs after feeding, this post-ecdysial plasticization is not under direct nervous control. Although it seems that there is some temporal link with the darkening of the cuticle, it is considered unlikely that plasticization is a direct consequence of the tanning process. The significance of this post-ecdysial plasticization is not obvious.     

Temperament and dominance relate to feeding behaviour and activity in beef cattle: implications for performance and methane emissions

In beef cattle, feeding behaviour and activity are associated with feed efficiency and methane (CH₄) emissions. This study aimed to understand the underlying traits responsible for the contribution of cattle behaviour to individual differences in feed efficiency, performance and CH₄ emissions. A total of 84 steers (530±114 kg BW) of two different breeds (crossbreed Charolais and Luing) were used. The experiment was a 2×2×3 factorial design with breed, basal diets (concentrate v. mixed) and dietary treatments (no additive, calcium nitrate or rapeseed cake) as the main factors. The individual dry matter intake (DMI; kg) was recorded daily and the BW was measured weekly over a 56-day period. Ultrasound fat depth was measured on day 56. Based on the previous data, the indexes average daily gain, food conversion and residual feed intake (RFI) were calculated. The frequency of meals, the duration per visit and the time spent feeding per day were taken as feeding behaviour measures. Daily activity was measured using the number of steps, the number of standing bouts and the time standing per day. Agonistic interactions (including the number of contacts, aggressive interactions, and displacements per day) between steers at the feeders were assessed as indicators of dominance. Temperament was assessed using the crush score test (which measures restlessness when restrained) and the flight speed on release from restraint. Statistical analysis was performed using multivariate regression models. Steers that spent more time eating showed better feed efficiency (P=0.039), which can be due to greater secretion of saliva. Feeding time was longer with the mixed diet (P<0.001), Luings (P=0.009) and dominant steers (P=0.032). Higher activity (more steps) in the pen was associated with poorer RFI, possibly because of higher energy expenditure for muscle activity. Frequent meals contributed to a reduction in CH₄ emissions per kg DMI. The meal frequency was higher with a mixed diet (P<0.001) and increased in more temperamental (P=0.003) and dominant (P=0.017) steers. In addition, feed intake was lower (P=0.032) in more temperamental steers. This study reveals that efficiency increases with a longer feeding time and CH₄ emissions decrease with more frequent meals. As dominant steers eat more frequently and for longer, a reduction in competition at the feeder would improve both feed efficiency and CH₄ emissions. Feed efficiency can also be improved through a reduction in activity. Selection for calmer cattle would reduce activity and increase feed intake, which may improve feed efficiency and promote growth, respectively.     

The effect of larval nutrition on egg production in Rhodnius prolixus

Rhodnius prolixus adults which had fed to repletion at each larval instar were frequently autogenous, while those allowed to take only partial blood meals at the 3rd, 4th and 5th larval instars were always anautogenous.Bugs fed to repletion at each larval instar had large abdominal fat bodies throughout adult life. In such bugs, the quantity of blood associated with the production of one egg was small and constant during the course of several blood meals.Bugs fed partial blood meals as larvae had small abdominal fat bodies following ecdysis to the adult; the quantity of blood associated with the production of one egg was large following the first adult feed because some of the blood meal was used to increase the size of the abdominal fat bodies.     

Relation between feeding behaviour and energy metabolism in pigs fed diets enriched in dietary fibre and wheat aleurone

Feed intake and its daily pattern are regulated both at a short and a long term by several control pathways, including energy balance regulation. This trial aimed to determine the effect of dietary fibre (DB) (mix of wheat, soy and sugar beet pulp fibres) and aleurone supplementation and their interaction on energy and nitrogen balances in growing pigs with ad libitum access to feed. Forty pigs (BW: 35 kg) were fed diets differing by fibre concentration (NDF concentration: 10% or 14% DM) and aleurone supplementation (0, 2 or 4 g/kg) during 3 weeks. Pigs were housed individually in a respiration chamber during the last week to record feeding behaviour and measure energy and nitrogen balances (n = 36). Glucose oxidation was studied on the 6th day with an injection of [U-¹³C] glucose and measurement of ¹³CO₂ production. There was no significant interaction between DB inclusion and aleurone supplementation on any variables characterizing feeding behaviour. Pigs had less but longer meals with high level of DB, with an increased interval between two meals without effect on daily feed intake. The meal frequency significantly decreased when aleurone supplementation increased. Total tract apparent digestibility coefficient of DM, organic matter, ash, nitrogen and gross energy decreased when pigs received high DB level. Dietary fibre level increased significantly faecal excreted nitrogen. Aleurone supplementation decreased nitrogen retention. Free access to the feed induced a great individual variability not only in feed intake level (from 784 to 2290 g/day) but also in feeding behaviour (from 5.5 to 21.5 meals per day). This variability can be linked with the importance of underlying feed intake regulation pathways and difference in energy balance and metabolism efficiency. Several profiles of metabolism efficiency can be discriminate, thanks to a clustering based on feeding behaviour and pre-prandial concentrations of metabolites and hormones. In conclusion, DB inclusion decreased meal frequency, increased average meal size, decreased total tract apparent faecal digestibility coefficient of nitrogen and gross energy. Supplementation of aleurone decreased average daily feed intake with a reduction of the meal number per day, without modification of average meal size. Aleurone supplementation decreased nitrogen retention and nutrient deposition. Independently of experimental diets, the high individual variability permitted discriminating different profiles with different metabolic strategies. Efficient pigs with a high energy retention as protein and lipid seem to be able to adapt their metabolism according to energy sources.     

Intravital microscopy and image analysis of Rhodnius prolixus (Hemiptera: Reduviidae) hematophagy: The challenge of blood intake from mouse skin

Hematophagous insects transmit many of the most dangerous parasitic diseases. The transmission usually occurs during hematophagy or just after as this is when the vector and the host are in contact. The contact time is determined by the feeding performance of the insect in each host. In triatomines, feeding performance interferes with both their life cycle and the vectorial competence to transmit the hemoflagellate Trypanosoma cruzi. Triatomine bugs are vessel feeders, obtaining their blood meals directly from the vessels (venules or arterioles) of their vertebrate hosts. The host blood intake rate is not constant during the feeding, and the sucking frequency of triatomines tends to be higher and to contain fewer interruptions in pigeons than in mice. To identify the difficulties encountered by triatomine bugs in obtaining blood meals from mouse skin, we used intravital microscopy techniques associated with electromyograms of the cibarial pump. To monitor the vibration of the cannulated vessels and the blood flow through the head of the insect during the engorgement phase, we introduced a novel method for image analysis. The mean number of vessels used during a Rhodnius prolixus blood meal was 3.4 ± 1.2, and the insects fed more in venules (63%) than in arterioles (37%). An important increase in vascular permeability was observed throughout the feeding. Platelet aggregation, rolling and leukocyte adherence were analyzed on the venular endothelium, showing remarkable increases for some time following the R. prolixus feeding. The reduction in sucking frequency that was observed during insect feeding was likely due to the increased cibarial pump filling time. The monitoring of the vessel wall pulsation also permitted the registration of regurgitation-like movements during blood pumping, with these movements being recorded mostly during the second half of the feeding. The evaluation of blood flow through the head of the insect suggested that the regurgitation-like movements were not true regurgitations and were caused by abrupt difficulties in the function of the cibarial pump. The role of the platelet plugs and the changes in blood viscosity at the R. prolixus feeding site are discussed. The method introduced in the present study to analyze the images brings new insights into the interaction between hematophagous vectors and their hosts, reinforcing the importance of insect saliva throughout the feeding process.     

The control of Malpighian tubule secretion in a predacious hemipteran insect, the spined soldier bug Podisus maculiventris (Heteroptera, Pentatomidae)

Spined soldier bugs, Podisus maculiventris, are heteropteran insects that feed voraciously on other insects, particular the soft bodied larval forms of Lepidoptera and Coleoptera. The response of P. maculiventris Malpighian tubules (MTs) to serotonin and known diuretic and antidiuretic peptides has been investigated, and is compared with that of MT from the hematophagous and phytophagous heteropteran bugs Rhodnius prolixus and Acrosternum hilare, respectively. A CRF-related peptide diuretic hormone (DH) from the termite Zootermopsis nevadensis (Zoone-DH) stimulated MT secretion, which was reversed by a member of the CAP_2b family of peptides from A. hilare (Acrhi-CAP_2b-2), an antidiuretic effect. Serotonin had no effect on secretion, neither did a representative calcitonin-like DH, kinin, tachykinin-related peptide, and an antidiuretic factor from the mealworm Tenebrio molitor (Tenmo-ADFb) in both P. maculiventris or A. hilare. Serotonin is a DH in R. prolixus, and its lack of effect on MT from P. maculiventris and A. hilare suggests this is an adaptation to hematophagy. On the other hand, the antidiuretic activity of members of the CAP_2b family in all three bugs is consistent with this being a heteropteran feature rather than a specialism for hematophagy.     

Feeding through artificial membranes reduces fecundity for females of the blood‐feeding insect,Rhodnius prolixus

The blood‐feeding insect, Rhodnius prolixus, has been raised in the laboratory for close to 100 years. Various feeding techniques have been employed ranging from the use of warm‐blooded hosts, to the use of previously collected blood offered through artificial membranes. This study compared the fecundity in mated and unmated females fed rabbit blood directly from the shaved belly of a rabbit to that of females fed defibrinated rabbit blood through an artificial membrane. These results confirm previous reports that this insect's feeding efficacy is reduced using an artificial membrane. It also demonstrates for the first time that the fecundity index, which measures the efficiency of turning the blood meal into eggs, is significantly reduced. We suggest that the natural feeding on a warm‐blooded host may provide cues that have the short‐term effect of enhancing the act of feeding and the long‐term effect of increasing egg production efficiency. Until an artificial feeding method that does not interfere with feeding and fecundity is devised, experiments on reproduction in R. prolixus warrant the use of a warm‐blooded host to emulate feeding in its natural setting. © 2010 Wiley Periodicals, Inc.     

Haemolymph ecdysteroid titres during larval-adult development in Rhodnius prolixus: Correlations with moulting hormone action and brain neurosecretory cell activity

A haemolymph ecdysteroid titre of the fifth (last)-larval instar of the hemipteran, Rhodnius prolixus has been determined by radioimmunoassay. During the last-larval stadium the ecdysteroid titre increases from a negligible level in the unfed insect to a detectable level within minutes following a blood meal. The titre reaches a plateau of ～50–70 ng/ml at 3–4 hr and this level is maintained until day 5–6, the time of the head-critical period in Rhodnius. At the head-critical period the titre begins to increase again, this time dramatically, reaching a peak of ～ 3500 ng/ml at day 13. From day 14 to ecdysis (day 21) the titre declines to a low level, ～ 30 ng/ml. Basal levels of ecdysteroids, ～ 15 ng/ml, were detectable in young adult males and females. A survey of haemolymph volumes during the last-larval instar indicates that the changes in the ecdysteroid titre reflect changes in the rates of ecdysteroid synthesis, and not changes in haemolymph volume. Excretion of ecdysteroids varies systematically during the instar, suggesting that control of ecdysteroid excretion may be important in regulation of the haemolymph titre. Qualitative analysis of the haemolymph ecdysteroid RIA activity revealed the presence of only ecdysone and 20-hydroxy-ecdysone. For the large peak preceding larval-adult ecdysis, 20-hydroxy-ecdysone was the predominant hormone. These results indicate that there may be two periods of release of prothoracicotropic hormone (PTTH) from the brain in Rhodnius, one immediately following the blood meal and the second on day 5 or 6. The significance of these times of PTTH release is discussed in relation to classical evidence of the timing of moulting hormone action, the response of target tissues, and with more recent findings on the timing of release of neurosecretory material from the brain of Rhodnius during moulting.