COMPARATIVE EFFECT OF SOME BIO-PESTICIDES ON THE MANAGEMENT OF AFRICAN PINK STEM BORER, Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae) ON SWEET CORN (Zea mays var. saccharata L.)

Abstract

The study was conducted at Institute for Agricultural Research (IAR) horticultural garden Ahmadu Bello University, Zaria under irrigation in two dry seasons (2019 and 2020). The region is located at Latitude11º11'¹N and Longitude7º38'E. The research was conducted to evaluate the effectiveness of two microbial pesticides: Emamectin benzoate and Beauveria bassiana, two botanical extracts: Karanjin from Pongamia glabra and Azadirachtin (Azadirachta indica), one synthetic insecticide: Lion Guard EC (with Cypermethrin 3% and dimethoate 25%) which served as Standard check. S. calamistis larvae were mass produced in the Insect Rearing Laboratory of the Department of Crop Protection using artificial diet to carry out field infestation. On the field, the treatments involved three maize varieties; Sweet Corn Yellow, Sugar King F₂ and SAMMAZ 52 and also the five (5) pesticides with untreated control laid out in a Randomized Complete Block Design (RCBD) in split plot with three replications on a plots size of 9m² (3 m x 3 m). Leaf damage, dead hearts, cob damage, exit holes, lodging, stem tunneling and yield ha^-1 were measured. The data was subjected to ANOVA using SAS 9.0 and the means were separated using Student Newman Keul’s (SNK). Azadirachtin with 1.53, Karanjin with 2.22, Emamectin 1.48 and B. bassiana 1.42 larval mortality on the field after treatment application. Azadirachtin, Karanjin, Emamectin and B. bassiana reduced dead heart incidence by 46%, 20%, 51% and 52% respectively when compared with control in which 60% dead hearts incidence was recorded. Azadirachtin, Emamectin and B. bassiana were very effective in suppressing S. calamistis population, mitigated its ability to cause serious damage to the leaves, hearts, stem and cob of the maize and produced higher when compared with control.  Even though Karanjin was less effective than the other three, it was better than control treatment. Azadirachtin can be applied at the rate of 0.44 Lha^-1 and Karanjin at the rate of 0.5 Lha^-1 to control of S. calamistis on sweet corn.  B. bassiana and Emamectin benzoate can be applied at the rate of 0.25 Kgha^-1 and 3 Kgha^-1 to manage of S. calamistis.