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BiocontrolNews and Information 2003 Vol. 24 No. 2 29N–46N General News Environment Prize years, the formerly devastating pest was When the Mist Clears, Recognizes Biocontrol’s controlled across all of continental Africa. What Will We See? Diversity In a rare ‘silver bullet’ success story, control has been sustained ever since, with this one One of the perceived disadvantages of Amongst the three recipients of the 2003 natural enemy keeping the pest in check. weed biological control is that because Tyler Prize for environmental achievement However, the programme was also respon- agents are generally chosen that will target are two leading lights of the biocontrol sible for introducing the concept of biolog- a single weed at a time, there is a danger world, Hans Herren of ICIPE (International ical control to many countries. The that the plant targeted will simply be Centre of Insect Physiology and Ecology, outstanding success of the programme was replaced by other unwanted exotics. There- Kenya) and Yoel Margalith (Ben-Gurion instrumental in facilitating acceptance of fore it is important not only to demonstrate University of the Negev, Israel). (The third this approach in Africa, and contributed that a weed has been reduced and main- recipient of the Tyler Prize is the pioneering substantially to building the capacity that tained below a desired threshold, but also to cancer scientist, Sir Richard Doll.) Although enabled countries to use biological control show the end result that is really wanted: both Herren and Margalith are well known against other pests. that the weed has been replaced by more and respected for subsequent work, the cen- desirable vegetation. This will be the true tral achievements for which they are hon- In 1976, during a World Health Organiza- measure of whether or not a weed biolog- oured illustrate two different biological tion sponsored project in Israel, Yoel Mar- ical control project has been successful. control approaches that have led to progress galith discovered a strain of Bacillus Mist flower (Ageratina riparia,Aster- in securing the world’s food supply and thuringiensis in the Negev Desert which aceae) is an aggressive and fast growing human health over the last three decades: was significantly more toxic to mosquitoes weed originating in Central America. It’s a than other known bacterial strains at that • Classical biological control of an perennial herb or sub-shrub, 0.3-2 m tall time. Later identified as B. thuringiensis exotic pest through the introduction of which produces masses of small white ssp. israelensis (Bti), it proved to have that a natural enemy from their common flowers that develop into highly mobile useful combination of being both lethal and area of origin seeds. The plant is particularly problematic relatively specific to dipteran immature in wet areas (such as riverbanks) in tropical • Inundative biological control using an stages. In particular, it was highly patho- and warm temperate regions including entomopathogen as a microbial agent, genic to culicids and simuliids. Its potential northern Australia, Hawaii and South which may be formulated and applied for controlling the vectors of diseases such Africa. In New Zealand it has invaded pas- as a biopesticide, against an as malaria, dengue, yellow fever and river tures and native forests in the North Island. indigenous or exotic disease vector blindness (onchocerciasis) was quickly rec- Landcare Research has been conducting an ognized. Its commercial potential has since active biological control programme During the 1980s, Hans Herren, then at the been exploited and many Bti-based prod- against this weed. Following the example International Institute of Tropical Agricul- Bti of a successful biological control pro- ture (IITA), led the team that coordinated ucts are now registered. The use of gramme against mist flower conducted in the implementation of one of the largest and transformed mosquito and blackfly control Hawaii, two natural enemies of the weed: most successful classical biological pro- in many countries, with extensive control the white smut fungus Entyloma agerat- grammes in the world. The Africa-wide programmes based on Bti implemented in inae, and the gall fly Procecidochares Biological Control Program was respon- West Africa, the USA and Europe. For alani, were introduced into New Zealand in sible within Africa for introducing the South example, Bti was used against river blind- 1998 and 2001 respectively. American encyrtid parasitoid, Anagyrus ness along the Volta River in eleven lopezi (=Epidinocarsis/Apoanagyrus African countries. The sight of millions In 1999 Landcare Research established a lopezi), to control the cassava mealybug, was saved and repopulation of deserted small, multi-year project, in an area of Phenacoccus manihoti, which was devas- river valleys initiated. What has made Bti native forest near Auckland (the Waitakere tating cassava production across vast areas even more useful is that little resistance has Ranges), to look at what plants replaced of Africa at that time. Uncontrolled, it was been reported, perhaps owing to synergistic mist flower as its cover (hopefully) feared that the pest, which had been acci- action of the complex of toxic proteins. Use declined. Small (4 m2) permanent moni- dentally introduced from cassava's own of Bti led to malarial infections from mos- toring plots were established in the summer home range in the New World, would cause quitoes resistant to other pesticides drop- of 1999/2000, some with mist flower and catastrophic losses to a crop that has vital ping by 90% along the Yangtze River, others without the weed. In the plots with significance as a security food crop in China, which has a population of over 20 mist flower, the health of the weed declined Africa. Widespread famine affecting up to million people. Thus Bti has had an enor- between 1999/2000 and 2001/2002, with 200 million people across tropical and sub- mous effect on human health and environ- the percentage of leaves infected by the tropical Africa was feared. At first, head- mental quality and, with increasing global white smut fungus increasing from 18% to line-catching touches, such as distributing travel and the emergence and spread of dis- 62%, and the total percentage of dead the natural enemies by a low-flying light air- easessuchasWestNilevirustonew leaves increasing from 8% to 23%. During craft, received more publicity than the regions, the existence of this environmen- these two years the total percentage cover spread of the biocontrol agent and its impact tally benign yet effective tool assumes new of mist flower decreased from 74% o 16%, on the pest and cassava yields. The scien- significance. a decline of more than 50%. We attribute tific evidence was clear, however, and this decline in cover to defoliation caused public acceptance followed when, within 12 ❑ by the white smut fungus: the gall fly had Are we on your mailing list? BiocontrolNews and Information is always pleased to receive news of research, conferences, new products or patents, changes in personnel, collaborative agreements or any other information of interest to other readers. If your organization sends out press releases or newsletters, please let us have a copy. In addition, the editors welcome proposals for review topics. 30N BiocontrolNews and Information 2003 Vol. 24 No. 2 not yet reached the plots and there appeared Biocontrol of Invasive dures were developed to address three key to be no other environmental or manage- Insect Threatening questions: ment changes that could have caused such Galápagos Islands •DoesI. purchasi weaken plant growth a dramatic loss of foliage. and contribute to the mortality of In January 2002, biological control was native flora and fauna in the When the plots were first examined, in used for the first time in the Galápagos Galápagos? 1999/2000, there were found to be signifi- Islands with the release of the Vedalia cantly fewer native plant species in the beetle Rodolia cardinalis to control the • Are there any natural enemies of I. plots with mist flower than in the plots invasive cottony cushion scale, Icerya pur- purchasi already present in the without it. In contrast, there was no signifi- chasi. In the presence of town officials and Galápagos that could be used to cant difference between the number of with the collaboration of college students, suppress this insect? beetles were released simultaneously on the exotic species (excluding mist flower) in • Will R. cardinalis have any detrimental inhabited islands of Santa Cruz, San plots with mist flower compared with those effects on nontarget organisms or the Cristòbal, Isabela, and Floreana. The without the weed. This appears to confirm environment in general? the view of land managers that mist flower release programme was a joint effort between the Galápagos National Park Field surveys and experimental studies was having a negative impact on the regen- Service (GNPS) and the Charles Darwin demonstrated that high infestations of the eration of native species while not inhib- Foundation (CDF) and followed a 6-month cottony cushion scale were influencing the iting other exotics. At least the presence of intensive educational campaign to inform survival of native plant communities mist flower was not correlated with a the public of the threats of invasive species including threatened species or their habi- higher number of other exotic species. and of the rigorous studies carried out to tats. However, the paucity of baseline data evaluate the safety of introducing this bio- on these endangered plant species, and the Encouragingly, we didn’t find more exotic logical control agent. Since then, beetles effects of other stress factors such as lack of species arriving in plots with mist flower as have been released in priority areas on the water and nutrients, made it difficult to iso- the cover of the weed declined. Even better, islands of Marchena, Fernandina, Pinta, late the effects of I.