Incidence of insect pests in groundnut (Arachis hypogaea) fields and storage in Karachuonyo and Nyakach Constituencies of Western Kenya

Groundnut is a popular grain legume crop, and an important cash crop in Western Kenya. However, farmers are facing various production constraints leading to low yields. Yearly, statistical reports by the Agriculture and Food Authority (AFA), Nuts and Oils Crops Directorate show a consistent decline in groundnut production in the potential. Lack of quality planting seeds, and pest infestation during growth and storage have been cited as major problems. Studies on the pests of the groundnut crop in the regions are still scarce. The study’s objective was to identify the key insect pests associated with the cultivation and storage of groundnuts in selected parts of the Western region of Kenya. The study was conducted in ten groundnut farms in Nyakach and Karachuonyo constituencies in two seasons, 2021 and 2022. Observation and direct field and storage insect sampling were done in the two regions. The species richness, abundance, and diversity of insects were calculated by analysis of variance (ANOVA) and Shannon Weiner index, respectively. In the present study, a total of 2,714 insect pests from 7 orders, 14 families, and 20 species of field pests and 2,396 individuals from 3 orders, 5 families, and 7 species of storage pests were recorded. This study shows that Empoasca kerri, was the most dominant field pest with a mean average of 344, followed by Aproaerema modicella (230), Frankliniella schultzei (136), Aphis craccivora (208), Microtermes sp. (96), Scirtothrips dorsali (64), Elasmolomus sordidus (69), Spodoptera litura (56) and Parastictococcus multispinosus (30), while storage pests were Liposcelis decolor (438), Tribolium castaneum (438), Plodia interpunctella (146), Cryptolestes minutus (137) and Ephestia cautella (30). These pests were causing physical damage to the groundnut plants, seeds and pods, leading to deterioration in the weight, quality, vigor, and reduction in the germination, thus leading to the loss of yield and market value. The study recommends further investigation of the actual damage potential of insect pests on groundnuts and the appropriate management strategies. Key words: Groundnut, insect pests, Empoasca kerri, Aproaerema modicella, Liposcelis decolor