A Cellulose Fiber-Based Diet for Screwworm (Diptera: Calliphoridae) Larvae

Authors: Chaudhury, Muhammad; Skoda, Steven

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2006
Publication Date: 2/1/2007
Citation: Chaudhury, M.F., Skoda, S.R. 2007. A cellulose fiber-based diet for screwworm (Diptera: Calliphoridae) larvae. Journal of Economic Entomology. 100(1):241-245.

Interpretive Summary: Improvements in mass production of high quality, sterile screwworms for use in the eradication and exclusion efforts against this important pest are crucial to maintaining an effective program that excludes this pest from the U.S. Currently the mass production facility in Chiapa de Corzo, Chiapas, Mexico, produces about 100 million flies per week and most of the cost and labor are dedicated to rearing larvae. In this research the efficacy of a new, less expensive and biodegradable larval rearing medium based on a highly absorbent cellulose fiber originating from recycled paper was compared to the current, expensive and non-biodegradable gel-based diet. Larval rearing medium was prepared from standard dietary ingredients - dried bovine blood, dried poultry eggs, milk substitute and water; the solidifying agent, cellulose fiber or gel, was then mixed in. Weights of pre-adult screwworms raised in the new cellulose fiber-based diet were markedly higher than those obtained from the current gel-based diet. Other life parameters (such as number of pupae produced, number of adults that emerged, amount of eggs laid, percentage of eggs hatched, and adult survival) compared for insects from cellulose fiber-based diet equaled or were slightly better than those from the gelled diet. It also appears that less of the cellulose fiber-based diet is necessary than the normal amount of gel-based diet to support normal larval growth. Because cellulose fiber is biodegradable and inexpensive, whereas the current gelling agent is not biodegradable and is relatively expensive, strongly supports replacing gel with cellulose fiber in the screwworm larval diet. The resulting substantial cost savings in material and labor along with elimination of concern of environmental pollution due to diet waste disposal benefit the eradication and exclusion efforts.

Technical Abstract: A highly absorbent cellulose fiber from recycled paper, CF100®, was tested and compared with a polyacrylate gelling agent Aquatain® normally used for bulking the larval rearing medium for the screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae). The cellulose fiber, when mixed with water and dietary ingredients, produced a diet medium of homogeneous texture that supported larval growth and development comparable to the standard gelled diet. Larval and pupal weights from two concentrations of cellulose fiber-based diet were significantly higher than those obtained using gelled diet. The number of pupae per tray, percent adult emergence, oviposition, percent egg hatch and adult longevity obtained from the insects reared in the cellulose fiber-based diet were comparable or slightly better than the biological parameters recorded from insects reared in the gelled diet. Moreover, results indicate that a lesser amount of the cellulose fiber-based diet than the normal amount of gelled diet per tray would support normal larval growth. Physical properties and texture of the new diet appears to allow the larvae to move and feed more freely than they do on the semi-solid gelled diet, resulting in less wasted diet. The cellulose fiber is biodegradable and inexpensive, whereas the polyacrylate gel polymer is not biodegradable and is relatively expensive. Replacing gel with cellulose fiber in the screwworm larval diet for mass rearing should result in substantial cost savings in material and labor as well as eliminating concern of environmental pollution due to diet waste disposal.