ISSN:0739-4462    

DOI:10.1002/arch.940170402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractOpportunities for genetic engineering of natural products are increasing, while discovery and development of synthetic insecticides and developmental regulators are declining. However, discovery and potential applications of natural compounds are constrained by present ecological knowledge and theory. Biochemistry offers additional perspective to chemical interaction across the interface between plant and herbivore. Phytochemical effects on an insect herbivore may be determined by physical, chemical, and biotic characteristics of the microenvironment during phytochemical transfer between plant and insect. The midgut lumen is often overlooked as part of this microenvironment. It initially determines rates of metabolism and uptake of phytochemicals into hemolymph, and ultimately the quantity of a compound seen by affected tissues. Additive processes such as absorption, binding, and transport by proteins in hemolymph may ultimately prove more crucial to toxication than subtractive processes such as metabolism and excretion. Uptake and transport of coumarins in hemolymph are being studied in larvae of the citrus root weevilDiaprepes abbreviatus. Studies with synthetic 7‐amino‐3‐phenyl coumarin (coumarin‐10) have preceded studies with natural coumarins. The fluorescence properties of coumarin‐10 have enabled determination of absorption and binding to hemolymph

ISSN:0739-4462    

DOI:10.1002/arch.940170403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractPlant phototoxins are broad‐spectrum biocides which adversely affect an array of potential plant enemies, including among others disease‐causing pathogens, nematodes, insect herbivores, and competing plant species. Thus far, plants which contain these broad‐spectrum allelochemicals have been found to occur in open habitats (i.e., in full sunlight) where a defensive mechanism mediated by light would seem to operate most effectively. The levels of available light in shaded environments, although considerably lower than full sun (1–10% of full sun), are equivalent to the intensities of light used to kill phototoxin‐treated insects in laboratory studies. This suggests that phototoxic reactions might mediate important organismal interactions in shaded environments as well. In this study, more than 230 Costa Rican rainforest plants were bioassayed for phototoxic metabolites in an effort to ascertain their prevalence among plants growing in moderate to extreme shade. Microbial bioassays, employingBacillus cereus(a gram positive bacterium),Escherichia coli(a gram negative bacterium), andSaccharomyces cerevisiae(a yeast) were used to rapidly and sensitively indicate phototoxic action and potential for insecticidal action. Tissue extracts from 12 plant families tested positive for phototoxins. This is the first report of phototoxins occurring in eight of those families (Acanthaceae, Campanulaceae, Gesnariaceae, Loganiaceae, Malpigaceae, Phytolaccaceae, Piperaceae, and Sapotaceae). The presence of phototoxins in rainforest plants suggests that phototoxic plant allelochemicals may function as important defenses in low‐light, as well as high‐light,

ISSN:0739-4462    

DOI:10.1002/arch.940170404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractWithin the family Papilionidae (Lepidoptera), species display a broad range of feeding patterns, from oligophagy on a single hostplant family to polyphagy on over a dozen families. Accompanying this diversity of feeding strategies is a diversity of physiological mechanisms for processing hostplant allelochemicals. Studies on members of this family as well as other Lepidoptera suggest that oligophagy is associated with high activity, in addition to high substrate specificity, of detoxicative enzymes.

ISSN:0739-4462    

DOI:10.1002/arch.940170405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe roles of plant and insect cuticular lipids in insect and plant interactions are reviewed. Emphasis is given to the influence that the host plant and the surface lipids of the host plant have upon insect herbivores and the predators and parasitoids of these herbivores. Variations in cuticular lipids of herbivorous insects are dependent upon the host plant, and these variations may affect the behavior of predators and parasitoids. The cuticular lipids of species which interact on multiple trophic levels are compared. Similarities were found between the hydrocarbons of herbivorous insects, their host plants, and their predators or parasitoids.

ISSN:0739-4462    

DOI:10.1002/arch.940170406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractFeeding by the spotted alfalfa aphid,Therioaphis maculata(Buckton), on susceptible alfalfa,Medicago sativaL., results in dramatic changes in plant biochemistry that in turn have profound effects on aphid physiology. These aphids select older leaves on the plant as feeding sites. One component of this selection process may be the amount and composition of plant epicuticular lipids, which vary with leaf age. Feeding aphids induce a senescence‐like state in the leaf that is characterized by loss of chlorophyll, decreased levels of soluble protein and fatty acids, and increased production of ethylene. This process involves lipid peroxidation and, like senescence, is probably free‐radical‐mediated. Leaves of alfalfa having resistance to spotted alfalfa aphid contain higher activities of catalase than do susceptible leaves. This enzyme may function in concert with other antioxidant enzymes to quench aphid‐induced free radical damage and thus impart resistance. Aphid fatty acid metabolism is altered by changes in plant metabolism and thus reflects the close relationship between aphid and plant bioch

ISSN:0739-4462    

DOI:10.1002/arch.940170407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe use, as opposed to the procurement, of transgenic crop plants is discussed in this paper. Transgenic crop plants must not be used until appropriate strategies for their use have been designed and not before crop plants with a variety of insect defenses have been developed. The use of a crop plant with a single defense will pose as strong a selection pressure as the use of a single synthetic insecticide, since insect herbivores are able to evolve effective counter‐defenses. The defenses of insects in natural plant‐insect associations and with regard to synthetic insecticides are described to demonstrate that there is nothing unique about insecticide resistance. It is the inevitable alternative to local extinction in response to a persistent and predictable selection pressure. Plants counteract insect defensive evolution by keeping the selection pressure as variable as possible. This leads to the conclusion that the best use of biotechnology in crop protection is to reintroduce chemical diversity into crop pla

ISSN:0739-4462    

DOI:10.1002/arch.940170408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940170401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY