Atividade inseticida e de repelência de óleos essenciais de cravo e canela sobre o caruncho Acanthoscelides obtectus (Say)

• Ano de defesa: 2013
• Autor(a) principal: Jumbo, Luis Oswaldo Viteri
• Orientador(a): Faroni, Lêda Rita D'antonino
• Banca de defesa: Khalid, Haddi
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Entomologia
• Departamento: Ciência entomológica; Tecnologia entomológica
• País: BR
• Palavras-chave em Português: Armazenamento; Insetos-praga; Taxa instantânea de crescimento populacional; Taxa de desenvolvimento; Repelência; Persistência
• Palavras-chave em Inglês: Storage; Insect pests; Instantaneous rate of population growth; Rate of development; Repellency; Persistence
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::ENTOMOLOGIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/3980

Beans are the major source of protein in developing countries, and still the storage losses are estimated in 30% as a result of pests attack including Acanthoscelides obtectus (Say). Although chemical pesticides are effective to control these pests, their overuse can compromise the quality of food. Essential oils of vegetable origin are presented as an attractive alternative for the synthetic chemical insecticides to pest control, because they have little or no effect on grain quality, human health and environment. This study aimed evaluate the toxicity of the essential oils of Syzygium aromaticum (Myrtaceae) or clove and Cinnamomun zeylanicum (Laureaceae) known as cinnamon on A. obtectus in beans (Phaseolus vulgaris L.). We evaluated the instantaneous rate of increase (ri) of these insects exposed to time-lethal, developmental rate, repellency, persistence and loss of mass of the beans. The toxicity of the oils was evaluated by preliminary tests to estimate the lethal dose to 50 and 95% (DL50 and DL95) of adult insects. The experimental unit consisted of 0.8 L bottles containing 200 g of beans (Queen variety) treated with doses of 2,80; 5,54; 8,88; 14,22; 28,09 μL of clove oil, and 4,26; 6,93; 9,70; 13,60; 22,17 μL of cinnamon oil. Later were added 25 adult insects per vial (four replicates per dose), and insect mortality was assessed after 24 h. The instantaneous rate of increase (ri) of the oils of clove and cinnamon was determined using lethal doses (LD10, LD30, LD50, LD70 and LD90), obtained in the toxicity bioassay. After 45 days, the adult progeny was recorded; bottles with 200 g of beans and 25 adult insects, non-sexed 1-3 days old, and four replicates were used for LD. A similar procedure was done to assess the rate of development, with the difference that in this test the insects were removed from the flasks after 15 days they were introduced, and counting was performed every two days after the emergence of the first adult. The persistence was evaluated in beans treated with LD100 oils. The repellent activity of oils was tested with the LD10, LD50, LD90 doses for each oil. The results indicate that the toxicity LD50 and LD95 were 8.88 L and 38.94 L for clove essential oil, and 9.71 L and 27.97 L for cinnamon essential oil, respectively. Furthermore, with increased doses of essential oils and ri, development rate decreases significantly. Regarding the persistence of oil, was observed mortality reduction of A. obtectus with increasing time between the treatments of treated grains, keeping a higher mortality at 50% of the insects within 7 days after exposure. However, repellency of essential oil of cinnamon to this insect was observed only when using LD90; clove essential oil showed no repellency against A. obtectus at the tested doses. The loss of grain weight during 48 days was directly proportional to the number of emerged insects in each test. For beans treated with clove essential oil the average of mass loss was 6.6%, and 9.6% in the control, whereas for tests with essential oil of cinnamon the average of loss was 6.8% and 9.2% for the treatment and control, respectively. Thus, with the results obtained in this study, it can be concluded that the essential oils of clove and cinnamon have effect on mortality of A. obtectus by contact, as an alternative to the use of traditional insecticides.