Wireworms are the most destructive soil insect pests affecting horticultural crops. The damage often renders them unsuitable for commercial purposes, resulting in substantial economic losses. RNA interference (RNAi) has been broadly used to inhibit gene functions to control insect populations. It employs double-stranded RNA (dsRNA) to knockdown essential genes in target organisms, rendering them incapable of development or survival. Although it is a robust approach, the primary challenges are identifying effective target genes and delivering their dsRNA into wireworms. Thus, the present study established a liquid ingestion methodology that efficiently delivers dsRNA into wireworms. We then investigated the effects of four target genes on wireworm mortality. The highest mortality rate reached 50% when the gene encoding vacuolar ATPase subunit A was targeted. Its transcript content in the fed wireworms was also significantly reduced. The mortality rates of the other three target genes of vacuolar ATPase subunit E, beta-actin, and chitin synthase 1 were 28%, 33%, and 35%, respectively. This is the first report demonstrating an efficient feeding methodology and the silencing of target genes in wireworms. Our findings indicate that RNAi is an effective alternative method for controlling the wireworm pest, and can be used to develop field treatment strategies.
Plant-parasitic nematodes (PPNs) are among the most serious phytopathogens and cause widespread and serious damage in major crops. In this study, using a genome mining method, we identified nonribosomal peptide synthetase (NRPS)-like enzymes in genomes of plant-parasitic nematodes, which are conserved with two consecutive reducing domains at the N-terminus (A-T-R1-R2) and homologous to fungal NRPS-like ATRR. We experimentally investigated the roles of the NRPS-like enzyme (MiATRR) in nematode (Meloidogyne incognita) parasitism. Heterologous expression of Miatrr in Saccharomyces cerevisiae can overcome the growth inhibition caused by high concentrations of glycine betaine. RT-qPCR detection shows that Miatrr is significantly upregulated at the early parasitic life stage (J2s in plants) of M. incognita. Host-derived Miatrr RNA interference (RNAi) in Arabidopsis thaliana can significantly decrease the number of galls and egg masses of M. incognita, as well as retard development and reduce the body size of the nematode. Although exogenous glycine betaine and choline have no obvious impact on the survival of free-living M. incognita J2s (pre-parasitic J2s), they impact the performance of the nematode in planta, especially in Miatrr-RNAi plants. Following application of exogenous glycine betaine and choline in the rhizosphere soil of A. thaliana, the numbers of galls and egg masses were obviously reduced by glycine betaine but increased by choline. Based on the knowledge about the function of fungal NRPS-like ATRR and the roles of glycine betaine in host plants and nematodes, we suggest that MiATRR is involved in nematode-plant interaction by acting as a glycine betaine reductase, converting glycine betaine to choline. This may be a universal strategy in plant-parasitic nematodes utilizing NRPS-like ATRR to promote their parasitism on host plants.
Insect pests cause severe crop damage, resulting in substantial economic losses and threats to global food security. Conventional insecticides are low-cost chemical agents that kill the target insects and some non-specific beneficial organisms. Due to their toxic and non-biodegradable nature, these conventional insecticides persist in the environment, thus causing pollution and accumulating in the food chain. The development of novel insecticidal products based on double-stranded (dsRNA)-based RNA interference (RNAi) technology is a sustainable tool to effectively control insect pests. The dsRNA-based insecticides are known for their specificity, non-toxicity, and biodegradability. The current review introduces the dsRNA-based RNAi technique as a novel tool to control crop insect pests. The review highlights the mechanism behind dsRNA uptake into insect cells. Furthermore, it discusses the commercial aspects of different dsRNA-based products available in the market, their penetration rates, and public acceptance. The review details the latest developments in the field and the regulatory landscape regarding the technology. The advantages and limitations of dsRNA-based insecticides are discussed, and future research directions to overcome the potential challenges have been briefly suggested. The dsRNA-based insecticidal products may be a better alternative to conventional insecticides, thus delineating the resistance among insects and increasing agricultural productivity.