~ 218 ~ International Journal of Chemical Studies 2020; 8(1): 218-222 P-ISSN: 2349–8528 E-ISSN: 2321–4902 www.chemijournal.com IJCS 2020; 8(1): 218-222 © 2020 IJCS Received: 23-11-2019 Accepted: 27-12-2019 Pankaj Kumar Mohanta Research Scholar, Department of Entomology and Agricultural Zoology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Utter Pradesh, India SVS Raju Professor, Department of Entomology and Agricultural Zoology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Utter Pradesh, India GS Giri Department of Entomology, Tirhut College of Agriculture, Dholi under RPCAU, Pusa Samastipur, Bihar, India Corresponding Author: Pankaj Kumar Mohanta Research Scholar, Department of Entomology and Agricultural Zoology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Utter Pradesh, India Bio-efficacy of certain insecticidal molecules against lepidopteran pests of rice Pankaj Kumar Mohanta, SVS Raju and GS Giri DOI: https://doi.org/10.22271/chemi.2020.v8.i2c.8771 Abstract Rice is one of the most important food crops grown worldwide. Though we use almost of the improved agronomic practices, we can not get optimum production and productivity. The reason behind its low productivity includes several factors. Among them insect pest infestation is prime and most important one. Among several insect pests, pests of lepidopteran order such as yellow stem borer and leaf folder are considered as most destructive and responsible for severe yield losses. As the larva are found inside the stem or within the leaf fold, cultural, mechanical, physical methods of pest management are not as effective as chemical control in reducing the pest population. So the present investigation was carried out in order to find out the efficacy of certain chemicals against lepidopteran pests infesting rice. Keywords: Lepidopteran pest, yellow stem borer, leaf folder, management, bio-efficacy Introduction Rice (Oryza sativa L.) is one of the mostly grown crops in the world and is the most important staple food of over half the world’s population (Khush, 1997) [4] . Approximately, 750 million of the world’s poor people depend on rice to survive (Zeigler, 2006) [9] . It is grown practically in all the tropical, sub-tropical and calm nations of the world. Among the several limiting factors for getting improved yields, insect-pests infestation is the prime and the most restraining factor in the successful cultivation of rice. More than 100 species of insects attack rice and among them 20 have potential to cause economic damage all over the world, causing more than 30 per cent yield loss from seedling to maturity (Cramer, 1967; Pathak and Dhaliwal, 1981 and Athwal and Dhaliwal, 2005) [2, 5, 1] . Some of them are Yellow stem borer (Scirpophaga incertulas), Leaf folder (Cnaphalocrocis medanalis), Gall midge (Orseolia oryzae), Brown plant hopper (Nilparvata lugens), Green leaf hopper (Nephotettix nigropictus, Nephotettix virescens), Gundhi bug (Leptocorisa acuta), Case worm (Nymphula depunctalis) and several others. Among quite a few insect pests linked with rice, pests of lepidopteran order are considered to be highly destructive. However, timely application of insecticides is the only and most commonly used measure for reducing pest population and sometimes the only practical solution to sudden outbreaks of insect pests in general. Thus it is imperative that alternate insecticides be explored for managing the pests. New molecules will be searched in the context of effective against rice pest as well as eco-friendly should be given top priority. Materials and Methods The experiment was carried out during the kharif season of 2018-19 at the Agricultural Research Farm, Banaras Hindu University, Varanasi (Uttar Pradesh) which is situated at latitude of 24° 56’ N to 25° 35’ N and longitude of 82° 14’ E to 83° 24’ E with an altitude of 82 m above the mean sea level (MSL). The place is situated in the centre of Indo-gangetic belt, falling under the sub-humid and sub-tropical climate zone Pests monitoring was done at regular intervals in the current experiment and when the economic threshold levels were reached in terms of pest population / damage, insecticides were sprayed as per the schedule laid out in two sprays: First Spray 10th October 2018 Second Spray 30th October 2018