Sweetpotato infestation by Cylas spp. in East Africa: Ii. Investigating the role of root characteristics

Abstract

The response of the sweetpotato weevil Cylas puncticollis (Coleoptera: Brentidae) to roots of different sweetpotato cvs was investigated as part of a project to examine the factors that affect susceptibility of sweetpotato cvs to weevil infestation in the field. Laboratory experiments were conducted at two sites (Ukiriguru and Kibaha) in Tanzania and at one site (Serere) in Uganda to determine if the harvested storage roots of sweetpotato cvs differed in their acceptability to C. puncticollis or if any root antibiosis towards C. puncticollis existed. For all experiments cultivar effects for the total number of emerging adults were significant to at least 10% and in most cases were much more significant. At Ukiriguru and Kibaha, the results showed reasonable consistency between years, and of the four cultivars used at both sites, fewer C. puncticollis adults emerged from roots of Sinia and Budagala than from SPN/0 and Mwanamonde on all occasions. A relationship between laboratory experiments and crown damage by Cylas spp. in the field suggests that cultivar differences in attraction/deterrence for Cylas spp. exist. However, correlations between adult emergence in laboratory antibiosis experiments and field infestation levels were generally not strong. Although this indicates that cultivar selection by laboratory experiments is not a useful strategy for reducing field infestation, there may be potential for using such techniques to select cultivars that are resistant to attack during longterm storage.

Chemical basis for resistance in sweetpotato Ipomoea batatas to the sweetpotato weevil Cylas puncticollis

“…This paper reports that, in contrast to earlier reports on other resistant African sweetpotato cultivars [3,4], resistance in New Kawogo is more than simply escape but is active, quantifiable, and potentially manageable for breeding purposes. Furthermore, the effect on adults feeding on the resistant roots is demonstrated to be deterrent or toxic.…”

“…were observed [3], the mechanism was reportedly escape. Specifically, the depth of roots and the tendency of shallow swollen roots to crack dry soil and so provide access for the insects were reportedly correlated with a root's tendency to be infested [4].…”

Sweet potato Weevil (Cylas puncticollis) Boheman Infestation: Cultivar Differences and the Effects of Mulching

“…Slipot 3 is known to be a deep-rooted cultivar; which makes it difficult for the sweet potato weevil to access even under low moisture condition. The sweet potato weevil Cylas spp cannot dig but, gain access to exposed roots through cracks in the soil, as such, deep-rooting can act as an escape mechanism [7,8]. Slipot 4 on the other hand, has a high dry matter content coupled with its hard peel makes it difficult for C. puncticollis to puncture and hence confers some form of resistance.…”

“…Host plant resistance is one of the strategies that had been adopted in the management of this pest. However, progress in breeding varieties with resistance to C. puncticollis and C. brunneus that is of dynamic rather than escape has been slow largely due to the scarcity of varieties with significant level of *Address correspondence to this author at the Mercy Hospital Research Laboratory, BO City, Sierra Leone; Tel: +232 76701269; E-mail: jasundufu@gmail.com resistance [7,8]. The application of crop residue (mulch) has also been reported to improve soil water supply to crops through reduced runoff, soil evaporation, increased infiltration and water storage thereby reducing cracks in the soil [9].…”

Pengaplikasian Dry Ice Untuk Pengendalian Cylas formicarius pada Ubi Ketela Rambat

“…Rasa pahit ini disebabkan karena kotoran dari larva C. formicarius. Stathers et al (2003) menambahkan, kerusakan kecil maupun besar akibat gerekan Cylas pada ubi jalar akan merangsang pembentukan senyawa toksik terpenoid sebagai reaksi ubi jalar terhadap serangan Cylas sehingga membuat rasanya tidak enak dan tidak bisa dikonsumsi. Senyawa racun yang terbentuk dapat mempengaruhi kerja hati dan paru-paru pada manusia dan mamalia KESIMPULAN…”