THE OPTIMUM DIET OF SPRAY-DRIED ANIMAL BLOOD CELLS AS PROTEIN SOURCE FOR ADULT SCREWWORMS (DIPTERA: CALLIPHORIDAE)

Authors: SAGEL, AGUSTIN - UNIVERSITY OF NEBRASKA; Berkebile, Dennis; FOSTER, JOHN - UNIVERSITY OF NEBRASKA; Skoda, Steven

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2002
Publication Date: 10/1/2002
Citation: Sagel, A., Berkebile, D.R., Foster, J.E., Skoda, S.R. 2002. The optimum diet of spray-dried animal blood cells as protein source for adult screwworms (diptera: calliphoridae). Journal of Entomological Science. 37(4): 353-362

Interpretive Summary: Screwworms are pests that feed on the living tissues of warm-blooded animals, including humans. The eggs, deposited at the periphery of open wounds, hatch and the maggots then invade the wound to feed. This condition, called myiasis, can kill an animal. Screwworms, once considered one of the most economically important livestock pests in the U.S., Mexico and Central America, have been eradicated from these regions using the sterile insect technique (SIT). SIT requires screwworms to be reared in-mass, sterilized and released. When sterile males mate with wild females no progeny are produced, causing the wild population to crash. To reduce the chances that screwworms re-infest the eradicated areas, sterile flies will continuously be released to form a barrier in eastern Panama. Cost reductions in mass rearing would benefit the screwworm eradication effort. We found that feeding adult flies a protein diet increased egg production in females and increased survival of the resulting immature screwworms. In this study, we incorporated spray-dried animal blood cells into the adult diet. We used spray-dried animal blood cells because, as a major component in the larval rearing media, it is readily accessible for this purpose. Seven protein concentrations were compared (0, 0.16, 0.2, 0.24, 1.25, 2, and 2.75%). Flies fed the 2% protein diet produced 148% more eggs than those fed no protein. This diet could reduce the number of adults required to produce an adequate number of eggs for mass production of screwworms and may be less costly than current adult rearing ingredients, thereby benefitting the screwworm eradication effort.

Technical Abstract: Research focused on improving mass rearing of the screwworm and minimizing expenditures in the screwworm eradication program. We conducted two tests to determine the optimum diet for rearing adult screwworm using spray dried animal blood cells as the protein source. Males and females were fed two control diets of corn syrup carrageenan-gelled diet (Control-1) and Control-1 plus 0.05% vitamins (Control-2). These were compared with six protein diets similarly formulated as Control-2 plus 0.16, 0.20 and 0.24% dried blood (Test-1) and 1.25, 2.0 and 2.75% dried blood (Test-2). Differences in mean egg production, female mortality, fertility and egg hatch were not significant (P=0.05) in Test-1. In Test-2, flies fed protein produced more eggs than those fed control diets. A diet of 2% protein from spray dried animal blood cells for rearing adult screwworms may be more efficient for the mass rearing facility of the screwworm eradication program than their current procedure.