Evaluation of Toxic Effect of Plant Extracts on Adults of Sitophilus Oryzae L., 1763 (Col., Curculionidae)
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Alternative Methods to Chemical Control PS7-30 – 6286 Evaluation of toxic effect of plant extracts on adults of Sitophilus oryzae L., 1763 (Col., Curculionidae) M.M.M. Rupp1,*, M.E. da S. Cruz1, J.C.T. Collella1, S.P. Souza Junior1, K.R.F. Schwan- Estrada1, M.J. da S. Cruz1, A.C. Fiori-Tutida1 Abstracts other essential oils provided quite promising results, and the insecticide activity was reached The natural products of plants come as an by the three essential oils, being emphasized the alternative ecologically more compatible in oil of E. globulus with 100 % of mortality, O. substitution to the synthetic insecticides. This basilicum and M. piperita, species that it has been study had the objective to evaluate the action of proven as botanical insecticide potentials being vegetable extracts and essential oils on S. oryzae proceeded, because the secondary metabolics of in the adult phase in stored wheat, through the plants have been used as pesticides or models assessment of toxic effect on exposed individuals for synthetic pesticides, there is, however the to wheat grains treated. The biossay was done at need of complemental researches. the Laboratory of Entomology, DAG/UEM. The extracts of P. nigrum were obtained through the Key words: grain weevil, botanical insecticide, maceration of the grains with acetone and natural insecticide, essential oil, aromatic methanol and the essential oils of Ocimum medicinal plants. basilicum and Eucalyptus globulus acquired of specialized companies.To study the toxic effects of the extracts on adults of S. oryzae, six Introduction concentrations were tested (50; 25; 12.5; 6.25; 3.125 and 1.5625 %) of each extract, in 40 g of When observing the history of the civilization wheat previously disinfectant, containing 20 along time, it can be seen that the human being adults of S. oryzae of 0-72 h of age. The has been using practices that, although empiric, experiments consisted of 4 repetitions for constituted of techniques for the conservation of treatment. The same conditions were repeated for grains. With the coming of the agro-chemical the experiments with essential oils of O. industry, the natural practices gave place to the basilicum and E.globulus, where each portion use of insecticides. received oil 0.1mL in 40 g of wheat. The The use of chemical products in order to evaluations were made to the 1, 3, 7, 10, 20 and control agricultural curses or plagues became a 30 days after the treatments on grains. The insects constant in the last 50 years thus, such a method dead were counted in each experiment, being of control has been highly recommended. discarded after each evaluation. The extracts of Chemical compounds artificially synthesized, on P. nigrum didn’t control in an effective way the the other hand, have been used in an irrational S. oryzae in the different concentrations. The way, besides not being incorporated to the 1 UEM/ Departamento de Agronomia. Avenida Colombo, 5790. Bairro Jardim Universitario. CEP - 87020-900, Maringá, Paraná, Brasil * E-mail: [email protected] 883 9th International Working Conference on Stored Product Protection integrated handling of pests, thus, increasing eucalyptus (Eucalyptus spp.), from chrysanthemum problems such as, the resistance of insects, the (Chrysanthemum cinerariaefolium) and from appearance of secondary pests, extinction of nim (Azadirachta indica), that have originated natural enemies, consumers´ intoxication, lefts many similar substances, which are more of residue in food - above the limits allowed by efficient as insecticides, and that were law and environmental contamination. synthesized and commercialized more than a The cereals globally considered as the most decade ago (Voss and Roman, 2005). important vegetable species in men and animals´ Saito (2004) argues that a class of substances feeding need to be stored for a long period of that has deserved a lot of attention are the time, which is fundamental to supply the constant substances that make part of the essential oil of world demand for food. some plants. The essential oils, or volatile oils, The pests are seen as the cause of physical can be found in aromatic plants and can present losses, besides being responsible for the loss in attractive, repellent, and even poisonous activity the quality of the grains and by-products at the to insects and microorganisms. Substances that moment they are being sent to the market and have been used in the control of insects, and are consumption. In Coleoptera (Curculionidae present in the essential oil compounds are, for family) there are significant species, due to the instance, the ones found in oils extracted from damage and losses by weevils or woodworms pine tree resin (Pinus sp.), the nerol extracted (Sitophilus oryzae and S. zeamais) caused in from the essential oil of ‘capim limão’ maize, wheat and rice. (Cymbopogon citratus), the limone extracted Considering the circumstances, the need to from the oil of fruit peel belonging to several make a more rational control of pests is evident. species of Citrus (orange, lemon), and some Such a control can be done through an integrated substances obtained from plants and used as food handling, where the insecticide vegetables would seasoning, such as, eugenol extracted from Indian be included in a process known as botanical clove (Eugenia caryophyllata), menthol insecticides or phito-insecticides. The extracted from mint (Mentha piperita), piperin rediscovering of plants that possess in their extracted from black pepper (Piper nigrum) and elements, metabolic or secondary compounds sulfurate substances obtained from garlic extract with insecticide property has been disseminating (Allium sativum). in the last 35 years; and in some countries of Latin Baptista et al., (2005) when evaluating the America, researches seeking for plants with insecticide activity of medicinal plants essential substances biologically active against pests, which oil against pests, such as, the fall armyworm cause smaller environmental impact, is growing (Spodoptera frugiperda), verified that the with promising results (Garcia-Belt, 2002). essential oils of Ocimum gratissimum (basil), Mechanisms of natural defense frequently Ocimum basilicum (sweet basil) and Ruta involve secondary metabolic then, the phito- graveolens (rue) were poisonous for caterpillar, chemical study of cultivated plants, associated and the calculated LD50 were: O.gratissimum to the natural resistance characteristics, can be (0,518 µL/insect), O.basilicum (0,33 µL/insect) used as a new alternative against pests. Extracts and R.graveolens (0,220 µL/insect). Maschio coming from plants, or their active components, (1998) describes that citral, the main component have been used in the control of noxious insects, of lemon grass oil (Cymbopogon citratus (D.C.) as a form of practicing a sustainable agriculture. STAPF, presents properties against larvae and Such metabolics are also known as natural works as insect repellent. According to products, and the most common examples in that researches, the action of species against larvae research line, are found in the successful attempts in the extermination of the yellow fever mosquito to control some insects. There are substances with is larger than the action of usual chemical insecticide effect, as the ones obtained from insecticides. 884 Alternative Methods to Chemical Control Hill (1990) reports that, 2000 species of camaldulensis have shown poisonous effect in plants, which produce chemical substances able insects through the cuticle and in ingestion and to act against insects are known. The substances fumigation, causing 100 % of mortality of S. can have poisonous and repellent effect, and can zeamais in a dilution 2:8 (essential oil: acetone). work as phagos restrainer, ovicide and can affect Considering the facts above exposed, the main the insects’ hormonal system. Moreover, a great aim of the present study was to evaluate the number of essential oils can reduce the potential use of organic extracts of Piper nigrum reproduction system of several insects found in and essential oils of Eucalyptus globulus, stored products and they can also hinder the Ocimum basilicum and Mentha piperita in order growth, the development and the reproduction to protect stored wheat, so that they can be used of some herbivore insects. The main groups of in the integrated handling of pests, specifically chemical substances are the terpins, which are Sitophilus oryzae. abundant compounds of many superior plants essential oils, such as, tannins and alkaloids. Su (1977) in studies regarding the use of Piper Materials and methods nigrum as protection to stored products, verified the high toxicity of the raw extract or essence of The Sitophilus oryzae stocks of reproduction the purified and of the powder of black pepper and the tests were carried out at the Laboratory dry fruits on adults of Sitophilus oryzae and of Entomology, DAG/UEM. The stocks of S. Callosobruchus maculatus, which was attributed oryzae reproduction has started from adults to the synergic action of the pepper chemical obtained from samples of infested wheat. The compounds. Sighamony et al. (1986) compared adults were previously put in glass flasks, the efficiency of Piper nigrum acetone extract to containing wheat disinfested at low temperature the efficiency of several essential oils extracted (-10 ºC) for 96 h. The removal of the insects was from native plants of India in the protection of made 10 days after the infestation. The adults wheat grains stored against S. oryzae. It was emerging in the flasks were used in the tests and verified that the persistence of the extract of P. also in the maintenance of the reproduction stock. nigrum was superior to 60 days. Thus, two tests were performed: Obeng-Ofori et al. (2000) when testing Regarding the First Test – that was made with species of Ocimum in the control of S. zeamais black pepper extract (P. nigrum), obtained in the found that each substance, either topically applied concentrations of 50 and 1.5625 %, by using two or impregnated in the maize grains, was highly solvents, acetone and methanol.