RESUMO
Alarm signalling is of paramount importance to communication in all social insects. In termites, vibroacoustic and chemical alarm signalling are bound to operate synergistically but have never been studied simultaneously in a single species. Here, we inspected the functional significance of both communication channels in Constrictotermes cyphergaster (Termitidae: Nasutitermitinae), confirming the hypothesis that these are not exclusive, but rather complementary processes. In natural situations, the alarm predominantly attracts soldiers, which actively search for the source of a disturbance. Laboratory testing revealed that the frontal gland of soldiers produces a rich mixture of terpenoid compounds including an alarm pheromone. Extensive testing led to identification of the alarm pheromone being composed of abundant monoterpene hydrocarbons (1S)-α-pinene and myrcene, along with a minor component, (E)-ß-ocimene. The vibratory alarm signalling consists of vibratory movements evidenced as bursts; a series of beats produced predominantly by soldiers. Exposing termite groups to various mixtures containing the alarm pheromone (crushed soldier heads, frontal gland extracts, mixture of all monoterpenes, and the alarm pheromone mixture made of standards) resulted in significantly higher activity in the tested groups and also increased intensity of the vibratory alarm communication, with the responses clearly dose-dependent. Lower doses of the pheromone provoked higher numbers of vibratory signals compared to higher doses. Higher doses induced long-term running of all termites without stops necessary to perform vibratory behaviour. Surprisingly, even crushed worker heads led to low (but significant) increases in the alarm responses, suggesting that other unknown compound in the worker's head is perceived and answered by termites. Our results demonstrate the existence of different alarm levels in termites, with lower levels being communicated through vibratory signals, and higher levels causing general alarm or retreat being communicated through the alarm pheromone.
RESUMO
OBJETIVO: Avaliar a tendência de mortalidade por pneumonia em crianças brasileiras até 4 anos de idade no período de 1991 a 2007. MÉTODOS: Foi realizado um estudo retrospectivo baseado em banco de dados do Departamento de Informática do Sistema Único de Saúde (DATASUS), do qual foram extraídos o número de óbitos por pneumonia e a população residente de até 4 anos de idade nas cinco regiões brasileiras e no país como um todo. O coeficiente de mortalidade foi calculado pelo número de óbitos por pneumonia dividido pela população, multiplicando por 1.000 na faixa etária menor de 1 ano e por 10.000 na faixa etária de 1 a 4 anos. Utilizou-se o teste de regressão linear para avaliar a tendência temporal de mortalidade. RESULTADOS: Observou-se um decréscimo significativo de mortalidade por pneumonia no período estudado em ambas as faixas etárias e em todas as regiões do país. No Brasil como um todo, a redução média anual dos coeficientes de mortalidade na população menor de 1 ano e naquela entre 1 e 4 anos foi de 0,12 e 0,07, respectivamente. As Regiões Sul e Sudeste apresentaram as maiores reduções (-0,14 e -0,18 para < 1 ano; -0,07 e -0,09 para 1 a 4 anos). As menores reduções foram nas Regiões Norte e Nordeste (-0,04 e -0,07) nas crianças menores de 1 ano, e nas Regiões Norte e Centro-Oeste (-0,03 e -0,04) na faixa etária entre 1 e 4 anos. CONCLUSÕES: Houve uma redução significativa na mortalidade por pneumonia em crianças até 4 anos de idade em todo o país no período de 1991 a 2007, porém, uma discrepância entre as diferentes regiões permanece em evidência.
OBJECTIVE: To evaluate the trend of pneumonia mortality in Brazilian children aged 4 years and younger from 1991 to 2007. METHODS: We conducted a retrospective study based on the database of the IT Department of the Brazilian Unified Health System (DATASUS), from which we obtained the number of deaths from pneumonia and the population aged 4 years and younger living in the five Brazilian regions and in the whole country. Mortality rate was calculated according to the number of deaths from pneumonia divided by the population, multiplied by 1,000 for the age group under 1 year old and by 10,000 in the age group from 1 to 4 years. The linear regression test was used to evaluate the time trend of mortality. RESULTS: There was a significant decrease in pneumonia mortality rates during the study period in both age groups and all regions of the country. In Brazil, the mean annual reduction in mortality rates in the population under 1 year old and between 1 and 4 years was 0.12 and 0.07, respectively. The South and Southeast regions showed the greatest reductions (-0.14 and -0.18 for < 1 year and -0.07 and -0.09 for 1 to 4 years). The smallest decreases were in the North and Northeast regions (-0.04 and -0.07) in children younger than 1 year, and in the North and Central West (-0.03 and -0.04) in the age group between 1 and 4 years. CONCLUSIONS: There was a significant reduction in pneumonia mortality in children aged 4 years and younger across the country from 1991 to 2007; however, a discrepancy between the different regions remains evident.
Assuntos
Pré-Escolar , Humanos , Lactente , Pneumonia/mortalidade , Distribuição por Idade , Brasil/epidemiologia , Modelos Lineares , Estudos Retrospectivos , Fatores de TempoRESUMO
OBJECTIVE: To evaluate the trend of pneumonia mortality in Brazilian children aged 4 years and younger from 1991 to 2007. METHODS: We conducted a retrospective study based on the database of the IT Department of the Brazilian Unified Health System (DATASUS), from which we obtained the number of deaths from pneumonia and the population aged 4 years and younger living in the five Brazilian regions and in the whole country. Mortality rate was calculated according to the number of deaths from pneumonia divided by the population, multiplied by 1,000 for the age group under 1 year old and by 10,000 in the age group from 1 to 4 years. The linear regression test was used to evaluate the time trend of mortality. RESULTS: There was a significant decrease in pneumonia mortality rates during the study period in both age groups and all regions of the country. In Brazil, the mean annual reduction in mortality rates in the population under 1 year old and between 1 and 4 years was 0.12 and 0.07, respectively. The South and Southeast regions showed the greatest reductions (-0.14 and -0.18 for < 1 year and -0.07 and -0.09 for 1 to 4 years). The smallest decreases were in the North and Northeast regions (-0.04 and -0.07) in children younger than 1 year, and in the North and Central West (-0.03 and -0.04) in the age group between 1 and 4 years. CONCLUSIONS: There was a significant reduction in pneumonia mortality in children aged 4 years and younger across the country from 1991 to 2007; however, a discrepancy between the different regions remains evident.