Effectiveness of Some Chemical and Biological Pesticides against Sitophilus zeamais (Motschulsky)

Maize development is a lifestyle for most farmers in the slopes of Nepal. It is a traditional crop which is cultivated as food, feed, and fodder on inclining land which is rain-fed upland in the hills. It is developed under downpour took care of conditions throughout the mid-year (April-August) as a solitary yield or transferred with millet later in the season. In the terai, internal terai, valleys, and low-lying river basin regions, maize is likewise grown in the winter and spring with irrigation system (Paudyal et al., 2001). Different cereal harvests have assumed significant parts intending to food security issues in Nepal. Lately, there have been vacillations in crop production and demand situations because of different reasons (Gairhe et al. 2018). Maize is the second most significant yield after rice as far as region and production in Nepal. It is a lifestyle for the farmers of the hilly area in Nepal. It is a traditional yield developed for food, feed, and fodder. Maize demand has been continually developing by about 5% yearly in last decades. Per capita, maize consumption in Nepal was 98 g/individual/day. The stored maize is attacked and harmed by a few pests that lead to quality fading driving farmers to sell at scaled down costs and underneath the production cost. Insect-Pests are frequently viewed as the main reason for maize grain losses. The main pests that cause harm to maize in the field and capacity are Lepidopterist stalk borers and Coleopterans weevils, respectively. In excess of 37 types of arthropod pests are related with maize grain in storage. During the storage time frame, insects-pests and diseases assume a huge part in diminishing production and productivity combined with germination potential (Alam et al., 2019). Among pests, maize weevil (Sitopilus zeamais) and Angoumois grain moth (Sitotroga cerealla) were the main pests found in stored maize in Nepal. This happens on the grounds that the majority of the maize produced by farmers stays on the open floor of their room without keeping up appropriate storage standards. The primary reason for this is farmer’sabsence of sufficient information in regards to the situation with insect pests in a stored condition. (Alam et al., 2019).

S. zeamais Motsch stays quite possibly the most serious and internal feeding pests of maize in storage (Pameru et al., 1997). It falls among the most dangerous pests in stored grain, particularly maize in tropical areas. Grown-up female of weevils causes harm by drilling into the kernel and laying eggs (ovipositing) (Longstaff., 1981). The larvae and pupae eat the inward pieces of the kernel, which brings about a harmed kernel and diminished grain weight. The pervasion boosts temperature and dampness content in the stored grain mass, which can prompt fungal growth, including toxigenic species, for example, Aspergillus favus Link. S. zeamais can cause an extensive loss in quality and amount of the grain on the field just as in the storage. (Bhusal and Khanal., 2019).

There have been different sorts of insecticides that have been suggested for the control of storage pests in Nepal (Neupane, 2000). In any case, direct utilization of such insecticides is neither relevant nor doable (Mallah et al., 2018.). The chemical control is compelling, quick, secure, and conservative yet it has some significant downsides: such as adverse consequence on products and surrounding environment; the steady peril of intoxication for people and animals; the presence of residue in various pieces of the plants; (RÖMBKE Jet al., 2000). Disposal of these downsides should be possible by utilizing some fewer contaminating insecticides, from the IIIrd and IVth groups of toxicity, and by utilizing efficient dosages, as least as possible (Porca et al., 2003). Some storage gain can be protected with chemical and biological pesticides for seed and feed purposes. Therefore, this study has been devised to study the effective pesticides and their residual effects on mortality of maize weevil along with the grain damage assessment.