Tobacco budworm, Heliothis virescens [Noctuidae] resistance to l-canavanine, a protective allelochemical

Berge, Milan A.; Rosenthal, Gerald A.; Dahlman, D. L.

doi:10.1016/0048-3575(86)90005-2

Cited by 29 publications

(24 citation statements)

References 14 publications

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“…Nevertheless, less than one percent of a dose ingested over three days was excreted unmetabolized (Berge et al, 1986). This insect, unlike the tobacco hornworm which is an alkaloid specialist, but like ~.…”

Section: Amino Acidsmentioning

confidence: 92%

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Molecular Aspects of Insect-Plant Associations

Brattsten¹,

Ahmad²

1987

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All rights reservedNo part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher PREFACE Thanks to the meticulous and enthusiastic work of insect collectors and taxonomists over the past hundred years and more, we have today a large amount of information on the feeding habits and life styles of several hundred thousands of insect species.Insects that feed on plants during at least one of their life stages constitute about half of the three-quarters of a million described species. Their numbers both in terms of species and individuals together with their small but macroscopic sizes makes the insect-plant biological interface perhaps the most conspicuous, diverse and largest assemblage of intimate interspecies interactions in existence. It is also perhaps the most important biological interface because of the plants' role as primary producers upon which all other forms of earthly life depend, thereby bringing herbivorous insects occasionally into direct competition with human food and fiber production.Early enthusiasm revealed many remarkable specializations and associations between insects and plants, and occasionally assigned chemical mediators for them. However, the modern practices of large scale crop protection by synthetic pesticides and their attendant problems, particularly with resistance in "pests" and destruction of natural enemies, have been in large measure responsible for drawing our attention to the mechanisms whereby plants control insect populations and insects adapt to the plants' defenses.These practices have also brought home the importance of chemical mediators in practically all aspects of insect activities and, in particular, the importance of plant allelochemicals in maintaining and balancing insect-plant associations.There are about 20,000 identified allelochemicals to date, estimated to be between ten and 50 percent of all possible such non-nutrient chemicals.Most of these have biological activity, mostly uncharacterized, when accumulated in sufficiently high concentrations.Many are acutely toxic to insects and other animals. A few have been used successfully for insect control and as drugs; more importantly, however, plant allelochemicals continue to provide model structures for the development of synthetic insecticides and drugs.With the recent availability of high-resolution analytical instruments, natural history is rapidly turning into a modern, multidisciplinary biological science. The elucidation of the mechanisms which maintain the observed ecological equilibria in the insect-plant interface provide fascinating work and rich intellectual rewards. It is also necessary to understand these interactions for purposes of local food and fiber production, the premise being that understanding the molecular details of insect adaptations to plant allelochemicals may allow manipulations of those mechanisms for crop protec...

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Section: Amino Acidsmentioning

confidence: 92%

“…The tobacco budworm, the corn earworm, and the fall armyworm, all generalists, are also relatively insensitive to the toxic effects of canavanine (Berge et al, 1986).…”

Section: Amino Acidsmentioning

confidence: 99%

Molecular Aspects of Insect-Plant Associations

Brattsten¹,

Ahmad²

1987

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“…Finally, prior studies of canavanine disposition in the hemolymph of H. virescens larvae established that an injected dose of 5 g L-canavanine͞kg Ϫ1 fresh body weight is cleared with a t1 ͞2 of 135 min by active metabolic processes (7). This route of administration bypassed the gut initially and such canavanine clearance from the hemolymph might be achieved by a CH of the fat body.…”

Section: Discussionmentioning

confidence: 99%

“…In contrast, tobacco hornworm larvae, Manduca sexta, maintained on a 2.5 mM canavanine-containing diet develop massive developmental aberrations (1,2). The appreciable natural resistance of H. virescens to this protective allelochemical instigated earlier studies to elucidate the biochemical basis for canavanine tolerance by H. virescens (7)(8)(9).…”

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confidence: 99%

“…The tobacco budworm, Heliothis virescens (Noctuidae), exhibits a remarkable degree of tolerance to dietary canavanine as the larvae can be reared on a diet containing 300 mM canavanine, or nearly 40% nonprotein amino acid by dry weight, with only a marginal effect on larval growth and without eliciting discernible developmental aberrations (7). In contrast, tobacco hornworm larvae, Manduca sexta, maintained on a 2.5 mM canavanine-containing diet develop massive developmental aberrations (1,2).…”

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The biochemical basis for l -canavanine tolerance by the tobacco budworm Heliothis virescens (Noctuidae)

Melangeli

Rosenthal

Dalman

1997

Proc. Natl. Acad. Sci. U.S.A.

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The tobacco budworm, Heliothis virescens (Noctuidae), a destructive insect pest, is remarkably resistant to L-canavanine, L-2-amino-4-(guanidinooxy)butyric acid, an arginine antimetabolite that is a potent insecticide for nonadapted species. H. virescens employs a constitutive enzyme of the larval gut, known trivially as canavanine hydrolase (CH), to catalyze an irreversible hydrolysis of L-canavanine to L-homoserine and hydroxyguanidine. As such, it represents a new type of hydrolase, one acting on oxygen-nitrogen bonds (EC 3.13.1.1). This enzyme has been isolated from the excised gut of H. virescens and purified to homogeneity; it exhibits an apparent K m value for L-canavanine of 1.1 mM and a turnover number of 21.1 mol⅐min ؊1 ⅐mol ؊1 . This enzyme has a mass of 285 kDa and is composed of two subunits with a mass of 50 kDa or 47.5 kDa. CH has a high degree of specificity for L-canavanine as it cannot function effectively with either L-2-amino-5-(guanidinooxy)pentanoate or L-2-amino-3-(guanidinooxy)propionate, the higher or lower homolog of L-canavanine, respectively. L-Canavanine derivatives such as methyl-L-canavanine, or L-canaline and O-ureido-L-homoserine, are not metabolized significantly by CH.

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Insect Detoxification and Sequestration Strategies

Heckel

2014

Annual Plant Reviews

119

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Tobacco budworm, Heliothis virescens [Noctuidae] resistance to l-canavanine, a protective allelochemical

Cited by 29 publications

References 14 publications

Molecular Aspects of Insect-Plant Associations

Molecular Aspects of Insect-Plant Associations

The biochemical basis for l -canavanine tolerance by the tobacco budworm Heliothis virescens (Noctuidae)

Insect Detoxification and Sequestration Strategies

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