Hemolymph Research Articles

Bedbug salivation patterns during hematophagy in the skin of a mammalian host

Cimex lectularius (Hemiptera:Cimicidae) infestations have increased over the past decades in several parts of the world, constituting a major urban pest with no reversion signs. The impact on human health caused by these insects, commonly known as bedbugs, is associated with their obligatory hematophagous habit. Allergies induced by hematophagous arthropod bites are related to the deposition of salivary molecules in the host tissues. Many reports of humans developing severe allergic reactions due to bedbug bites have been recorded, however, there is limited information on the salivation of bedbugs on the host, which was the objective of this study. C. lectularius females were fed on blood containing acridine orange fluorochrome, which labeled the principal salivary glands content. The salivation pattern of bedbugs was investigated using intravital microscopy during its blood meal on the ear skin of hairless mice. Saliva deposition occurred during all insect blood-feeding phases, beginning as soon as the mouthpart touched the host skin. During the probing phase, saliva was deposited in large quantities in the host dermis. In contrast, during the engorgement phase (which represents the largest blood meal of the insects), saliva was released at a much slower rate. The apparent release of saliva into the cannulated vessel and/or adjacent tissue occurs only sporadically during insect blood ingestion. However, a small area (spot) of fluorescence was detected around the proboscis tip during this feeding phase. An interesting feature of bedbugs is that they release saliva inside and outside the vessels without removing their mouthparts from the vessel lumen. This is an effective feeding strategy because it does not interrupt blood ingestion and decreases the mouthparts movements on the host’s skin, minimizing the damage to tissues and contact time with the host (feeding time).

Observation of phagocytosis by insect blood cells using fluorescent ink as a foreign substance

Observation of phagocytosis by insect blood cells using fluorescent ink as a foreign substance

Starvation and pH stress conditions induced mitochondrial dysfunction, ROS production and autophagy in Trypanosoma cruzi epimastigotes

Chagas disease is a neglected illness endemic in Latin America that mainly affects rural populations. The etiological agent of Chagas disease is the protozoan Trypanosoma cruzi, which has three different parasite stages and a dixenous life cycle that includes colonization of the vertebrate and invertebrate hosts. During its life cycle, T. cruzi is subjected to stress conditions, including variations in nutrient availability and pH, which impact parasite survival and differentiation. The plasticity of mitochondrial function in trypanosomatids has been defined as mitochondrial activity related to substrate availability. Thus, mitochondrial remodeling and autophagy, which is a constitutive cellular process of turnover and recycling of cellular components, may constitute a response to the nutritional and pH stress in the host. To assess these processes, epimastigotes were subjected to acidic, alkaline, and nutritional stress conditions, and mitochondrial function and its influence on the autophagic process were evaluated. Our data demonstrated that the three stress conditions affected the mitochondrial structure, inducing organelle swelling and impaired oxidative phosphorylation. Stressed epimastigotes produced increased ROS levels and overexpressed antioxidant enzymes. The stress conditions resulted in an increase in the number of autophagosomes and exacerbated the expression of different autophagy-related genes (Atgs). A correlation between mitochondrial dysfunction and autophagic phenotypes was also observed. After 24 h, acid stress and nutritional deprivation induced metacyclogenesis phenotypes (mitochondrial remodeling and autophagy). On the other hand, alkaline stress was transient due to insect blood feeding and culminated in an increase in autophagic flux as a survival mechanism.

Enhanced Antioxidant and Cytotoxic Potentials of Lipopolysaccharides-Injected Musca domestica Larvae.

The usage of insects as a sustainable and functional natural products resource is a new promise in complementary and alternative medicine. The present study aimed to investigate the ability of Musca domestica (housefly) larval hemolymph (insect blood) to display the enhanced in vitro antioxidant and cytotoxic effects. The oxidative stress (OS) was elicited by inducing lipopolysaccharides (LPS) treatment as an exogenous stressor. Determination of superoxide dismutase 1 (SOD1), glutathione (GSH), malondialdehyde (MDA) and total antioxidant capacity (TAC), and mRNA and protein expressions of SOD1, was investigated as confirmatory markers of oxidative stress induction. Cytotoxicity on cancerous MCF-7 and normal Vero cells were also evaluated using an MTT assay at 24 h post-injection. The injection of LPS induced a significant (p < 0.05) increase in SOD, GSH and TAC, whereas, the MDA was diminished. Hemolymph was collected from normal and treated larvae after 6, 12 and 24 h. The M. domestica superoxide dismutase (MdSOD1) transcripts were significantly (p < 0.05) upregulated 6 and 12 h post-treatment, while a significant downregulation was observed after 24 h. Western blot analysis showed that MdSOD1 was expressed in the hemolymph of the treated larvae with an increase of 1.2 folds at 6 and 12 h and 1.6 folds at 24 h relative to the control group. LPS-treated larval hemolymphs exhibited significant cytotoxicity with respect to the untreated ones against MCF-7 while Vero cells showed no cytotoxicity for both hemolymphs. The DPPH free radical scavenging activity was examined and a significant antioxidant potential potency was observed at 6 h (50% maximal inhibitory concentration (IC50): 63.3 ± 3.51 µg/mL) when compared to the control M. domestica larval hemolymph (IC50: 611.7 ± 10.41 µg/mL). Taken together, M. domestica larval hemolymph exhibited enhanced antioxidant and consequently increased cytotoxic capacities under stressed conditions.

Dynamics of food sources, ecotypic distribution and Trypanosoma cruzi infection in Triatoma brasiliensis from the northeast of Brazil.

Innovative approaches used to combat Chagas disease transmission tend to combine a set of comprehensive efforts to understand the ecology of local vectors. In this work we identified molecularly the blood meal of 181 Triatoma brasiliensis, distributed in 18 populations (8 sylvatic and 10 peridomestic), which were collected across a range of 240 km (East-West) and 95 km (North-South) in the semi-arid region of northeastern, Brazil. We used the vertebrate mitochondrial gene (cytochrome B) sequencing applied to DNA isolated from bug midgut to identify the insect blood meal sources via the BLAST procedure. The peridomestic populations were classified according to two main hypotheses of site-occupancy for T. brasiliensis: the first says that the infestation is mainly driven by structures that resemble its natural habitat (stony-like ecotopes) and the second assumes that it is associated with key-hosts (rodents and goats). Rodents of the Caviidae family (Galea spixii and Kerodon rupestris) were identified as the key-host of T. brasiliensis, but also the potential Trypanosoma cruzi reservoir–able to connect the sylvatic and domestic T. cruzi cycle. Cats also deserve to be studied better, as potential T. cruzi reservoirs. By modeling the food sources + site-occupancy + T. cruzi natural infection, we identified man-made ecotopes suitable for forming dense triatomine infestations with high rates of T. cruzi natural infection, which may be taken into account for vector control measures.

Circulation in Insect Wings.

Insect wings are living, flexible structures composed of tubular veins and thin wing membrane. Wing veins can contain hemolymph (insect blood), tracheae, and nerves. Continuous flow of hemolymph within insect wings ensures that sensory hairs, structural elements such as resilin, and other living tissue within the wings remain functional. While it is well known that hemolymph circulates through insect wings, the extent of wing circulation (e.g., whether flow is present in every vein, and whether it is confined to the veins alone) is not well understood, especially for wings with complex wing venation. Over the last 100 years, scientists have developed experimental methods including microscopy, fluorescence, and thermography to observe flow in the wings. Recognizing and evaluating the importance of hemolymph movement in insect wings is critical in evaluating how the wings function both as flight appendages, as active sensors, and as thermoregulatory organs. In this review, we discuss the history of circulation in wings, past and present experimental techniques for measuring hemolymph, and broad implications for the field of hemodynamics in insect wings.

Nitric oxide effects on Rhodnius prolixus’s immune responses, gut microbiota and Trypanosoma cruzi development

The immune system of Rhodnius prolixus comprehends the synthesis of different effectors that modulate the intestinal microbiota population and the life cycle of the parasite Trypanosoma cruzi inside the vector midgut. One of these immune responses is the production of reactive nitrogen species (RNS) derived by the action of nitric oxide synthase (NOS). Therefore, we investigated the effects of L-arginine, the substrate for nitric oxide (NO) production and Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME), an inhibitor of NOS, added in the insect blood meal. We analyzed the impact of these treatments on the immune responses and development of intestinal bacteria and parasites on R. prolixus nymphs. The L-arginine treatment in R. prolixus nymphs induced a higher NOS gene expression in the fat body and increased NO production, but reduced catalase and antimicrobial activities in the midgut. As expected, L-NAME treatment reduced NOS gene expression in the fat body. In addition, L-NAME treatment diminished catalase activity in the hemolymph and posterior midgut reduced phenoloxidase activity in the anterior midgut and increased the antimicrobial activity in the hemolymph. Both treatments caused a reduction in the cultivatable intestinal microbiota, especially in insects treated with L-NAME. However, T. cruzi development in the insect’s digestive tract was suppressed after L-arginine treatment and the opposite was observed with L-NAME, which resulted in higher parasite counts. Therefore, we conclude that induction and inhibition of NOS and NO production are associated with other R. prolixus humoral immune responses, such as catalase, phenoloxidase, and antibacterial activities in different insect organs. These alterations reflect on intestinal microbiota and T. cruzi development.

Triatoma petrocchiae (Hemiptera, Reduviidae, Triatominae): A Chagas disease vector of T. brasiliensis species complex associated to reptiles

In semi-arid areas of northeastern Brazil, Chagas disease vectors of Triatoma brasiliensis species complex comprise a monophyletic group of kissing bugs that inhabit rock outcrops. Most of them exhibit allopatric or parapatric distribution; the exception is T. petrocchiae, which is found in cohabitation with T. brasiliensis in rock outcrops. We used vertebrate mitochondrial gene sequencing applied to DNA isolated from bug midgut to identify the insect blood meal sources via BLAST procedure. Fourteen sylvatic insects from four geographic districts in the states of Rio Grande do Norte and Paraíba had their blood meal sources detected. While T. brasiliensis is recorded to be associated mainly (52–71%) with rodents, T. petrocchiae samples were strongly associated (86%) with reptiles of Tropidurus and Hemidactylus genera. We suggest that T. petrocchiae is the single member within this complex to be associated with reptiles, indicating a distinct niche occupation related to the trophic resources.

Lipid Peroxidation in Hepatopancreas, Gill, and Hemolymph of Male and Female Crabs Platyxanthus Orbignyi after Air Exposure

Levels of lipid peroxidation in hepatopancreas (HP), gill (G), and hemolymph (HYM) of stone violaceous crab Platyxanthus orbignyi (Milne Edwards and Lucas (1843)) were performed to examine the effect of short exposure to air. After four hours animals were collected, 14 from exposure to air and 10 from seawater were dissected and their lipid peroxidation (LPO) levels were evaluated using the ferrous oxidation-xylenol orange (FOX) method, in gill, hepatopancreas, and hemolymph. The total mortality of those crabs was evaluated after seven hours at 22 ± 1 °C on exposure to air conditions. Levels of LPO in hepatopancreas (female/male = 4.68 ± 1.60/5.12 ± 1.59 Eq-H2O2/g wet tissue) and hemolymph (female/male = 1.48 ± 1.42/1.28 ± 1.06 Eq-H2O2/g wet tissue) displayed no significant differences, in contrast, gills displayed significant differences (male/female = 5.63 ± 0.83/4.63 ± 0.44 Eq-H2O2/g wet tissue, p &lt; 0.05). The results showed that air exposure in the short term in this study induces a different response in oxidative stress levels and damage could be accompanied by accumulation of peroxide lipids (LOOH). These results suggest that different organs can show different responses to oxidative stress between male and female crabs to this species.

Nephrocytes Remove Microbiota-Derived Peptidoglycan from Systemic Circulation to Maintain Immune Homeostasis

Preventing aberrant immune responses against the microbiota is essential for the health of the host. Microbiota-shed pathogen-associated molecular patterns translocate from the gut lumen into systemic circulation. Here, we examined the role of hemolymph (insect blood) filtration in regulating systemic responses to microbiota-derived peptidoglycan. Drosophila deficient for the transcription factor Klf15 (Klf15NN) are viable but lack nephrocytes-cells structurally and functionally homologous to the glomerular podocytes of the kidney. We found that Klf15NN flies were more resistant to infection than wild-type (WT) counterparts but exhibited a shortened lifespan. This was associated with constitutive Toll pathway activation triggered by excess peptidoglycan circulating in Klf15NN flies. In WT flies, peptidoglycan was removed from systemic circulation by nephrocytes through endocytosis and subsequent lysosomal degradation. Thus, renal filtration of microbiota-derived peptidoglycan maintains immune homeostasis in Drosophila, a function likely conserved in mammals and potentially relevant to the chronic immune activation seen in settings of impaired blood filtration.

Effects of BDE-47 exposure on immune-related parameters of Mytilus galloprovincialis

The persistent pollutants polybrominated diphenyl ethers (PBDEs) have been demonstrated to produce several negative effects on marine organisms. Although Mytilus galloprovincialis was extensively studied as model system, the effects of PBDEs on the innate immune system of mussels remains unclear. In this study, except for the control treatment, specimens of M. galloprovincialis were fed with microalgae treated with increasing concentrations of PBDEs (maximum level 100 ng L−1 of BDE-47 per day). BDE-47 treatment was maintained for 15 days and then the animals were fed with the same control diet, without contaminants, for 15 days. Samples of haemolymph (HL) were obtained at T0, T15 and T30 days of the experiment to evaluate different parameters related to immunity, such as neutral red retention time, and peroxidase, protease, antiprotease, lysozyme and bactericidal activities. BDE-47 exposure for 15 days affected both the stability of haemocytes and humoral parameters. In addition, the obtained results indicated that, at 30 days, after 15 days of culture without contaminant, the immune parameters were still affected, as some of them did not return to the basal levels, and others remained stimulated. Overall the results indicate that BDE-47 exposures at environmentally realistic levels may affect various aspects of immune function in M. galloprovincialis, acting as stressor that can compromise the general welfare.

Firebugs fight infection with egg yolk protein

Fighting off an infection is never easy, but insects are prepared. By releasing antimicrobial peptides (mini-proteins) from the fat body – the insect equivalent of the liver – and mobilising specialised cells that target invading infections in the haemolymph (insect blood), insects are able to defend themselves when wounded or at risk of infection. However, Dalibor Kodrík and colleagues from the Biology Centre of the Czech Academy of Sciences, wondered whether a group of proteins known as vitellogenins – which are usually produced by female animals and go on to create egg yolk proteins – might also contribute to insect immunity. Kodrík says, ‘Studies in the silkworm and honeybee reported strong antibacterial activity of vitellogenins’. Could the proteins contribute to the immunity of his favourite insects, firebugs (Pyrrhocoris apterus)? Knowing that the nematode Steinernema carpocapsae, which infects insects with toxic Xenorhabdus bacteria, and the lethal Isaria fumosorosea fungus are used to control insect numbers, Kodrík decided to investigate whether either biological control agent triggers vitellogenin production in firebugs and whether the proteins offered any protection from these infections.After injecting one group of firebugs with the toxic nematodes and a second group with the fungus, Emad Ibrahim and Umesh Guatam collected the infected insects’ haemolymph and fat bodies several days later to find out whether the insects were producing vitellogenins to combat the infections. When they measured the levels of vitellogenin mRNA and protein, Radmila Čapková Frydrychová, Andrea Bednářová and Pavel Jedlička discovered that the nematode infection significantly boosted the males’ vitellogenin mRNA production 7.7-fold and protein 1.5-fold. However, the infection caused the females’ vitellogenin mRNA levels in the fat body to crash, dramatically dropping 150-fold, while their haemolymph vitellogenin protein levels also plummeted.In contrast, the male firebugs’ response to the slower developing fungal infection was only modest, while the females experienced the same haemolymph and fat body reductions in vitellogenin that the scientists had discovered in the nematode-infected insects. In addition, when the team tested the mortality rates from both infections, it seemed that the female firebugs were better protected than their male counterparts. And when Václav Krištu˚fek treated the nematode's toxic Xenorhabdus lodgers with vitellogenin, the bacteria succumbed, although the protein made little impact on the fungal infection.So, it appears that vitellogenin does contribute to the insect's immunity, offering some protection from nematode and fungal infections. Kodrík also suspects that the reduction in vitellogenin levels experienced by infected females may not be as unexpected as it first appears. ‘One can speculate that the vitellogenin level sufficient for effective defence against pathogens might be much lower than that required for nutritional supply of developing eggs’, says Čapková Frydrychová, who suggests that infected females may shut down non-essential processes, such as egg development, at times of crisis to invest energy in fighting the infection. And Kodrík is keen to discover whether the essential egg protein is also a key player in the immune response of other insects, including Drosophila, which could allow him to begin unravelling vitellogenin's antibiotic mechanism.

Two Nimrod receptors, NimC1 and Eater, synergistically contribute to bacterial phagocytosis in Drosophilamelanogaster.

Eater and NimC1 are transmembrane receptors of the Drosophila Nimrod family, specifically expressed in haemocytes, the insect blood cells. Previous ex vivo and in vivo RNAi studies have pointed to their role in the phagocytosis of bacteria. Here, we have created a novel NimC1 null mutant to re‐evaluate the role of NimC1, alone or in combination with Eater, in the cellular immune response. We show that NimC1 functions as an adhesion molecule ex vivo, but in contrast to Eater it is not required for haemocyte sessility in vivo. Ex vivo phagocytosis assays and electron microscopy experiments confirmed that Eater is the main phagocytic receptor for Gram‐positive, but not Gram‐negative bacteria, and contributes to microbe tethering to haemocytes. Surprisingly, NimC1 deletion did not impair phagocytosis of bacteria, nor their adhesion to the haemocytes. However, phagocytosis of both types of bacteria was almost abolished in NimC1 1 ;eater 1 haemocytes. This indicates that both receptors contribute synergistically to the phagocytosis of bacteria, but that Eater can bypass the requirement for NimC1. Finally, we uncovered that NimC1, but not Eater, is essential for uptake of latex beads and zymosan particles. We conclude that Eater and NimC1 are the two main receptors for phagocytosis of bacteria in Drosophila, and that each receptor likely plays distinct roles in microbial uptake.

Nucleation and Formation of a Primary Clot in Insect Blood

Blood clotting at wound sites is critical for preventing blood loss and invasion by microorganisms in multicellular animals, especially small insects vulnerable to dehydration. The mechanistic reaction of the clot is the first step in providing scaffolding for the formation of new epithelial and cuticular tissue. The clot, therefore, requires special materials properties. We have developed and used nano-rheological magnetic rotational spectroscopy with nanorods to quantitatively study nucleation of cell aggregates that occurs within fractions of a second. Using larvae of Manduca sexta, we discovered that clot nucleation is a two-step process whereby cell aggregation is the time-limiting step followed by rigidification of the aggregate. Clot nucleation and transformation of viscous blood into a visco-elastic aggregate happens in a few minutes, which is hundreds of times faster than wound plugging and scab formation. This discovery sets a time scale for insect clotting phenomena, establishing a materials metric for the kinetics of biochemical reaction cascades. Combined with biochemical and biomolecular studies, these discoveries can help design fast-working thickeners for vertebrate blood, including human blood, based on clotting principles of insect blood.

Changes in Vitellogenic Proteins During The Reproductive Cycle of The Female Tick, Argas persicus

Proteins in the freshly deposited eggs of mated fed female Argas persicus were electrophoretically separated into twelve fractions or egg vitellins (EVts) with Mwt of 24.72-131.45kD. One fraction (131.45kD) existed only in the egg and eleven were exogenous EVts with extraovarian counterparts (vitellogenins) in the hemolymph (HL). Six of them were common EVts (24.72-65.53kD) with similar counterparts in the HL of both male and female and five were female-specific EVts (78.65-112.92 and 48.67kD) with similar counterparts only in the female HL. Eleven vitellogenins (Vgs) and ten exogenous vitellins (Vts) with similar electrophoretic mobilities to EVts were identified in the HL and ovaries, respectively, of mated females. The number and percent amount of the detected vitellogenic protein fractions varied in the different physiological states (10) studied (unfed, 0-7 and 20 day after feeding, daf). Generally, there was an increase of the two parameters in ovary vitellin fractions (with appearance of new Vts) and a decrease in HL vitellogenin fractions during vitellogenesis at the late period of the female reproductive cycle (4-7 and 20 daf). The obtained results support the concept of the uptake of hemolymph Vgs by the ovaries and deposition as Vts in the oocytes during vitellogenesis which may extend till the end of the oviposition period (20 daf) in the female A.persicus.

Candidatus Liberibacter asiaticus Minimally Alters Expression of Immunity and Metabolism Proteins in Hemolymph of Diaphorina citri, the Insect Vector of Huanglongbing.

Huanglongbing (HLB), also known as citrus greening disease, is the most serious disease of citrus plants. It is associated with the Gram-negative bacterium ' Candidatus Liberibacter asiaticus' ( CLas), which is transmitted between host plants by the hemipteran insect vector Diaphorina citri in a circulative, propagative manner involving specific interactions with various insect tissues including the hemolymph, fluid that occupies the body cavity akin to insect blood. High resolution quantitative mass spectrometry was performed to investigate the effect of CLas exposure on D. citri hemolymph at the proteome level. In contrast to the broad proteome effects on hundreds of proteins and a diverse array of metabolic pathways previously reported in gut and whole insect proteome analyses, the effect of CLas on the hemolymph was observed to be highly specific, restricted to key immunity and metabolism pathways, and lower in magnitude than that previously observed in the whole insect body and gut. Vitellogenins were abundantly expressed and CLas-responsive. Gene-specific RNA expression analysis suggests that these proteins are expressed in both male and female insects and may have roles outside of reproductive vitellogenesis. Proteins for fatty acid synthesis were found to be up-regulated, along with metabolic proteins associated with energy production, supported at the organismal level by the previously published observation that D. citri individuals experience a higher level of hunger when reared on CLas-infected plants. Prediction of post-translational modifications identified hemolymph proteins with phosphorylation and acetylation upon CLas exposure. Proteins derived from the three most prominent bacterial endosymbionts of the psyllid were also detected in the hemolymph, and several of these have predicted secretion signals. A DNAK protein, the bacterial HSP70, detected in the hemolymph expressed from Wolbachia pipientis was predicted to encode a eukaryotic nuclear localization signal. Taken together, these data show specific changes to immunity and metabolism in D. citri hemolymph involving host and endosymbiont proteins. These data provide a novel context for proteomic changes seen in other D. citri tissues in response to CLas and align with organismal data on the effects of CLas on D. citri metabolism and reproduction.

Salinity Variation in a Mangrove Ecosystem: A Physiological Investigation to Assess Potential Consequences of Salinity Disturbances on Mangrove Crabs.

Dimitri Theuerkauff, Georgina A. Rivera-Ingraham, Jonathan A.C. Roques, Laurence Azzopardi, Marine Bertini, Mathilde Lejeune, Emilie Farcy, Jehan-Hervé Lignot, and Elliott Sucré (2018) Salinity is one of the main environmental factors determining coastal species distribution. However, in the specific case of mangrove crabs, salinity selection cannot be understood through ecological approaches alone. Yet understanding this issue is crucial in the context of mangrove conservation, since this ecosystem is often used as biofilter of (low- salinity) wastewater. Crabs are keystone species in this mangrove ecosystem and are differentially affected by salinity. We hypothesize that crab salinity selection may be partly explained by specific salinity-induced physiological constraints associated with osmoregulation, energy and redox homeostasis. To test this, the response to salinity variation was analysed in two landward mangrove crabs: the fiddler crab Tubuca urvillei, which inhabits low-salinity areas of the mangrove, and the red mangrove crab Neosarmatium meinerti, which lives in areas with higher salinity. Results confirm that both species are strong hypo-/hyper-osmoregulators that deal easily with large salinity variations. Such shifts in salinity do not induce changes in energy expenditure (measured as oxygen consumption) or in the production of reactive oxygen species. However, T. urvillei is physiologically suited to habitats with brackish water, since it presents i) high hemolymph osmolalities over a wider range of salinities and lower osmoregulatory capacity in seawater, ii) high Na+/K+-ATPase (NKA) activity in the posterior osmoregulatory gills and iii) a thicker osmoregulatory epithelium along the posterior gill lamellae. Therefore, while environmental salinity alone cannot directly explain fiddler and red mangrove crab distributions, our data suggest that salinity selection is indeed influenced by specific physiological adjustments.

Low H2O2 and enhanced oxidative resistance in the diapause-destined pupa of silkworm, Antheraea mylitta (Lepidoptera:Saturniidae) suggest their possible involvement in dormancy and lifespan extension

BackgroundInsect diapause is associated with physiological dormancy, extension of life span and an altered developmental programme. Reactive oxygen species, oxidative damaged products and antioxidants are being increasingly linked to such processes in insects. Tropical tasar silkworm, Antheraea mylitta Drury (Lepidoptera:Saturniidae), has an impressive pupal diapause and exhibits a distinct pattern of development in nondiapausing (NDP) pupa compared to that of diapausing (DP) pupa. In this study, we have analysed the amount of hydrogen peroxide (H2O2) and oxidative damaged products along with the levels of antioxidant protection in the hemolymph (HL) and fat body (FB) tissues of developing pupa of A. mylitta from DP and NDP generations having identical chronological age but distinct physiological status.ResultsSignature of oxidative predominance was clearly marked in the tissues of diapause-destined pupa as evident from a higher level of lipid peroxidation and protein carbonyl content, despite a lower level of H2O2 in the said group. Specific activity of catalase, exclusively observed in the FB was significantly higher in diapause-destined pupae. Total superoxide dismutase activity was found to be higher in both tissue types of diapause-destined pupae compared to their NDP counterpart. In contrast, pupae committed for diapause displayed less activity for glutathione S-transferase than the NDP group. Reduced glutathione exhibited tissue specificity being higher in the FB of NDP pupae.ConclusionsFindings of this study suggest that low H2O2 pool with a strategic antioxidant protection is associated with induction of dormancy and enhanced oxidative resistance during an extended lifespan.

Biogenic Amines in Insect Antennae.

Insect antenna is a multisensory organ, each modality of which can be modulated by biogenic amines. Octopamine (OA) and its metabolic precursor tyramine (TA) affect activity of antennal olfactory receptor neurons. There is some evidence that dopamine (DA) modulates gustatory neurons. Serotonin can serve as a neurotransmitter in some afferent mechanosensory neurons and both as a neurotransmitter and neurohormone in efferent fibers targeted at the antennal vessel and mechanosensory organs. As a neurohormone, serotonin affects the generation of the transepithelial potential by sensillar accessory cells. Other possible targets of biogenic amines in insect antennae are hygro- and thermosensory neurons and epithelial cells. We suggest that the insect antenna is partially autonomous in the sense that biologically active substances entering its hemolymph may exert their effects and be cleared from this compartment without affecting other body parts.

Relaciones huésped-parásito en Tripanosomiasis Rangeli I. Infección intestinal y hemolinfática comparativa de Rhodnius prolixus y Triatoma infestans

In this initial contribution on host-parasite relationships in Rangeli Trypanosomiasis, the results on the infection of 837 nymphs of Rhodnius prolixus and 827 of Triatoma infestans , by artificial xenodiagnosis, with two different strains of T. rangeli , are discussed. The insects were divided in groups in different experiments and in sorne cases the feces were examined and in others only the hemolymph. R. prolixus gave higher rates of infection, by feces exam· ination, than T. infestans at 15 and 30 days. The Venezuelan strain produced higher rates than the Costa Rican strain in both species. The rates in the two species were even higher when the insects were examined by dissecting the intostine, due to the lack of colonization of the flagellates in the rectum: With the Venezuelan strain T. infestans tended to lose the infection, and the same was true for both species with the Costa Rican strain. In the groups where hemolymph was examined for up to two months, it was shown that the haemocoele is more commonly invaded in Rhodnius, and at a higher rate with Venezuelan strain. With this strain a few T. infestans gave light infections with only a few flagellates present, and the Costa Rican strain gave not a single infection in this species. There was no correlation between the feces and hemolymph since it was possible to find insects positive in the latter and negative in the former or viceversa. The implications of the results as far as the experimental conditions used, the life cycle in the invertebrate, and the influence of the insect and different strains of the flagellate are discussed.