Farmer Knowledge of Tagetes sp. and Its Potential Use as Alternative to Synthetic Insecticides for the Control of Maize Weevils in Rwanda

Abstract

This study addresses storage pest challenges maize producers face in Rwanda, specifically Sitophilus zeamais. It aims to explore the  potential of Marigold (Tagetes species) as a botanical pesticide for maize weevil control. The prevailing reliance on synthetic insecticides,  which are costly and environmentally hazardous, necessitates alternative pest management strategies. The research involves two phases:  a survey and bioassays. The survey evaluates the availability of pesticidal plants and farmer awareness regarding their use as  botanical pesticides, emphasizing Marigold. Five districts (Rusizi, Muhanga, Gicumbi, Musanze, Gasabo, and Bugesera) are covered, with  thirty farmers randomly selected from sectors within these districts. The survey assesses awareness of both pesticidal plants and maize  weevils as pests. Bioassays are conducted in the University of Rwanda-College of Agriculture, Animal Sciences, and Veterinary Medicine laboratories, employing a Complete Randomized Design (CRD) with eight treatments and three replications. Maize grains infested with  weevils are treated with varying doses of air-dried and ground Marigold biomass and positive control (Malathion). Over four weeks,  weevil survival and grain damage are monitored every two days, alongside recording temperature and relative humidity. Survey results  indicate the presence of pesticidal plants but low awareness (10%) of Marigold's potential as a botanical pesticide. Similarly, only 31% of  farmers know maize weevils as pests. Bioassay findings reveal Marigold's comparatively lower effectiveness (40% and 53%) in contrast to  Malathion (90%) for weevil control. Nonetheless, studies in Zimbabwe highlight Marigold's potential, achieving 100% weevil mortality  after 56 days. While this study showcases Marigold's potential in achieving notable weevil reduction (40-53%), factors like humidity, temperature, dose, and bioassay duration may have influenced outcomes. Further investigations are recommended to encompass  diverse climatic conditions, increased dosages, extended bioassay periods, and alternative formulations to validate Marigold's efficacy as  a maize weevil control method in stored grains. This research signifies a significant step towards developing sustainable alternatives to  synthetic insecticides for pest management in Rwandan maize production.