Evaluation of Sweet Potato Cultivars for Differences in Cylas puncticollis (Curculionidae: Brentidae) Damage in South Western Cameroon
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- Bioassay, Choice, Cultivars, Food Preference, No-Choice, Oviposition, Sweet Potato Weevils
- Parr, Mbua. C.; Ntonifor, Nelson. N.; Jackai, Louis E. N.
- This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. CC BY-NC-SA 4.0 Creative Commons License: https://creativecommons.org/licenses/by-nc-sa/4.0/
- Sweet potato sometimes dubbed “a crop for the poor” is a food security crop for smallholder farmers in Cameroon. However, its increased production is constrained by the sweet potato weevil, Cylas puncticollis (Curculionidae: Brentidae), a serious sweet potato pest throughout Sub-Saharan Africa. A study was therefore conducted to screen 18 indigenous and exotic sweet potato cultivars for their responses to Cylas puncticollis through laboratory free-choice and no-choice oviposition as well as host suitability for development bioassays. Correlation and regression analysis for the free-choice bioassay revealed that dry matter content was positively correlated to number of eggs laid (r = 0.55). For the no choice bioassay, there was a positive correlation (r = 0.67) between number of feeding punctures and number of eggs laid. A significantly higher number of eggs were laid on sweet potato cultivars with higher dry matter content compared to those with lower dry matter content. These findings support the hypothesis that a female will choose those hosts for oviposition on which larvae perform best. Storage roots with high dry matter content probably had appropriate food reserves to support adequate offspring development. In the free-choice test, the indigenous sweet potato cultivars were slightly preferred for oviposion and feeding by C. puncticollis more than the exotic ones while in the no-choice food and oviposition tests, the cultivars IRAD 048 had the highest number of feeding punctures followed by Buea local white and Kekem in that order. For developmental bioassays, a higher number of weevil adults emerged from the indigenous sweet potato cultivars between 36-45 days compared to the exotic cultivars. None of the sweet potato cultivars tested was completely resistant to Cylas sp. However the exotic cultivars were less susceptible to Cylas feeding and led to fewer adults emergence from them.
Full text: IJRAS_319_Final.pdf