Survey of Soil Arthropod Pests and Assessment of Yield Loss in Peanut in Northern Ghana

Abstract

Soil arthropod pests are important constraints to peanut production in Ghana. Surveys of peanut fields were conducted from 2003–2005 to identify and estimate densities of key soil arthropod pests, and also to quantify their damage to peanut in the three regions (Northern, Upper East and Upper West) of northern Ghana. The main soil pests were termites (Isoptera: Termitidae), millipedes (Myriapoda: Odontopygidae), white grubs (Coleoptera: Scarabaeidae) and wireworms (Coleoptera: Elateridae). Across regions, termites and millipedes were the most abundant while wireworms were the least recorded. Significantly higher pest densities and pod damage by scarification and penetration were generally recorded in the Northern Region than in the Upper East and Upper West Regions. A checklist administered to farmers during the survey showed that no control practices were carried out for the pests though farmers generally were aware of the damaging effects of these pests on peanut. Field studies also were conducted at Nyankpala and Bagurugu in the Northern Region during 2005 and 2006 to determine the effects of insecticide (chlorpyrifos or carbofuran) applications to peanut at planting, pegging or at both planting and pegging on control of soil arthropod pests and on yield. Results showed that the insecticides used were similar in their efficacy against the pests. Generally, insecticide treatment lowered pest densities and pod damage resulting in increased yield over the untreated control. Yield losses in untreated plots ranged between 23 and 39%. Treatment at planting or pegging did not differ in the level of control compared with treatment at both planting and pegging. Yield was negatively correlated with pest densities and pod damage. These findings are discussed in the context of control of soil pests of peanut in Ghana.