Assessment of pests incidence and their impact on yield of sweetpotato in Mozambique

The sweetpotato (Ipomoea batatas L.) is important food and cash crop and is considered as one of the most important crop for food security in Mozambique. Sweetpotato is grown extensively by small scale households and mostly managed by women. Currently, the International Centre of Potato (CIP) is promoting the production and use of 15 OrangeFleshed Sweetpotato (OFSP) cultivars as a means to combat Vitamin A deficiency (VAD) and food insecurity in Mozambique. Among the factors affecting the production of sweetpotatoes is the infestation of pests and diseases that contribute to the low yields and quality of the tubers in Mozambique. However, there is limited information on the incidence and impact of pests affecting the yield of sweetpotato in the country. Therefore, this study was conducted with the aim of assessing the incidence of pests and their associated impact in cultivars of Orange-Fleshed Sweetpotato. Data were collected in 11 Orange-Fleshed Sweetpotato cultivars in equal number of plots established by CIP/Reaching Agents of Change (RAC) project located in Boane district, Maputo province. Each plot was divided into four sub-plots of 4 m2 each as replicates. The tubercles were harvested and evaluated for pest infestation and damage and then counted and weighted. All insects and other organisms found were collected, identified and counted. The main pest species identified were the tortoiseshell beetles, Aspidomorpha spp. (in the foliage) and sweetpotato weevils, Cylas puncticollis and C. formicarius, and damage by rodents (in the tubercles). While the highest tuber damage was reported on the Ester cultivar accounting for 75.03% and the lowest of 9.7% was on Gloria. Total yield losses ranging from 18.2 (on Lourdes cultivar) to 88.9% (on Jane) were observed. Commercial yield losses varying from 64.8 to 98.6% were reported where Ininda and Jane cultivars showed the lowest and highest yield losses, respectively. The sweetpotato weevil species are recognized as serious pests of sweetpotato in the area of study. The results from this study suggest that sweetpotato weevils have significant impact on the Orange-Fleshed Sweetpotato production in the country, and therefore, their management should be taken into consideration.