Laboratory bioassays

3 Plant-Plant AUelopathic Interaction. Phase 11 Held/Laboratory Experiments 

Effects of phenolic acids, wheat Triticum aestivum L. Southern States 555 ) or sunflower tissues Helianthus anmus L.) on phenolic acid-utilizing bacteria in the bulk soil and rhizosphere of cucumber seedlings and growth inhibition of cucumber seedlings were determined (Staman et al. 2001) as previously described. Eor details see Section 2.2.11. The effect of sunflower leaf tissue on pigweed seedling emergence was also determined, as described above. 

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Field and laboratory bioassay of chemosignals from related sympatric and allopatric species (overlapping and discrete distributions) are essential to an understanding of the relatedness or otherwise of functionally active compounds. The semiochemicals involved in speciation surely utilise the main and vomeronasal senses, but their relative contributions cannot be predicted at present. 

We have recently observed in our laboratory that water washes of undamaged leaves in a number of plants contained sterols and other lipids in sufficiently high concentration comparable with concentrations used in typical laboratory bioassays. These aqueous lipid solutions are frequently accompanied by long-chain (C-12 to C-18) fatty acids. We therefore suggest that micelle formation between the lipids and fatty acids may occur. By this mechanism the lipid solubility in the aqueous medium is significantly enhanced, thus allowing the release of otherwise water-insoluble plant constituents into the environment. Presently, experiments are in progress in our laboratory to provide further evidence for the "micelle-mechanism" of allelopathlc lipids. 

Field Applicability Testing (FAT) Workshop. In March 1982, the EPA Office of Research and Development convened a workshop with the specific objectives to (1) assess the state of knowledge on determining the field applicability of laboratory bioassay tests, toxicity studies, microcosm studies, and mathematical chemical exposure models (i.e., the extent to which these methods have been tested/compared with field data), and (2) recommend research objectives and priorities to advance the current level of field testing. Workshop attendees included representatives from EPA research laboratories, universities, and private industry. 

Following a report that male P. hybneri were attractive to both sexes [99], males were found to produce a mixture containing the sesquiterpene 6-sesquiphellandrene, (R)- 15-hexadecanolide 114, and methyl (Z)-8-hexade-cenoate [100]. Odors from live males were attractive to adults of both sexes, with males also becoming sexually stimulated. Each component alone had some slight activity, with the 3-component blend being the best attractant in laboratory bioassays. The (S)-enantiomer of the macrolide lactone component was not inhibitory. 

Two male specific volatiles of Anoplophora glabripennis were found to elicit strong electrophysiological responses in the antenna of both males and females. The very unusual 4-(n-heptyloxy)butanal 187 and the corresponding alcohol form a 1 1 mixture [348]. A synthetic blend proved to be attractive in laboratory bioassays. 

Of the three compounds isolated, piplaroxide and demethoxypiplartine (Fig. 7) demonstrated significant activity in a laboratory bioassay measuring repellency to the leafcutter ant Atta cephalotes. 

The male produced sex pheromone of the red-shouldered stink bug, Thyantapallidovirens Stal (Hemiptera Pentatomidae), was shown to consist of a blend of methyl ( "2, Z 4,. Z6)-decatrienoate and the sesquiterpenes (+)-a-curcumene, (—)-zingiberene and (—)-P-sesquiphellandrene. In laboratory bioassays, sexually mature males attracted sexually mature females but not males, and females did not attract either sex. Pheromone... 

PSEP (Puget Sound Estuary Program) (1995) Recommended Guidelines for Conducting Laboratory Bioassays on Puget Sound Sediments, Puget Sound Estuary Program, Olympia, WA, USA. 

As pointed out previously, any bioassay can be employed (see Section 2), but microscale tests are preferred because of their small sample volume requirements. This ensures a sufficient quantity of leachate for subsequent laboratory bioassays. Table 4 lists some basic features of five small-scale bioassays that can be used for WASTOXHAS applications. 

Low molecular weight phenolic compounds have been identified in fresh leaves and in soils in which leaves of five varieties of Capsicum annuum were decomposing. Six phenolic compounds were tested in laboratory bioassays for their allelopathic... 

Inderjit, Weston, L.A. Are laboratory bioassays for allelopathy suitable for prediction of field responses J Chem Ecol 2000 26 2111-2118. 

Assessments of environmental impacts from herbicides are usually done at the single-species level. These assessments use toxicological data from laboratory bioassay tests and estimates of exposure from laboratory or field studies of environmental chemistry. Few tests have assessed the impacts of herbicides on organisms in the field and few, if any, at the ecosystem level. There are two main reasons why there have been so few field or ecosystem tests They are exceedingly difficult and costly, and the current philosophies of risk assessment have evolved from classical toxicology and the federal regulatory framework that covers pharmaceuticals, food additives, and pesticides. 

Beckmann M., Harder T., and Qian, P.Y., Induction of larval attachment and metamorphosis in the serpulid polychaete Hydroides elegans by dissolved free amino acids mode of action in laboratory bioassays, Mar. Ecol. Prog. Ser, 190, 167, 1999. 

Blight M. M., Wadhams L. J. and Wenham M. J. (1978) Volatiles associated with unmated Scolytus scolytus beetles on English elm differential production of a-multistriatin and 4-methyl-3-heptanol, and their activities in a laboratory bioassay. Insect Biochem. 8, 135-142. 

Blight M. M., Henderson N. C. and Wadhams L. J. (1983) The identification of 4-methyl-3-heptanone from Scolytus scolytus (F.) and Scolytus multistriatus (Marsham). Absolute configuration, laboratory bioassay and electrophysiological studies on S. scolytus. Insect Biochem. 13, 27-38. 

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