* Corresponding author's E-mail address: illakwahhi@gmail.com, Tel.: + 255765267180 Chemistry Department, College of Natural and Mathematical Sciences, University of Dodoma, Tanzania Advanced Journal of Chemistry-Section A, 2019, 2(3), 216-224 Research Article http://ajchem-a.com Improving the Efficacy of Abamectin Using Neem Oil in Controlling Tomato Leaf miners, Tuta absoluta (Meyrick) Daniel T. Illakwahhi, a, *, Bajarang Bali Lal Srivastava, b A R T I C L E I N F O A B S T R A C T Received: 1 January 2019 Revised: 26 January 2019 Accepted: 13 February 2019 Available online: 5 March 2019 DOI: 10.29088/SAMI/AJCA.2019.2.216224 K E Y W O R D S Tomato leaf miners, Tuta absoluta pose a control challenge against dozens of chemical pesticides including abamectin as a result of increase in resistance with time. This study aimed at improving the field performance of abamectin using crude neem oil . The oil was obtained from the healthy neem seeds by cold pressing method. A total of 10 larvae were used in each bioassay experiment. Abamectin at 1000 ppm caused corrected mortality of 79% and its concentration that kills half of the experimental larvae (LC50) was 363 ppm. The crude neem oil at concentration of 2500 ppm caused corrected mortality of 61% with LC50 at 1089 ppm. The 1:1 mixture of abamectin and crude neem oil (without heating) at concentration of 1000 ppm gave 83% as highest corrected mortality and LC50 at 251 ppm. The findings from bioassay experiments revealed that, both neem oil and abamectin are potential pesticides; however their performance was even high after mixing. It was the synergism effect that gave the mixture high performance. Biopotency Pesticide Bioassay Tomato leaf miners Pest control G R A P H I C A L A B S T R A C T