RNAi knock-down of the Bemisia tabaci Toll gene ( BtToll ) increases mortality after challenge with destruxin A

Abstract

Bemisia tabaci (Gennadius) Middle East-Asia Minor 1 (MEAM1) is a well known invasive insect species. Little information is available on immune system of B. tabaci to date. In this study, one of the Toll-like receptors (TLR; namely BtToll) was cloned in MEAM1 B. tabaci which contains an open reading frame of 3153bp, encoding putative 1050 amino acids. Phylogenetic analysis indicated that BtToll is highly identitical with other members of the TLR family. Transcripts of BtToll detected through qRT-PCR were expressed in all developmental stages of B. tabaci and the highest expression level was observed in the 3rd nymphal instar. BtToll was highly expressed in response to immune challenge. RNA interference was used to knockdown the BtToll expression in adults through the oral route which resulted in significant reduction of BtToll transcript. When the adults were challenged with a mycotoxin from entomogenous fungi - destruxin A (DA) and RNAi, the median lethal concentration (LC) decreased by 70.67% compared to DA treatment only. Our results suggest that BtToll is an important component of the B. tabaci immune system. RNAi technology using dsToll combined with general control methods (using toxin only) can be used as a potential strategy in integrated B. tabaci management programs.

Evaluation of a cuticle protein gene as a potential RNAi target in aphids

“…insecticides and pathogens) would be desirable in controlling pests as well as for delaying insecticide resistance development . Silencing of immunity genes, Gram‐negative binding protein 3 and Toll receptor reduced the resistance of the insects to fungal infection . In addition to immunity genes, RNAi mediated knock‐down of a cuticle‐related gene encoding chitin synthase A enhanced the virulence of Beauveria bassiana against Spodoptera exigua .…”

“…38,39 Silencing of immunity genes, Gram-negative binding protein 3 and Toll receptor reduced the resistance of the insects to fungal infection. 40,41 In addition to immunity genes, RNAi mediated knock-down of a cuticle-related gene encoding chitin synthase A enhanced the virulence of Beauveria bassiana against Spodoptera exigua. 42 As a key factor in cuticle waterproofing, decreased expression of CPs combined with insect pathogen treatment could be important in the integrated population management of aphids.…”

Tiny Flies: A Mighty Pest That Threatens Agricultural Productivity—A Case for Next-Generation Control Strategies of Whiteflies

“…Table 4 represents all target genes from several metabolic pathways of the sweetpotato whitefly including their impact and efficacies that have been evaluated for control. Among them, genes involved in energy metabolism, detoxification, cellular transport and osmoregulation, defense, and metamorphosis have gained the maximum attention of researchers around the globe [ 120 , 121 , 122 , 123 ]. The silencing of genes involved in the regulation of energy metabolism, cellular transport, and osmoregulation has shown mortality of the pest ( Table 4 ).…”

Potential of RNA interference in the study and management of the whitefly, Bemisia tabaci

“…By silencing the TLR in B. tabaci via oral RNAi the efficiency of its immune system could be significantly decreased. Zhang et al () reported that when TLR gene‐specific dsRNA‐treated adults were exposed to a mycotoxin, destruxin A (DA), from the entomogenous fungal strain MZ16 of Metarhizium anisopliae , the toxicity increased by 71% compared with DA treatment only. This study opened the new possibility of managing B. tabaci by weakening its immune system.…”