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Location: Biological Control of Insects Research
Title: Dietary composition affect levels of trace elements in the predator Podisus maculiventris (Say) (Heteroptera: Pentatomidae)
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 20, 2012
Publication Date: January 30, 2012
Citation: Coudron, T.A., Mitchell, L.C., Sun, R., Robertson, J.D., Pham, N.V., Popham, H.J. 2012. Dietary composition affect levels of trace elements in the predator Podisus maculiventris (Say) (Heteroptera: Pentatomidae). Biological Control. 61:141-146.
Interpretive Summary: Our knowledge of insect nutrition and the role of trace elements in nutrition are extensive yet information on the concentration of trace elements in insects and in their diet is limited. Knowing the levels of trace elements would enable us to better understand trace element requirements in insects and the involvement of trace elements in insect performance. New instrumentation has made possible the simultaneous and sensitive quantification of the levels of several trace elements within food and insect tissues. We used that technology to measure the levels of ten trace elements in the spined soldier bug, a beneficial predatory insect, and two food sources that differed in trace element content. We found the levels of the trace elements varied greatly in insects reared on the two food sources and differed from the concentrations in the food. We found that females normalized the content of trace elements in eggs to low levels, regardless of the content in diet. Some trace elements were more easily acquired from one food source than the other and some trace elements were more difficult for the insect to excrete. Together our results indicate physiological parameters within the insect affect the levels of trace elements. This information improves the ability of researchers to determine optimal dietary requirements for trace elements and the impact of dietary trace elements on the performance of beneficial insects used in biological control measures.
Insects require small amounts of dietary minerals because of the roles minerals serve as antioxidants, enzyme co-factors and as constituents of metalloproteins. We measured the levels of ten trace elements (Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se and Zn) in the predatory insect, Podisus maculiventris reared on natural prey and artificial diet; two food sources that differed in trace element content. The levels of the trace elements varied greatly in insects reared on the two food sources and differed from the concentrations in the food. We also found low, and near equal concentrations of most trace elements in the eggs laid by females reared on either food source. The homeostatic level of most trace elements in the eggs may reflect a commitment by the female to minimize the effect of dietary variations. From these results we conclude that trace element levels in P. maculiventris are substantially affected by the food source and can vary significantly from levels in the food source. Knowing this will improve the ability of researchers to determine optimal dietary requirements for trace elements.