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Title: Research Advances in the Screwworm Eradication Program over the Past 25 Years

Author
item SCOTT, MAXWELL - North Carolina State University
item CONCHA, CAROLINA - Smithsonian Tropical Research
item WELCH, JOHN - Animal And Plant Health Inspection Service (APHIS)
item Phillips, Pamela
item Skoda, Steven

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Screwworms are devastating pests of warm blooded animals that cause significant economic damage to livestock. The successful campaign to eradicate screwworms from continental North America using the sterile insect technique, led by the US Department of Agriculture, has received constant support that improved technology for all aspects of the program. The processes and ingredients for mass rearing screwworms, because of the large input of resources, have received considerable attention and have been made more efficient and sustainable. The protocol for developing new strains used in mass rearing has been standardized. Cryopreservation of screwworm embryos allows strains to be preserved and recovered if necessary and also reduces rearing requirements for backup and research strains. Sterile fly release procedures and equipment have been updated leading to optimized sterile fly release rates. Surveillance for screwworm infestations and outbreaks have incorporated new trap designs, habitat analysis and molecular genetic techniques that enhance monitoring the progress of the program as well as early detection and response to outbreaks. Genetic analyses of screwworm populations across their current range have increased the understanding of genetic differentiation, which may aide in developing new strains and determining the geographic origin of screwworms causing outbreaks when they occur. The ability to release only sterile males, which has been a goal of the program for over 60 years, has recently been accomplished through the development of transgenic sexing strains. The strains carry a conditional female lethal gene and have been shown to be comparable to the wild type strain for several biological parameters that are important for mass production and performance in the field. The strains should improve efficiency of population suppression of the current and future eradication and prevention programs against screwworms. These research advances as well as future considerations are presented.

Technical Abstract: Screwworms, Cochliomyia hominivorax (Coquerel) (Calliphoridae: Chrysomyinae), are devastating pests of warm blooded animals that cause significant economic damage to livestock. The successful campaign to eradicate screwworms from continental North America using the sterile insect technique, led by the US Department of Agriculture, has received constant support that improved technology for all aspects of the program. The processes and ingredients for mass rearing screwworms, because of the large input of resources, have received considerable attention and have been made more efficient and sustainable. The protocol for developing new strains used in mass rearing has been standardized. Cryopreservation of screwworm embryos allows strains to be preserved and recovered if necessary and also reduces rearing requirements for backup and research strains. Sterile fly release procedures and equipment have been updated leading to optimized sterile fly release rates. Surveillance for screwworm infestations and outbreaks have incorporated new trap designs, habitat analysis and molecular genetic techniques that enhance monitoring the progress of the program as well as early detection and response to outbreaks. Genetic analyses of screwworm populations across their current range have increased the understanding of genetic differentiation, which may aide in developing new strains and determining the geographic origin of screwworms causing outbreaks when they occur. The ability to release only sterile males, which has been a goal of the program for over 60 years, has recently been accomplished through the development of transgenic sexing strains. The strains carry a conditional female lethal gene and have been shown to be comparable to the wild type strain for several biological parameters that are important for mass production and performance in the field. The strains should improve efficiency of population suppression of the current and future eradication and prevention programs against screwworms. These research advances as well as future considerations are presented.