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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT OF HIGH QUALITY, COST-EFFECTIVE, MASS-REARED BIOCONTROL AGENTS FOR SMALL AND URBAN FARMS, ORGANIC FARMS AND GREENHOUSES

Location: Biological Control of Insects Research

Title: Biotransfer, bioaccumulation and effects of herbivore dietary Co, Cu, Ni, and Zn on growth and development of the insect predator Podisus maculiventris (Say)

Authors
item Cheruiyot, Dorothy -
item Boyd, Robert -
item Coudron, Thomas
item Cobine, Paul -

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 19, 2013
Publication Date: May 26, 2013
Citation: Cheruiyot, D.J., Boyd, R.S., Coudron, T.A., Cobine, P. 2013. Biotransfer, bioaccumulation and effects of herbivore dietary Co, Cu, Ni, and Zn on growth and development of the insect predator Podisus maculiventris (Say). Journal of Chemical Ecology. 39:764-772.

Interpretive Summary: Elevated levels of metals in the environment, whether caused naturally or by human activity, can be detrimental to a wide range of terrestrial life, by entering, and moving throughout, a food web. Metals can be stored within an organism in the food web or transferred when one organism is consumed by another. A common pathway is the uptake of metals by plants, which are then consumed by herbivores, which in turn are consumed by predators. Some organisms exposed to high levels of metals will store the metals (bio-accumulate) and thereby create exceptionally high concentrations of the metals within their food web. Four metals known to bio-accumulate are cobalt, copper, nickel and zinc. We investigated the movement of these four metals within an insect food web by evaluating the development of a predatory insect fed prey insects raised on food containing different levels of the four metals and also recording the concentrations of the metals in the prey and predator. Elevated levels of copper and zinc lowered the weight and slowed the development of the predator. Nickel decreased in concentration from prey to predator while copper and zinc increased in concentration in the predator. These results demonstrate transfer and accumulation of metals among insects and the potential detrimental effect on beneficial insects. This information benefits researchers by improving their understanding of how environmental contaminants affect insects and how insects have developed elemental defenses.

Technical Abstract: Increased metal availability in the environment can detrimentally impact the growth and development of organisms at all trophic levels of a food web, in part because metals can be biotransferred or bioaccumulated between trophic levels. We evaluated the survival, growth, and development of a generalist Hemipteran predator (Podisus maculiventris) when fed herbivorous prey (Spodoptera exigua) reared on artificial diet amended with two different concentrations of Co, Cu, Ni and Zn. Predator nymphs were fed S. exigua larvae raised on diet amended with sublethal (Minimum Sublethal Concentration or MSC) or lethal (Minimum Lethal Concentration or MLC) concentrations of each metal, as well as control (unamended) diet. We determined if metals were biotransferred or bioaccumulated from the diet to herbivore and predator, as well as if predator growth or survival was affected by herbivore diet metal concentration. Survival of P. maculiventris was not affected by prey diet metal concentration for any metal, but predators fed herbivores raised on MLC levels of both Cu-amended and Zn-amended diets took significantly longer to mature to adults. Also, adult weights were significantly reduced for predators raised on herbivores reared on diets amended with MLC levels of Cu and Zn. Of the metals tested, Ni, Cu and Zn were biotransferred from the plant to the prey and predator. Ni decreased in concentration with each increase in trophic level while Cu and Zn increased in concentration with each trophic level. The pattern for Co was more complex, with biotransfer the main outcome. Our results show that metals in a food web can affect growth and development of a hemipteran predator and that metals are transferred between trophic levels, with metal-specific biotransfer and bioaccumulation outcomes.

Last Modified: 9/23/2014
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