Investigation of Rhodnius prolixus head anatomy using microtomography.

In the last years, microtomography has proved to be a powerful technique on insects' studies, allowing a detailed view of the structures' internal with a high resolution. One of the most important advantages about the use of microtomography in these studies is the fact that the dissection is not necessary, which decreases considerably the number of samples used on the insects' research. Some insects are used constantly in studies about morphology, metamorphosis, and reproduction, because they work as a model for others, and Rhodnius prolixus is one of the most studied in this group. This insect is also one of the main insect vectors of Chagas disease that kills around 12,000 people every year in Latin America. Some studies using laboratory microtomography conventional scanners combining with the correct staining methods have proved that it could be a powerful tool in biological research, allowing the visualisation of low-density tissues. The main goal of the present work was to use staining protocols to study Rhodnius prolixus with laboratory microtomography conventional scanners. The experiments were carried out at the imaging lab in the Theoretical Biology Department, University of Vienna, using an Xradia MicroXCT and at the University of Oslo, using a Skyscan 2211.

Late effects of Beauveria bassiana on larval stages of Aedes aegypti Linneo , 1762 (Diptera: Culicidae) / Efeitos tardios de Beauveria bassiana nos estágios larvais de Aedes aegypti Linneo, 1762 (Diptera: Culicidae)

Aedes aegypti is a culicide that has gained relevance over the years due to its ability to transmit various viruses that cause diseases in humans that all the years cause high mortality rates in the world population. The main problem is that Ae. aegypti has managed to establish and maintain a close relationship with humans and their habitat, which is why the search for alternatives to control vector populations becomes imperative. The objective of the present work was to study the effects of two Beauveria bassiana strains on Aedes aegypti. Third instar larvae of Ae. aegypti in 250 mL plastic containers were inoculated with the GHA and NB3 strains at different concentrations (1.5 × 104 , 1.5× 105 , 1.5 × 106 and 1.5 × 107 conidia/mL). The NB3 strain presented highest mortality values with 63% in the highest concentration i.e., 1.5 × 107 , while for the GHA strain the highest mortality value was 30.7% at the same concentration. The results showed significant difference in mortality with respect to the strain and days post treatment (P = 0.0001), but not with respect to the conidial concentration (P = 0.634). The average mortality of larvae per day for the NB3 for different concentrations ranged from 20 to 25 larvae per day, while for the GHA daily mortality ranged from 5 to 12 larvae. In post-treatment mortality, the highest mortality was recorded in the third stage larvae for the NB3, while for GHA the highest percentage mortality was observed in individuals who managed to reach the adult state. The findings of the current research depicted the noteworthy role of B. bassiana for the management of an important vector of human disease.

O Aedes aegypti é um culicida que vem ganhando relevância ao longo dos anos devido à sua capacidade de transmitir diversos vírus causadores de doenças em humanos que ao longo dos anos ocasionam altas taxas de mortalidade na população mundial. O principal problema é que Ae. aegypti tem conseguido estabelecer e manter uma relação próxima com o homem e seu habitat, por isso a busca por alternativas para o controle das populações de vetores torna-se imperativa. O objetivo do presente trabalho foi estudar os efeitos de duas cepas de Beauveria bassiana sobre Ae. aegypti. Larvas de terceiro instar de Ae. aegypti em recipientes plásticos de 250 mL foram inoculados com as cepas GHA e NB3 em diferentes concentrações (1.5 × 104, 1.5 × 105, 1.5 × 106 e 1.5 × 107 conídios/mL). A cepa NB3 apresentou os maiores valores de mortalidade com 63% na concentração mais alta, ou seja, 1.5 × 107, enquanto para a cepa GHA o maior valor de mortalidade foi 30.7% na mesma concentração. Os resultados mostraram diferença significativa na mortalidade com relação à cepa e dias pós-tratamento (P = 0.0001), mas não com relação à concentração de conídios (P = 0.634). A mortalidade média de larvas por dia para o NB3 para diferentes concentrações variou de 20 a 25 larvas por dia, enquanto para o GHA a mortalidade diária variou de 5 a 12 larvas. Na mortalidade pós-tratamento, a maior mortalidade foi registrada nas larvas de terceiro estágio para o NB3, enquanto para o GHA o maior percentual de mortalidade foi observado em indivíduos que conseguiram atingir o estado adulto. Os resultados da pesquisa atual retratam o papel notável de B. bassiana no manejo de um importante vetor de doenças humanas.

Late effects of Beauveria bassiana on larval stages of Aedes aegypti Linneo, 1762 (Diptera: Culicidae) / Efeitos tardios de Beauveria bassiana nos estágios larvais de Aedes aegypti Linneo, 1762 (Diptera: Culicidae)

Aedes aegypti is a culicide that has gained relevance over the years due to its ability to transmit various viruses that cause diseases in humans that all the years cause high mortality rates in the world population. The main problem is that Ae. aegypti has managed to establish and maintain a close relationship with humans and their habitat, which is why the search for alternatives to control vector populations becomes imperative. The objective of the present work was to study the effects of two Beauveria bassiana strains on Aedes aegypti. Third instar larvae of Ae. aegypti in 250 mL plastic containers were inoculated with the GHA and NB3 strains at different concentrations (1.5 × 104, 1.5× 105, 1.5 × 106 and 1.5 × 107 conidia/mL). The NB3 strain presented highest mortality values with 63% in the highest concentration i.e., 1.5 × 107, while for the GHA strain the highest mortality value was 30.7% at the same concentration. The results showed significant difference in mortality with respect to the strain and days post treatment (P = 0.0001), but not with respect to the conidial concentration (P = 0.634). The average mortality of larvae per day for the NB3 for different concentrations ranged from 20 to 25 larvae per day, while for the GHA daily mortality ranged from 5 to 12 larvae. In post-treatment mortality, the highest mortality was recorded in the third stage larvae for the NB3, while for GHA the highest percentage mortality was observed in individuals who managed to reach the adult state. The findings of the current research depicted the noteworthy role of B. bassiana for the management of an important vector of human disease.

O Aedes aegypti é um culicida que vem ganhando relevância ao longo dos anos devido à sua capacidade de transmitir diversos vírus causadores de doenças em humanos que ao longo dos anos ocasionam altas taxas de mortalidade na população mundial. O principal problema é que Ae. aegypti tem conseguido estabelecer e manter uma relação próxima com o homem e seu habitat, por isso a busca por alternativas para o controle das populações de vetores torna-se imperativa. O objetivo do presente trabalho foi estudar os efeitos de duas cepas de Beauveria bassiana sobre Ae. aegypti. Larvas de terceiro instar de Ae. aegypti em recipientes plásticos de 250 mL foram inoculados com as cepas GHA e NB3 em diferentes concentrações (1.5 × 104, 1.5 × 105, 1.5 × 106 e 1.5 × 107 conídios/mL). A cepa NB3 apresentou os maiores valores de mortalidade com 63% na concentração mais alta, ou seja, 1.5 × 107, enquanto para a cepa GHA o maior valor de mortalidade foi 30.7% na mesma concentração. Os resultados mostraram diferença significativa na mortalidade com relação à cepa e dias pós-tratamento (P = 0.0001), mas não com relação à concentração de conídios (P = 0.634). A mortalidade média de larvas por dia para o NB3 para diferentes concentrações variou de 20 a 25 larvas por dia, enquanto para o GHA a mortalidade diária variou de 5 a 12 larvas. Na mortalidade pós-tratamento, a maior mortalidade foi registrada nas larvas de terceiro estágio para o NB3, enquanto para o GHA o maior percentual de mortalidade foi observado em indivíduos que conseguiram atingir o estado adulto. Os resultados da pesquisa atual retratam o papel notável de B. bassiana no manejo de um importante vetor de doenças humanas.

Late effects of Beauveria bassiana on larval stages of Aedes aegypti Linneo, 1762 (Diptera: Culicidae)

Abstract Aedes aegypti is a culicide that has gained relevance over the years due to its ability to transmit various viruses that cause diseases in humans that all the years cause high mortality rates in the world population. The main problem is that Ae. aegypti has managed to establish and maintain a close relationship with humans and their habitat, which is why the search for alternatives to control vector populations becomes imperative. The objective of the present work was to study the effects of two Beauveria bassiana strains on Aedes aegypti. Third instar larvae of Ae. aegypti in 250 mL plastic containers were inoculated with the GHA and NB3 strains at different concentrations (1.5 × 104, 1.5× 105, 1.5 × 106 and 1.5 × 107 conidia/mL). The NB3 strain presented highest mortality values with 63% in the highest concentration i.e., 1.5 × 107, while for the GHA strain the highest mortality value was 30.7% at the same concentration. The results showed significant difference in mortality with respect to the strain and days post treatment (P = 0.0001), but not with respect to the conidial concentration (P = 0.634). The average mortality of larvae per day for the NB3 for different concentrations ranged from 20 to 25 larvae per day, while for the GHA daily mortality ranged from 5 to 12 larvae. In post-treatment mortality, the highest mortality was recorded in the third stage larvae for the NB3, while for GHA the highest percentage mortality was observed in individuals who managed to reach the adult state. The findings of the current research depicted the noteworthy role of B. bassiana for the management of an important vector of human disease.

Resumo O Aedes aegypti é um culicida que vem ganhando relevância ao longo dos anos devido à sua capacidade de transmitir diversos vírus causadores de doenças em humanos que ao longo dos anos ocasionam altas taxas de mortalidade na população mundial. O principal problema é que Ae. aegypti tem conseguido estabelecer e manter uma relação próxima com o homem e seu habitat, por isso a busca por alternativas para o controle das populações de vetores torna-se imperativa. O objetivo do presente trabalho foi estudar os efeitos de duas cepas de Beauveria bassiana sobre Ae. aegypti. Larvas de terceiro instar de Ae. aegypti em recipientes plásticos de 250 mL foram inoculados com as cepas GHA e NB3 em diferentes concentrações (1.5 × 104, 1.5 × 105, 1.5 × 106 e 1.5 × 107 conídios/mL). A cepa NB3 apresentou os maiores valores de mortalidade com 63% na concentração mais alta, ou seja, 1.5 × 107, enquanto para a cepa GHA o maior valor de mortalidade foi 30.7% na mesma concentração. Os resultados mostraram diferença significativa na mortalidade com relação à cepa e dias pós-tratamento (P = 0.0001), mas não com relação à concentração de conídios (P = 0.634). A mortalidade média de larvas por dia para o NB3 para diferentes concentrações variou de 20 a 25 larvas por dia, enquanto para o GHA a mortalidade diária variou de 5 a 12 larvas. Na mortalidade pós-tratamento, a maior mortalidade foi registrada nas larvas de terceiro estágio para o NB3, enquanto para o GHA o maior percentual de mortalidade foi observado em indivíduos que conseguiram atingir o estado adulto. Os resultados da pesquisa atual retratam o papel notável de B. bassiana no manejo de um importante vetor de doenças humanas.

Late effects of Beauveria bassiana on larval stages of Aedes aegypti Linneo, 1762 (Diptera: Culicidae) / Efeitos tardios de Beauveria bassiana nos estágios larvais de Aedes aegypti Linneo, 1762 (Diptera: Culicidae)

Aedes aegypti is a culicide that has gained relevance over the years due to its ability to transmit various viruses that cause diseases in humans that all the years cause high mortality rates in the world population. The main problem is that Ae. aegypti has managed to establish and maintain a close relationship with humans and their habitat, which is why the search for alternatives to control vector populations becomes imperative. The objective of the present work was to study the effects of two Beauveria bassiana strains on Aedes aegypti. Third instar larvae of Ae. aegypti in 250 mL plastic containers were inoculated with the GHA and NB3 strains at different concentrations (1.5 × 104, 1.5× 105, 1.5 × 106 and 1.5 × 107 conidia/mL). The NB3 strain presented highest mortality values with 63% in the highest concentration i.e., 1.5 × 107, while for the GHA strain the highest mortality value was 30.7% at the same concentration. The results showed significant difference in mortality with respect to the strain and days post treatment (P = 0.0001), but not with respect to the conidial concentration (P = 0.634). The average mortality of larvae per day for the NB3 for different concentrations ranged from 20 to 25 larvae per day, while for the GHA daily mortality ranged from 5 to 12 larvae. In post-treatment mortality, the highest mortality was recorded in the third stage larvae for the NB3, while for GHA the highest percentage mortality was observed in individuals who managed to reach the adult state. The findings of the current research depicted the noteworthy role of B. bassiana for the management of an important vector of human disease.(AU)

O Aedes aegypti é um culicida que vem ganhando relevância ao longo dos anos devido à sua capacidade de transmitir diversos vírus causadores de doenças em humanos que ao longo dos anos ocasionam altas taxas de mortalidade na população mundial. O principal problema é que Ae. aegypti tem conseguido estabelecer e manter uma relação próxima com o homem e seu habitat, por isso a busca por alternativas para o controle das populações de vetores torna-se imperativa. O objetivo do presente trabalho foi estudar os efeitos de duas cepas de Beauveria bassiana sobre Ae. aegypti. Larvas de terceiro instar de Ae. aegypti em recipientes plásticos de 250 mL foram inoculados com as cepas GHA e NB3 em diferentes concentrações (1.5 × 104, 1.5 × 105, 1.5 × 106 e 1.5 × 107 conídios/mL). A cepa NB3 apresentou os maiores valores de mortalidade com 63% na concentração mais alta, ou seja, 1.5 × 107, enquanto para a cepa GHA o maior valor de mortalidade foi 30.7% na mesma concentração. Os resultados mostraram diferença significativa na mortalidade com relação à cepa e dias pós-tratamento (P = 0.0001), mas não com relação à concentração de conídios (P = 0.634). A mortalidade média de larvas por dia para o NB3 para diferentes concentrações variou de 20 a 25 larvas por dia, enquanto para o GHA a mortalidade diária variou de 5 a 12 larvas. Na mortalidade pós-tratamento, a maior mortalidade foi registrada nas larvas de terceiro estágio para o NB3, enquanto para o GHA o maior percentual de mortalidade foi observado em indivíduos que conseguiram atingir o estado adulto. Os resultados da pesquisa atual retratam o papel notável de B. bassiana no manejo de um importante vetor de doenças humanas.(AU)

Diagnostico de Chagas Congénito en el Hospital de Niños "Sor María Ludovica" / Diagnosis of Congenital Chagas in the Children's Hospital "Sor María Ludovica"

Introducción:La transmisión congénita de Trypanosoma cruzi constituye, en la actualidad, la vía que genera mayor cantidad de nuevos casos de infección aguda. El diagnóstico y tratamiento temprano aseguran una elevada probabilidad de cura parasitológica. El objetivo del trabajo fue evaluar el seguimiento de potenciales casos de Chagas Congénito, estimar la tasa de transmisión materno-fetal y la capacidad diagnóstica del microhematocrito. Materiales y métodos: Se realizó un estudio descriptivo transversal sobre hijos de mujeres con Chagas, que concurrieron al Laboratorio Central del H.I.A.E.P. Sor María Ludovica durante abril 2013-febrero 2019. Los niños fueron estudiados por microhematocrito y pruebas serológicas. Los resultados se obtuvieron del Sistema Informático de Laboratorio de Wiener®. Resultados: En el período de tiempo evaluado, fueron estudiados por microhematocrito un total de 268 niños (edad promedio= 2,35 meses), obteniéndose 16 resultados positivos. De los 252 niños con microhematocrito negativo, 58 fueron seguidos por pruebas serológicas hasta el año de vida, obteniéndose 3 resultados positivos. Se evidenció una pérdida de seguimiento serológico del 77%. La tasa de transmisión congénita estimada fue del 6,9% y el porcentaje de detección diagnóstica de la técnica directa, del 84,2%. Conclusión: La búsqueda de infección congénita en hijos de mujeres con Chagas, y su seguimiento hasta el año de vida, resulta esencial para lograr la detección y tratamiento temprano de nuevos casos. Sin embargo, la pérdida de seguimiento de potenciales casos de Chagas Congénito resulta alarmante. Esto enfatiza la necesidad de plantear estrategias sólidas para mejorar la aplicación del algoritmo diagnóstico

Introduction:Congenital Trypanosoma cruzi transmission is currently the route that generates the largest number of new cases of acute infection. Early diagnosis and treatment ensure a high probability of parasitological cure. The aim of this article was to evaluate the follow-up of possible cases of Congenital Chagas, to estimate the maternal-fetal transmission rate and the diagnostic capacity of microhematocrit. Materials and methods: A cross-sectional descriptive study was carried out on children born from Chagasic women, who attended the Central Laboratory of the H.I.A.E.P Sor María Ludovica during April 2013-February 2019. The children were studied by microhematocrit and serological tests. The results were obtained from the Wiener® Laboratory Information System. Results: In the evaluated time period, a total of 268 children (mean age = 2.35 months) were studied by microhematocrit, obtaining 16 positive results. Among the 252 children with negative microhematocrit, 58 were followed by serological tests up to one year of life, obtaining 3 positive results. A 77% loss of serological follow-up was evidenced. The estimated congenital transmission rate was 6.9% and the percentage of diagnostic detection of the direct technique was 84.2%. Conclusion: The search for congenital infection in children born from Chagasic women, and its follow-up until one year of life, is essential to achieve the early detection and treatment of new cases. However, the loss of follow-up of potential cases of Congenital Chagas is alarming. This emphasizes the need to propose solid strategies to improve the application of the diagnostic algorithm

Late effects of Beauveria bassiana on larval stages of Aedes aegypti Linneo , 1762 (Diptera: Culicidae).

Aedes aegypti is a culicide that has gained relevance over the years due to its ability to transmit various viruses that cause diseases in humans that all the years cause high mortality rates in the world population. The main problem is that Ae. aegypti has managed to establish and maintain a close relationship with humans and their habitat, which is why the search for alternatives to control vector populations becomes imperative. The objective of the present work was to study the effects of two Beauveria bassiana strains on Aedes aegypti. Third instar larvae of Ae. aegypti in 250 mL plastic containers were inoculated with the GHA and NB3 strains at different concentrations (1.5 × 104, 1.5× 105, 1.5 × 106 and 1.5 × 107 conidia/mL). The NB3 strain presented highest mortality values ​​with 63% in the highest concentration i.e., 1.5 × 107, while for the GHA strain the highest mortality value was 30.7% at the same concentration. The results showed significant difference in mortality with respect to the strain and days post treatment (P = 0.0001), but not with respect to the conidial concentration (P = 0.634). The average mortality of larvae per day for the NB3 for different concentrations ranged from 20 to 25 larvae per day, while for the GHA daily mortality ranged from 5 to 12 larvae. In post-treatment mortality, the highest mortality was recorded in the third stage larvae for the NB3, while for GHA the highest percentage mortality was observed in individuals who managed to reach the adult state. The findings of the current research depicted the noteworthy role of B. bassiana for the management of an important vector of human disease.

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 0.05mg of triflumuron were applied directly to the abdomen on half of the insects immediately after feeding. The insects were sacrificed 25days 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.

Análisis de los pacientes que reconsultaron a un servicio de emergencias pediátricas de un hospital materno infantil como indicador de calidad asistencial / Analysis of patients who consulted for a second time at a pediatric emergency department at a mother-and-child hospital as a marker of quality of care

Objetivos: 1) Analizar las reconsultas (RC) de pacientes a las 72 horas de su primera consulta en el Servicio de Emergencias Pediatría (SEP) de un hospital materno infantil del conurbano bonaerense. 2) Comparar las reconsultas entre dos periodos, luego de implementar mejoras en los procesos asistenciales y de contrarreferencia. Materiales y Metodos: Diseño: retrospectivo, observacional y transversal. Criterios de inclusión: pacientes de 30 días a 15 años de edad, que reconsultaron en el SEP del 01/01 al 31/03 de los años 2010 y 2014. Resultados: Las consultas que se atendieron en el periodo de estudio fueron: 14.003 en 2010 y 13.011 en 2014. Los diagnósticos más frecuentes fueron: infección respiratoria aguda alta (19.2%), fiebre (13%) y diarrea/ gastroenteritis (13.3%). Hubo 7.11% (n=966) de RC en el 2010 y 12.21% (n=1589) en el 2014. La mediana de edad de los pacientes con RC fue 24 meses en ambos años. Los motivos de RC más frecuentes fueron: persistencia de los síntomas (41% y 53.67%); progresión de la enfermedad (25% y 11.43%); otros diagnósticos nuevos (14.07% y 19.5%) y control (14% y 8.3%). Las RC de los domiciliados en San Isidro fueron 72.97% (n=694) en el 2010 y 69.32% (n=1071) en el 2014 del total de RC. La disminución de las RC observada al comparar ambos períodos es estadísticamente no significativa. (Pearson chi2 2.4506, p = 0.117). Conclusiones: 1) Los principales motivos de consulta fueron fiebre, diarrea y patología de la vía aérea superior. 2) Las RC dentro de las primeras 72 horas fueron 7% en 2010 y 12.9% en 2014. 3) La mayoría de los niños que concurren por RC lo hacen por la persistencia de síntomas de procesos que revisten poca gravedad. 4) Hubo una leve disminución, estadísticamente no significativa, de la RC de los pacientes domiciliados en San Isidro (AU)

Aims: 1) To analyze second consultations (SC) in patients within 72 hours of the first consultation at the Pediatric Emergency Department (PED) of a mother-and-child hospital in Greater Buenos Aires. 2) To compare SC between two time periods, after implementing a program of care and counter-referral. Material and Methods: Study design: a retrospective, observational, and cross-sectional study was conducted. Inclusion criteria: patients between 30 days of life and 15 years of age, who consulted at the PED between 01/01 and 31/03 from 2010 to 2014. Results: Patients seen during the study period were: 14,003 in 2010 and 13,011 in 2014. The most common diagnoses were: Acute upper respiratory infection (19.2%), fever (13%) and diarrhea/gastroenteritis (13.3%). SC were 7.11% (n=966) in 2010 and 12.21% (n=1589) in 2014. Median age of patients with a SC was 24 months in both years. Most common reasons for SC were persistent symptoms (41% and 53.67%); disease progression (25% and 11.43%); new diagnosis (14.07% and 19.5%) and control (14% and 8.3%). Home visits for SC in San Isidro were 72.97% (n=694) in 2010 and 69.32% (n=1071) in 2014 of all SC. The decrease in SC when comparing both periods was not statistically significant (Pearson chi2 2.4506, p = 0.117). Conclusions: 1) The main reasons for consult were fever, diarrhea, and upper airway infections. 2) SC within 72 hours were 7% in 2010 and 12.9% in 2014. 3) The majority of childrenwho were seen in a SC had persistent symptoms that were not severe. 4) A slight decrease, that was not statistically significant, was observed in SC of patients seen in the area of San Isidro (AU)

Zanthoxylum caribaeum (Rutaceae) essential oil: chemical investigation and biological effects on Rhodnius prolixus nymph.

A chemical investigation and bioassays against fifth-instar nymphae of the hematophagous insect Rhodnius prolixus, vector of Chagas disease, were conducted with the essential oil from Zanthoxylum caribaeum. The main results may be summarized as follows: (i) 54 components were identified, corresponding to 90.4% of the relative composition; sesquiterpenes (47.3%) and monoterpenes (41.2%) are the major constituents; (ii) muurola-4,5-trans-diene and isodaucene are described for the first time as chemical constituents of the essential oil from leaves of this species; (iii) topical treatment with the crude essential oil induced high levels of paralysis (from 18.88 to 33.33%) and mortality (from 80 to 98.9%) depending on the dose applied (0.5 to 5.0 µl per insect); (iv) feeding treatment with the crude essential oil also induced high levels of mortality (from 48.8 to 100%) but low levels of paralysis (from 2.22 to 7.77%) depending on the dose applied (0.5 to 5.0 µl/ml of blood); (v) in the continuous treatment, only the dose of 5.0 µl/cm(2) was able to promote statistical significant levels of mortality (63.3%) but no paralysis were detected. However in this group, occasionally, only few insects displayed malformations of legs and wings after treatment; and (vi) any treatment was able to disrupt the metamorphosis process since the low adult stage emergence observed to all groups was due the high insect mortality. These observations suggest the interference of Z. caribaeum compounds on the triatomine neuroendocrine system. The significance of these results in relation to the relevant biological events in R. prolixus as well as the possible use of insect growth regulators present in Z. caribaeum oil in integrated vector control programs against hematophagous triatomine species is herein discussed.

Trypanosoma cruzi: effects of azadirachtin and ecdysone on the dynamic development in Rhodnius prolixus larvae.

The effects of azadirachtin and ecdysone on the Trypanosoma cruzi population in the Rhodnius prolixus gut were investigated. T. cruzi were rarely found in the gut compartments of azadirachtin-treated larvae. High parasite numbers were observed in the stomach of the control and ecdysone groups until 10 days after treatment and in the small intestine and rectum until 25 days after treatment. High percentages of round forms developed in the stomachs of all groups, whereas azadirachtin blocked the development of protozoan intermediate forms. This effect was counteracted by ecdysone therapy. In the small intestine and rectum, epimastigotes predominated for all groups, but more of their intermediates developed in the control and ecdysone groups. Azadirachtin supported the development of round forms and their intermediates into trypomastigotes. In the rectum, trypomastigotes did not develop in the azadirachtin group and developed much later after ecdysone therapy. The parallel between the effects of azadirachtin and ecdysone on the host and parasite development is discussed on the basis of the present results because ecdysone appears to act directly or indirectly in determining the synchronic development of T. cruzi forms from round to epimastigotes, but not metacyclic trypomastigotes, in the invertebrate vector.

Trypanosoma cruzi heparin-binding proteins mediate the adherence of epimastigotes to the midgut epithelial cells of Rhodnius prolixus.

Heparin-binding proteins (HBPs) have been demonstrated in both infective forms of Trypanosoma cruzi and are involved in the recognition and invasion of mammalian cells. In this study, we evaluated the potential biological function of these proteins during the parasite-vector interaction. HBPs, with molecular masses of 65·8 kDa and 59 kDa, were isolated from epimastigotes by heparin affinity chromatography and identified by biotin-conjugated sulfated glycosaminoglycans (GAGs). Surface plasmon resonance biosensor analysis demonstrated stable receptor-ligand binding based on the association and dissociation values. Pre-incubation of epimastigotes with GAGs led to an inhibition of parasite binding to immobilized heparin. Competition assays were performed to evaluate the role of the HBP-GAG interaction in the recognition and adhesion of epimastigotes to midgut epithelial cells of Rhodnius prolixus. Epithelial cells pre-incubated with HBPs yielded a 3·8-fold inhibition in the adhesion of epimastigotes. The pre-treatment of epimastigotes with heparin, heparan sulfate and chondroitin sulfate significantly inhibited parasite adhesion to midgut epithelial cells, which was confirmed by scanning electron microscopy. We provide evidence that heparin-binding proteins are found on the surface of T. cruzi epimastigotes and demonstrate their key role in the recognition of sulfated GAGs on the surface of midgut epithelial cells of the insect vector.

Laboratory evaluation of the effects of triflumuron on the development of Rhodnius prolixus nymph

Studies were carried out to evaluate the efficacy of the growth regulator, triflumuron (TFM) (Starycide® sc 480 Bayer), for disrupting the development of Rhodnius prolixus fifth-instar nymph by oral, topical or continuous treatment. All treatments were able to induce high levels of mortality, delay development and molt inhibition. Oral treatment induced molt inhibition in all insects that survived at doses of 0.25, 0.50 and 5.0 mg/mL of a blood meal. The highest levels of both mortality in 24 h and molt inhibition were always observed after topical treatment. The lowest doses needed to obtain considerable biological effects were always observed after continuous treatment. In this way, the highest levels of mortality within 30 days were detected after continuous treatment, which also induced an extended inter-molting period, a lower number of over-aged nymphs and the highest level of molting in nymphs that survived. Moreover, the effects of TFM on insects were often displayed in a dose response manner. These results indicate that TFM acts as a potent growth inhibitor of R. prolixus nymphs and has the potential to be used in integrated vector control programs against hematophagous triatomine species.

Laboratory evaluation of the effects of triflumuron on the development of Rhodnius prolixus nymph.

Studies were carried out to evaluate the efficacy of the growth regulator, triflumuron (TFM) (Starycide sc 480 Bayer), for disrupting the development of Rhodnius prolixus fifth-instar nymph by oral, topical or continuous treatment. All treatments were able to induce high levels of mortality, delay development and molt inhibition. Oral treatment induced molt inhibition in all insects that survived at doses of 0.25, 0.50 and 5.0 mg/mL of a blood meal. The highest levels of both mortality in 24 h and molt inhibition were always observed after topical treatment. The lowest doses needed to obtain considerable biological effects were always observed after continuous treatment. In this way, the highest levels of mortality within 30 days were detected after continuous treatment, which also induced an extended inter-molting period, a lower number of over-aged nymphs and the highest level of molting in nymphs that survived. Moreover, the effects of TFM on insects were often displayed in a dose response manner. These results indicate that TFM acts as a potent growth inhibitor of R. prolixus nymphs and has the potential to be used in integrated vector control programs against hematophagous triatomine species.

Trypanosoma cruzi: attachment to perimicrovillar membrane glycoproteins of Rhodnius prolixus.

Studies were carried out to identify proteins involved in the interface of Trypanosoma cruzi with the perimicrovillar membranes (PMM) of Rhodnius prolixus. Video microscopy experiments demonstrated high level of adhesion of T. cruzi Dm 28c epimastigotes to the surface of posterior midgut cells of non-treated R. prolixus. The parasites however were unable to attach to gut cells obtained from decapitated or azadirachtin-treated insects. The influence of carbohydrates on the adhesion to insect midgut was confirmed by inhibition of parasite attachment after midgut incubation with N-acetylgalactosamine, N-acetylmannosamine, N-acetylglucosamine, D-galactose, D-mannose or sialic acid. We observed that hydrophobic proteins in the surface of epimastigotes bind to polypeptides with 47.7, 45.5, 44, 43, 40.5, 36, 31 and 13kDa from R. prolixus PMM and that pre-incubation of lectins specifically inhibited binding to 31, 40.5, 44 and 45.5kDa proteins. We suggest that glycoproteins from PMM and hydrophobic proteins from epimastigotes are important for the adhesion of the parasite to the posterior midgut cells of the vector.

First Report of Powdery Mildew on Tomato Caused by Oidium neolycopersici in Venezuela.

During 2004 and 2005, a powdery mildew was observed in tomato (Lycopersicon esculentum Mill. cv. Rio Grande) fields in several states in Venezuela. Symptoms included development of patches of dense white mycelium, predominantly on the upper leaf surface. Leaves in the middle and lower canopies were the most affected. Similar symptoms sometimes were observed on stems. The foliage of infected plants turned yellow and showed necrosis followed by desiccation and rapid defoliation. Microscopic examination revealed the presence of typical structures of the Oidium genus. Hyphae were hyaline and septate. Conidiophores were unbranched, erect, measured 51 to 108 (80) µm, and consisted of 3 or 4 cells. Conidia were hyaline, ellipsoidal to ovoidal, and measured 16 to 43 (30) × 12 to 22 (16) µm. Conidia were produced singly, without fibrosin bodies. Conidial polar germination was common. Appressoria were lobed. The sexual stage was not found. The fungus was identified as Oidium neolycopersici, recently recognized as a distinct species (1,2). Conidia from infected tomato leaves were shaken onto leaves of 10 plants of L. esculentum and L. pimpinellifolium (Jusl.) Mill. and five plants of a weed (Physalis peruviana L.). Noninoculated plants served as a control. Symptoms that developed on all inoculated plants were similar to those of plants naturally infected. Within 7 to 8 days, symptoms in L. esculentum consisted of small colonies that quickly covered large portions of foliar tissue. L. pimpinellifolium showed small and localized symptoms after 10 days and P. peruviana showed symptoms after 15 days. To our knowledge, this is the first report of O. neolycopersici in Venezuela. References: (1) H. Jones et al. Mol. Plant Pathol. 2:303, 2001. (2) L. Kiss et al. Mycol. Res. 105:684, 2001.

First Report of Exserohilum rostratum Associated with Rice Seed in Venezuela.

Rice (Oryza sativa L.) is an important cereal crop in Venezuela and is planted on approximately 200,000 ha. Fungal diseases caused by the Helminthosporium complex of fungi are considered a major constraint to rice production. In 2005, a blotter method was used to identify fungi associated with rice seed. Seeds (150) of cv. INIA-017 were placed on a plate with moistened filter paper and incubated at 26 ± 2°C with a 12-h light/12-h dark cycle for 5 days until fungal sporulation. Single spores were transferred to 2% water agar (WA). Germinated spores were then transferred to potato dextrose agar (PDA), and resultant colonies were preserved until used. To induce sporulation, 4-mm-diameter discs were cut from 72-h-old cultures, transferred to WA, and incubated at 26 ± 2°C for 48 h (modified technique of Alcorn [1]). Discolored seed yielded isolates of Bipolaris oryzae (Berda de Haan) Shoemaker and Exserohilum rostratum (Drechs.) Leonard and Suggs (2). Pathogenicity tests were performed on 60-day-old rice plants of cv. Blue Bonnet 50. Four plants per pot were used for each isolate. Before inoculation, plants were placed in humidity chambers for 48 h. Spores were harvested from discs into a beaker containing 50 mL of a dilute gelatin solution (Gelatin Difco; 5 g/100 mL of sterile distilled water [SDW]). Spore suspensions were filtered through cheesecloth and adjusted to 7 × 104 spores per ml. The inoculated plants were placed in humidity chambers for 72 h. Control plants were sprayed with SDW. Inoculated plants were removed from humidity chambers and placed on a greenhouse bench. Plants inoculated with B. oryzae were symptomatic 5 days after inoculation; resultant lesions were red-brown with chlorotic borders. Lesions subsequently turned gray with reddish borders and were rhombic in shape. Plants inoculated with E. rotratum were symptomatic 7 days after inoculation with elliptical lesions that were orange-brown along venation. These lesions turned gray with reddish borders. Both fungi were reisolated from symptomatic leaf tissue. To our knowledge, this is the first report of E. rostratum from rice in Venezuela. References: (1) J. L. Alcorn. Mycotaxon. 17:1, 1983. (2) A. Sivanesam. Mycol. Pap. 158, 1987.

Antiserum against perimicrovillar membranes and midgut tissue reduces the development of Trypanosoma cruzi in the insect vector, Rhodnius prolixus.

Antiserum raised against Rhodnius prolixus perimicrovillar membranes (PMM) and midgut tissue interfered with the midgut structural organization and reduced the development of Trypanosoma cruzi in the R. prolixus insect vector. SDS-PAGE and Western blot analyses confirmed the specific recognition of midgut proteins by the antibody. Feeding, mortality, molt, and oviposition of the insects were unaffected by feeding with the antiserum. However, the eclosion of the eggs were reduced from R. prolixus females treated with antiserum. Additionally, in vivo evaluation showed that after oral treatment with the antiserum, the intensity of infection with the Dm-28c clone of T. cruzi decreased in the digestive tract of fifth-instar nymphs and in the excretions of R. prolixus adults. These results suggest that the changes observed in the PMM organization in the posterior midgut of R. prolixus may not be important for triatomine survival but the antiserum acts as a transmission-reduction vaccine able to induce significant decreases in T. cruzi infection in the vector.

Effect of troglitazone on the desaturases in a rat model of insulin-resistance induced by a sucrose-rich diet.

A sucrose-rich diet generates time-dependent metabolic disorders similar to those found in diabetes type 2. After 8 month (mo) this diet evoked in the rat an increase of blood glucose, free fatty acids (FFA) and triacylycerides (TG) without insulin modification, an interruption of liver stearoyl-CoA desaturase-1 (SCD-1) mRNA and activity increase found at 6 mo, and an enhacement of Delta6 and Delta5 desaturase mRNA and Delta6 activity. We found that the administration of troglitazone (TRO), a peroxisome-proliferator-activated receptors gamma (PPAR-gamma) agonist, for 2 mo normalized plasma FFA, TG, and glucose without altering the insulinemia. It depressed liver SCD-1 mRNA in both control and sucrose-fed rats, decreasing the 18:1n-9/18:0 ratio in serum and liver lipids, and eliminated the increasing effect on mRNA and activity of Delta6 and Delta5 desaturases. These findings evidence again that desaturases are not affected through an insulin resistant effect evoked by the sucrose-rich diet and TRO recovers the altered metabolic plasma parameters as it corresponds to a PPAR-gamma agonist, but its effect on hepatic desaturases can not be attributed to a direct action on liver by PPAR-gamma, insulin, and even by an insulin sensitizing mechanism, suggesting it would be evoked indirectly through hepatic PPAR-alpha deactivation induced by the FFA decrease.

First Report of Guignardia psidii, an Ascigerous State of Phyllosticta psidiicola, Causing Fruit Rot on Guava in Venezuela.

During August 2003, guava fruit (Psidium guajava L.) cv. Red Dominicana from Cojedes state in Venezuela showed circular, purple-to-brown lesions (0.5 to 1.0 cm) that spread over all surfaces and became black and shrunken on severely affected fruit. Symptomatic tissues were plated aseptically on potato dextrose agar (PDA). Colonies that were initially gray and turned black with age were consistently isolated. The fungus was characterized by dense, submerged, brown-to-black mycelium with septate hyphae. Ascocarps were perithecial, abundant, granulose, subglobose to cylindric obpyriform, solitary or aggregated, mostly unilocular with prominent long necks; ascocarp walls were stromatic, composed of several layers of cells, thick walled, and deeply pigmented on the outside. Asci were subclavate to cylindrical, stipitate, 44 to 84 × 7 to 9 µm, and eight-spored; asci walls were thick and bitunicate. Ascospores were unicellular, hyaline, guttulate, fusiform ellipsoid, widest in the mid-region with rounded ends and gelatinous plugs, and 12 to 17 × 4.5 µm. Conidiomata were pycnidial, intermixed among ascocarps, variable in shape, dark brown, solitary or aggregated, ostiolate, and with long necks up to 1 mm. Pycnidial walls were pseudoparenchymatic, multicellular, and composed of many layers of brown compressed cells. Conidiogenous cells were hyaline, subglobose to cylindrical, and smooth, and holoblastic. Conidia were hyaline, unicellular, obovate, 6 to 12 (7.5) × 5 to 8 µm, slightly truncate at the bases, rounded at apices, guttulate, and provided a gelatinous envelope and apical appendage. Appendages were hyaline, tubular, smooth, and 3.0 to 4.5 × 0.5 µm. The fungus is homothallic because single ascospores and single conidia developed ascigerous states. The ascigerous state was identified as Guignardia psidii (1) and the anamorph as Phyllosticta psidiicola (1,2). Pathogenicity tests were conducted on detached fruits inoculated with monosporic cultures. Pathogenesis and symptom development only occurred when a mixture of mycelium, ascospores, and conidia was used as inoculum. The fungus was reisolated from symptomatic fruit tissues. To our knowledge, this is the first report of Guignardia psidii, an ascigerous state of Phyllosticta psidiicola from guava fruits in Venezuela. References: (1) B. A. Ullasa and R. D. Rawal. Curr. Sci. 53:435, 1984. (2) H. A. van der Aa. Page 95 in: No. 5, Stud. Mycol., 1973.