A Química na agricultura: perspectivas para o desenvolvimento de tecnologias sustentáveis

Food production and preservation of the environment are among the challenges faced by contemporary society. In Brazil, as in most parts of the world, the possibility of increasing the agricultural area is limited by several factors. Thus, an increase in productivity through the application of innovative technologies is regarded as the best solution to overcome such a problem. For long, chemistry has contributed to agricultural innovations such as synthetic pesticides for pest management. However, due to the well-known adverse effects of these compounds, new "greener" strategies are being explored. Research in chemical ecology, in combination with other emerging sciences, is leading to the development of new technologies such as plant-based pesticides (biopesticides); synthetic pheromones and plant volatile organic compounds, both of them to manipulate insect behavior; chemical elicitors to boost plant resistance; and genetic engineering of plant varieties. In these, chemistry plays an important role in the identification and synthesis of functional compounds. These techniques may be incorporated in integrated pest management programs and may contribute to a sustainable agriculture in the future

Insect pheromone research in South America

Insect pheromone research has a long and rich history built up primarily by studies conducted in the Northern hemisphere. Not surprisingly, these studies have largely targeted species relevant to these regions of the world, for the most part agricultural and forest pests. Pheromone research in South American countries came a few decades behind, albeit their strong dependence in agriculture and therefore in pest management. In the last 20 years, a combination of economic, environmental and technical factors have come together to generate a small but rising number of chemical ecologists working in pheromone chemistry and biology in South America. In this article we summarize the results of this trend. We review pheromone studies in which South American scientists have participated in collaboration with foreign scientists, mostly chemistry groups, as well as the ever-growing number of studies carried out completely within the region. We have focused mainly in research involving the characterization of pheromones from native species, which involve the most important insect orders, namely Lepidoptera, Coleoptera, Heteroptera and Hymenoptera. We also present a simple meta-analysis including geographical distribution, trends in collaborative or independent work, and a 20-year evolution of published articles in the field. Finally, we emphasize the importance of a coordinated effort to further promote the growth of this field in Latin America, through the endorsement of international collaborations within the region. Such goal would be facilitated by a regional academic organization, which would in turn initiate the occurrence of regular scientific meetings

Male-Produced Sex Pheromone of the Carrion Beetles, Oxelytrum discicolle and its Attraction to Food Sources

Abstract Carrion beetles are part of the great diversity of insects collected on cadavers. In Brazil, beetles of the genus Oxelytrum have great forensic importance in post mortem interval (PMI) estimation. We investigated the system of chemical communication in the attraction of these necrophagous beetles. Gas chromatographic analysis (GC) of female and male aeration extracts revealed the presence of two male-specific compounds, produced in a ratio of 94:6. Bioassays showed that the combination of male produced volatiles and the odor of a food source (carcass volatiles) were attractive to females. Mass and infrared spectral analyses of the male-specific compounds suggested that they were both unsaturated hydrocarbons. Several microderivatizations were carried out with the natural products, and the target structures were identified as (Z)-1,8-heptadecadiene (major) and 1-heptadecene (minor). The structure of the minor component was assigned by co-injection with a commercial standard. A seven-step synthesis was developed to synthesize (Z)-1,8-heptadiene, which co-eluted with the major natural product on three different GC stationary phases. Y-tube olfactometer assays showed that the mixture of synthetic standards in the naturally occurring proportion was slightly attractive to females. The results contribute both to the understanding of the chemical ecology of O. discicolle and to its potential to improve the accuracy of PMI estimation

An Alternative Route for the Synthesis of (E)-(+)-5(S)-Methylhept-2-en-4-one (Filbertone)

Foi estudada uma metodologia alternativa para a obtenção da (+)-Filbertone (1), um aromatizante natural isolado de avelãs. Utilizou-se o álcool comercial (-)-2(S)-metilbutan-1-ol (2) como material de partida, sendo a síntese realizada em quatro etapas com rendimento global de 42%. A rotação óptica e pureza enantiomérica do produto final foram determinados. We are reporting an alternative methodology to prepare (+)-Filbertone (1), a natural flavor isolated from hazelnut extracts. Commercially available (-)-2(S)-methylbutan-1-ol (2) was used as starting material and the synthesis was carried out in four steps with an overall yield of 42%. The optical rotation and the enantiomeric purity of the final compound were determined

Volatile Chemicals of Adults and Nymphs of the Eucalyptus

Thaumastocoris peregrinus is an introduced “true bug” that is now a severe pest in Eucalyptus plantations of various Southern Hemisphere countries. The semiochemicals of thaumastocorids are completely unknown. Therefore, volatile chemicals from T. peregrinus nymphs and adults were identified as possible leads for pheromones potentially useful for control. The contents of nymphal exocrine glands, which are shed at molting, were identified from extracts of exuviae. Adults lack functional metathoracic scent glands that are characteristic of most heteropterans; however, both males and females possess a glandular-appearing hold-fast organ that they quickly extrude posteriorly when disturbed. Whole body hexane extracts from males and females were prepared by freezing the insects in a flask so that they extruded the hold-fast organ, and then they were extracted with hexane. Volatiles from nymphal exuviae included benzaldehyde, octanol, (E)-2-octenol, octanoic acid, decanal, and hexanoic acid. Adult volatiles included 3-methylbut-2-en-1-yl butyrate and 3-methylbut-3-en-1-yl butyrate

Feromônios de insetos: tecnologia e desafios para uma agricultura competitiva no Brasil

Pheromones are chemical compounds used by species to communicate intra and inter specifically. As strategy of integrated pest management (IPM), the use of these compounds allows the monitoring of target insects that results in more reliable interventions and consequently avoiding unnecessary use of pesticides. In certain crops these compounds are used as a control measure, not only monitoring. The Brazilian agriculture has a portfolio of 49 major crops that are attacked by 447 species of insects. Of this total, 103 species have already been the subject of study in the research with pheromones. Currently, in the Brazilian market, 28 pheromone products are indicated for the control of 19 insect pests. However, these products are not used regularly in major crops of the country. This stems from the lack of implementation of IPM of these crops. While the research focused on the main species of agribusiness pests, marked of pheromones products is serving to more marginal crops like apples and peaches at the expense of major crops like soybean and corn