Abstract

The experiments were conducted in the laboratory of the Department of Entomology and Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during May-December 2017 to evaluate the toxicity of five medicinal plant extracts (water hyacinth Eichhornia crassipes, swamp smartweed Polygonum coccineum, ariach Cassia tora, wild capsicum Croton bonplandianum and hill glory bower Clerodendrum viscosum) against maize weevil, Sitophilus zeamais (Mots.) on stored maize. Data were statistically significant of each treatment (p < 0.05). Among the five weed extract; the wild capsicum extract provided the highest average mortality (93.33 ± 3.33), following the hill glory bower (86.67 ± 3.33) and swamp smartweed (86.67 ± 3.33) at 3% concentration. But it was zero in control. The average numbers of lowest numbers of adult emergence among the five weed extract was found in wild capsicum (3.00 ± 0.39) following Swamp smartweed (5.11 ± 0.95) at 3% concentration; whereas, in control it was (54.00 ±1.15). The lowest percent of seed damage was found in wild capsicum (3.00 ± 0.38%) following Swamp smartweed (4.22 ± 0.58). But in control it was 44.00 ± 1.15.The repellency class of different plant extracts at different concentration level varied between I to IV. But the hill glory bower at 3.0% showed statistically best as it showed the highest repellency rate was 66.0 ± 5.31% and group was IV. However, the toxicity order was wild capsicum > swamp smartweed > hill glory bower > water hyacinth >, ariach.

Keywords: Toxicity, Medicinal plant, Extracts, Sitophilus zeamais (Mots.)