The Biological Control of Weeds

Wilson, Frank E.

doi:10.1146/annurev.en.09.010164.001301

Cited by 52 publications

(18 citation statements)

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“…More targeted biocontrol can be achieved by invertebrate herbivores, which typically show greater specificity for macrophyte species relative to vertebrate herbivores (Lodge, 1991;Newman, 1991). Since Wilson (1964) argued that "no insects have yet been used for the biological control of aquatic weeds", a wide range of species of coleopteran, lepidopteran, and dipteran biocontrol agents have been used successfully (Newman, 2004;Cuda et al, 2008). Both the conflicts related to overgrazing, and the use of herbivores as biocontrol agents, show the importance of improving our understanding plant-herbivore interactions.…”

Section: Herbivore Impacts Under Human Controlmentioning

confidence: 99%

Herbivory on freshwater and marine macrophytes: A review and perspective

et al. 2016

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on freshwater and marine macrophytes: a review and perspective.Aquatic Botany http://dx.doi.org/10. 1016/j.aquabot.2016.04.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractUntil the 1990s, herbivory on aquatic vascular plants was considered to be of minor importance, and the predominant view was that freshwater and marine macrophytes did not take part in the food web: their primary fate was the detritivorous pathway. In the last 25 years, a substantial body of evidence has developed that shows that herbivory is an important factor in the ecology of vascular macrophytes across freshwater and marine habitats. Herbivores remove on average 40-48% of plant biomass in freshwater and marine ecosystems, which is typically 5-10 times greater than reported for terrestrial ecosystems. This may be explained by the lower C:N stoichiometry found in submerged plants.Herbivores affect plant abundance and species composition by grazing and bioturbation and therewith alter the functioning of aquatic ecosystems, including biogeochemical cycling, carbon stocks and primary production, transport of nutrients and propagules across ecosystem boundaries, habitat for other organisms and the level of shoreline protection by macrophyte beds.With ongoing global environmental change, herbivore impacts are predicted to increase.There are pressing needs to improve our management of undesirable herbivore impacts on macrophytes (e.g. leading to an ecosystem collapse), and the conflicts between people 4 associated with the impacts of charismatic mega-herbivores. While simultaneously, the longterm future of maintaining both viable herbivore populations and plant beds should be addressed, as both belong in complete ecosystems and have co-evolved in these long before the increasing influence of man. Better integration of the freshwater, marine, and terrestrial herbivory literatures would greatly benefit future research efforts.

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Section: Herbivore Impacts Under Human Controlmentioning

confidence: 99%

Herbivory on freshwater and marine macrophytes: A review and perspective

et al. 2016

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“…In the new environment they can develop high population densities when compared to the biomass of their host plant, which they can never reach in the community where they evolved. Thus, Wilson (1950) rightly concludes that if an introduced insect successfully controls an introduced weed, this does not mean that it is also an effective factor controlling the plant species's population density in its old environment. So the cases of successful biological control of weeds do not prove the insects being potent density controlling factors, i.e.…”

Section: A Criticism Of the Co-evolutionary Theorymentioning

confidence: 99%

Insect—Host-plant Relationship — Co-evolution or Sequential Evolution?

Jermy

1976

The Host-Plant in Relation to Insect Behaviour and Reproduction

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Co-evolution is the generally accepted theory for the evolution of insect-host-plant relationships, however, it can be shown that its main premisses are inadequate: (1) most phytophagous insects have very low population densities compared to the biomass of their host·plants, therefore, they can hardly be important selection factors for the plant; (2) insect-host-plant interactions are not necessarily antagonistic: mono-and oligophagous insects, if their number is fairly high, may ideally regulate the abundance of their host-plants (mutual advantage); consequently, (3) resistance to insects is not a general necessity in plants and it cannot explain the presence of secondary plant substances; (4) parallel evolutionary lines of plants and insects which should result from co-evolutionary interactions are rare, while many closely related insects feed on botanically very distant plant taxa -a relationship which cannot be related to co-evolution.Therefore, the theory of sequential evolution is proposed: the evolution of flowering plants propelled by selection factors (e.g. climate, soil, plant-plant interactions, etc.), which are much more potent than insect attacks, creates the biochemically diversified trophic base for the evolution of phytophagous insects, while the latter do not appreciably influence the evolution of plants. A CRITICISM OF THE CO-EVOLUTIONARY THEORYThe insect-host-plant relationship represents a challenging problem for evolutionary considerations. The most generally accepted co-evolutionary theory has been expounded in detail by Ehrlich and Raven (1964) claiming that the trophic relations of phytophagous insects result from a very tight evolutionary interaction between plants and insects in which, on the one hand, the selection pressure represented by insect attacks induces the appearance of resistance mechanisms (mostly secondary substances) in the plants against the insects, while on the other hand, some insects succeed in overcoming this resistance by adapting themselves to these substances which may become feeding stimulants (token stimuli in host plant recognition). It is also supposed that such insects enter a new adaptive zone where they are free to diversify largely in the absence of other competing phytophagous insect species. The co-evolutionary theory is thought to be proved mainly by the fact that often closely related insect species feed on closely related plant species characterized by the presence of a group of specific plant chemicals (e.g. the lepidopterous tribe Pierini on cruciferous plants containing mustard oil glucosides). Fraenkel (1959) even asserts that the secondary substances in plants exist solely for the purpose of repelling and attracting insects.In connection with the premisses of the co-evolutionary theory postulated

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“…Adjuvants such as fatty alcohol ethoxylate and alkyl ether sulphate sodium salt are reported to increase the efficacy of foliar applied herbicides (Zabkiewicz, 2000;Hazen, 2000) and could be integrated potentially into a reduced herbicide rate program. Biological control of E. spinosa has been published by many researchers (Burdon & Marshall 1981;Wilson 1964) but no work has been done on chemical control of E. spinosa. The objective of this study was to determine the potential of five herbicides at reduced rates with adjuvants in controlling E. spinosa at different growth stages.…”

Section: Introductionmentioning

confidence: 99%