Gene Editing and Genetic Control of Hemipteran Pests: Progress, Challenges and Perspectives

Abstract

The origin of the order Hemiptera can be traced to the late Permian Period more than 230 MYA, well before the origin of flowering plants 100 MY later in during the Cretaceous period. Hemipteran species consume their liquid diets using a sucking proboscis; for phytophagous hemipterans their mouthparts (stylets) are elegant structures that enable voracious feeding from plant xylem or phloem. This adaptation has resulted in some hemipteran species becoming globally significant pests of agriculture resulting in significant annual crop losses. Due to the reliance on chemical insecticides for the control of insect pests in agricultural settings, many hemipteran pests have evolved resistance to insecticides resulting in an urgent need to develop new, species-specific and environmentally friendly methods of pest control. The rapid advances in CRISPR/Cas9 technologies in model insects such as Drosophila melanogaster, Tribolium castaneum, Bombyx mori, and Aedes aegypti has spurred a new round of innovative genetic control strategies in the Diptera and Lepidoptera and an increased interest in assessing genetic control technologies for the Hemiptera. Genetic control approaches in the Hemiptera have, to date, been largely overlooked due to the problems of introducing genetic material into the germline of these insects. The high frequency of CRISPR-mediated mutagenesis in model insect species suggest that, if the delivery problem for Hemiptera could be solved, then gene editing in the Hemiptera might be quickly achieved. Significant advances in CRISPR/Cas9 editing have been realized in nine species of Hemiptera over the past 4 years. Here we review progress in the Hemiptera and discuss the challenges and opportunities for extending contemporary genetic control strategies into species in this agriculturally important insect orderr.

Keywords: CRISPR/Cas9; Hemiptera; gene editing; genetic control; mutations; whiteflies.

FIGURE 1

The number of publications on Hemiptera deposited in Web of Science and the National Library of Medicine (United States). The most numerous published species within Hemiptera are also shown. Data from 2012–2022

FIGURE 2

The number of genome projects for each species within each insect order based on depositions at the NCBI (all species) and at the i5K project (http://i5k.github.io/about). Data as at 2022.

FIGURE 3

The number of Hemiptera genome assemblies at the NCBI and the number of publications reporting CRISPR/Cas9 mutagenesis in Hemiptera from 2010–2021.

FIGURE 4

The ten most sequenced species (or species complex) within the Hemiptera with the number of submissions for each shown, based on NCBI data.

FIGURE 5

The progress made in establishing genetic technologies in the Hemiptera with green circles and panels depicting tasks that have been accomplished, pale green to tan circles and panels depicting relevant biological traits among Hemiptera that may affect our ability to efficiently extend genetic technologies to some species, and orange to dark red circles and panels depicting tasks that still need to be accomplished.