KATTERINNE PRENTICE(1),(2)*, OLIVIER CHRISTIAENS0(2),, MARC GHISLAIN(3), GODELEIVE GHEYSEN(2), GUY SMAGGHE(1)
1 Department of Crop Protection, Ghent University, B-9000 Ghent, Belgium.
2 Department of Molecular Biotechnology, Ghent University, B-9000 Ghent, Belgium.
3 International Potato Center (CIP), Genomics and Biotechnology Program, Nairobi 00603, Kenya.
*email@example.com, Tel: +32 474 288 640
The African sweetpotato weevils Cylas puncticollis and Cylas brunneus (SPW) are considered the major threats to sweetpotato, which plays a vital role in food security and income generation for both the urban and rural poor in Sub-Saharan Africa (SSA). RNA interference (RNAi) technology can add genetic resistance against SPW in sweetpotato. The presence of an efficient RNAi response and the identification of suitable target genes are important prerequisites to use RNAi as pest control strategy. In this study, we confirmed the functionality of the RNAi mechanism in SPW by silencing laccase2 through microinjection, a gene which is involved in the sclerotization of the exoskeleton. Subsequently, we performed a screening for lethality of 24 potential target genes by microinjection. Twelve and fourteen dsRNAs showed high toxicity with more than 90% mortality for both C. puncticollis and C. brunneus, respectively. Based on these results, the three most lethal dsRNAs were chosen for oral delivery assays. These revealed that dsRNA by oral exposure could elicit a significant toxicity on both insects, although less sensitive for C, puncticollis. Ex vivo assays confirmed that dsRNA uptake is affected by degradation in C. puncticollis digestive system. In this research, we proved that RNAi has the potential to control sweetpotato weevils, especially for C. brunneus, while the delivery of dsRNA and possible protection against degradation might have to be optimized in C. puncticollis.