Inhibitory activity, reducing loss and repulsive of methanolic extracts from sheets of plectranthus glandulosus against sitophilus zeamais

Abstract

The extracts of the leaves of Plectranthus glandulosus were evaluated on population growth, the losses caused to the seeds by Sitophilus zeamais and their repulsive effect were also tested. The reference insecticide Delvap Super® (Dichlorvos 1%, Cypermethrin 0.36% [PI]) was applied as a positive control at the recommended dose (0.1 g / kg), while the extracts were used at four different doses (5, 10, 20 and 40 g / kg). The growth rate of S. zeamais and the losses caused to the seeds were recorded. The methanolic extracts of the leaves of P. glandulosus significantly reduced the growth of of S. zeamais from 61.67 to 100% and the losses from 84.12 to 100% comparable to the inhibitory and reducing effect of the losses of Delvap Super® 100% saved with its recommended dose. The maximum repulsion rate (83.33%) for S. zeamais was recorded with the highest dose (40 g / kg) after 2 hours of exposure by the olfactometer method. In view of these results, we could affirm that these extracts could be recommended as alternatives to synthetic insecticides against S. zeamais in storage.