I forward an article recently posted on bionet.population-biology:
In article <36h4mn$bok at mserv1.dl.ac.uk> , Neve at ecol.ucl.ac.be writes:
> Dear networkers,
>> Recently, there has been much debate on this list on viral-vectored
> immunocontraception. In the last issue or Journal of Applied Ecology, N.D.
> Barlow discusses this issue as a mean of controlling possums in New
> Zealand.
> I think that such methods of population control are interesting, but the
> risk of spread to a non-targetted species should always be kept in mind. If
> this is put in practice for mammals such as rabbits, foxes or possums,
> would mean that applying to humans will eventually occur.
>> It seems that this issue is not as much 'only theoretical' or fiction, as
> some have thought it is...
>>>> Here the summary and two references from this paper :
>> Predicting the effect of a novel vertebrate biocontrol agent: a model for
> viral-vectored immunocontraception of New Zealand possums
>> N.D. BARLOW
> Biological Control Croup, AgResearch, Canterhury Agriculture & Science
> Centre, PO Box 60, Lincoln, New Zealand
>> Journal of Applied Ecology (1994) 31, 454-462
>> Summary
>> 1. A model is described for predicting the outcome of biological control of
> New Zealand possums, using viral-vectored immunocontraception based on a
> sexually transmitted herpes-type vector.
> 2. The model shows that success is possible in ecological terms, and
> identifies the probable circumstances under which it is achievable. These
> provide targets which a genetically modified virus must meet, aiding in the
> quest for suitable vectors and appropriate genetic modifications to them.
> 3. In particular, the female reproductive system rather than the male's
> should be targeted, contact rate (i.e. number of potentially infectious
> contacts) per possum carrying the virus (i.e. infected, not infectious)
> must be in the order of one or more per year and at least 75% of females
> carrying the virus must be sterile at mating. Achieving this incidence is
> critical, with only slightly lower values exerting a disproportionately
> lower effect on possum densities.
> 4. Spatial aggregation of the viral vector and the existence of a recovered
> and immune class of possums would both reduce substantially the impact of
> the control agent, but the presence of even limited vector-induced
> mortality would dramatically enhance it.
> 5. Immunocontraception is likely to confer a selective advantage on the
> engineered virus by allowing multiple matings for an affected female. This
> will raise the contact rate and prevalence, and allow the vector to compete
> successfully with any existing wild strains.
> 6. Given an appropriate mechanism of action on the reproductive system,
> viral vectored immunocontraception of this kind would, if successful, offer
> a uniquely acceptable control for a vertebrate pest such as the possum,
> being humane, species specific, cost-effective and environmentally benign.
> 7. Even if immunocontraception caused only limited suppression of an
> otherwise uncontrolled population, it could contribute to successful
> integrated control by greatly reducing the need for conventional poisoning
> operations. Such integrated control also reduces possum densities more
> rapidly than would occur with immunocontraception alone.
>> References
>> Bradley, M.P. & Reed, K.C. (1990) Fertility control of
> animal populations: a prospective study of gonads,
> gametes, genes. Proceedings of the Fertility Control in
> Wildlife Conference. Melbourne, November 199O.
>> Tyndale-Biscoe, H. & Jackson, R. (1990) Viral-vectored
> immunocontraception: a new concept in biological
> control of wild animals. Proceedings of the Fertility
> Control in Wildlife Conference, Melbourne, November
> 199O.
>>>> ===========================================================
> Gabriel NEVE o o
> Unite d'Ecologie et de Biogeographie \ /
> Universite Catholique de Louvain *** Y ***
> Croix du Sud 5 * * I * *
> B-348 Louvain-la-Neuve * *I* *
> Belgium * *I* *
> * * I * *
> EMAIL: NEVE at ECOL.UCL.AC.BE *** I ***
> Fax : +32/10/473490
> Tel : +32/10/473495
> "The death of the butterfly is the one drawback to an
> entomological career"
> - Margaret E. Fountaine (1892)
> ===========================================================
