1 Invasive Species and Biological Control
Total Page：16
File Type：pdf, Size：1020Kb
Bio Control 01 - 16 made-up 14/11/01 3:16 pm Page 1 Chapter 1 1 1 Invasive Species and Biological Control D.J. Parker and B.D. Gill Introduction ballast, favouring aquatic invaders (Bright, 1999). While the rate of introductions has Invasive alien species are those organisms increased greatly over the past 100 years that, when accidentally or intentionally (Sailer, 1983), the period 1981–2000 has introduced into a new region or continent, seen political and technological changes rapidly expand their ranges and exert a that may unleash an even greater wave of noticeable impact upon the resident flora invasive species. The collapse of the for- or fauna of their new environment. From a mer Soviet Union and China’s interest in plant quarantine perspective, invasive joining world trade have opened up new species are typically pests that cause prob- markets in Asia. These vast areas, once iso- lems after entering a country undetected in lated, can now serve as source populations commercial goods or in the personal bag- for additional cold-tolerant pests, e.g. the gage of travellers. Under the International Asian longhorned beetle, Anoplophora Plant Protection Convention (IPPC), ‘pests’ glabripennis (Motschulsky), and the lesser are defined as ‘any species, strain or bio- Japanese tsugi borer, Callidiellum type of plant, animal or pathogenic agent rufipenne (Motschulsky). Examples of a injurious to plants or plant products’, few insects introduced to Canada since while ‘quarantine pests’ are ‘pests of eco- 1981 include apple ermine moth, nomic importance to the area endangered Yponomeuta malinellus Zeller, European thereby and not yet present there, or pre- pine shoot beetle, Tomicus piniperda (L.), sent but not widely distributed and being leek moth, Acrolepiopsis assectella officially controlled’ (FAO, 1999). (Zeller), cherry bark tortrix, Enarmonia formosana (Scopoli), and the yellow underwings, Noctua pronuba (L.) and Origins Noctua comes (Hübner). Canada is no longer susceptible to inva- Traditionally, most invasive pests in North sion of pests from temperate locations only. America came from Europe, reflecting trad- Cultivation under glass, currently about ing patterns of the past 500 years (Mattson 1470 ha (K. Fry, Vegreville, 2000, personal et al., 1994; Niemela and Mattson, 1996). communication), is expanding rapidly and Vast numbers of weeds, phytophagous there is growing concern about possible insects and stored products pests arrived as introductions from tropical and subtropical stowaways in cargo or on horticultural regions that may adversely affect horticul- products exported from Europe. In Canada, tural plants and greenhouse vegetable pro- 881 exotic plants have become established, duction. Recent introductions have representing 28% of the total flora included western flower thrips, (Heywood, 1989). A diversity of soil- Frankliniella occidentalis (Pergande), to dwelling insects arrived in the ballast of eastern Canada, sweetpotato whitefly, ships (Lindroth, 1957; Sadler, 1991), until Bemisia tabaci (Gennadius), and leafminers, this pathway was inadvertently curtailed Liriomyza spp. Other technological when soil ballast was replaced by water advances that facilitate the movement of Bio Control 01 - 16 made-up 12/11/01 4:03 pm Page 2 2 Chapter 1 pests are the greatly increased volume of fore regulated as quarantine pests. traffic and increased speed of transport of Biological control agents can also be con- commodities and people around the world. sidered as invasive species. In this case, Container ships cross the oceans in record the invasive species are intentionally intro- time, offloading their sealed containers duced to reduce problems caused by for- directly on to railcars that are promptly eign or native pests. delivered to the heart of the continent. Since the enactment of the Destructive Many hitch-hiking species now arrive alive Insect and Pest Act (DIP 1912), ‘an act to instead of dying in transit. Finally, estab- prevent the introduction or spreading of lishment of the World Trade Organization, insects, pests and diseases destructive to which promotes expansion of global trade, vegetation’, the Federal government has both in volume and extent, is sure to been charged with protecting Canada’s increase the problem. All of these factors plant resources from invasive plant pests. point towards invasive species or ‘biological Under the current Plant Protection Act, the pollution’ as being a major threat to the bio- Plant Health and Production Division of diversity and the economic health of North the Canadian Food Inspection Agency reg- America (Office of Technology Assessment, ulates the importation of plants. In the 1993; Wallner, 1996; Bright, 1999). past, plants were regulated on the basis of their role as carriers of diseases and pests and not in terms of their potential invasive- Costs ness or weediness. Although most of the weeds causing problems in agriculture and The costs of invasive organisms are difficult natural environments today were intro- to estimate. A report on harmful, non- duced into Canada well before the indigenous species in the USA estimated Destructive Insect and Pest Act of 1912, that losses from invasive pests between 1906 some sanctioned introductions of exotic and 1991 amounted to US$97 billion (Office (non-indigenous) agricultural, horticultural of Technology Assessment, 1993). Insects and ornamental plants have indeed become accounted for $92 billion of this amount. invasive (e.g. purple loosestrife, Lythrum Pimentel et al. (2000) have estimated that salicaria L.; European buckthorn, Rhamnus the economic and environmental losses due cathartica L.; Norway maple, Acer pla- to non-indigenous species in the USA, com- tanoides L.; and Russian olive, Elaeagnus bined with their control costs, amount to angustifolia L.). All importations of exotic US$137 billion per year. While the values of plants should undergo a risk assessment, control costs and economic losses can be both for their potential to harbour pests estimated with a fair degree of precision, the and diseases, and to determine their poten- damaging cost to the environment through tial invasiveness in natural and disturbed habitat loss or species extirpation (even habitats. extinction) due to invasive organisms cannot The same legislation that is used to be estimated in monetary terms. In the exclude exotic plant pests has also been words of Pimentel et al. (2000), ‘the true used to regulate the importation of plant challenge for the public lies not in determin- pests for biological control. The Act has ing the precise costs of the impacts of exotic been amended several times (DIP, 1954; species but in preventing further damage to Plant Quarantine Act, 1969; Plant natural and managed ecosystems caused by Protection Act, 1990) and the regulations non-indigenous species’. have been modified to reflect changes in pest and disease conditions in Canada and throughout the world. While the definition Regulations of a pest in the legislation has changed over the years, permits for the introduction Alien species may cause economic damage of foreign biological control agents have to plants or plant products and are there- been issued under the authority of the Bio Control 01 - 16 made-up 12/11/01 4:03 pm Page 3 Chapter 1 3 Plant Protection Act and its predecessors biological control agents are regulated by for about 90 years. Biological control the Pest Management Regulatory Agency organisms that attack plants are strictly (PMRA). regulated and cannot be released into the environment until they have successfully passed a pest risk assessment. This is car- Exotic Introductions and Classical ried out by Canadian Food Inspection Biological Control Agency (CFIA) entomologists, assisted by the Biological Control Review Committee As regulators, it is our responsibility to (BCRC) of Agriculture and Agri-Food review import applications and to issue per- Canada in consultation with the United mits and conditions for all insects, mites States Department of Agriculture, Animal and terrestrial molluscs entering Canada. and Plant Health Inspection Service Our legislative mandate is to prevent the (USDA-APHIS) and their review panel, the introduction and spread of exotic plant Technical Advisory Group (TAG). Most pests. We also assess petitions for the impor- releases have been of phytophagous agents tation and release of non-indigenous agents for the control of exotic weeds (classical for the classical biological control of intro- biological control). Entomophagous biolog- duced weeds and plant pests. Balancing ical control organisms are regulated with these two, often contradictory, viewpoints is regard to their potential to be indirectly difficult. Classical biological control is only injurious to plants, because plant pests are one technique of integrated pest manage- loosely defined under the Act. Recently, ment. Augmentation of numbers of existing attempts have been made to formalize the natural enemies, conservation of habitats for review of entomophagous insect petitions predators and parasites, crop rotation, diver- for biological control by developing guide- sification, as well as the more conventional lines and protocols for import and release. chemical methods may be as important to The North American Plant Protection successful farming and forestry as is classi- Organization (NAPPO) has developed cal biological control. The challenge facing information guidelines, i.e. standards for scientists and regulators alike will be to the import and release