Spray mechanism of crepidogastrine bombardier beetles (Carabidae; Crepidogastrini)

Summary.   The defensive glandular apparatus of primitive bombardier beetles of the tribe Crepidogastrini (Carabidae) is described for the first time. As exemplified by two African species (Crepidogaster ambreana and C. atrata), the apparatus conforms to the basic bombardier plan, in that the glands are bicompartmented and the secretion is quinonoid (it contains 1,4-benzoquinones and hydrocarbons), hot, and discharged audibly. In a number of morphological respects the crepidogastrine apparatus resembles that of the classical bombardiers of the tribe Brachinini (rather than that of bombardiers of the paussoid lineage), reinforcing the view, already held on taxonomic grounds, that the Crepidogastrini and Brachinini are closely related. That the Crepidogastrini may be primitive relative to Brachinini is underscored by the finding that, unlike brachinines, crepidogastrines do not pulse their secretory emissions. Moreover, they discharge their secretion as a mist, rather than forcibly in the form of jets. Received 22 May 2001; accepted 29 May 2001.     

ENVIRONMENTAL AND ECONOMIC DAMAGE CAUSED BY SEDIMENT FROM AGRICULTURAL NONPOINT SOURCES1

Environmental and economic damages caused by agricultural nonpoint source inputs of sediment and associated pollutants are examined. Widespread water quality problems are identified in lakes, rivers, and estuaries in agricultural areas, and billions of dollars of on-site and offsite costs result from this eroded soil every year. Some water bodies have been irretrievably damaged, and expensive rehabilitation programs are needed to remedy in-place water pollution problems if Clean Water Act goals are to be achieved. Unless effective abatement and rehabilitation programs are established, billions of dollars of benefits to future generations will not be realized as more waters become irretrievably damaged, and billions more will continue to be spent by government to treat symptoms of these sediment-related problems.     

Arbuscular mycorrhizal fungi involvement in zinc and cadmium speciation change and phytoaccumulation

Over the past few years, there has been a greater study and understanding of the application of phytoremediation to remediate contaminated soil. The enhancement of phytoaccumulation of heavy metals—zinc (Zn), cadmium (Cd), arsenic (As), and selenium (Se)—in plants has been shown by inoculation of roots using arbuscular mycorrhizal fungi (AMF). This article presents the results of in vitro lab experiments conducted to verify the effects of AMF ( Glomus intraradices) hyphae on speciation of essential Zn and nonessential Cd heavy metals in order to change these metals from a water‐ insoluble carbonate to a soluble and phytoavailable form. Results show that in the presence of heavy metals in a nonavailable form to plants, endomycorrhizal hyphae can change the metal from carbonate to a water‐ soluble species. This phenomenon is more apparent with a nonessential (Cd) than with an essential metal (Zn). Zn saturation is reached in the G. intraradices colonized roots at around 400 ppm, independently of initial ZnCO₃ concentrations. Cd saturation is not reached; in the lower Cd treatment, the plant/media metal ratio is 3:1, and in the higher treatment, the ratio is 1:1. © 2005 Wiley Periodicals, Inc.     

Arsenic geochemistry and health

Arsenic occurs naturally in the earth's crust and is widely distributed in the environment. Natural mineralization and activities of microorganisms enhance arsenic mobilization in the environment but human intervention has exacerbated arsenic contamination. Although arsenic is useful for industrial, agricultural, medicinal and other purposes, it exerts a toxic effect in a variety of organisms, including humans. Arsenic exposure may not only affect and disable organs of the body, especially the skin, but may also interfere with the proper functioning of the immune system. This paper, therefore, generally highlights the toxic effects of arsenic as well as its mobilization in the natural environment and possible controls. It also briefly attempts to outline the impact of arsenic on the immune system, whose alteration could lead to viral/bacterial infections.     

Prospecting for nature's chemical riches

Reprinted with permission from Issues in Science and Technology (1990) 6(2):31–34