Seasonal Abundance, Population Growth, and Within-Plant Distribution of Sweetpotato Weevil (Coleoptera: Curculionidae) on Sweet Potato in Southern Florida

Abstract

Abundance and population growth rates of the sweetpotato weevil, Cylas formicarius elegantulus (Summers), were compared on different cultivars of sweet potato, Ipomoea batatas (L.) Lam. (cvs. Campeon, Centennial, Picadito, and Regal) in southern Florida. The within-vine and within-root distributions of the weevil on plants also were determined. Studies were conducted during the cool, dry, winter and the warm, wet, summer growing seasons. Weevils were more abundant and populations increased more rapidly during the summer than during the winter season. During the summer season, they tended to be most abundant on ‘Centennial’ followed in decreasing order by ‘Regal’ and ‘Picadito.’ Weevils were more abundant and populations increased more rapidly in roots than in vines of ‘Centennial,’ ‘Regal,’ and ‘Campeon,’ whereas they were more abundant or as abundant, and populations increased more rapidly, in vines than in roots of ‘Picadito.’ In vines, weevil populations increased more rapidly on ‘Picadito’ and on one planting of ‘Centennial.’ In roots, populations increased most rapidly on ‘Centennial’ and on one planting of ‘Regal.’ Overall, populations increased most rapidly on ‘Centennial’ and least rapidly on ‘Campeon.’ The weevil displayed a characteristic within-plant distribution that differed among cultivars, Overall, 81.6, 90.2, 91.2, and 91.3% of the total weevil populations within the vines and roots of ‘Picadito,’ ‘Centennial,’ ‘Regal,’ and ‘Campeon,’ respectively, were found below the soil surface. Also, 87.4, 78.7, 89.3, and 78.0% of the total weevil population in vines and roots were found in the region of the plant extending from 15 cm below the crown to 10 cm above the crown on ‘Campeon,’ ‘Centennial,’ ‘Regal,’ and ‘Picadito,’ respectively. These data will help to develop a sampling plan for sweetpotato weevil on cultivated sweet potato.