RESUMO
ABSTRACT The excessive use of chemical insecticides has led to negative effects on human health and the environment. Volatile oils are one of the possible potential alternatives to chemical insecticides. Traditionally Seriphidium brevifolium (Wall. ex DC.) Ling & Y.R.Ling, Asteraceae, powder from its leaves is used to treat gastric problems and expel intestinal worms by local peoples, but yet there is no literature available regarding its insecticidal activity. In this study fumigant toxicity and enzyme inhibition activities of the S. brevifolium volatile oil collected from the highlands of Skardu Baltistan, Pakistan, was evaluated against the red imported fire ant Solenopsis invicta. The phytochemical studies indicated that monoterpenes were the most abundant constituents, accounting for 88% of the total oil. The major dominant constituents were 2-bornanone (28.2%), 1,8-cineole (19.9%), α-thujone (7.5%), β-thujone (6.7%) which accounts for 62.3% of total constituents identified, with volatile oil yield of 4.11% (w/w). The fumigation assay indicated that the volatile oil was acutely toxic to fire ants, with an LC50 of 16.47 µl/l. Among the constituents tested, only (α + β) thujone and 1,8-cineole were toxic, with LC50 of 17.68 and 30.66 µl/ after 12 h of exposure. The volatile oil, (α + β) thujone and 1, 8-cineole showed strong fumigant activity against the red imported fire ant workers in a time- and dose-dependent manner. The volatile oil caused 100% mortality of the red imported fire ant workers, even at the lowest concentration of 20 µl/l after 24 h of exposure. In addition, the volatile oil and 1,8-cineole inhibited acetylcholinesterase activity, while (α + β) thujone inhibited carboxylesterase activity in the fire ant workers. It has been concluded that the volatile oil and some of the compounds from S. brevifolium might be developed as eco-friendly approaches for the control of red imported fire ants.
RESUMO
Bioactivity of Indonesian mahogany, Toona sureni (Blume) (Meliaceae), against the red flour beetle, Tribolium castaneum (Coleoptera, Tenebrionidae). The insecticidal activity of Toona sureni (Blume) Merr. was evaluated considering repellency, mortality and progeny production of F1 adults of Tribolium castaneum (Herbst, 1797) (Coleoptera, Tenebrionidae). Dried extract of seeds of T. sureni was dissolved in acetone to prepare solution of various concentrations (0.5, 1.0, 2.5 and 5.0%). To test for repellency, the insects were exposed to treated filter paper. Mortality of larvae, pupae and adults was evaluated by the treatment of spraying the insects with different concentrations of T. sureni extract. Residual effect of the extract was also evaluated considering the production of progeny of F1 adults. The highest repellency (93.30%) of T. castaneum occurred at the highest concentration (5.0% suspension of T. sureni); while the lowest (0.0%) repellency occurred at 0.5% suspension after 1 day of treatment. The highest mortality against adults (86.71%), larvae (88.32%) and pupae (85%) occurred at 5% suspension at 8 days after application. There was a negative correlation between the concentrations of T. sureni and the production of F1 adult's progeny of T. castaneum. The highest number of progeny (147) of T. castaneum occurred in the control at 7 days after treatment; and the lowest number of progeny (43) occurred at 5.0% concentration in 1 day after treatment. The results show that T. sureni is toxic to T. castaneum and has the potential to control all stages of this insect in stored wheat.
Bioatividade do mogno da Indonésia, Toona sureni (Blume) (Meliaceae), contra o besouro-das-farinhas, Tribolium castaneum (Coleoptera, Tenebrionidae). A atividade inseticida de Toona sureni (Blume) Merr. foi avaliada considerando repelência, mortalidade e a produção de progênie de adultos F1 de Tribolium castaneum (Herbst, 1797) (Coleoptera, Tenebrionidae). Extrato seco de sementes de T. sureni foi dissolvido em acetona, para preparar soluções de várias concentrações (0,5; 1,0; 2,5 e 5,0%). Para testar a repelência, os insetos foram expostos a papel de filtro tratado. A mortalidade de larvas, pupas e adultos foi avaliada pulverizando os insetos com diferentes concentrações do extrato de T. sureni. O efeito residual do extrato também foi avaliado pela produção de progênie dos adultos F1. A maior repelência (93,30%) de T. castaneum ocorreu na maior concentração (5,0% suspensão de T. sureni); enquanto que a mais baixa repelência (0%) ocorreu na suspensão de 0,5% em um dia após o tratamento. A mortalidade mais elevada de adultos (86,71%), larvas (88,32%) e de pupas (85%) ocorreu com a suspensão a 5%, aos oito dias após a aplicação. Houve uma correlação negativa entre a concentração das suspensões de T. sureni e a produção de progênie de T. castaneum. O maior número de progênie (147) foi produzido na testemunha aos sete dias após o tratamento; enquanto o menor número de progênie (43) foi na suspensão de 5,0% no primeiro dia após o tratamento. Os resultados demostram que T. sureni é tóxico para T. castaneum e tem potencial para ser usado no controle de todos os estágios deste inseto em trigo armazenado.