~ 1617 ~ Journal of Entomology and Zoology Studies 2017; 5(4): 1617-1620 E-ISSN: 2320-7078 P-ISSN: 2349-6800 JEZS 2017; 5(4): 1617-1620 © 2017 JEZS Received: 29-05-2017 Accepted: 30-06-2017 K Deekshita Department of Entomology, Agricultural College, Bapatla, Guntur, Andhra Pradesh, India CV Rama Rao Principal Scientist & Head, Rice Research Unit (RRU), Bapatla, Guntur, Andhra Pradesh, India C Sandhya Rani Associate Professor, Department of Entomology, Agricultural College, Bapatla, Guntur, Andhra Pradesh, India V Prasanna Kumari Assistant Professor, Department of Plant Pathology, Agricultural College, Bapatla, Guntur, Andhra Pradesh, India Correspondence K Deekshita Department of Entomology, Agricultural College, Bapatla, Guntur, Andhra Pradesh, India Effect of new insecticide molecules on predators of rice ecosystem K Deekshita, CV Rama Rao, C Sandhya Rani and V Prasanna Kumari Abstract Field experiment was conducted to evaluate the toxicity of newer insecticide molecules viz., imidacloprid 17.8 SL, thiamethoxam 25 WG, acetamiprid 20 SP, sulfoxaflor 25 SC, dinotefuran 20 SG, pymetrozine 50 WG, buprofezin 25 SC, monocrotophos + dichlorvos 36 SL + 76 EC against spiders and mirid bugs of rice ecosystem in Agricultural College Farm, Bapatla during kharif 2015. Among all the insecticides pymetrozine 50 WG @ 0.5 g l -1 proved safer to the green mirid bugs with lowest percent mortality of 16.96 redcution over precount after two rounds of spray. The safest treatment to spiders is sulfoxaflor with 20.40 percent mortality of spiders over precount followed by pymetrozine 50 WG @ 0.5 g l -1 (23.89 percent). Keywords: Toxicity, pymetrozine, sulfoxaflor, mirid bugs, spiders 1. Introduction Rice (Oryza sativa L.) is an important staple food crop for more than half of the world population and accounts for more than 50 percent of the daily calorie intake [5] . Approximately 21 percent of the global production losses of rice are attributed to the attack of insect pests [10] . Among the 20 serious insect pests of rice, brown planthopper (BPH), Nilaparvata lugens Stal. (Homoptera: Delphacidae), are considered to be most destructive insect pests in Asian countries [8] . To combat these pests, chemical insecticides are used as frontline defense sources. Though, the over dependence and excessive use of pesticides may resulted in development of resistance to the insecticides, induces secondary outbreak of pests, reduces the bio diversity of natural enemies and contamination of the natural ecosystem. But still under such circumstances several new molecules selective to target pests are required to be evaluated for the justification of chemical control as the first line of defence [9] . As, the use of insecticides remains an important component of integrated pest management (IPM), it is necessary to evaluate the new groups, new formulations of insecticides and their combinations for their bio efficacy. Hence it is necessary to protect and preserve the natural enemies of the pests. Among the natural enemies, spiders and mirids are important in rice ecosystem. These natural enemies are directly exposed to the chemicals during spraying, as well as to the left over insecticides. Keeping in mind the ill effects of indiscriminate use of insecticides and the importance of the natural enemies the present work was carried out to evaluate the effect of newer insecticide molecules against natural enemies in the rice ecosystem. 2. Materials and Methods Field experiment was conducted at Agricultural College Farm, Bapatla during kharif 2015 to evaluate the effect of newer insecticide molecules on natural enemies of rice. The experiment was carried out with the variety Sambha mashuri (BPT 5204) in plots of 5x4 m size in a Randomised Block Design (RBD). In this experiment nine treatments were tested viz., imidacloprid 17.8 SL, thiamethoxam 25 WG, acetamiprid 20 SP, sulfoxaflor 25 SC, dinotefuran 20 SG, pymetrozine 50 WG, buprofezin 25 SC and monocrotophos+dichlorvos 36 SL + 76 EC and untreated control, and were replicated thrice. The treatments were imposed at 15 days intervals with hand compressed knapsack sprayer. The spray fluid required per plot is 1 litre. Applications were made during morning hours. Observations on the population of spiders and mirid bugs were recorded in ten randomly selected hills per plot before and after three days and five days after application. The percent reduction of natural enemies over precount was worked out.