Is CRISPR/Cas9 a Viable Solution for the Control of Crop Insect Pests?

In my article “A Breakthrough In Biotechnology And The Future Of The Fruit Industry,” I described the precision genome editing technology, called CRISPR/Cas9 (clustered regularly interspersed short palindromic repeats/CRISPR associated-nuclease) and its applications in crop plant improvement. Here, I would like to cover how the CRISPR/Cas9 technology has been repurposed as a gene drive system that may become a potentially viable solution for managing crop insect pests.

The Gene Drive Process
What is CRISPR/Cas9-based gene drive and how can it be used for insect pest control?

Gene drive is a term that describes a process in which a particular gene or genetic element is spread quicker than what is expected according to genetic principles in a sexually reproducing population. CRISPR/Cas9-based gene drive is an engineered gene drive that can drive a rapid spreading of a CRISPR/Cas9-altered gene in a target population.

 

Figure 1. Spotted wing drosophila adult flies (A), genitalia (B) and dissected reproductive tissue (C) of wild type female, male (WT), and homozygous mutants (M) for the CRISPR/Cas9 interrupted sex lethal (Sxl) gene. Note that the mutants developed an intersexual phenotype with abnormal genitalia and abnormal ovaries. (Graphic: Adapted from Li and Scott 2016 Biochem Biophys Res Commun)

For insect pest control, genes involved in reproduction, development, feeding, and/or immune system are desirable targets. The vision is that fast spreading of the mutations created by CRISPR/Cas9 will skew sex ratios, reduce fitness, or restore susceptibility to insecticides in target populations.

 

In addition to agriculture insect pest control, controlling human and animal disease vectors such as mosquitos using CRISPR/Cas9 based gene drive has been envisioned as well. In fact, considerably more resources and efforts have been committed to this area to fight deadly diseases such as dengue, malaria, and Zika fever.

In practice, designing and constructing a specific CRISPR/Cas9 -based gene drive is a straightforward process. For delivering the gene drive into cells, embryo injection is commonly used. Through a series of selections in subsequent generations, insect carrying a desirable CRISPR/Cas9-based gene drive will be identified and raised. Like many other biological control agents, field trials in a contained environment will be conducted to evaluate both the intended and unintended effects. Before releasing these transgenic insects into the farm field or orchard for pest control, they also must be approved by the government, which will conduct an extensive regulatory review.

CRISPR/Cas9 Control of Insects
What studies have been done toward CRISPR/Cas9-based control of crop insect pests?

So far, several major insect pests have been investigated for the feasibility of pest control using CRISPR/Cas9-based gene drive, including drosophila, moth, beetle, grasshopper, and others. The progress has been encouraging. Below are two examples:

Spotted Wing Drosophila (SWD) (Drosophila suzukii). In a proof-of-concept study for the gene-drive-based control of SWD, a nasty pest for cherry and berry crops, the female specific sex lethal (Sxl) gene was targeted, which is a master regulator in female development. The study finds that if both of their Sxl alleles (copies of the gene) are interrupted by CRISPR/Cas9, the female flies will die in early developmental stages due to abnormal development of their reproductive system (Figure 1).

Figure 2. Male and female larvae of diamondback moth wild type and their abdominal-A gene mutants. The squares and arrows in red indicate the region of the testis in male and the disordered segments in mutants, respectively. (Graphic: Adapted from Huang et al. 2016 Insect Biochem Mol Biol)

 

Since most, if not all, females carrying the CRISPR/Cas9-based gene drive will become homozygous for the interrupted Sxl gene, the number of female flies will decline, which will eventually collapse the population.

Diamondback Moth (Plutella xylostella). The damage of diamondback moth to the cruciferous crops is a pressing problem

worldwide. To explore a genetics-based control of diamondback moth, a moth gene, called abdominal-A that plays a crucial role in determining the identity and functionality of abdominal segments, was targeted by the CRISPR/Cas9 system in another proof-of-concept study. The study demonstrates that disrupting abdominal-A led to a range of inheritable defects, such as abnormal prolegs and malformed segments in both male and female larvae (Figure 2).

Implementation Timeline
How close are CRISPR/Cas9-based gene drives to a practical solution for crop pest control?

As mentioned earlier, rapid progress has been accomplished to make CRISPR/Cas9-based gene drives a solution for crop pest control. From a technical point of view, implementation could occur soon. However, considering the time needed for government approval and for evaluation of unintended effects on related species to minimize the risk of biosafety, it may take years to see commercial application of CRISPR/Cas9-based gene drives for insect pest control.

Topics: , , ,

Leave a Reply

One comment on “Is CRISPR/Cas9 a Viable Solution for the Control of Crop Insect Pests?

Fruits Stories
Crop Protection
October 17, 2017
EPA Takes Steps to Reduce Risk of Drift-Related Herbicide Injury
With reports of dicamba injuries in tomatoes, peaches, grapes, and other crops, the agency works to reduce the impact of spray drift on vulnerable crops. Read More
Fruits
October 16, 2017
New Broad-Spectrum Herbicide Released by Nufarm
Grapple herbicide works on pre- and post-emergent weeds in orchards and vineyards. Read More
Flooded peach and grape groves from Irma at UF/IFAS HAEC
Citrus
October 16, 2017
Wrath of Hurricane Irma’s Rainfall Measured by the Trillions
Report says storm dropped enough gallons of water on Florida’s St. Johns River Water Management District to swamp 6.7 million football fields. Read More
Checking hop cones at UF/IFAS MREC
Fruits
October 14, 2017
USDA Seeks Applications for Next Round of Specialty Crop Research Grants
SCRI grants to total $48 million for 2018 fiscal year. Read More
Grapes
October 13, 2017
Fairgrounds Host California Fire Evacuees
Gallo will contribute $1 million to fire recovery effort and will match employee donations two-for-one. Read More
Grapes
October 10, 2017
Wildfires Hit California Wine Country
California Gov. Jerry Brown declares state of emergency for northern counties impacted by flames. Read More
A water-logged citrus grove in Southwest Florida following Irma
Citrus
October 10, 2017
Impressions from Irma Indelible on the Florida Farmscape [Slideshow]
Striking images from the field reveal not only the storm’s destructive nature, but also paths to recovery and reconstruction. Read More
Citrus
October 9, 2017
(We Won’t Back Down … ) Stand Your Ground for Agriculture
You don’t have to be a super hero, rock star, or award-winning scientist to aid farming. You can help by supporting professionalism in fields. Read More
Apples & Pears
October 9, 2017
How to Transition to Multileader Production
Use this guide to help you determine whether multileader production is a good fit for your farm. Read More
Grapes
October 7, 2017
Tips for Effective Vine Mealybug Management in Grapes
Scouting, trapping, and mating disruption can help prevent populations of this pest increasing in your vineyard. Read More
Apples & Pears
October 6, 2017
What You Need to Know About Multileader Systems for Apple Trees
While multiple leaders shrink the tree canopy, experts warn there are places where missteps can be made. Read More
Apples & Pears
October 5, 2017
Apple Growers Moving to Multileaders
Growers shift from single leader to multiple leader systems to increase light interception and production. But this system isn’t without its risks and costs. Read More
Growers boot up drone technology on the farm
Citrus
October 5, 2017
Are You a Precision Grower?
Gathering, analysis, and application still seems to be the best basic definition of precision agriculture. Read More
Fruits
October 5, 2017
Environmental Monitoring Helps With Food Safety Modernization Act
Monitoring may be most effective way to meet the preventative controls component of the Food Safety Modernization Act. Read More
Greenhouse structures flattened by Irma at C&B Farms
Citrus
October 5, 2017
Hurricane Irma Toll on Florida Farming in the Billions
Preliminary damage estimates confirm storm’s ferocity. Read More
The Latest
Citrus
October 18, 2017
How to Keep Track of Climate Change
Use cool tools to find out how your production methods may change in the future, how much your area is at risk, and how to limit your own impact on the climate. Read More
Citrus
October 17, 2017
USDA Issues Disaster Declaration for Hur…
Operators in designated counties eligible for emergency assistance. Read More
Fruits
October 17, 2017
Hirst Named American Society of Horticul…
Honor was presented during society’s annual meeting. Read More
Crop Protection
October 17, 2017
EPA Takes Steps to Reduce Risk of Drift-…
With reports of dicamba injuries in tomatoes, peaches, grapes, and other crops, the agency works to reduce the impact of spray drift on vulnerable crops. Read More
Fruits
October 16, 2017
New Broad-Spectrum Herbicide Released by…
Grapple herbicide works on pre- and post-emergent weeds in orchards and vineyards. Read More
Citrus
October 16, 2017
Wrath of Hurricane Irma’s Rainfall…
Report says storm dropped enough gallons of water on Florida’s St. Johns River Water Management District to swamp 6.7 million football fields. Read More
Fruits
October 14, 2017
USDA Seeks Applications for Next Round o…
SCRI grants to total $48 million for 2018 fiscal year. Read More
Citrus
October 10, 2017
Impressions from Irma Indelible on the F…
Striking images from the field reveal not only the storm’s destructive nature, but also paths to recovery and reconstruction. Read More
Citrus
October 9, 2017
(We Won’t Back Down … ) Stan…
You don’t have to be a super hero, rock star, or award-winning scientist to aid farming. You can help by supporting professionalism in fields. Read More
Citrus
October 5, 2017
Are You a Precision Grower?
Gathering, analysis, and application still seems to be the best basic definition of precision agriculture. Read More
Fruits
October 5, 2017
Environmental Monitoring Helps With Food…
Monitoring may be most effective way to meet the preventative controls component of the Food Safety Modernization Act. Read More
Citrus
October 5, 2017
Hurricane Irma Toll on Florida Farming i…
Preliminary damage estimates confirm storm’s ferocity. Read More
Citrus
October 4, 2017
Goodlatte Officially Introduces the Ag G…
On Monday, Rep. Bob Goodlatte (R-VA) introduced his Agricultural Guestworker Act of 2017 bill, which would replace H-2A with an H-2C program. Rep. Goodlatte introduced the bill to the House Judiciary Committee, which he chairs. Read More
Fruits
October 3, 2017
Bill Introduced to Crack Down on Fake Or…
Organic Farmer and Consumer Protection Act seeks stricter enforcement of imports, modernization of documentation. Read More
Citrus
October 2, 2017
$10 Million for Honeybee Health
National Honey Board, Project Apis.m investing in pollinator research. Read More
Citrus
October 2, 2017
Perseverance a Priority for Florida Farm…
Commissioner of Agriculture Adam Putnam heartened by the strides being made by growers around the state as they begin to recover from the hurricane. Read More
Citrus
October 2, 2017
$18 Million in Grants Available for Valu…
Farmers in need of planning or working capital funds to move their ideas forward encouraged to check out program. Read More
Citrus
September 27, 2017
Research on Jet Fuel Cover Crop Ready fo…
Scientists seeking to find if carinata can sustainably feed future renewable energy demands. Read More