Field evaluation of selected synthetic insecticides against major insect pests of amaranthus in Ogbomoso, Nigeria
Vegetable production in Nigeria is predominantly subsistence and insect pest infestation is the major factor militating against its cultivation especially in the western part of the country. Synthetic insecticides still remain the most effective control of insect pests due to rapid action before the insect pests attain economic threshold. This study was therefore designed to evaluate the efficacy of selected insecticides against major insect pests of amaranthus in Ogbomoso, Nigeria. This experiment was carried out at Ladoke Akintola University of Technology Teaching and Research Farm Ogbomoso, during 2018 to 2019 major planting season to determine the effects of Cypermethrin and Lambda-cyhalothrin on major insect pests of Amaranthus varieties. The experiment was laid out in Randomized Complete Block design replicated three times, Five Amaranthus varieties namely: NGB01662, NGB01271, NGB01276, NGB01667 and NGB01613 were planted on the field. Data were collected on level of insect population density and the number of leaf defoliation. Data collected were subjected to analysis of variance (ANOVA) and significant means were separated using Duncan Multiple Range Test at 5% probability level. Three major insect pests of Amaranthus varieties were identified Dichromorpha viridis, Aspavia armigera and Hymenia recurvalis. The two tested synthetic insecticides caused 73.5% reduction of the insect pests’ attack irrespective of the varieties. The highest leaf defoliation was observed on untreated varieties ranging from 53.3% to 86.7%. The two treated synthetic insecticides had similar insecticide efficacy against the observed insect pests, irrespective of variety. The two synthetic insecticides can be used in the control of insect pests of Amaranthus varieties.