Efeito inseticida do extrato hidroalcoólico de folhas de Lippia sidoides Cham. (Alecrim-pimenta) sobre o desenvolvimento do besouro bruquídeo Callosobruchus maculatus (FAB).

Abstract

The aim of this work has been evaluate the effect of hydroalcoholic extract of Lippia sidoides Cham. leaves on the development parameters of weevil Callosobruchus maculatus (Fab.). The parameters observed were: total number of eggs, total number of emerged eggs, number of emerged insects separated by sex, total time of development, and loss of seed mass. To performed the experiment we have used 100 seeds of cowpea beans. These seeds were put on plastic containers, measuring 5 cm of high and 6.5 cm of diameter. The containers were closed and some holes were made on the wall. We used three volumes of extract 10, 50 and 100 pL. These volumes were add on filter paper discs and these discs were placed into the containers under the seeds. Inside of all containers, 2 to 4 females were put on it. The insects laid on 24 hours and they were discarted after that time. We observed significant decreasing (Tukey test, p<0.05 e p<0.01) on some parameters. The total number of eggs for the treatment with 2 females, decreased significativelly for all tested volumes (p<0.05 e p<0.01). For total number of hatched eggs, the experiment wiht 4 females, only the volumes of 10 and 50 pL decreased the values compared with the control (p<0.05). The number of birth females reduced for the volumes 10 and 50 pL (p<0.05), in the experiment with 4 females. On the other hand, the number of birth males was lower than the control in the experiment with 4 females (p<0.05). In conclusion, the number of females influenciated on the observed parameters. We can suggest 2 and 4 the ideal number of females for the experiment.