Evaluation of potential RNA‐interference‐target genes to control cotton mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcuidae)

Abstract

RNA interference (RNAi) of vital insect genes is a potential tool for targeted pest control. However, selection of the right target genes is a challenge because the RNAi efficacy is known to vary among insect species. Cotton mealybug, Phenacoccus solenopsis, is a phloem-feeding economically important crop pest. We evaluated the RNAi of 2 vital genes, Bursicon (PsBur) and V-ATPase (PsV-ATPase) as potential targets in P. solenopsis for its control. PCR fragments of PsBur and PsV-ATPase were amplified using cDNA synthesized from the total RNA. The PCR amplicons were cloned into Potato virus X (PVX) to develop recombinant PVX for the inoculation of Nicotiana tabacum plants for bioassays with healthy P. solenopsis. Reverse-transcription-polymerase chain reaction (RT-PCR) was used to validate the expression of transgenes in the recombinant-PVX-inoculated plants (treated), and suppression of the target genes in the mealybugs exposed to them. The RT-PCR confirmed the expression of transgenes in the treated plants. Mealybug individuals on treated plants either died or showed physical deformities. Further, the population of mealybug was significantly reduced by feeding on N. tabacum expressing RNAi triggers against PsBur and PsV-ATPase. The results conclude that RNAi is activated in P. solenopsis by feeding on N. tabacum expressing RNAi triggering elements of PsBur and PsV-ATPase genes through recombinant PVX vector. Further, V-ATPase and Bursicon genes are potential targets for RNAi-mediated control of P. solenopsis.

Using de novo transcriptome assembly and analysis to study RNAi in Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

“…8 B-2 and B-3). Bursicon , known as insect tanning hormone, has vital role in development of insect cuticle 56,57 . Earlier studies have suggested that RNAi mediated knockdown of AmBurs α and AmBurs βbursicon genes in Apis mellifera prevented the complete formation and tanning of the adult cuticle 56 .…”

The Roles of DNA Methyltransferases 1 (DNMT1) in Regulating Sexual Dimorphism in the Cotton Mealybug, Phenacoccus solenopsis

“…Therefore, we tried two different RNAi methods to deliver siRNA into the cotton mealybugs. RNAi delivery methods have been documented in various insects, including hemipteran species [29,37,[49][50][51][52]. The microinjection method is the most common method for RNAi delivery in scientific research and is time-consuming and requires a high degree of technical skill.…”

The functional difference of eight chitinase genes between male and female of the cotton mealybug, Phenacoccus solenopsis

“…Although many RNA silencing methods have been successfully demonstrated among several hemipteran insects, RNAi on piercing–sucking insects such as mealybugs remains a tremendous challenge (Christiaens and Smagghe, ; Ghosh et al ., ). Previous studies have shown successful RNAi in Hexapoda through feeding, or through transgenic modified plants expressing small interfering RNAs (Bucher et al ., ; Araujo et al ., ; Mutti et al ., ; Li et al ., ; Zha et al ., ; Khan et al ., , ). However, delivering dsRNA by injection or through transgenic plants is expensive, needs a long time and is labour intensive, and it is especially difficult with small and soft insects such as mealybugs.…”

“…Group I PsCht5 contributes to pupation and adult eclosion, where it is possible this chitinase participates in the degradation of the pupal cuticle in the pupal–adult transition. We speculated that the small body size of mealybugs after feeding with dsCht10 (group II) might due to its precise role in hampering growth and development of mealybugs; this observation is consistent with previous studies (Khan et al ., ) where knockdown of PsV ‐ ATPase and PsBur in mealybugs disturbed development of cotton mealybugs. RNAi has clearly been addressed by researchers, and its ability to transport through the phloem to plant sap‐sucking insects and successfully induce silencing of mRNA has been reported (Yoo et al ., ; Wuriyanghan and Falk, ).…”