Insecticidal activity of selected botanicals on maize weevil, Sitophilus zeamais L., in stored maize grains

Laboratory studies were conducted to find the effect of powdered leaf of five plant species such as lantanas or shrub verbenas (Lantana camera), neem (Azadiracta indicia), annona (Annona squamosa), Adathodai (Justicia adhatoda) and Tulsi (Ocimum tenuiflorum) along with chemical pesticide Actellic 5EC (500g/l pirimphos-methyl) against maize weevil, Sitophilus zeamais L., infesting maize grains in storage. Among them Ocimum tenuiflorum (Tulsi) was found to be significantly the best compared to other treatments. It was registered that Ocimum tenuiflorum (Tulsi) and Annona squamosa (Annona) killed 86 percentage of adult weevils by about 6th week. Furthermore, the damage was completely controlled in the grains treated with Ocimum tenuiflorum after eight weeks and almost same in grains applied with Annona squamosa. In addition, significant differences were found between the numbers of emerged weevils in different treatments. In the grains treated with Actellic, Ocimum tenuiflorum and Annona squamosa, the new emerged weevils were not observed and the appearance of newly emergrd weevils were observed in Lantana camera, Azadiracta indica and Justicia adhatoda from 6th week and it was higher in Lantana camera compared to the Azadiracta indica and Justicia adhatoda from 6th week onwards.