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Title: SURVEY OF INSECTS AND BIOTRANSFER OF SE TO THE INSECT VIA PLANTS USED FOR PHYTOREMEDIATION OF SELENIUM

Author
item Banuelos, Gary
item Tebbets, John
item Johnson, Judy
item Vail, Patrick
item Mackey, Bruce

Submitted to: International Journal of Phytoremediation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/1/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: A variety of plant species are being considered for the phytoremediation of selenium (Se) contaminated soils in agricultural regions of central California. With the introduction of this plant-based technology, also arrives the potential advantage or disadvantage of attracting a wide range of insects to these Se-accumulating plants. Moreover, the possibility may exist that Se extracted by the plant may be transferred to insects that feed on them. In our field study we collected more than 7000 insect specimens from four different plant species used for phytoremediation of Se. Most of the collected species were beneficial insects with some pestiferous species. Flowering plants attracted a greater number of insects. In our greenhouse study, the biotransfer of Se from Indian mustard to the cabbage looper was investigated. Plants grown in a Se-solution were infected with larvae and then enclosed in an insect cage. Fourteen days later, cocoons were collected from plants, allowed to hatch, and moths wer analyzed for Se. We observed that a biotransfer of plant Se to insect occurs in a confined, no-choice environment. Both studies showed that flowering plants used in phytoremediation of Se-laden soils, should be monitored for insects in agricultural regions.

Technical Abstract: The present investigation was firstly to survey the insects attracted to plants, tall fescue, birdsfoot trefoil, kenaf, and Indian mustard used in field phytoremediation of Se and secondly to investigate the potential biotransfer of Se from greenhouse-grown Indian mustard to one major insect pest - cabbage looper. Fifteen insect sweep samples were taken. Over 7500 specimens were collected and identified by family. Most of the 84 families identified were associated with beneficial insects, although pestiferous insects, e.g., thrips, aphids, lygus, and leafhoppers, were also found. The greatest number of specimens were found on birdsfoot trefoil. In the second study the biotransfer of Se from Indian mustard to the cabbage looper (Trichoplusia ni Hubner) was investigated on plants grown in Se-rich water culture solution. Larvae were transferred to plants and then enclosed within an insect cage. Fourteen days later, cocoons were collected, allowed to pupate, and analyzed for Se. Selenium concentrations in the insects were as high as 28 ug Se compared to <1 ug in the Se and control treatments, respectively. Based on both studies we concluded that insects should be monitored on plants used for phytoremediation in agricultural regions. Under field conditions phytophagous insects may avoid feeding upon Se-rich crops and thus reduce the likelihood of a biotransfer from plant to insect.