Efficacy of Various Botanicals against Maize Weevil (Sitophilus Zeamays) in Laboratory Condition

Maize (Zea mays L. Gramineae) is one of the major cereal crops produced worldwide (Blackie & Jones, 1993). Maize is the second most important staple food crops in hills of Nepal (Upadhya et al., 2007). Maize can be grown in all kinds of agro-ecological zones irrespective of land type and seasons because it is widely adaptable to different stress environments and is widely grown from the terai to high mountains in Nepal (Adhikari,2007).It is also known as queen of cereal crops and has high potential in terms of yield and production (Singh, 2002). Maize is cultivated in an area of 891583ha with the production of 2231517Mt and total yield is 2503kg/ha (MOAD, 2015/2016). It contributes about 30% of the total cereal production in the high hills and 40% in the mid-hills and plays important role in the food supply as well as regarding major staple food in the remote area of Nepal (Pandey et al., 2001). In the last decades, annual growing demand of maize production is increasing constantly at the rate of 5% (Sapkota & Pokhrel, 2010). According to Ranum, Pena Rosas, Garcia-Casal (2014) per capita maize consumption in Nepalis 98 g/person/day.

Different insect pest attacked crops both in the field and in the storage condition (Neupane et al., 1991). That attacks may range from sap sucking or leaf damaging or ear damaging insects. Overall 60-70% reductions in the final yield of maize production have been reported due to insect pest hazards (Sharma, 2009). Such attacks are not only confined to the developmental stage of the plant but also continue in the storage period.

On an average about 20-30% yield losses after post harvest of maize due to pest infested have been seen by scatter and accidental (GC, 2006) The major reasons for post harvest losses are ;inadequate knowledge about post harvest losses, careless after harvest or post harvest losses, unavailability of synthetic pesticides in time, misuse of pesticides, poor economic condition, unavailability of improved storage structures, careless and ignorance about importance of botanical pesticide for controlling stored pests, etc. Several researchers have evaluated insecticide, repellent or antifeedent and development inhibiting effects of various plant parts and plant products on S. zeamays with varying degree of success. Among the botanicals used sweet flag rhizome, neem oil, neem seed powder timur, (Zantthoxylum armatum DC.) and mugwort (Artimisia vulgaris) have been reported to be superior to control the maize weevils (Paneru, Duwadi, Khanal, and Bhandari, 1996; Anonymous, 1988). Some of the metabolites of plants are toxic such as pyrethrum, nicotine, rotenone etc. and some are repellents, antifeedants like azadirachtin, rapeseed extract and others, like Acorus calamus act as sterilants (Ignatowicz and Wesolowska, 2015). Asian countries have abundantaly used of these plant products which are traditionally used by the rural people for preparations against insect control (Talukder and Howse, 1993). Thus,these plant products can be utilized either alone or mixed for controlling stored pest. So, with an objective To develop effective management technique for storage insect pests and particularly, assess damage by maize weevil in storage and identify the effective management option against maize weevil this experiment was performed.