ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<1::AID-ARCH1>3.0.CO;2-3

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

年代:1996

数据来源: WILEY

摘要:

AbstractChemical defense of the tomato plant against noctuid larvae is argued to result from suites of interactive chemical traits that simultaneously impair the acquisition of nutrients and toxify the insect. Defense results from tomatine, catecholic phenolics and phenol oxidases, proteinase inhibitors, and lipoxygenase. The catalytic role of plant oxidative enzymes in activating a variety of defense mechanisms is discussed. It is argued that the terms “digestibility reducer,” “toxin,” and “nutrient” signify ecological outcomes, not properties of molecules. Current views on the roles and the modes of activity of plant natural products against herbivorous insects are challenged. It is proposed that chemical context and mixture are critical determinants of biological activity, and that viewing natural products as isolated defensive factors is often misleading. © 1996 Wil

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<3::AID-ARCH2>3.0.CO;2-1

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

年代:1996

数据来源: WILEY

摘要:

AbstractPlant serine proteinase inhibitors (Pls) have the potential to restrict the growth and/or development of herbivorous insects. However, there are limitations to the efficacy of these Pls. An insect's susceptibility to a Pl is determined, at least in part, by the relative proportion of proteolytic enzyme activity in the midgut that is suppressed by that inhibitor. Insects adapt to dietary trypsin inhibitor in their host plant by secreting “inhibitor‐resistant” trypsin(s). These “inhibitor‐resistant” enzyme(s) may be the standard proteinase(s) secreted into the midgut (e.g.,Pieris rapae), or may be enhanced following ingestion of proteinase inhibitor (e.g.,Helicoverpa zea). In addition, insects may be pre‐adapted to specific Pl(s), following adaptation to a Pl from the same family. For example,Pieris rapaeis a crucifer specialist that is resistant to cabbage Pl, but is also resistant to Kunitz soybean trypsin inhibitor, a Pl in the same family as cabbage Pl, but from a non‐host plant. The ultimate value of this pre‐adaptation to herbivory by a species of insect will be determined by the number of different families of Pl in host plant(s) to which the species has adapted, and the distribution of those families among other species of plants. Thus, it is possible that the presence of a plant Pl limits herbivory by insect(s). However, multiple inhibitors, matched to the complement of enzymes in the insect's midgut, may be required to enhance this resistance of plants to herbivorous insects. © 19

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<39::AID-ARCH3>3.0.CO;2-S

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

年代:1996

数据来源: WILEY

摘要:

AbstractFundamental differences in midgut structure, physiology, brush border proteins, and transporters amongLeptinotarsa decemlineata,lepidopteran caterpillars, other insect taxa, and vertebrates are reviewed. The effects of dietary protein concentration onManduca sextamidgut amino acid transport and brush border membrane proteins are reported.M. sextafed diet with reduced protein had elevated levels of leucine aminopeptidase in the brush border membrane. No changes in amino acid transport or alkaline phosphatase activity due to dietary differences were detected. Changes in brush border proteins could affect the toxicity and pathogenicity of microbial agents. © 1996 Wiley‐Liss, I

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<55::AID-ARCH4>3.0.CO;2-W

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

年代:1996

数据来源: WILEY

摘要:

AbstractFeeding experiments were conducted to assess development of the polyphagous leafhopper,Homalodisca coagulata,on single host species. Insects were reared from eggs on two cultivars ofEuonymus japonica,two cultivars ofLagerstroemia indica,and two species ofPrunus.Only insects on nonvariegatedE. japonicaandL. indicacv. Osage survived to maturity, although a substantial proportion of those onP. saliciniadeveloped to the fourth instar. Chemical profiles of food source (xylem fluid), insect excreta and body composition, and consumption rates were used to estimate assimilation efficiencies, daily assimilation rates, and efficiency of conversion of food into biomass for all primary nutrients identified in the xylem fluid. Rates of successful maturation were greatest on the highest nitrogen and carbon source (nonvariegatedE. japonica) and were associated with low consumption rates, high assimilation efficiencies, and prolonged instar durations. Developmental period onL. indicawas shorter and consumption rates were higher, yet assimilation efficiencies were reduced and young nymphs had lower survivorship. Low consumption rates, coupled with the low nutritional value ofP. salicinia,precluded sufficient accumulation of nutrients to complete development. Insects fed on hosts with xylem fluid containing high ratios of amides to total organic compounds (indicative of low carbon to nitrogen ratios) had higher consumption rates but less efficient assimilation of primary nutrients. Carcass analyses of newly enclosed adults suggest that regulation of consumption rates and assimilation efficiencies to provide adequate accumulation of essential amino acids may be pivotal for successful development. © 1996 Wiley‐Liss, I

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<65::AID-ARCH5>3.0.CO;2-W

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

年代:1996

数据来源: WILEY

摘要:

AbstractEarly insect physiologists recognized the importance of gut physicochemistry, primarily pH, redox potential, and ionic strength, on digestive processes, but studies to date have been primarily restricted to keratin‐ and wood‐feeding insects. Recent investigations show that herbivorous insects have a broad range of gut redox conditions, with pHs ranging from 6.0 to 11.8 and measured redox potentials from −200 to +240 mV. The redox state of the gut is largely dependent on pH, which is well regulated, and the redox activity of ingested material, including plant chemicals, at that pH. Inter‐ and intraspecific variation in midgut redox conditions appears to be substantial enough to affect digestion via effects on the structure and function of dietary proteins and proteolytic enzymes. The impact of reducing conditions on proteins probably depends on characteristics such as tertiary structure and the number and arrangement of disulfide linkages. In addition to the effects of reducing conditions in dietary proteins, there can be effects on the activities of digestive enzymes, depending on their structure and the nature of their catalytic site. We speculate that phylogenetic and environmental determinants of gut physicochemistry may place constraints on the efficacy of different digestive processes, and may thus influence the evolution of digestive strategies in insects. © 1996 Wiley

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<85::AID-ARCH6>3.0.CO;2-W

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

年代:1996

数据来源: WILEY

摘要:

AbstractProtein quality has received comparatively little attention as a factor in host plant suitability for insects. It is argued here that plant protein quality is subject to considerable variation from genetic and environmental influences and thus may significantly impact herbivore performance. Furthermore, other phytochemicals that are ingested with protein may negatively impact protein utilization. There is a wide distribution of alkylating agents found in plants (e.g., quinones, phenolics, aldehydes, pyrrolizidine alkaloids, sesquiterpene lactones, isothiocyanates) that form covalent bonds with nucleophilic side chains of proteins (e.g., ‐SH, ‐NH, ‐NH2) and potentially limit amino acid availability. The behavioral and physiological adaptations of insects to variation in protein quality are also discussed. Finally, preliminary evidence for physiological adaptation to low protein quality inHelicoverpa zeais provided. The potential role of protein quality in host plant specialization is summarized. © 1996 Wiley‐L

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<107::AID-ARCH7>3.0.CO;2-X

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

年代:1996

数据来源: WILEY

摘要:

AbstractThe peritrophic envelope has long been considered an important microbial barrier to midgut infection and as a selective filter for the exclusion of dietary toxins. In this paper, we present data indicating that the peritrophic envelope (PE) ofHelicoverpa zeaserves as a functional antioxidant, protecting the midgut epithelium from damage by dietary prooxidants. Results from in vitro assays indicate that PE effectively scavenges hydroxyl radicals and reduces hydroperoxide formation in isolated midgut tissues exposed to model free radical generating systems. The extraordinary similarity in location and function of the PE to gastric mucins of vertebrates is discussed. © 1996 Wiley‐Liss, I

ISSN:0739-4462    

DOI:10.1002/(SICI)1520-6327(1996)32:1<131::AID-ARCH8>3.0.CO;2-2

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

年代:1996

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/1520-6327(1996)32:1<::AID-ARCH940320101>3.0.CO;2-7

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

年代:1996

数据来源: WILEY