Locating and Using Native Biocontrols for Invasive Non-native Plants, a New Paradigm.
ABSTRACT: The debate over using classical biocontrolto control invasive non-native organisms is redundantand stale. Instead of searching for new methods and synergies, the debate is over the pros and cons of classical biocontrol. This presentation will offer examples of native biocontrol systems. At the same time it will offer practical insights into finding nativebiocontrols for non-native invasive plants. The goal of this presentation is to help end the continuing unethical and scientifically flawed introduction and use of non-native organisms in hopes of controlling other non-native organisms.
Richard Gardnerrtgardner3@yahoo.com (410) 726-3045
Non-native invasive Native biocontrol Population Native congeners of non-native invader timeThe expected population curves for native biocontrol use. The baseline population for native organisms changes as the native biocontrols adapt to the non-native invasive and eat a fewmore of the native while the system comes back into balance as the non-native is destroyed. There is some recoverable risk to the native ecosystem, but not the unrecoverable risk of introducing non-native biocontrols.
Non-native invasive Non-native biocontrol Population Native congeners of non-native invader timeSimplified expected curves for what happens when a non-native biocontrol is introduced after the establishment of a non-native invasive.
Pioneer non- native invasive Native organisms Secondary non-native invasives Native congeners of non-native invasive Population Non-native biocontrols time A more complex version of what happens when a (pioneer) non-native plant is introducedfollowed by its non-native biocontrol. The native system collapses allowing secondary non- natives to enter.
Non-native invasive Chemical defenses of non-native invasive population Population or concentration Non-native specialist biocontrol timeThis diagram demonstrates what happens when a non-native specialist biocontrol is reintroduced to its non-native host.
Classical biocontrol – the use of non-native organisms in the attempt to minimize the effects of other non- native organisms on ecosystems. This is a losing proposition as it does not attempt to remove the problems, just minimize their effects.Bioeradication – the extinction of a non-native invasive from an ecosystem using native biocontrols, the goal.This is a winning proposition as it is the regeneration of the ecosystem by eliminating the problem from the ecosystem using naturally available native organisms.
Biocontrol – any organism in any time frame fromseconds to centuries that partially or fully inhibits anon-native organism. Usually the goal of using non-native biocontrols on non-native invasives. This is a losing proposition. Biocontrol system – a group of organisms whichthrough any biological relationship partially or fully inhibits a non-native organism.
Direct biocontrol – use of a native organism or system as a biocontrol for a specific organism. Indirect biocontrol – providing the native resources such as food, breeding sites or shelter needed for anative biocontrol or biocontrol system to develop for a specific organism.
Biocontrol garden – a garden of local native plants thatprovide a resource that a native biocontrol needs to be effective as a biocontrol such as food, egg laying sites, overwintering sites, protection from predators, …, in any life stage. Biocontrol resource – any local naturally occurringenvironmental resource a native biocontrol needs to be effective as a biocontrol.
Resource familiarity – the amount of use of a resource by a native biocontrol. In the case of non-native resources(invasive) it requires time for a native biocontrol to adapt to it through either behavioral or genetic changes. Resource use – the use by a native biocontrol of a native ornon-native resource. In the case of a non-native resource ittakes time to adapt to using it through either learning to use it (behavioral changes) or genetic changes, often both.
Resource heritage – the passing on of a social or genetic adaptation to a resource by a native biocontrol. This can be through learning, by genetic change or more probably a combination of both. It can spread through a specieshorizontally as one organism learns from another or vertically as it is passed on to/through offspring through learning or genes.
Mutualism – two or more organisms which cooperate to the benefit of each other. Commensalism – two or more organisms livingtogether where at least one benefits and the effects on other organisms are neutral.Competition – relationships where certain organisms benefit through a variety of mechanisms to thedetriment of others without necessarily using them as an energy source.Herbivory, predation and parasitism – relationships inwhich one organism or groups of organisms benefit by using other organisms as an energy source.
In Biocontrol/Bioeradication we are tryingto understand all these relationships within an ecosystem and use them to find native organisms to hinder and eradicate non- native organisms.
Examples of apparentbiocontrol systems and potential biocontrol systems.
herbivory and disease? Elaeagnus umbellata, Autumn Olive
Ailanthus altissima• A family of plants with native congeners.• Birds move between stands carrying Aculops ailanthii mites with them.• Atteva aurea females pick up and move Aculops ailanthii between trees while laying eggs on various trees.• Atteva aurea carries disease ingested as a larva, incubated as a pupa and deposited as an adult on leaves while laying eggs.• Disease enters tree through the feeding wounds of Atteva aurea larvae on branches and leaves.• Disease is carried by the Aculops ailanthii.• Pollinators also carry Aculops ailanthii between trees.• Wind carries Aculops ailanthii between nearby trees.
Rosa multiflora:• Large family of plants with native congeners from which diseases and herbivores can become biocontrols.• Birds move between bushes carrying Phyllocoptes fructiphilus mites between them.• Rose rosette disease, an Emaravirus, is carried by Phyllocoptes fructiphilus.• Birds move mites between the bushes which they also nest in.• Pollinators carry mites between parts of the same bush and nearby bushes.• Pollinators also carry mites between bushes.• Wind carries the mites between nearby bushes.
Lonicera morrowii: possible scenario• Large family of plants with native congeners.• Disease is carried by mites.• Deer carry mites in a way similar to ticks.• Deer browse on local vegetation as a source of food, use the shrubs for cover and move between stands of shrubs as they move between environmental resources.• Birds move mites between the shrubs in which they roost, nest and feed on the fruit.• Pollinators carry the mites between shrubs.• Wind carries the mites between nearby plants.
Most likely scenario for the movement of Aculops ailanthii and pathogens across landscapes Birds – long distances searching for familiar shelter during migrations. - medium and short distances between nearby stands. Atteva aurea – mostly medium and short distances between egg laying sites.Wind - short distances within stands and between close stands with high mite densities.
Probable scenario for the spread of rose rosette disease across the ecosystems.Birds - long distances searching for food and shelter during migrations. - medium distances between nests and food sources. - short distances as part of normal random movement. Pollinators - medium and short distances between food sources. Wind - short distances within stands and between close stands.
Possible scenario for the movement of biocontrol pathogens and insect herbivores between Lonicera morrowii plants. Deer - mostly within and between thickets in the short and medium distances. Birds - across long distances through migration, medium distances while searchingfor food and short distances while using the plants as shelter and nesting locations. Pollinators - across medium and short distances while moving between flowers. Wind - across short distances primarily within thickets.
The more native congeners the moreapt the native biocontrol system is to form and the more complexity possible.
As complexity increases so does theprobability of a control system and the more stable the system is.
Complexity may involve multiple food sources, multiple families of organisms which contribute to control but do not directly control the target, multiple types of plant use (herbivory, pollination, nesting and roosting sites, disease), multiple types of control organisms such as mammals, birds, insects, diseases and different feeding strategies(browsing, grazing, nectarivory, frugivory, parasitism among others) .
Reintroducing a coevolvedherbivore specialist to its original host will fail.
By inference, this has been shown with wildparsnip, Senecio jacobaea. (Zangerl, et al, 2005)
WhenTyria jacobaeae, one of its specialist biocontrols from Europe was accidently reintroduced after at least 230 years,
In other words, the highest fitness level of the plant shifted from its original chemical defenses to growth andreproduction in the absence of a specialist herbivore as it invaded a new ecosystem, i.e. enemy release.
When the herbivore wasreintroduced, the highest fitnesslevel shifted back towards using the original or similar chemical defenses at the cost of energy expended for growth and reproduction.
Since the genes for the originalchemical defenses were already present, turning them on was easy.
It did not involve the muchslower process of evolving defenses to a new threat.
The energy output shifted awayfrom defense in the absence of many of its specialist herbivores. It then shifted back when the specific herbivore was accidently introduced from Europe.
Since the chemical defense reversion was small becausethe threat was small, the plant continues to thrive as an invasive.
Examples of catastrophic failures by introduced biocontrols:
The moth Cactoblastis cactorum was introduced in the island of Nevis in Caribbean to control Opuntia monacantha (Willd.) Haw. in 1957 (Pemberton, 1995).
Now it is spreading throughout the Caribbean eating nativecongeners. It is only a matter of time before it reaches North American Opuntia species.
The weevil Rhinocyllus conicus was introduced to control Canadathistle, Cirsium arvense. Instead itjumped to native thistles. This has put several of them in danger of extinction.
Example of already presentorganisms controlling a non- native:
Euhrychiopsis lecontei,a native North American weevilprefers the exotic aquatic plant Eurasian watermilfoilMyriophyllum spicatum over native watermilfoils. (Sallie P. Sheldon, Robert P. Creed, Jr, 2003)
This was expected as the non-native had no defenses to the native generalist herbivore.
The key to finding a nativebiocontrol (system) is to find an organism which a generalist (herbivore) that feeds broadly on a family or genus and a specialist (herbivore) to that feeds only on that family or genus.
This means that the biocontrol has a the genetic ability toswitch from one plant to another and yet will not cause the extinction of coevolved food sources.
The necessary conditions for a biocontrol system:• food sources for all organisms at all life stages• shelter for the various life stages• breeding sites and egg laying locations
Path forward/2013 research plan:1.) plant biocontrol garden of a wide variety of mostly Asteraceae seeds to determine which plants Atteva aurea uses as nectar sources.2.) culture and identify to family the diseases which affect Ailanthus.3.) walk a lot to continue finding and understanding native biocontrol systems.
Non-native biocontrol has highrates of failure and low rates of success, an average of 2.44introduced organisms for every species on which control is being attempted.
Using natives to control non-natives is a much lower risk andtherefore safer than using non- natives to try to control non- natives.
Non-natives, regardless of how much they are studied have a high risk associated with themas is seen by the introduction of non-natives in the first place.
Collateral environmental effects are unknown with non-native biocontrols such as:• breeding site competition with natives,• acting as food supplements for native predators which shifts population balance,• susceptibility to native diseases or magnifying them in the local ecosystems as a disease sink,• disease vectoring and … .
Whereas with native biocontrols, the collateralenvironmental effects are known or predictable.
I challenge the developers of non-native biocontrols to prove that what they are doing:1.) is safe2.) is ethical3.) is necessary4.) that they understand the problems they are trying to solve5.) that they understand the total consequences of their apparent solutions.6.) that they have spent time in the field to prove that there are no possible alternatives already present.
If bad theory and bad practice caused a problem, then badtheory and bad practice are not going to solve it.
One small mistake with a non-native is thebioecosystem equivalent of a Chernobyl, even though more subtle.
Are we willing to risk that whenthere are already good theoryand good examples in place to guide us?