RESUMO Extratos vegetais foram utilizados para o controle das formigas cortadeiras. Os objetivos deste estudo foram avaliar a sobrevivência de operárias de formigas cortadeiras após aplicação tópica de extratos de Ageratum conyzoides (mentrasto) e Manihot esculenta (mandioca); e avaliar o efeito por ingestão do extrato de Manihot esculenta extraído com hexano na sobrevivência de operárias de Atta sexdens Forel 1908 isoladas ou não de suas colônias, a fim de verificar se o fungo simbiótico Leucoagaricus gongylophorus confere proteção às operárias contra o extrato. Primeiro, dez operárias médias foram removidas de suas colônias e receberam a aplicação de 1 μL de extrato no pronoto. O extrato de mandioca (125 µg.mL-1) foi diluído em uma solução de mel com água para o bioensaio de ingestão. Foram realizadas cinco repetições (dez formigas dentro de um recipiente de plástico transparente) em cada uma das quatro colônias utilizadas no experimento. O número de formigas mortas foi registrado diariamente até que o tratamento controle também morresse. A solução do extrato Manihot esculenta com hexano apresentou resultado significativo na concentração de 100 µg.mL-1, com 100% de mortalidade após 4 dias. Formigas mantidas com o fungo simbionte que ingeriu o extrato hexânico da mandioca apresentaram menor mortalidade (40% ao final de 25 dias) do que as operárias mantidas isoladas (90%). A simbiose entre as formigas e o fungo significa mais do que uma fonte de alimento para as formigas-cortadeiras, devido ao fato de reduzir o efeito tóxico de extratos vegetais nas formigas quando elas permanencem em contato constante com o mesmo.

ABSTRACT Plant extracts have been considered for the control the leaf-cutting ants. The objectives of this study were to evaluate the survival leaf-cutting worker ants after topical application of Ageratum conyzoides (mentrasto) and Manihot esculenta (cassava) extracts; and to evaluate the effect of Manihot esculenta hexane extract via ingestion on the survival of the workers of Atta sexdens Forel 1908 isolated or not from their colonies, in order to verify whether the symbiotic fungus Leucoagaricus gongylophorus confers protection to the workers against the extract. First, ten medium workers were removed from their colonies and received the application of 1 μL of extract on the pronotum. The cassava extract (125 µg.mL-1) was diluted in a solution of honey with water for the ingestion bioassay. Five repetitions (ten ants inside a transparent plastic container) were performed in each of the four colonies used in the experiment. The numbers of dead ants were recorded daily until the control also died. The solution of the hexane Manihot esculenta extract gave a significant result at the concentration of 100 µg.mL-1, with 100% of mortatily after 4 days. The ants maintained with the symbiont fungus that ingested the cassava hexanic extract showed a lower mortality rate (40% at the end of 25 days) than the workers who were kept isolated (90%). The symbiosis between the ants and the fungus means more than a food source for leaf-cutting ants because it reduces the toxic effect on the ants when the ants remain in contact with the fungus and is offered an unsafe vegetable.

RESUMO Determinou-se a composição do perfil volátil de frutos de cambuizeiro (Myrciaria floribunda) utilizando-se microextração em fase sólida no modo headspace e cromatografia gasosa acoplada a espectrometria de massas. As fibras PA (polyacrylate) e DVB/CAR/PDMS (divinylbenzene/carboxen/polydimethylsiloxane) foram otimizadas quanto aos parâmetros de extração (agitação, tempo e temperatura de extração), a fim de selecionar a fibra com maior número de compostos isolados. Um total de 48 compostos voláteis foram identificados através do HS-SPME / GC-MS presentes nos frutos maduros de cambuí. Os compostos voláteis foram classificados em cinco classes químicas, sendo a maioria pertencente à classe dos sesquiterpenos (71 %). Além disso, foi possível verificar que a fibra revestida com poliacrilato (PA) teve melhor desempenho, permitindo a extração de um maior número de compostos voláteis (n = 35). As condições de extração que permitiram o isolamento de um maior número de compostos voláteis, corresponderam a tempos superiores de 26 min e temperaturas acima de 85 °C com agitação de 79 rpm, isto para a fibra PA. Da mesma forma, verificou-se que os sesquiterpenos hidrocarbonetos foi a classe química mais presente nos frutos, o que está relacionado principalmente ao perfil volátil dos frutos de cambuí.

ABSTRACT The composition of the volatile profile of rumberry fruits (Myrciaria floribunda) was determined using solid- phase microextraction in headspace mode and gas chromatography, coupled with mass spectrometry. The PA (polyacrylate) and DVB/CAR/PDMS (divinylbenzene/carboxen/polydimethylsiloxane) fibers were optimized for the extraction parameters (agitation, extraction time and temperature), in order to select the fiber with the highest number of isolated compounds. A total of 48 volatile compounds were identified using HS-SPME/GC-MS present in the ripe fruits of rumberry. The volatile compounds were classified into five chemical classes, the majority belonging to the sesquiterpenes class (71%). In addition, it was possible to verify that the fiber coated with polyacrylate (PA) had better performance, allowing for the extraction of a greater number of volatile compounds (n = 35). The extraction conditions that allowed the isolation of a greater number of volatile compounds corresponded to times greater than 26 minutes and temperatures above 85 °C, with agitation of 79 rpm for the PA fiber. Likewise, it was found that the hydrocarbon sesquiterpenes was the chemical class most present in the fruits, which is mainly related to the volatile profile of rumberry fruits.

ABSTRACT Plant indirect induced defenses against herbivores are characterized by the production of plant volatiles that to attract natural enemies. The objective of this study was to evaluate whether the attack of the two-spotted spider mite Tetranychus urticae or the multiple herbivory of T. urticae together with the fall armyworm Spodoptera frugiperda are able to elicit indirect induced defense in conventional and Bt maize plants. The experiment was carried out in the laboratory using Y-tube olfactometer, evaluating the predatory mite Neoseiulus californicus olfactory preference for plant volatiles. The treatments involved: Clean Conventional Plant; Conventional Plant Infested with T. urticae; Clean Bt Plant; Bt Plant Infested with T. urticae; Conventional Plant Infested with T. urticae + fall armyworm; Bt Plant Infested with T. urticae + fall armyworm. For the chemical analyzes the Trace GC Ultra gas chromatograph was used, paired with the Polaris Q mass spectrometer, GC - MS system. Neoseiulus californicus was also unable to distinguish between volatiles from both conventional and Bt infested maize plants. Moreover, there was no discrimination of the predator mite between plants under single and multiple infestations, both in conventional and Bt maize. When comparing conventional and Bt plants, both with multiple infestation, the predator mite N. californicus had no preference among these sources of odors. However, there was observed chemical changes of the volatiles among the groups of plants studied. Thus, it is suggested that the groups of plants under study have chemical modifications, but they are not able to attract N. californicus. In addition, Bt plants response was similar to conventional plants on attracting N. californicus.

RESUMO O Cerrado é o maior bioma no Estado de Minas Gerais-Brasil, representado uma biodiversidade de espécies frutíferas, destacando a cagaiteira (Eugenia dysenterica). Frutos de cagaiteira são considerados uma opção importante para fruticultura, por apresentarem fonte de compostos fenólicos com propriedades antioxidantes e teores de minerais que podem contribuir com efeitos benéficos à saúde. Neste estudo, caracterizaram-se os compostos fenólicos por cromatografia líquida de alta eficiência e avaliaram-se os teores de minerais presentes em frutos de cagaiteira em estádio de maturação maduros e verdes. Em relação aos minerais, frutos maduros e verdes destacam-se por serem ricos em potássio. Os frutos verdes são ricos em boro, enquanto os frutos maduros são fonte desse mineral. Nos frutos de cagaiteira maduros e verdes, foram identificados os compostos fenólicos: os ácidos gálico, cafeico, vanílico, p-cumárico, siríngico, ferúlico e salicílico, epicatequina, quercetina e rutina, sendo os maiores teores dos compostos os ácidos cafeico, p-cumárico, siríngico e ferúlico, epicatequina e rutina identificados nos frutos verdes, enquanto para frutos maduros o destaque foi para os ácidos gálico, vanílico esalicílico e quercetina. Assim, frutos de cagaita podem apresentar grande potencial para aplicações alimentares, terapêuticas e medicinais, trazendo benefícios à saúde.

ABSTRACT Cerrado is the largest biome in the state of Minas Gerais-Brazil, represented by a biodiversity of fruit species, especially cagaita (Eugenia dysenterica). Cagaita fruits are considered an important option for fruit growing, because they are source of phenolic compounds with antioxidant properties and mineral content that can contribute with beneficial health effects. In this study, phenolic compounds were characterized by high-performance liquid chromatography and the mineral content of ripe and unripe cagaita fruits was evaluated. Regarding minerals, ripe and unripe fruits stand out due to their high potassium content. Unripe fruits are rich in boron while ripe fruits are source of this mineral. ripe and unripe cagaita fruits have the following phenolic compounds: gallic, caffeic, vanillic, p-coumaric, siringeic, ferulic and salicylic acids, epicatechin, quercetin and rutin, the highest contents of these compounds are caffeic, p-coumaric, siringeic and ferrulic, epicatechin and rutin identified in unripe fruits, while ripe fruits have high contents of gallic, vanillic and quercetin acids. Thus, cagaita fruits have great potential for food, therapeutic and medicinal applications bringing health benefits.