ABSTRACT
Among the plants defense mechanisms, the induction and emission of volatile organic compounds, which can be used to attract natural enemies, such predators insects. Although well studied, the induction of plant volatiles that attract natural enemies can vary according to intensity of infestation of herbivores and the species of host plant. We investigated the olfactory behavioral responses of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) to the volatiles of infested maize (Zea mays) plants by the two-spotted spider mite Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae) in early and advanced infestations. The Bt (Viptera) maize cultivar Impact® was used for tests the behavior of N. californicus. After initial and advanced infestations, the phytophagous mites T. urticae were removed, and the plants were tested using a "Y" olfactometer. The following treatments were evaluated: air vs. air, uninfested plants vs. air, uninfested plants vs. plants infested with 10 females of T. urticae, uninfested plants vs. plants infested with 100 females of T. urticae, uninfested plants vs. plants infested with 200 females of T. urticae and plants infested with 10 vs. plants infested with 200 females of T. urticae. The predatory mite N. californicus did not show preference to the treatments tested, suggesting that maize plants infested by T. urticae do not induce volatiles capable of attracting the predatory mite N. californicus. We concluded that N. californicus is not attracted by maize plants infested by T. urticae.
Dentre os mecanismos de defesa de plantas, a indução e emissão de compostos orgânicos voláteis, podem ser utilizados para atrair inimigos naturais, como insetos predadores. Embora bem estudada, a indução dos voláteis de plantas que atraem inimigos naturais pode variar de acordo com a intensidade de infestação de herbívoros e a espécie de planta hospedeira. Investigamos as respostas comportamentais olfativas do ácaro predador Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) aos voláteis de plantas infestadas pelo ácaro-rajado Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae). A cultivar de milho Bt (Viptera) Impact® foi utilizada para testar o comportamento de N. californicus. Após infestações iniciais e avançadas, os ácaros fitófagos T. urticae foram removidos e as plantas testadas em olfatômetro "Y". Os seguintes tratamentos foram avaliados: ar vs. ar, plantas não infestadas vs. ar, plantas não infestadas vs. plantas infestadas com 10 fêmeas de T. urticae, plantas não infestadas vs. plantas infestadas com 100 fêmeas de T. urticae, plantas não infestadas vs. plantas infestadas com 200 fêmeas de T. urticae e plantas infestadas com 10 vs. plantas infestadas com 200 fêmeas de T. urticae. O ácaro predador N. californicus não mostrou preferência aos tratamentos testados, sugerindo que plantas de milho infestadas por T. urticae não induzem voláteis capazes de atrair o ácaro predador N. californicus. Concluímos que N. californicus não é atraído por plantas de milho infestadas por T. urticae.
Subject(s)
Animals , Female , Tetranychidae , Acari , Mites , Predatory Behavior , Smell , Zea maysABSTRACT
Galls, neo-formed plant structures that can occur in different organs, are generated by species-specific interaction with an inducing organism. Inducers manipulate the metabolism of its host. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. is a Neotropical epiphytic fern that hosted two stem galls, one induced by a midge species (Diptera) and other by a micromoth species (Lepidoptera). The aim of this study was to evaluate the impact of these two gall-inducing insects on the biochemistry of phenolic acids and the cyanogenesis in galls, stems and leaves of M. vacciniifolia. High performance liquid chromatography (HPLC) indicated a total of 14 phenol derivatives, including caffeic and coumaric acid. Principal Coordinates Analysis (PCoA) of the phenolic substances indicated three groups consisting (1) non-galled stems and micromoth-induced galls; (2) midge-induced galls; (3) midgeinduced galls with parasitoids. Regarding the frequency of cyanogenesis assessed by the picrate paper test, the chi-squared test showed significant difference between fertile leaves (8.3%), sterile leaves (27.7%), non-galled stems (0%) and galls. Among galls, only the midge-induced galls analyzed were cyanogenic (15%). Our results indicated that the different gall-inducers (midge and micromoth) promote species-specific alterations to the phenolic substance composition of the host fern.
Galhas são estruturas vegetais neo-formadas que ocorrem em diferentes órgãos. Elas são geradas por uma interação espécie-específica com um organismo indutor. Os indutores manipulam o metabolismo do hospedeiro. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. é uma samambaia epífita neotropical que hospeda duas galhas caulinares, uma induzida por uma espécie de mosquito (Diptera) e outra por uma micromariposa (Lepidoptera). O objetivo deste estudo foi avaliar o impacto desses dois insetos indutores de galhas na bioquímica dos ácidos fenólicos e da cianogênese em galhas, caules e folhas de M. vacciniifolia. Em análise de cromatografia líquida de alta eficiência (CLAE) foi possível indicar a presença de um total de 14 derivados fenólicos, incluindo ácido cafeico e ácido cumárico. Análise das Coordenadas Principais (ACoP) indicou três grupos (1) caules não galhados e galhas induzidas pela micromariposa; (2) galhas induzidas pelo mosquito; (3) galhas induzidas pelo mosquito com parasitoides. Em relação a frequência da cianogênese analisada com o teste do papel picrato, o teste do qui-quadrado apresentou diferença significativa entre as folhas férteis (8,3%), folhas estéreis (27,7%), caules não galhados (0%) e galhas. Entre as galhas, somente aquelas induzidas pelo mosquito foram cianogênicas (15%). Os resultados encontrados indicam, ao menos para as substâncias fenólicas, que os insetos indutores de galha (mosquito e micromariposa) promovem alterações espécie-específica na composição química da samambaia hospedeira.
Subject(s)
Animals , Ferns , Diptera , Lepidoptera , Phenols , Plant Tumors , Plant Leaves , InsectaABSTRACT
Galls, neo-formed plant structures that can occur in different organs, are generated by species-specific interaction with an inducing organism. Inducers manipulate the metabolism of its host. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. is a Neotropical epiphytic fern that hosted two stem galls, one induced by a midge species (Diptera) and other by a micromoth species (Lepidoptera). The aim of this study was to evaluate the impact of these two gall-inducing insects on the biochemistry of phenolic acids and the cyanogenesis in galls, stems and leaves of M. vacciniifolia. High performance liquid chromatography (HPLC) indicated a total of 14 phenol derivatives, including caffeic and coumaric acid. Principal Coordinates Analysis (PCoA) of the phenolic substances indicated three groups consisting (1) non-galled stems and micromoth-induced galls; (2) midge-induced galls; (3) midge induced galls with parasitoids. Regarding the frequency of cyanogenesis assessed by the picrate paper test, the chi-squared test showed significant difference between fertile leaves (8.3%), sterile leaves (27.7%), non-galled stems (0%) and galls. Among galls, only the midge-induced galls analyzed were cyanogenic (15%). Our results indicated that the different gall-inducers (midge and micromoth) promote species-specific alterations to the phenolic substance composition of the host fern.
Galhas são estruturas vegetais neo-formadas que ocorrem em diferentes órgãos. Elas são geradas por uma interação espécie-específica com um organismo indutor. Os indutores manipulam o metabolismo do hospedeiro. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. é uma samambaia epífita neotropical que hospeda duas galhas caulinares, uma induzida por uma espécie de mosquito (Diptera) e outra por uma micromariposa (Lepidoptera). O objetivo deste estudo foi avaliar o impacto desses dois insetos indutores de galhas na bioquímica dos ácidos fenólicos e da cianogênese em galhas, caules e folhas de M. vacciniifolia. Em análise de cromatografia líquida de alta eficiência (CLAE) foi possível indicar a presença de um total de 14 derivados fenólicos, incluindo ácido cafeico e ácido cumárico. Análise das Coordenadas Principais (ACoP) indicou três grupos (1) caules não galhados e galhas induzidas pela micromariposa; (2) galhas induzidas pelo mosquito; (3) galhas induzidas pelo mosquito com parasitoides. Em relação a frequência da cianogênese analisada com o teste do papel picrato, o teste do qui-quadrado apresentou diferença significativa entre as folhas férteis (8,3%), folhas estéreis (27,7%), caules não galhados (0%) e galhas. Entre as galhas, somente aquelas induzidas pelo mosquito foram cianogênicas (15%). Os resultados encontrados indicam, ao menos para as substâncias fenólicas, que os insetos indutores de galha (mosquito e micromariposa) promovem alterações espécie-específica na composição química da samambaia hospedeira.
Subject(s)
Phenolic Compounds/analysis , Diptera , Ferns/parasitology , Lepidoptera , Plant Tumors/parasitologyABSTRACT
Among the plants defense mechanisms, the induction and emission of volatile organic compounds, which can be used to attract natural enemies, such predators insects. Although well studied, the induction of plant volatiles that attract natural enemies can vary according to intensity of infestation of herbivores and the species of host plant. We investigated the olfactory behavioral responses of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) to the volatiles of infested maize (Zea mays) plants by the two-spotted spider mite Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae) in early and advanced infestations. The Bt (Viptera) maize cultivar Impact® was used for tests the behavior of N. californicus. After initial and advanced infestations, the phytophagous mites T. urticae were removed, and the plants were tested using a "Y" olfactometer. The following treatments were evaluated: air vs. air, uninfested plants vs. air, uninfested plants vs. plants infested with 10 females of T. urticae, uninfested plants vs. plants infested with 100 females of T. urticae, uninfested plants vs. plants infested with 200 females of T. urticae and plants infested with 10 vs. plants infested with 200 females of T. urticae. The predatory mite N. californicus did not show preference to the treatments tested, suggesting that maize plants infested by T. urticae do not induce volatiles capable of attracting the predatory mite N. californicus. We concluded that N. californicus is not attracted by maize plants infested by T. urticae.
Dentre os mecanismos de defesa de plantas, a indução e emissão de compostos orgânicos voláteis, podem ser utilizados para atrair inimigos naturais, como insetos predadores. Embora bem estudada, a indução dos voláteis de plantas que atraem inimigos naturais pode variar de acordo com a intensidade de infestação de herbívoros e a espécie de planta hospedeira. Investigamos as respostas comportamentais olfativas do ácaro predador Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) aos voláteis de plantas infestadas pelo ácaro-rajado Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae). A cultivar de milho Bt (Viptera) Impact® foi utilizada para testar o comportamento de N. californicus. Após infestações iniciais e avançadas, os ácaros fitófagos T. urticae foram removidos e as plantas testadas em olfatômetro Y. Os seguintes tratamentos foram avaliados: ar vs. ar, plantas não infestadas vs. ar, plantas não infestadas vs. plantas infestadas com 10 fêmeas de T. urticae, plantas não infestadas vs. plantas infestadas com 100 fêmeas de T. urticae, plantas não infestadas vs. plantas infestadas com 200 fêmeas de T. urticae e plantas infestadas com 10 vs. plantas infestadas com 200 fêmeas de T. urticae. O ácaro predador N. californicus não mostrou preferência aos tratamentos testados, sugerindo que plantas de milho infestadas por T. urticae não induzem voláteis capazes de atrair o ácaro predador N. californicus. Concluímos que N. californicus não é atraído por plantas de milho infestadas por T. urticae.
Subject(s)
Animals , Pest Control, Biological/methods , Volatilization , Acari/parasitology , Zea maysABSTRACT
Abstract Galls, neo-formed plant structures that can occur in different organs, are generated by species-specific interaction with an inducing organism. Inducers manipulate the metabolism of its host. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. is a Neotropical epiphytic fern that hosted two stem galls, one induced by a midge species (Diptera) and other by a micromoth species (Lepidoptera). The aim of this study was to evaluate the impact of these two gall-inducing insects on the biochemistry of phenolic acids and the cyanogenesis in galls, stems and leaves of M. vacciniifolia. High performance liquid chromatography (HPLC) indicated a total of 14 phenol derivatives, including caffeic and coumaric acid. Principal Coordinates Analysis (PCoA) of the phenolic substances indicated three groups consisting (1) non-galled stems and micromoth-induced galls; (2) midge-induced galls; (3) midge-induced galls with parasitoids. Regarding the frequency of cyanogenesis assessed by the picrate paper test, the chi-squared test showed significant difference between fertile leaves (8.3%), sterile leaves (27.7%), non-galled stems (0%) and galls. Among galls, only the midge-induced galls analyzed were cyanogenic (15%). Our results indicated that the different gall-inducers (midge and micromoth) promote species-specific alterations to the phenolic substance composition of the host fern.
Resumo Galhas são estruturas vegetais neo-formadas que ocorrem em diferentes órgãos. Elas são geradas por uma interação espécie-específica com um organismo indutor. Os indutores manipulam o metabolismo do hospedeiro. Microgramma vacciniifolia (Langsd. & Fisch.) Copel. é uma samambaia epífita neotropical que hospeda duas galhas caulinares, uma induzida por uma espécie de mosquito (Diptera) e outra por uma micromariposa (Lepidoptera). O objetivo deste estudo foi avaliar o impacto desses dois insetos indutores de galhas na bioquímica dos ácidos fenólicos e da cianogênese em galhas, caules e folhas de M. vacciniifolia. Em análise de cromatografia líquida de alta eficiência (CLAE) foi possível indicar a presença de um total de 14 derivados fenólicos, incluindo ácido cafeico e ácido cumárico. Análise das Coordenadas Principais (ACoP) indicou três grupos (1) caules não galhados e galhas induzidas pela micromariposa; (2) galhas induzidas pelo mosquito; (3) galhas induzidas pelo mosquito com parasitoides. Em relação a frequência da cianogênese analisada com o teste do papel picrato, o teste do qui-quadrado apresentou diferença significativa entre as folhas férteis (8,3%), folhas estéreis (27,7%), caules não galhados (0%) e galhas. Entre as galhas, somente aquelas induzidas pelo mosquito foram cianogênicas (15%). Os resultados encontrados indicam, ao menos para as substâncias fenólicas, que os insetos indutores de galha (mosquito e micromariposa) promovem alterações espécie-específica na composição química da samambaia hospedeira.
ABSTRACT
Abstract Among the plants defense mechanisms, the induction and emission of volatile organic compounds, which can be used to attract natural enemies, such predators insects. Although well studied, the induction of plant volatiles that attract natural enemies can vary according to intensity of infestation of herbivores and the species of host plant. We investigated the olfactory behavioral responses of the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) to the volatiles of infested maize (Zea mays) plants by the two-spotted spider mite Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae) in early and advanced infestations. The Bt (Viptera) maize cultivar Impact® was used for tests the behavior of N. californicus. After initial and advanced infestations, the phytophagous mites T. urticae were removed, and the plants were tested using a Y olfactometer. The following treatments were evaluated: air vs. air, uninfested plants vs. air, uninfested plants vs. plants infested with 10 females of T. urticae, uninfested plants vs. plants infested with 100 females of T. urticae, uninfested plants vs. plants infested with 200 females of T. urticae and plants infested with 10 vs. plants infested with 200 females of T. urticae. The predatory mite N. californicus did not show preference to the treatments tested, suggesting that maize plants infested by T. urticae do not induce volatiles capable of attracting the predatory mite N. californicus. We concluded that N. californicus is not attracted by maize plants infested by T. urticae.
Resumo Dentre os mecanismos de defesa de plantas, a indução e emissão de compostos orgânicos voláteis, podem ser utilizados para atrair inimigos naturais, como insetos predadores. Embora bem estudada, a indução dos voláteis de plantas que atraem inimigos naturais pode variar de acordo com a intensidade de infestação de herbívoros e a espécie de planta hospedeira. Investigamos as respostas comportamentais olfativas do ácaro predador Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) aos voláteis de plantas infestadas pelo ácaro-rajado Tetranychus urticae (Koch, 1836) (Acari: Tetranychidae). A cultivar de milho Bt (Viptera) Impact® foi utilizada para testar o comportamento de N. californicus. Após infestações iniciais e avançadas, os ácaros fitófagos T. urticae foram removidos e as plantas testadas em olfatômetro Y. Os seguintes tratamentos foram avaliados: ar vs. ar, plantas não infestadas vs. ar, plantas não infestadas vs. plantas infestadas com 10 fêmeas de T. urticae, plantas não infestadas vs. plantas infestadas com 100 fêmeas de T. urticae, plantas não infestadas vs. plantas infestadas com 200 fêmeas de T. urticae e plantas infestadas com 10 vs. plantas infestadas com 200 fêmeas de T. urticae. O ácaro predador N. californicus não mostrou preferência aos tratamentos testados, sugerindo que plantas de milho infestadas por T. urticae não induzem voláteis capazes de atrair o ácaro predador N. californicus. Concluímos que N. californicus não é atraído por plantas de milho infestadas por T. urticae.
ABSTRACT
ABSTRACT Green lacewings (Chrysopidae) are important predators in agroecosystems. Frequently there are studies which treat these beneficial insects at family level as a whole. This approach, despite its practical advantages, may, however, include many species with markedly different life history traits. As green lacewings are also rather diverse in their chemical ecology, treating several different species within one unit may lead to confusion and confounding effects of natural phenomena in research. Besides interspecific differences, sex-specificity is another important factor to consider in respect of insect chemical ecology. This is especially important for green lacewings, in particular the attraction of females, since oviposition is crucial in their application as biological control agents. The aim of our paper is to provide a brief insight into the diversity of the chemical ecology of green lacewings with a special emphasis on the species- and sex-specific differences in their responses to semiochemicals.
ABSTRACT
This study aimed to analyse the allelopathic bioactivity of fresh and infused aqueous extracts of Brazilian cherry leaves on the germination of lettuce and the initial development of maize. Brazilian cherry leaves were used to prepare a fresh aqueous extract (200 g L-1) and an infused extract (100 g L-1), which were diluted to concentrations of 0.4, 0.8, 1.2, 1.6 or 2.0% w/v. The variables evaluated in lettuce were the germination rate (GR), germination time index (GTI), germination speed index (GSI) and root length (RL). To determine the effect on the initial development of maize, we measured the shoot (SL) and root (RL) length. The experimental design included a factorial 2 × 5 design (two extracts and five concentrations), in addition to a control treatment (no extract). In general, the allelopathic bioactivity differed between the fresh and infused extracts. The fresh extract was more phytotoxic for the GR and RL of lettuce. Some beneficial results were observed for the infused extract, including an increase in the RL of lettuce and SL of maize. These effects were dependent on the extract concentration. Thus, there is evidence that Brazilian cherry extracts have allelopathic bioactivity.
O presente trabalho tem por objetivo em analisar a bioatividade alelopática do extrato fresco e infuso de pitangueira sobre a germinação de alface e no desenvolvimento inicial de milho. Para tanto, utilizaram-se folhas frescas de pitangueira para preparação de extratos aquosos fresco (200 g L-1) e infuso (100 g L-1), diluídos em 0,4; 0,6; 1,2; 1,6 e 2,0% p/v de concentração. Os parâmetros avaliados em alface foram porcentagem (PG), tempo médio (TMG) e velocidade média de germinação (VMG) e comprimento de raiz (CR). Já no desenvolvimento inicial do milho, obteve-se o comprimento de raiz (CR) e parte aérea (CPA). Os experimentos foram conduzidos em esquema fatorial 2x5 + tratamento controle (ausência de extrato), com dois tipos de extratos e cinco concentrações. De modo geral, a bioatividade alelopática dos extratos frescos e infusos foi diferente, sendo que o extrato fresco mostrou-se fitotóxico sobre a PG e CR de alface. Alguns resultados benéficos foram observados com o extrato infuso como aumento no CR de alface e no CPA de milho. Os efeitos desses extratos dependem das concentrações onde são testados. Dessa forma, há evidência de que os extratos de pitangueira possuem bioatividade alelopática.
Subject(s)
Allelopathy , Infusion Pumps , Eugenia/cytology , Eugenia/chemistry , Zea mays/chemistryABSTRACT
ABSTRACT Aspergillus spp. cause economic impacts due to aflatoxins production. Although the toxicity of aflatoxins is already known, little information about their ecological roles is available. Here we investigated the compounds produced by Aspergillus nomius ASR3 directly from a dead leaf-cutter queen ant Atta sexdens rubropilosa and the fungal axenic culture. Chemical analyses were carried out by high-resolution mass spectrometry and tandem mass spectrometry techniques. Aflatoxins B1 and G1 were detected in both the axenic culture and in the dead leaf-cutter queen ant. The presence of these mycotoxins in the dead leaf-cutter queen ant suggests that these compounds can be related to the insect pathogenicity of A. nomius against A. sexdens rubropilosa.
ABSTRACT
Abstract Sponges of the genus Aplysina are among the most common benthic animals on reefs of the Caribbean, and display a wide diversity of morphologies and colors. Tissues of these sponges lack mineralized skeletal elements, but contain a dense spongin skeleton and an elaborate series of tyrosine-derived brominated alkaloid metabolites that function as chemical defenses against predatory fishes, but do not deter some molluscs. Among the earliest marine natural products to be isolated and identified, these metabolites remain the subject of intense interest for commercial applications because of their activities in various bioassays. In this study, crude organic extracts from 253 sponges from ten morphotypes among the species Aplysina archeri,Aplysina bathyphila,Aplysina cauliformis,Aplysina fistularis,Aplysina fulva,A. insularis, and Aplysina lacunosa were analyzed by liquid chromatography–mass spectrometry (LC–MS) to characterize the pattern of intra- and interspecific variabilities of the twelve major secondary metabolites present therein. Patterns across Aplysina species ranged from the presence of mostly a single compound, fistularin-3, in A. cauliformis, to a mixture of metabolites present in the other species. These patterns did not support the biotransformation hypothesis for conversion of large molecular weight molecules to smaller ones for the purpose of enhanced defense. Discriminant analyses of the metabolite data revealed strong taxonomic patterns that support a close relationship between A. fistularis,A. fulva and A. insularis, while two morphotypes of A. cauliformis (lilac creeping vs. brown erect) were very distinct. Two morphotypes of A. lacunosa, one with hard tissue consistency, the other soft and thought to belong to a separate genus (Suberea), had very similar chemical profiles. Of the twelve metabolites found among samples, variation in fistularin-3, dideoxyfistularin-3 and hydroxyaerothionin provided the most predictive influence in decreasing order. Except for one morphotype, weak relationships were found from within-morphotype analyses of metabolite concentrations as a function of geographic location (Florida, N Bahamas, S Bahamas) and depth (<10 m, 10–20 m, >20 m). Our data suggest that metabolite profiles are strongly influenced by sponge phenotype rather than by the diverse microbiome which many Aplysina species share.
ABSTRACT
The Brazilian cerrado presents strong climate seasonality. During the dry season, plants may be exposed to stressful situations, such as a soil surface water deficit, that stimulate their chemical defenses. However, the seasonality effect on the production of allelopathic compounds of cerrado plant species is poorly understood. In this study, the phytotoxic activities of common native cerrado plants were evaluated during rainy and dry seasons. Crude leaves extracts (10% concentration: weight/volume, with dry leaves and distilled water) from eleven species were tested on lettuce and sesame germination. The negative effects on germination percentages, rates and informational entropies of the target species were higher when submitted to plant extracts from the dry season, where the germination rate was the most sensible parameter. The higher sensibility of lettuce and the germination rate parameter showed this difference. Only two exceptions had higher effects for rainy season extracts; one species showed higher negative effects on germination informational entropy of lettuce and another species on the germination rate of sesame. Thus, increases in the allelopathic activity were seen in the majority of the studied cerrado plant species during the dry season. These distinct responses to stressful situations in a complex environment such as the Brazilian cerrado may support the establishment and survival of some species.
O cerrado brasileiro apresenta forte sazonalidade climática. Durante a estação seca as plantas podem estar expostas a situações estressantes, tais como um déficit de umidade nas camadas superficiais do solo, que estimulam suas defesas químicas. No entanto, o efeito da sazonalidade na produção de compostos alelopáticos de espécies vegetais de cerrado é pouco conhecido. Neste estudo, as atividades fitotóxicas de plantas nativas comuns de cerrado foram avaliadas durante as estações chuvosa e seca. Extratos brutos de folhas (concentração 10%: peso/volume, com folhas secas e água destilada) de onze espécies foram testados sobre a germinação de alface e gergelim. Os efeitos negativos sobre as porcentagens de germinação, velocidades e entropias informacionais das espécies-alvo foram maiores quando submetidas a extratos vegetais da estação seca. A maior sensibilidade da alface e do parâmetro velocidade de germinação mostraram essa diferença. Apenas duas exceções tiveram maiores efeitos para extratos da estação chuvosa; uma espécie mostrou maiores efeitos negativos sobre a entropia informacional de germinação de alface e outra espécie sobre a velocidade de germinação de gergelim. Assim, aumentos na atividade alelopática foram vistos na maioria das espécies vegetais do cerrado estudadas durante a estação seca. Estas respostas distintas a situações estressantes em um ambiente complexo como o cerrado brasileiro podem auxiliar no estabelecimento e na sobrevivência de algumas espécies.
ABSTRACT
The Brazilian cerrado presents strong climate seasonality. During the dry season, plants may be exposed to stressful situations, such as a soil surface water deficit, that stimulate their chemical defenses. However, the seasonality effect on the production of allelopathic compounds of cerrado plant species is poorly understood. In this study, the phytotoxic activities of common native cerrado plants were evaluated during rainy and dry seasons. Crude leaves extracts (10% concentration: weight/volume, with dry leaves and distilled water) from eleven species were tested on lettuce and sesame germination. The negative effects on germination percentages, rates and informational entropies of the target species were higher when submitted to plant extracts from the dry season, where the germination rate was the most sensible parameter. The higher sensibility of lettuce and the germination rate parameter showed this difference. Only two exceptions had higher effects for rainy season extracts; one species showed higher negative effects on germination informational entropy of lettuce and another species on the germination rate of sesame. Thus, increases in the allelopathic activity were seen in the majority of the studied cerrado plant species during the dry season. These distinct responses to stressful situations in a complex environment such as the Brazilian cerrado may support the establishment and survival of some species.
O cerrado brasileiro apresenta forte sazonalidade climática. Durante a estação seca as plantas podem estar expostas a situações estressantes, tais como um déficit de umidade nas camadas superficiais do solo, que estimulam suas defesas químicas. No entanto, o efeito da sazonalidade na produção de compostos alelopáticos de espécies vegetais de cerrado é pouco conhecido. Neste estudo, as atividades fitotóxicas de plantas nativas comuns de cerrado foram avaliadas durante as estações chuvosa e seca. Extratos brutos de folhas (concentração 10%: peso/volume, com folhas secas e água destilada) de onze espécies foram testados sobre a germinação de alface e gergelim. Os efeitos negativos sobre as porcentagens de germinação, velocidades e entropias informacionais das espécies-alvo foram maiores quando submetidas a extratos vegetais da estação seca. A maior sensibilidade da alface e do parâmetro velocidade de germinação mostraram essa diferença. Apenas duas exceções tiveram maiores efeitos para extratos da estação chuvosa; uma espécie mostrou maiores efeitos negativos sobre a entropia informacional de germinação de alface e outra espécie sobre a velocidade de germinação de gergelim. Assim, aumentos na atividade alelopática foram vistos na maioria das espécies vegetais do cerrado estudadas durante a estação seca. Estas respostas distintas a situações estressantes em um ambiente complexo como o cerrado brasileiro podem auxiliar no estabelecimento e na sobrevivência de algumas espécies.
Subject(s)
Allelopathy/physiology , Seasons , Trees/physiology , Brazil , Trees/classificationABSTRACT
Defensive behavior associated with secretions from the prosternal paired glands of the larvae of Heliconius erato phyllis Fabricius (Lepidoptera, Nymphalidae). Our work presents for the first time, the defensive behavior associated with the release of the product of the prosternal paired glands of the larva of Heliconius erato phyllis Fabricius, 1775 (Lepidoptera, Nymphalidae, Heliconiinae). The prosternal glands were first described for larvae of H. erato phyllis. They are formed by two types of glandular structures: the impair gland and the paired glands. The prosternal glands are located within the conical integumentary sac, which in turn is situated on the individual's prosternum. The main goal of this study is to analyze the existence of any secretion from the prosternal paired glands, and check the action mode of this secretion. The methodology used for chemical analysis of the glands included the aeration and, analysis in gas chromatography and gas chromatography-mass spectrometry. The results show that the prosternal glands do not produce volatiles. Bioassays were conducted with simulated and natural attacks and revealed that the prosternal paired glands produce secretions of defense together with silk produced by labials glands as a defense strategy, described for the first time, against ants. The strategy consists in wrapping the ant with silk threads, the entire wrapped object moved to the end of the body, with the aid of the legs and prolegs, and possibly fixed in a nearby place. Evidence for the existence of a conical integumentary sac in larvae of other species and families of Lepidoptera allows us to propose the possibility of occurrence of prosternal paired glands with defensive function in these other groups as well.
ABSTRACT
La investigación se desarrolló con el fin de implementar una metodología que permitiera la realización de ensayos de interacciones alelopáticas entre corales y esponjas, minimizando la interacción física provocada por el uso de dispositivos que producen roce y efecto abrasivo sobre los pólipos del coral. Se llevó a cabo un estudio de preformulación utilizando polímeros con características mucoadhesivas sobre mucus que recubre los pólipos de coral, con el fin de obtener un gel, incorporando en las formulaciones un extracto de la esponja Cliona delitrix. Se caracterizaron propiedades como extensibilidad y adherencia, así como la capacidad bioadhesiva de las formulaciones propuestas, considerando su comportamiento reológico. Estas mostraron una buena estabilidad física frente a las condiciones del medio marino tanto in vitro como in situ. De igual manera, se diseñó un dispositivo que facilitó la aplicación del gel sobre la superficie de los corales por parte de los buzos en el arrecife coralino. Finalmente se estudió el comportamiento de liberación al medio acuoso simulado del gel con el extracto de la esponja objeto de estudio.
This study was carried out with the purpose of implementing a methodology to assess allelopathic interactions assays between corals and reef sponges reducing the physical interaction caused by the use of devices that involve abrasion and harm over the coral polyps. Was carried out a preformulation study using polymers with mucoadhesive on the mucus that cover the coral polyps, with the purpose of develop a gel, incorporating an extract from Cliona Delitrix into the formulations. Obtained formulations were characterized by properties such as extensibility, adherence and mucoadhesive capacity. These formulations showed great physical stability under prevalent marine conditions both in vitro and in situ. In the same way was designed a device that let the smearing of the gel over the coral surfaces carried out for the divers in the coral reefs. Finally, was studied the releasing behavior of the gel with the sponge´s extract into the sea water conditions.
ABSTRACT
Capsaicinoids are unique to the chili pepper genus Capsicum within the plant family Solanaceae. The family is also known for species that produce powerful alkaloids such as nicotine (tobacco) and atropine (Atropa). This is the same family to which tomatoes, potatoes, and aubergines belong. Members of this family have a diversity of fruit types ranging from dry dehiscent capsules to fl eshy drupes and berries. Botanically speaking, chili peppers are berries (Knapp 2002) and capsaicinoids are synthesized mostly, if not exclusively, in the interlocular septum that separates seeds in the fruit (Stewart et al. 2007). Capsaicin and dihydrocapsaicin are the most abundant of the capsaicinoids, which are vanillin alkaloids responsible for the hot or burning sensation experienced on contact with chili peppers. This sensation is transduced by TRP (transient receptor potential) ion channels, specifi cally TRPV1 (transient receptor potential, vanilloid). TRP channels are nociceptors or noxious stimulus detectors on specialized sensory neurons. They are usually polymodal in their activation, responding to stimuli such as heat, chemicals, and protons (pH), but only at high thresholds (e.g. 42°C and pH 4) (Woolf and Ma 2007; Patapoutain et al. 2009). Consequently, nociceptors have considerable survival value since they signal the presence of extreme external and internal threats; internally they respond to the danger of tissue infl ammation and ensuing damage. They are also believed to be relatively ancient receptors, although they have not yet been found in bacteria, archaebacteria or in plants; trp-related genes have been found in fungi and the most ancient trp genes in animals have been discovered in unicellular choanofl agellates (Damann et al. 2008). The ecology of pungency in Capsicum as well as the behavioural response of organisms to capsaicin and other irritants transduced by TRP receptors provide extremely interesting insights into the evolution of plant secondary metabolites (see Borges 2001) and also into why some special higher mammals such as naked mole rats are unresponsive to these irritants. The centre of origin of pungent chili peppers is now believed to be the desert chaco of Bolivia and Peru (Walsh and Hoot 2001; Tewksbury et al. 2006). Pungency is a monophyletic derived trait, and a nonpungent species Capsicum ciliatum is regarded to be basal to all pungent taxa (Walsh and Hoot 2001). Contrary to popular conception, all wild Capsicum species are not pungent, and more importantly, nonpungent populations of pungent species also occur (Tewksbury et al. 2006). In the highlands of Bolivia, there appears to be an altitudinal gradient in pungency with the most pungent populations of at least one species, C. chacoense, occurring at the highest altitudes (Tewksbury et al. 2006). While the degree of pungency is encoded by several QTLs (Ben-Chaim et al. 2006), double recessive mutants at the Pun1 locus, which probably codes for an acyltransferase, are always non-pungent (Stewart et al. 2005). The pungent chili species are dispersed by birds since mammals are deterred by the pungency; moreover, mammalian guts destroy chili seeds and consequently mammals are not suitable seed dispersers for these species (Tewksbury and Nabhan 2001). The TRPV1 nociceptor in birds is insensitive to capsaicin although it demonstrates sensitivity to pH and heat (Jordt and Julius 2002). Non-pungent seeds of C. chacoense were found to be 12% thicker than pungent seeds, indicating a possible trade-off between the production of capsaicin and seed coat lignin in the phenylpropanoid pathway (Tewksbury et al. 2008b); however, since capsaicin had a constipative effect on birds, affecting the retention of seeds in their guts, pungent seeds with thinner seed coats were retained longer and suffered more damage in the gut. Yet, the longer that seeds were retained in the guts of dispersal agents, the farther they may move from their parent plants. This movement away from parental sites is usually considered an advantage since it affords escape.
ABSTRACT
Este estudo avaliou a influência do efeito de borda e da pluviosidade sobre a produção de flavonóides em indivíduos de Bauhinia cheilantha (Bong.) Steud., Fabaceae, em uma área de caatinga no estado de Pernambuco, Nordeste do Brasil. Foi utilizada metodologia analítica por complexação com cloreto de alumínio para quantificar a concentração de flavonóides contidos nos extratos foliares de B. cheilantha, por meio de espectrofotometria no visível. De forma geral, o efeito de borda afeta a produção de flavonóides, entretanto, não foi possível correlacionar a produção de flavonóides e a pluviosidade, demonstrando que a espécie avaliada utiliza outra estratégia como resposta às pressões ambientais.
The present study evaluated the influence of the edge-effect and rainfall on flavonoid content in individuals of Bauhinia cheilantha (Bong.) Steud., Fabaceae, in an area of caatinga vegetation in Pernambuco State, northeastern Brazil. The analytical methodology used aluminum chloride binding to quantify flavonoid concentrations by visible light spectrophotometry in leaf extracts of B. cheilantha. In general, forest edges influenced flavonoid production, but it was not possible to relate production with rainfall levels. These results demonstrate that this species uses various strategies to respond to environmental variables.