Time course of pyrrolizidine alkaloid sequestration in <Emphasis Type="Italic">Longitarsus</Emphasis> flea beetles (Coleoptera,Chrysomelidae)

Summary. Several species of Longitarsus take up, metabolize and store pyrrolizidine alkaloids (PAs) from their host plants. In feeding experiments using radioactively labeled PAs of different types we examined the time course of the sequestration process in L. jacobaeae and L. aeruginosus. We found that adapted species efficiently store PAs for at least two weeks without major losses. During that time, there is virtually no change in the ratio of tertiary alkaloids to stored non-toxic N-oxides, regardless of chemical form fed to the beetles. This implies a transient N-oxidation process where the alkaloids are only temporarily accessible to the enzyme. A dissection experiment with L. aeruginosus six days after uptake of labeled PAs showed that the tertiary alkaloids are not found in the hemolymph but are stored in the elytra and other body compartments. This conforms with earlier experiments that localized the enzymes site of action in the hemolymph. Furthermore we show that different total alkaloid doses in the diet of L. jacobaeae and the potentially less adapted L. succineus do not affect the ratio of recovered N-oxides to tertiary molecules. Thus, the efficiency of the N-oxidizing enzyme is not dependent on the concentration of alkaloids offered.     

Choosing a home: how the scouts in a honey bee swarm perceive the completion of their group decision making

This study considers the mystery of how the scout bees in a honey bee swarm know when they have completed their group decision making regarding the swarm's new nest site. More specifically, we investigated how the scouts sense when it is appropriate for them to begin producing the worker piping signals that stimulate their swarm-mates to prepare for the flight to their new home. We tested two hypotheses: "consensus sensing," the scouts noting when all the bees performing waggle dances are advertising just one site; and "quorum sensing," the scouts noting when one site is being visited by a sufficiently large number of scouts. Our test involved monitoring four swarms as they discovered, recruited to, and chose between two nest boxes and their scouts started producing piping signals. We found that a consensus among the dancers was neither necessary nor sufficient for the start of worker piping, which indicates that the consensus sensing hypothesis is false. We also found that a buildup of 10–15 or more bees at one of the nest boxes was consistently associated with the start of worker piping, which indicates that the quorum sensing hypothesis may be true. In considering why the scout bees rely on reaching a quorum rather than a consensus as their cue of when to start preparing for liftoff, we suggest that quorum sensing may provide a better balance between accuracy and speed in decision making. In short, the bees appear to begin preparations for liftoff as soon as enough of the scout bees, but not all of them, have approved of one of the potential nest sites.

Extinction, Colonization, and Metapopulations: Environmental Tracking by Rare Species

Extinction and metapopulation theories emphasize that stochastic fluctuations in local populations cause extinction and that local extinctions generate empty habitat patches that are then available for recolonization. Metapopulation persistence depends on the balance of extinction and colonization in a static environment. For many rare and declining species, I argue (1) that extinction is usually the deterministic consequence of the local environment becoming unsuitable (through habitat loss or modification, introduction of a predator, etc.); (2) that the local environment usually remains unsuitable following local extinction, so extinctions only rarely generate empty patches of suitable habitat; and (3) that colonization usually follows improvement of the local environment for a particular species (or long-distance transfer by humans). Thus, persistence depends predominantly on whether organisms are able to track the shifting spatial mosaic of suitable environmental conditions or on maintainance of good conditions locally.     

Achieving and maximizing ISM code compliance with ISO 14001

This summer, July 1, 1997, to be exact, marks the deadline for compliance with the International Code for the Safe Management of Ships and Pollution Prevention (ISM Code or simply the Code) as set forth in Chapter IX of the Safety of Life at Sea Convention (SOLAS). As widely reported, enforcement officials in the United States, Australia, and other major flag and port states are promising stepped-up criminal enforcement of marine pollution laws and “zero tolerance” for non-compliance with the ISM Code. The Department of Justice has highlighted this area in enforcement policy announcements, including a statement by the Assistant Attorney General last autumn.¹ Especially given Justice's recent indictments of vessel owners for modest pollution events and these new admonitions, prudent vessel owners will be striving to meet the SOLAS timetable. For shipping firms discerning enough to have successfully navigated a course to certification, the issue instead will be how to sustain safety and environmental management improvement and build on this excellence to advance a broader range of objectives. This article will show how firms in either position may find inspiration in ISO 14001—the environmental management system (EMS) specification developed by the International Organization for Standardization.     

Stabilization of APC residues from waste incineration with ferrous sulfate on a semi-industrial scale

A stabilization method for air pollution control (APC) residues from municipal solid waste incineration (MSWI) involving mixing of the residue with water and FeSO4 has been demonstrated on a semi-industrial scale on three types of APC residues: a semidry (SD) APC residue, a fly ash (FA), and an FA mixed with sludge (FAS) from a wet flue gas cleaning system. The process was performed in batches of 165-175 kg residue. It generates a wastewater that is highly saline but has a low content of heavy metals such as Cd, Cr, and Pb. The stabilized and raw residues have been subject to a range of leaching tests: the batch leaching test, the pH-static leaching test, the availability test, and the column test. These tests showed that the stabilized residues have remarkably improved leaching properties, especially with respect to Pb but also with respect to Cd, Cu, and Zn. The release of Pb was reduced by a factor of 250-36,000.     

A simplified method for sampling and analysis of high volume surface water for organic contaminants using XAD-2

A simple compressed-gas driven system for field processing and extracting water for subsequent analyses of hydrophobic organic compounds is presented. The pumping device is a pneumatically driven pump and filtration system that can easily clarify at 4 L/min. The extraction device uses compressed gas to drive filtered water through two parallel XAD-2 resin columns, at about 200 mL/min. No batteries or inverters are required for water collection or processing. Solvent extractions were performed directly in the XAD-2 glass columns. Final extracts are cleaned-up on Florisil cartridges without fractionation and contaminants analyzed by GC-MS. Method detection limits (MDLs) and recoveries for dissolved organic contaminants, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides are reported along with results of surface water analysis for the San Francisco Bay, CA.