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.


© Scoop Media

Business Headlines | Sci-Tech Headlines


Trade: NZ Trade Deficit Widens To A Record In September

Oct. 27 (BusinessDesk) - New Zealand's monthly trade deficit widened to a record in September as meat exports dropped to their lowest level in more than three years. More>>


Animal Welfare: Cruel Practices Condemned By DairyNZ Chief

DairyNZ chief executive Tim Mackle says cruel and illegal practices are not in any way condoned or accepted by the industry as part of dairy farming.

Tim says the video released today by Farmwatch shows some footage of transport companies and their workers, as well as some unacceptable behaviour by farmers of dragging calves. More>>


Postnatal Depression: 'The Thief That Steals Motherhood' - Alison McCulloch

Post-natal depression is a sly and cruel illness, described by one expert as ‘the thief that steals motherhood’, it creeps up on its victims, hiding behind the stress and exhaustion of being a new parent, catching many women unaware and unprepared. More>>


DIY: Kiwi Ingenuity And Masking Tape Saves Chick

Kiwi ingenuity and masking tape has saved a Kiwi chick after its egg was badly damaged endangering the chick's life. The egg was delivered to Kiwi Encounter at Rainbow Springs in Rotorua 14 days ago by a DOC worker with a large hole in its shell and against all odds has just successfully hatched. More>>


International Trade: Key To Lead Mission To India; ASEAN FTA Review Announced

Prime Minister John Key will lead a trade delegation to India next week, saying the pursuit of a free trade agreement with the protectionist giant is "the primary reason we're going" but playing down the likelihood of early progress. More>>



MYOB: Digital Signatures Go Live

From today, Inland Revenue will begin accepting “digital signatures”, saving businesses and their accountants a huge amount of administration time and further reducing the need for pen and paper in the workplace. More>>

Oil Searches: Norway's Statoil Quits Reinga Basin

Statoil, the Norwegian state-owned oil company, has given up oil and gas exploration in Northland's Reinga Basin, saying the probably of a find was 'too low'. More>>


Modern Living: Auckland Development Blowouts Reminiscent Of Run Up To GFC

The collapse of property developments in Auckland is "almost groundhog day" to the run-up of the global financial crisis in 2007/2008 as banks refuse to fund projects due to blowouts in construction and labour costs, says John Kensington, the author of KPMG's Financial Institutions Performance Survey. More>>


Get More From Scoop

Search Scoop  
Powered by Vodafone
NZ independent news