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

Abstract

Abstract:The effects of infestation by the sweet potato weevil, Cylas puncticollis Bohemen, on yield in 3 sweet potato cultivars, in relation to different mulching levels were compared. The experiment was laid out in a randomized complete split plot design at three levels. It consisted of a main plot factor, the three sweet potato cultivars (slipot 2, 3 and 4) with mulching at three levels (0, 1, 3 and 5t/ha) as sub plot. The factors were replicated thrice. The results of the studies revealed that increase in mulching level resulted in significantly decreased infestation of sweet potato weevil and higher root yield. Mulching at the rate of 5t/ha recorded the least infestation (12.13% for the year 2012; 13.32% for the year 2013) followed by 3t/ha (17.86% for the year 2012; 21.24% for the year 2013), 1t/ha (25.18% for the year 2012; 29.49% for the year 2013) whilst the unmulched plot recorded the highest (35.75% for the year 2012; 41.30% for the year 2013). Root yield was the highest with mulching at the rate of 5t/ha (6242.42Kg/ha for the year 2012; 4828.45Kg/ha for the year 2013) followed by 3t/ha (5863.64Kg/ha for the year 2012; 4883.82Kg/ha for the year 2013), 1t/ha (4580.81Kg/ha for the year 2012; 3818.18Kg/ha for the year 2013) whilst the unmulched plot recorded the highest (4202.03Kg/ha for the year 2012; 3489.89Kg/ha for the year 2013). Significant negative correlation (r = -0.91, p = 0.0001) was observed between weevil root damage and root dry matter. Only two cultivars, Slipot 3 and Slipot 4 were observed to be less susceptible to the sweetpoto weevil. Thus, using mulch cover at the rate of 3-5t/ha in a field planted with slipot 3 or slipot 4 will increase yield, while at same time reduce sweet potato weevil infestation.

Organic mulches reduce crop attack by sweetpotato weevil (Cylas formicarius)

“…This level of prior acceptance is likely to predispose farmers to be prepared to adopt mulches to serve a wider range of functions including pest management. In sweetpotato production, straw or plastic mulches have been used to reduce weed growth and extend the season in cooler climates 20 and there has been one study suggesting utility against a congeneric of the species we studied, C. puncticollis 7 . In that African field study, freshly harvested, dried, chopped aerial parts of elephant grass ( Panicum maximum ) were applied to plots at 0, 1, 3 and 5t/ha.…”

“…Though the present study did not include elephant grass, the apparent repellence of several of the mulches tested and reductions in feeding hole numbers are consistent with the effects reported by Mansaray et al . 7 . The Poaceae species tested in the present study, sugarcane, lemongrass and wheat straw, had inconsistent effects on C. formicarius , suggesting that taxonomic identity of the plant from which mulch material is sourced is likely to be less important as a predictor of efficacy than specific plant traits.…”

“…Direct feeding damage to the storage roots is compounded by the plant producing defensive sesquiterpenes that make the roots strongly distasteful, as well as by promoting damage by fungi and bacteria 6 . Losses to weevils are especially severe under dry seasons when soil cracking makes access to the roots easier for gravid females 7 . Storage roots may also be exposed to pest attack when their swelling, possibly combined with soil erosion from rainfall, leads to the cover of soil being breached.…”

“…Even developed countries may benefit from the availability of new methods to lessen reliance on costly inputs and slow the development of insecticide resistance. Mulches have previously been used in sweetpotato cropping to suppress weeds, provide nitrogen, minimise soil erosion, encourage beneficial insects 11,12 and to reduce pest attack 7 .…”

Integrasi komponen pengendalian hama penggerek ubi jalar (Cylas formicarius Fab.) (Coleoptera: Curculionidae)

“…Kondisi lahan entisol umumnya miskin bahan organik dan kemampuan menahan air juga sangat rendah. Oleh karena itu, komponen pengendalian yang dapat diterapkan untuk mengatasi kondisi lahan tersebut adalah penambahan bahan organik, pemberian mulsa sebagai penutup guludan agar imago terhalang tidak mampu menjangkau pangkal batang ubi jalar (Tesfaye 2003;Reddy et al 2014;Mansaray et al 2015).…”