Developing a Genetic Sexing Line of Screwworms: Laboratory Support
Project Number: 3094-32000-040-04
Specific Cooperative Agreement
Start Date: Oct 01, 2013
End Date: Sep 30, 2018
The New World screwworm, Cochliomyia hominivorax, was eradicated from North America through a multi-national program led by USDA. The sterile insect techniques developed by ARS scientists were the keystone in the eradication program; the eradication status of North America is maintained by the USDA-APHIS Screwworm Eradication Program working in conjunction with counterparts in Panama. The Screwworm Production Facility in Pacora, Panama, is producing flies to maintain the barrier zone at the Panama-Columbia border. To pursue opportunities at optimizing Pacora's production capacity, research is ongoing to develop a female conditional-lethal transgenic strain of C. hominivorax. In this project, the recombinant vectors and necessary protocols to facilitate the transformation of C. hominivorax have been developed through collaboration between ARS and North Carolina State University and transferred to Pacora for application in C. hominivorax. Rearing, especially rearing at mass production levels, the putative genetic sexing lines require collaboration between ARS and the Technical Direction of COPEG (Panama – U.S. Commission for Eradication and Prevention of Screwworms). Successful implementation of the genetic sexing line, through these collaborations, will greatly optimize the production capacity, with concurrent capacity for large cost reductions, of the Program to Eradicate Screwworms.
The project to develop genetic sexing in screwworms has advanced to the stage where evaluations of transgenic screwworm lines into which female conditional-lethal vectors were inserted are ongoing, and will continue, in the Screwworm Eradication Program's facility at Pacora, Panama. This agreement will not only fund this ongoing, stochastic effort but also will be used to develop additional, perhaps more efficient, vector systems (in facility at North Carolina State University) as a contingency in case the current vectors do not meet the Program's needs. Transgenic strains will be reared under laboratory conditions, with ARS transferring information to Technical Direction, for several generations to evaluate the quality of resultant genetic sexing line(s) as they are developed. Then, in collaboration with Technical Direction, rearing parameters will be optimized relative to levels of tetracycline used in the 'colony' replacement larval pans, optimum temperature to maintain the larval media (both for flies intended for sterile, mass release and those for colony replacement), evaluation of the potential to develop a 'filter rearing' system, and consideration of requirements for handling waste (particularly larval diet containing tetracycline).