Classical and augmentative biological control against ... - IOBC-WPRS

Ris & Malausa
Bulletin of Entomological Research (7%). Impact Factors are respectively 1.805, 1.957,
0.874, 0.886 and 1.415.
The types of the works were categorized according to the simplified sequential steps in
R&D of biological programmes: BCA Inventories BCA characterization (systematic,
molecular tools) Pest or BCA rearing BCA biology (life history traits, thermal biology,
behavioural ecology) Pre-release survey BCA introduction Post-release survey.
Studies related to “non-target effects” (i.e. the direct or indirect impacts of the ClBCA on
non-target species) as well as those related to the “biocontrol disruption” (i.e. the negative
impacts of organisms on the ClBCA) (details in Appendix 9.3) were also categorized. As
shown in Figure 10, most of the ClBC related publications logically deals either with BCA
biology, BCA introductions or post-release surveys which are central steps of the ClBC
programmes. A strong discrepancy nevertheless exists between the different types of work in
term of scientific publication; highest Impact Factors are relied to studies linked to Nonintended
effects, Biocontrol disruption or BCA Biology.
[Remark: The different steps of R&D in Classical Biological Control are currently
unequally promoted with regard to “scientific criteria”, with a clear emphasis on community
ecology including non target effects. Such trend may be detrimental to the short-term
development of less gratifying tasks and consequently on the whole dynamism of ClBC.]
BCA Introductions
As shown in Table 9, 65 introductions were recorded during the period of 1991-2006. This
list is probably not exhaustive insofar as “cryptic introductions” may have been missed. This
list does not also cover all the R&D in classical biocontrol programmes since some
programmes may have been interrupted before releases. A faunistic inventory of the natural
enemies of the North American leafhopper Scaphoideus titanus has for instance been led by
our lab in 2000-2002 but the rearing of BCA candidates (mainly dryinids and eggparasitoids)
were not successful.
All these releases involve 55 different biocontrol agents (all hymenopteran except
the Pseudacteon species used against the fire ant Solenopsis invicta) and 35 pests. 57% of
these pests were Hemiptera, other being quite equally distributed between Lepidoptera,
Diptera, Hymenoptera and Coleoptera.
Most of these introductions were realized against pest found on orchards and in
particular Citrus. Other targeted crops were mainly tropical productions, ornamental or forest.
Most of the BCA introductions (42%) were realized in Europe or neighbouring
countries (including Mediterranean Basin) and in North America (26%). The percentages of
introductions in other geographical areas were: Australia-New Zealand and neighbouring
islands (12%), South America (8%), sub-Saharan Africa (8%), Pacific Islands (3%), Asia
(1%).
The total number of released parasitoids and number of sites were highly variable
ranging respectively from 456 to 660000 individuals and from 2 to 132 sites. The percentage
of establishment was 83% and, when established, high parasitism was found in 42% of the
cases. It is noteworthy that these values are relatively high compared to other estimates and
we are currently unable to say if this is linked to an improvement of practices or
methodological differences or biases.
[Remark: With regard to natural or other human-mediated introductions of exotic
species, species flow associated with the ClBC seems to be rather limited. Although possible
non-intended effects cannot be excluded (their studies having to be increased), we fear that
too drastic regulations could severely disturbed R&D programmes]
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