Submitted to: American Chemical Society Midwest Regional Meeting
Publication Type: Abstract Only
Publication Acceptance Date: September 30, 2003
Publication Date: November 5, 2003
Citation: POPHAM, H.J., SHELBY, K., COUDRON, T.A. EFFECT OF DIETARY SELENIUM SUPPLEMENTATION ON SUSCEPTIBILITY TO BACULOVIRUS INFECTION. AMERICAN CHEMICAL SOCIETY MIDWEST REGIONAL MEETING. 2003. pg. 134. Technical Abstract: Herbivorous insects encounter a range of dietary nutrients, antioxidants, co-factors and plant secondary metabolites which may modulate their susceptibility to microbial infections. We have found that supplementation of the diet of lepidopteran larvae with 1-10 ppm sodium selenite significantly boosted survival to subsequent baculovirus infection. A colony of the lepidopteran pest insect Trichoplusia ni has been maintained at BCIRL for many generations on an artificial diet with no added Se. We determined that supplementation of the diet of these Se-depleted larvae with 25 ppm or more sodium selenite resulted in delayed growth of larvae as compared with those individuals fed less than 25 ppm which developed normally. To determine the effect of Se on resistance to viral infection, larvae were reared on a Se-supplemented diet until the molt into the 4th larval instar then infected per os with increasing doses of the baculovirus Autographa californica multiple nucleopolyhedrovirus (AcMNPV). Subsequent mortality rates resulting from baculovirus infection were then observed. Larvae fed Se-supplemented diet in the 1-10 ppm range exhibited an increased survival rate compared to those receiving no Se supplement. For example, larvae reared on Se-free diet exhibited a mortality of 52% when challenged with 9x103 PIBs/ml of AcMNPV, while larvae reared on 1, 5, or 10 ppm and challenged with the same dose of virus exhibited a mortality of 30, 30, and 8%, respectively. The mechanisms whereby dietary Se-supplementation boosts resistance of T. ni larvae to baculovirus infection are not known. However, it is known that Se is a cofactor required for the activity of a number of selenoenzymes involved in the stress response and maintenance of high tissue antioxidant levels which may contribute to a more robust antimicrobial defense.