SUMMARYMinimizing the impact of invasive alien species (IAS) on islands and elsewhere requires researchers to provide cogent information on the environmental and socioeconomic consequences of IAS to the public and policy makers. Unfortunately, this information has not been readily available owing to a paucity of scientific research and the failure of the scientific community to make their findings readily available to decision makers. This review explores the vulnerability of islands to biological invasion, reports on environmental and socioeconomic impacts of IAS on islands and provides guidance and information on technical resources that can help minimize the effects of IAS in island ecosystems. This assessment is intended to provide a holistic perspective on island-IAS dynamics, enable biologists and social scientists to identify information gaps that warrant further research and serve as a primer for policy makers seeking to minimize the impact of IAS on island systems. Case studies have been selected to reflect the most scientifically-reliable information on the impacts of IAS on islands. Sufficient evidence has emerged to conclude that IAS are the most significant drivers of population declines and species extinctions in island ecosystems worldwide. Clearly, IAS can also have significant socioeconomic impacts directly (for example human health) and indirectly through their * Correspondence: Dr Jamie K. Reaser Tel: +1 434 990 9494 e-mail: ecos@nelsoncable.com effects on ecosystem goods and services. These impacts are manifest at all ecological levels and affect the poorest, as well as richest, island nations. The measures needed to prevent and minimize the impacts of IAS on island ecosystems are generally known. However, many island nations and territories lack the scientific and technical information, infrastructure and human and financial resources necessary to adequately address the problems caused by IAS. Because every nation is an exporter and importer of goods and services, every nation is also a facilitator and victim of the invasion of alien species. Wealthy nations therefore need to help raise the capacity of island nations and territories to minimize the spread and impact of IAS.

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Keywords: Invasive species Ecosystem function Insect pests Invasive plants Ecological restoration Biological control Natural ecosystems a b s t r a c tOf the 70 cases of classical biological control for the protection of nature found in our review, there were fewer projects against insect targets (21) than against invasive plants (49), in part, because many insect biological control projects were carried out against agricultural pests, while nearly all projects against plants targeted invasive plants in natural ecosystems. Of 21 insect projects, 81% (17) provided benefits to protection of biodiversity, while 48% (10) protected products harvested from natural systems, and 5% (1) preserved ecosystem services, with many projects contributing to more than one goal. In contrast, of the 49 projects against invasive plants, 98% (48) provided benefits to protection of biodiversity, while 47% (23) protected products, and 25% (12) preserved ecosystem services, again with many projects contributing to several goals. We classified projects into complete control (pest generally no longer important), partial control (control in some areas but not others), and ''in progress," for projects in development for which outcomes do not yet exist. For insects, of the 21 projects discussed, 62% (13) achieved complete control of the target pest, 19% (4) provided partial control, and 43% (9) are still in progress. By comparison, of the 49 invasive plant projects considered, 27% (13) achieved complete control, while 33% (16) provided partial control, and 49% (24) are still in progress. For both categories of pests, some projects' success ratings were scored twice when results varied by region. We found approximately twice as many projects directed against invasive plants than insects and that protection of biodiversity was the most frequent benefit of both insect and plant projects. Ecosystem service protection was provided in the fewest cases by either insect or plant biological control agents, but was more likely to be provided by projects directed against invasive plants, likely because of the strong effects plants exert on landscapes. Rates of complete success appeared to be higher for insect than plant targets (62% vs 27%), perhaps because most often herbivores gradually weaken, rather than outright kill, their hosts, which is not the case for natural enemies directed against pest insects. For both insect and plant biological control, nearly half of all projects reviewed were listed as currently in progress, suggesting that the use of biological control for the protection of wildlands is currently very active.

The BIOCAT database of introductions of insect biological control agents for the control of insect pests was updated to the end of 2010 to include 6158 introductions, using 2384 different insect biological control agents against 588 pest species in 148 countries. Of the introductions, 2007 (32.6 %) led to establishment, and 620 (10.1 %) resulted in satisfactory control being reported against 172 (29.3 %) different pest species. The number of introductions has decreased each decade since the 1970s, but in the same period a higher proportion of introductions became established and contributed to successful control of target pests, and the number of countries implementing classical biological control increased. These positive trends reflect the greater research effort now made to optimize the chances of successful outcomes and increased confidence in classical biological control as a viable pest management strategy against a backdrop of a risk-averse culture that has developed in some key countries in recent years.

Over the years, Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) has been used in both classical and augmentative biological control programmes. The ladybird is also considered important in certain conservation biological control programmes. This paper provides a critical review of the literature pertaining to its biology, ecology and use, with a particular emphasis on potential impact on non-target organisms. C. montrouzieri has many of the attributes of an effective natural enemy, including a rapid development rate, high reproductive potential, good adaptation to a range of tropical and subtropical climates, high prey consumption rates by both adults and larvae and ease of rearing. The coccinellid has been introduced into at least 64 countries/territories to control more than 16 pest species. C. montrouzieri is a polyphagous predator that exploits hosts in at least eight hemipteran families. It is noteworthy that it has adapted to feed on new insect families in some new localities where it has been introduced. Although the wide host range has allowed its use against a variety of pest species, it is also a good indicator of the potential to feed on non-target species. In view of the continued interest to utilize the predator in new non-native localities, questions have arisen regarding its potential to cause negative impacts, especially against non-target organisms. Given the wide recorded host range, it seems unnecessary to conduct additional host range tests as significant decisions can be made based on the available information. Thus, when the available data are interpreted based on a centrifugal process, it is apparent that the ladybird has a potentially very broad host range. Therefore, even without additional studies, it would be reasonable to assume that the ladybird has the potential to extend its host range in unpredictable ways. Clearly, the beetle would provide a good model for conducting post-release studies, especially where the predator has been established for a long time. Such studies would not only provide insight into the impact of introducing generalist non-native coccinellid predators but also help to increase our understanding of the mechanisms limiting host range.

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Entomopathogenic fungal isolates of Arachnid origin were assessed for their ability to produce mortality and inhibit egg hatching in Boophilus microplus with the aim of selecting an isolate for development into a myco-acaricide for control of cattle ticks. The ability of the most promising isolate to target developmental stages of more than one tick species and the optimum concentration of fungal inoculum to be used for future studies were determined. Metarhizium anisopliae was the most pathogenic of the three fungal species tested on B. microplus, producing shorter average survival times (ASTs) for engorged adults (AST = 5.2 +/- 0.1 days) and larvae (AST = 9.3 +/- 0.4 days), and a longer average hatching times (AHT; AHT = 19.8 +/- 0.5 days) in comparison to Simplicillium lamellicola and Paecilomyces farinosus. In comparative studies on two tick species with similar life cycles, M. anisopliae produced a shorter AST in engorged adult B. microplus (AST = 8.8 +/- 0.3 days) than Rhipicephalus sanguineus (AST = 10.3 +/- 0.3 days). M. anisopliae was pathogenic to larvae of B. microplus (AST = 7.7 +/- 0.4 days), however, had no effect on larvae of R. sanguineus (AST = 14.6 +/- 0.3 days) as the AST of this treatment was similar to its untreated control (AST = 14.1 +/- 0.4 days). M. anisopliae lengthened the AHTs in both B. microplus (AHT = 16.4 +/- 0.3 days) and R. sanguineus (AHT = 16.7 +/- 0.3 days) in comparison to the controls. The ASTs of engorged adult B. microplus treated with M. anisopliae shortened as the concentration was increased from 1 x 10(7) to 5 x 10(8) conidia/ mL. A further increase in concentration, 1 x 10(9) conidia/mL (AST = 10.2 +/- 0.4 days) did not shorten or lengthen the AST in comparison to 5 x 10(8) conidia/mL (AST = 9.4 +/- 0.3 days).

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