Oviposition behavior of wild Zabrotes subfasciatus (Coleoptera, Chrysomelidae) females deprived of the host Phaseolus vulgaris (Fabaceae)

The insects oviposition behavior is fundamental to study population dynamics, life history evolution, insect-plant and parasitoid-host interactions. Zabrotes subfasciatus (Boheman, 1833) females oviposition behavior in the presence and absence of a host is unknown. The main objective of this study was to describe in detail the oviposition behavior of host deprived or non-deprived females, and observe how the several situations of deprivation (days without host) influence oviposition. Six groups were assembled, three deprived of the host (for 2, 5 and 8 days) and three control groups (with host), each containing one newly-emerged couple (0-24h) of wild Z. subfasciatus, The non-deprived (control) groups received the hosts every day (5 bean seeds Phaseolus vulgaris (Fabaceae)) and the others were deprived for 2, 5 and 8 days, respectively. For each group 12 repetitions were made. Consequently, 12 couples were host deprived during two days, 12 couples were host deprived during five days and 12 couples were host deprived during eight days. When the seeds of the deprived groups were added the experiments started. There was a control group for each deprived group. The experiments and the insects were maintained at constant temperature 29 ± 2ºC and 70-80% relative humidity. At 15 minutes interval, the number of times the females manifested the different categories of behavior was observed (frequency). The behavior categories were: rest inside the box, locomotion, resource exploration (seeds), copulation and oviposition. The deprived females stayed most of the time in contact with the host to carry out oviposition, while the non-deprived (control) females spent most of the time at rest. This was observed in all the deprivation times. The results show that host deprivation influences the oviposition behavior of the studied species and also shows the flexibility in the oviposition strategies that these females present when the environment changes (absence and presence of resources)

Observation on the host parasitoid interaction between Periplaneta americana, the American cockroach and Tetrastichus hagenowii, an oothecal parasitoid

Investigations were carried out on the host parasitoid interaction between Periplaneta americana, the American cockroach and Tetrastichus hagenowii, an oothecal parasitoid. This gregarious female parasitoid infected and or oviposited in only one host and caused 100 por cento mortality of the infected host. However, increase in parasitoid density decreased the progeny production and influenced the sex ratio. The progenies produced were male biased. When host preference was tested by offering oothecae of different species of cockroaches, T. hagenowii showed a predilection towards the oothecae of P. americana, suggestings its host specificity.

Olfactory mediated interactions between Citrus aurantium Toxoptera citricida and Lysiphlebus testaceipes

The objective of this study was to establish whether there are olfactory interactions in the Lysiphlebus testaceipes Toxoptera citricida and Citrus aurantium tritrophic system. The response of male and female L. testaceipes to different odour sources of the host plant C. aurantium, the aphid host T. citricida and aphid-plant complex were investigated using a Y-tube olfactometer. Laboratory experiments were conducted by exposing individually aged male and female L. testaceipes to eight different odour treatments. Response of the parasitoids was taken after 15 min exposure to the volatiles from the different odour sources and based on their orientation to the particular chamber. Seventy percent of both male and female L. testaceipes showed high attractivity to aphid infested leaves. There was no significant difference based on age and sex of the parasitoid on their choice of odour. The organic compounds released by these combinations acted as semiochemicals in the tritrophic interactions and it is suggested that insect feeding induced attraction of the parasitoid L. testaceipes.

Trypanosoma cruzi isolated from a triatomine found in one of the biggest metropolitan areas of Latin America

Abstract: INTRODUCTION: To characterize Trypanosoma cruzi (TcI) isolated from a Panstrongylus megistus specimen found in one of the biggest metropolitan areas of Latin America, the relationship between the TcI group of T. cruzi and the transmission cycle in the urban environment was studied. METHODS: The T. cruzi strain, Pm, was isolated in a culture medium from the evolutionary forms present in the hindgut of a live male specimen of P. megistus found in the Jabaquara subway in São Paulo City. The sample from the triatomine showed trypomastigote forms of Trypanosomatidae, which were inoculated in the peritoneum of Balb/c mice. The sample was then inoculated in Liver Infusion Tryptose medium and J774 cells for the molecular identification and characterization of the parasite. The Pm strain of T. cruzi was identified by isolation in axenic culture medium, and based on the morphology, cell infection, growth kinetics, and molecular characterization. RESULTS: After isolation, the protozoan was identified as T. cruzi. No parasites were detected in the peripheral blood of the animal, which can be a characteristic inherent to the strain of T. cruzi that was isolated. Cell invasion assays were performed in triplicate in the J774 cell line to confirm the invasive ability of the Pm strain and revealed amastigote forms of the parasite within macrophages. CONCLUSIONS: Our biological and molecular characterizations helped understand parasite-host interactions and their evolutionary history in context of the associations between vectors, ecotopes, hosts, and groups of the parasite.

Inter and intra-guild interactions in egg parasitoid species of the soybean stink bug complex

The objective of this research was to evaluate the parasitism behavior of Telenomus podisi Ashmead, Trissolcus basalis (Wollaston) e Trissolcus urichi Crawford (Hymenoptera: Scelionidae) on eggs of Nezara viridula L., Euschistus heros F., Piezodorus guildinii Westwood and Acrosternum aseadum Rolston (Heteroptera: Pentatomidae), in no choice and multiple choice experiments. For all parasitoid species, the results demonstrated the existence of a main host species that maximizes the reproductive success. The competitive interactions among the parasitoid species were investigated in experiments of sequential and simultaneous release of different combinations of parasitoid pairs on the hosts N. viridula, E. heros and A. aseadum. Exploitative competition was observed for egg batches at the genus level (Telenomus vs. Trissolcus) and interference competition at the species level (T. basalis vs. T. urichi). Trissolcus urichi was the most aggressive species, interfering with the parasitism of T. basalis. Generally, T. basalis showed an opportunistic behavior trying to parasitise eggs after T. urichi had abandoned the egg batch. The selection of parasitoid species for use in augmentative biological control programs should take into account the diversity of pentatomids present in soybean in addition to the interactions among the different species of parasitoids.

Coevolution of hosts and microorganisms: an analysis of the involvment of cytokines in host-parasite interactions

Parasites may employ particular strategies of eluding an immune response by taking advantage of those mechanisms that normally guarantee immunological self-tolerance. Much in the way as it occurs during the establishment of self-tolerance, live pathogens may induce clonal deletion, functional inactivation(anergy) and immunosupression. At this latter level, it appears that certain pathogens produce immunosupresive cytokine-like mediators or provoke like host the secrete cytokines that will compromise the anti-parasite immune response. It appears that immune responses that preferentially involve T helper l cells (secretors of interleukin-2-and interferon-y) tend to be protective, whereas T helper 2 cells (secretors of IL-4, IL5, IL-6, and IL-10), a population that antagonizes T helper cells, mediate disease susceptibility and are immunopathological reactions. Cytokines produced by T helper 2 cells mediate many symptoms of infection, including eosinophilia, mastocytosis, hyperimmunoglobulinemia, and elevated IgE levels. Administration of IL-2 and IFN-y has beneficial effects in many infections mediated by viruses, bacteria, and protozoa. The use of live vaccinia virus might be an avenue for the treatment of or vaccination against infection. We have found that a vaccinia virus expressing the gene for human IL-2, though attenuated, precipitates autoimmune disease in immunodeficient athymic mice. Thus, although T helper l cytokines may have desired immunostimulatory properties, they also may lead to unwarranted autoaggressive responses.

Current millennium biotechniques for biomedical research on parasites and host-parasite interactions

The development of biotechnology in the last three decades has generated the feeling that the newest scientific achievements will deliver high standard quality of life through abundance of food and means for successfully combating diseases. Where the new biotechnologies give access to genetic information, there is a common belief that physiological and pathological processes result from subtle modifications of gene expression. Trustfully, modern genetics has produced genetic maps, physical maps and complete nucleotide sequences from 141 viruses, 51 organelles, two eubacteria, one archeon and one eukaryote (Saccharomices cerevisiae). In addition, during the Centennial Commemoration of the Oswaldo Cruz Institute the nearly complete human genome map was proudly announced, whereas the latest Brazilian key stone contribution to science was the publication of the Shillela fastidiosa genomic sequence highlythed on a Nature cover issue. There exists a belief among the populace that further scientific accomplishments will rapidly lead to new drugs and methodological approaches to cure genetic diseases and other incurable ailments. Yet, much evidence has been accumulated, showing that a large information gap exists between the knowledge of genome sequence and our knowledge of genome function. Now that many genome maps are available, people wish to know what are we going to do with them. Certainly, all these scientific accomplishments will shed light on many more secrets of life. Nevertheless, parsimony in the weekly announcements of promising scientific achievements is necessary. We also need many more creative experimental biologists to discover new, as yet un-envisaged biotechnological approaches, and the basic resource needed for carrying out mile stone research necessary for leading us to that "promised land"often proclaimed by the mass media.

Inhibition of Trypanosoma cruzi proline racemase affects host-parasite interactions and the outcome of in vitro infection

Proline racemase is an important enzyme of Trypanosoma cruzi and has been shown to be an effective mitogen for B cells, thus contributing to the parasite's immune evasion and persistence in the human host. Recombinant epimastigote parasites overexpressing TcPRAC genes coding for proline racemase present an augmented ability to differentiate into metacyclic infective forms and subsequently penetrate host-cells in vitro. Here we demonstrate that both anti T. cruzi proline racemase antibodies and the specific proline racemase inhibitor pyrrole-2-carboxylic acid significantly affect parasite infection of Vero cells in vitro. This inhibitor also hampers T. cruzi intracellular differentiation.

Hymenoepimecis neotropica (Brues & Richardson) (Hymenoptera, Ichneumonidae, Pimplinae) parasitoid of Araneus omnicolor (Keyserling) (Araneae, Araneidae): first host record and new occurrence to Brazil

Hymenoepimecis neotropica (Brues & Richardson) (Hymenoptera, Ichneumonidae, Pimplinae) parasitoid of Araneus omnicolor (Keyserling) (Araneae, Araneidae): first host record and new occurrence to Brazil. The species of the genus Hymenoepimecis occur only in Neotropical region, being recognized for using as their hosts spiders which build orbicular webs. That wasp was described occurring only in the Guyana. This work expands the geographical distribution of the species to Brazil and records the spider Araneus omnicolor (Araneae, Araneidae) as its host. Furthermore, it provides information about the natural history of this interaction.

Involvement and interactions of different immune cells and their cytokines in human visceral leishmaniasis

Visceral leishmaniasis (VL) or kala-azar, a disseminated infection of the lymphoreticular system of the body, is marked by severe defect in immune system of the host. Successful cure of VL depends on the immune status of the host in combination with the effects of the antileishmanial drugs. The rationale approach towards eradication of this disease would be to potentiate the immune functioning of the host in addition to parasite killing. This review deals with different aspects of adaptive and innate immune responses and explores their role in protection or pathogenesis of VL. IL-10 has emerged as the principal cytokine responsible for disease pathogenesis, although evidences regarding its source during active VL remain inconclusive. On the other hand, IFNγ, under the influence of IL-12, is mostly correlated with healing of the disease. Chemokines are important in mounting cell-mediated immune response as they can prevent parasite invasion in association with cytokines. Different types of T cells like CD4, CD8 and NK T cells also contribute to the immunology of this disease. In spite of conflicting reports, the role of regulatory T cells in VL pathogenesis is important. Recently discovered Th17 subset and its different members have been reported to perform diverse functions in the course of VL and leishmaniasis as a whole. Innate immune responses, depending on the cell types, are essential in early parasite detection and subsequent development of an efficient NK cell response. Immunotherapy targeting IL-10 could be looked upon as an interesting option for the treatment of VL.

Interactions between Leishmania mexicana mexicana promastigotes and amastigotes and murine peritoneal macrophages in vitro

Unstimulated adherent mouse peritoneal cells were cultured in vitro and infected with equal numbers of a single strain of Leishmania m. mexicana amastigotes (AM), virulent promastigotes (VP), avirulent promastigotes (AVP) and fixed promastigotes (FP). Duplicate May-Grünwald-Giemsa stained coverslips were examined at time intervals up to 13 days. By 3 hr post infection, the number of macrophages containing parasites varied between 60.5% (VP) and 84% (AM) for macrophages exposed to living parasites, compared to 6.5% for macrophages exposed for FP. However, variable numbers of parasites showed degenerative changes by 3 hr, and the number of macrophages containing morphologically intact parasites varied significantly between cells infected with AM (84%) and those infected with VP (42%) or AVP(40%). The mean number on intacte parasites/macrophage also differed significantly between AM-infected cells and living or fixed promastigotes-infected cells. Quantitation of intact and degenerated parasites indicated parasite multiplication, as well as destruction, in VP-infected cells and parasite survival and multiplication in AM-infecte monolayers; in contrast no evidence of parasite multiplication was seen in AVP-infected cells. Changes in the mono layer itself (cell loss and macrophage vacuolization) were also evaluated. These results suggest that crucial events determining the outcome of infection occur in the host-parasite relationship during the fist 24 hours of infection. These events are apparently influenced not only by parasite or host strain but by environmentally induced variation within a given strain.

Trypanosoma cruzi: effect of phenothiazines on the parasite and its interaction with host cells

Phenothiazines were observed to have a direct effect on Trypanosoma cruzi and on its in vitro interaction with host cells. They caused lysis of trypomastigotes (50 uM/24 h) and,to a lesser extent, epimastigote proliferation. Treatment of infected peritoneal macrophages with 12.5 uM chlorpromazine or triflupromazine inhibited the infection; this effect was found to be partially reversible if the drugs were removed after 24 h of treatment. At 60 uM, the drugs caused damage to amastigotes interiorized in heart muscle cells. However, the narrow margin of toxity between anti-trypanossomal activity and damage to host cells mitigates against in vivo investigation at the present time. Possible hypothesis for the mechanism of action of phenothiazines are discussed.

Interactions between parasites and insects vectors

This review stresses the importance of studies that will provide a basic understanding of the pathology of parasite-infected vector insects. This knowledge should be a vital component of the very focussed initiatives currently being funded in the areas of vector control. Vector fecundity reduction is discussed as an example of such pathology. Underlying mechanisms are being investigated in a model system, Hymenolepis diminuta-infected Tenebrio molitor and in Onchocerca-infected blackflies and Plasmodium-infected Anopheles stephensi. In all cases, host vitellogenesis is disrupted by the parasite and, in the tapeworm/beetle model, interaction between the parasite and the endocrine control of the insect's reproductive physiology has been demonstrated.

Human eosinophil-lymphocyte interactions

While the eosinophil's effector functions clearly can contribute to the pathogenesis of allergic diseases, the evolutionary benefit to having eosinophils as a distinct class of leukocytes is not clear, especially if one must reconsider the nominally beneficial role of eosinophils in parasite host defense. Eosinophils are equipped to respond to lymphocytes and their cytokines (and not solely the eosinophil growth factor cytokines), but the functional consequences of such eosinophil responses need to be defined. Conversely, eosinophils, as antigen-presenting cells (APCs) or sources of lymphocyte-active cytokines, may stimulate and effect lymphocyte functioning. Eosinophils share with CD4+ lymphocytes expression of a number of receptors, including CD4 and IL-2R, and specific alpha4 integrins that may help in their common recruitment and activation. Further, elucidation of the interactions between lymphocytes and eosinophils will contribute to a broader understanding of the functioning of eosinophils in "normal" ongoing immune responses and in allergic disorders.