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Title: Moisture Content in a wheat germ diet and its effect on the growth of Plodia interpunctella (Hubner)

item Silhacek, Don
item Murphy, Curtis

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2006
Publication Date: 1/1/2008
Citation: Silhacek, D.L., Murphy, C.L. 2008. Moisture Content in a wheat germ diet and its effect on the growth of Plodia interpunctella (Hubner). Journal of Stored Products Research. 44:36-40.

Interpretive Summary: Infestation of processed cereal products by Indian meal moths prior to reaching the consumer is a major loss to the grain processing and consumer products industries. Growth rates of Indian meal moths can vary widely depending upon the nutritive and physical qualities of the cereal product. Pesticide use can be decreased or eliminated by prolonging or preventing the growth of insect pests. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA-ARS, Gainesville, FL studied why Indian meal moths consume the different kernel tissues in a predetermined sequence. We found that this larval behavior was dictated by it's immediate nutrient needs for tissue development and growth. Newly hatched larvae require the specific nutrients located in the germ. As the larvae develops, the nutrient requirements become less demanding and it's nutrient needs can be satisfied by the bran. Finally, in the last larval stadium, the larvae require immediate energy for wandering and spinning and precursors for the storage of energy for the adult in the form of fats; both of these needs can be adequately provided by the nutrients located in the endosperm. The identification of the nutrients in the germ that are critical for initiating early development of the Indian meal moth could be a key for designing new, more effective control procedures for Indian meal moths in retail outlets and storage facilities.

Technical Abstract: An earlier study reported that newly hatched larva seeks out and enters a damaged wheat kernel, consuming the germ first, the bran next and the endosperm last (Madrid and Sinha, 1982). We formulated and tested the hypothesis that each kernel tissue contains an array of nutrients that is unique to that tissue and that each in sequence fulfill the immediate nutritional requirements of the larva at that specific stage of development. Feeding newly hatched larvae the isolated kernel tissues (germ, bran and endosperm) from wheat indicated that these tissues are not nutritionally equivalent for this developmental stage. Growth of was fully supported by wheat germ, suboptimally supported by wheat bran and not supported by endosperm. We conclude that the neonate larvae seeks the germ first because this part of the kernel contains all of the nutrients needed for the development of new larval tissues. Bran supports larval growth, but at a slower rate than germ. Endosperm does not support the growth of neonate larvae, but may have a role later in larval development. Wheat bran, supplemented with 5% Brewer's yeast, 2% wheat germ oil, 20% sucrose and 20% glycerol has been used in this laboratory for standardized rearing of Indian meal moths for over two years.