Video | Business Headlines | Internet | Science | Scientific Ethics | Technology | Search

 


Genetic Control Mechanism for Major Livestock Pest

June 19, 2014

Researchers Develop Genetic Control Mechanism for Major Livestock Pest

Researchers from North Carolina State University have developed a technique to control populations of the Australian sheep blowfly – a major livestock pest in Australia and New Zealand – by making female flies dependent upon a common antibiotic to survive.

Dr. Max Scott, professor of entomology at NC State, and his research team genetically modified lines of female Australian sheep blowflies (Lucilia cuprina) so that they required doses of tetracycline in order to live. Female blowflies that did not receive the antibiotic died in the late larval or pupal stages, before reaching adulthood. Several genetically modified lines lacking tetracycline showed 100 percent female deaths.

Scott says that the gene construct responsible for lethality in antibiotic-free diets is female-specific. Interestingly and unexpectedly, the genetically modified female larvae containing the tetracycline lethality genes also took on a crimson color due to overexpression of the linked red fluorescent protein “marker gene.” This allows scientists to tell which larvae will be females and which will be males.

Overexpression of the gene responsible for the reliance on tetracycline also seems to overexpress this marker gene,” Scott says.

Since the females will die when not provided tetracycline in their diets, the males can be separated out in the larval stage. This is essential for a “male-only” genetic control program to reduce blowfly populations, Scott says, as fertile males would pass the lethality construct on to female offspring, which would die in the absence of tetracycline. Male larval offspring, however, would still be dangerous to livestock.

In the study, the researchers showed that the tetracycline gene construct also works in Drosophila, the fruit fly “lab rat” of the insect world that is a distant cousin of the sheep blowfly. This holds promise that the genetic system will function in the New World and Old World screwworm, two major livestock pests that are close relatives of the sheep blowfly. Scott is working with the U.S. Department of Agriculture to make “male-only” strains of the New World screwworm (Cochliomyia hominivorax).

“The New World screwworm is a devastating pest of livestock that was eradicated from North and Central America by releasing sterilized male and female flies,” Scott says. However, a male-only strain offers several advantages, including potentially more efficient population suppression for the ongoing program. “Efficient genetic control systems have the potential to help eradicate some of the biggest problem pests across the globe,” he said.

The research is funded by the U.S. Department of Agriculture, National Institute of Food and Agriculture and NC State.

“Transgenic sexing system for genetic control of the Australian sheep blow fly Lucilia cuprina

Authors: Fang Li, Holly Wantuch, Rebecca Linger, Esther Belikoff and Max Scott, North Carolina State University
Published: June 2014 online in Insect Biochemistry and Molecular Biology
DOI: 10.1016/j.ibmb.2014.06.001

Abstract: The New World screwworm and the Australian sheep blow fly Lucilia cuprina are devastating pests of livestock. The larvae of these species feed on the tissue of the living animal and can cause death if untreated. The sterile insect technique or SIT was used to eradicate screwworm from North and Central America. This inspired efforts to develop strains containing complex chromosomal rearrangements for genetic control of L. cuprina in Australia. Although one field trial was promising, the approach was abandoned due to costs and difficulties in mass rearing the strain. As the efficiency of SIT can be significantly increased if only sterile males are released, we have developed transgenic strains of L. cuprina that carry a dominant tetracycline repressible female lethal genetic system. Lethality is due to overexpression of an auto-regulated tetracycline repressible transactivator (tTA) gene and occurs mostly at the pupal stage. Dominant female lethality was achieved by replacing the Drosophila hsp70 core promoter with a Lucilia hsp70 core promoter-5/UTR for tTA overexpression. The strains carry a dominant strongly expressed marker that will facilitate identification in the field. Interestingly, the sexes could be reliably sorted by fluorescence or color from the early first instar larval stage as females that overexpress tTA also overexpress the linked marker gene. Male-only strains of L. cuprina developed in this study could form the basis for a future genetic control program. Moreover, the system developed for L. cuprina should be readily transferrable to other major calliphorid livestock pests including the New and Old World screwworm.

ENDS

© Scoop Media

 
 
 
 
 
Business Headlines | Sci-Tech Headlines

 

Media: Julian Wilcox Leaves Māori TV

Māori Television has confirmed the resignation of Head of News and Production Julian Wilcox. Mr Maxwell acknowledged Mr Wilcox’s significant contribution to Māori Television since joining the organisation in 2004. More>>

ALSO:

Genetics: New Heat Tolerant Cow Developed

Hamilton, New Zealand-based Dairy Solutionz Ltd has led an expert genetics team to develop a new dairy cow breed conditioned to thrive in lower elevation tropical climates and achieve high milk production under heat stress. More>>

Fractals: Thousands More Business Cards Needed To Build Giant Sponge

New Zealand is taking part in a global event this weekend to build a Menger Sponge using 15 million business cards but local organisers say they are thousands of business cards short. More>>

Scoop Business: NZ Net Migration Rises To Annual Record In September

New Zealand’s annual net migration rose to a record in September, beating government forecasts, as the inflow was spurred by student arrivals from India and Kiwis returning home from Australia. More>>

ALSO:

Scoop Business: Fletcher To Close Its Christchurch Insulation Plant, Cut 29 Jobs

Fletcher Building, New Zealand’s largest listed company, will close its Christchurch insulation factory, as it consolidates its Tasman Insulations operations in a “highly competitive market”. More>>

ALSO:

Scoop Business: Novartis Adds Nine New Treatments Under Pharmac Deal

Novartis New Zealand, the local unit of the global pharmaceuticals firm, has added nine new treatments in a far-ranging agreement with government drug buying agency, Pharmac. More>>

ALSO:

Crown Accounts: English Wary On Tax Take, Could Threaten Surplus

Finance Minister Bill English is warning the tax take may come in below forecast in the current financial year, as figures released today confirm it was short by nearly $1 billion in the year to June 30 and English warned of the potential impact of slumping receipts from agricultural exports. More>>

ALSO:

Get More From Scoop

 
 
Standards New Zealand

Standards New Zealand

Mosh Social Media
 
 
 
 
 
 
 
 
Sci-Tech
Search Scoop  
 
 
Powered by Vodafone
NZ independent news