Evaluation of cultural control practices in the management of sweet potato weevil (Cylas formicarius) (Apionidae : Colepotera)

Abstract

The sweet potato weevil, Cylas formicarius, constitutes a major constraint to sweet potato production and utilization in Africa. Host plant resistance/tolerance, mulching and varying harvesting dates could provide an approach that fits well into an integrated pest management programme of this insect pest. In this study, a trial was conducted to evaluate the effect of host plant, mulching with freshly harvested, dried and chopped up aerial parts of elephant grass (Panicum maximum), and the manipulation of harvesting date, on crop damage by the sweet potato weevil. Cylas formicarius incidence was observed to decrease with increase in mulching level. Also, significant cultivar variation with respect to Cylas formicarius tuber damage and the total number of tubers produced were recorded. Karur local (White) and Arun (White) were observed to be significantly less susceptible to the sweetpotato weevil. Harvesting date was also significantly different, with respect to the number of damaged tubers. More tubers were damaged when harvesting was delayed. Hence, using Karur local (White) or Arun (White), coupled with mulching at the rate of 3-5t/ha and harvesting at 104 DAP resulted in increased number of tubers and reduced sweetpotato weevil infestation in the field.

Screening of some sweet potato (Ipomoea batatas (L.) Lam) genotypes for yield and damage by Cylas puncticollis under rainfed conditions in Umudike, Southeastern Nigeria

“…Sweet potato production in Nigeria is challenged with numerous constraints ORIGINAL RESEARCH ARTICLE including biotic, abiotic, unavailability of improved varieties, which have contributed to the existing low yields of 3t/ha compared to the potential productivity of the crop varying from 15 to 23 t ha-1 (Sebastiani et al, 2007). Among these constraints, sweet potato weevil (Cylas puncticollis) has caused considerable damage and losses in the production of sweet potato in Sub Saharan Africa (Devi et al, 2016). Sweet potato weevil (Cylas spp.)…”

“…attacks sweet potato tuber in the field as well as in storage. Infested tubers are dotted with several small holes and cracks, often dark in colour and squishy in appearance Consequent upon the damaging activities caused by this pest, entry of soil-borne pathogens intensifies (Devi, 2016). Even minimal incidence of sweet potato weevil reduces the storage root quality and produces an unpleasant taste, drastically reducing its nutritive and market values as well as its shelf life (Mbua et al, 2016).…”

Control of the sweet potato weevil (cylas puncticollis) with entomopathogenic nematodes.

“…In Stage 3, the pupal stage, typically lasts for 7-10 days (from day 25-35). In Stage 4, adult weevils emerge from the pupal cocoons after 35 days, depending on the environmental conditions (Devi et al, 2014).…”