John M. Kean

Optimal surveillance and eradication of invasive species in heterogeneous landscapes.

Cost-effective surveillance strategies are needed for efficient responses to biological invasions and must account for the trade-offs between surveillance effort and management costs. Less surveillance may allow greater population growth and spread prior to detection, thereby increasing the costs of damages and control. In addition, surveillance strategies are usually applied in environments under continual invasion pressure where the number, size and location of established populations are unknown prior to detection. We develop a novel modeling framework that accounts for these features of the decision and invasion environment and determines the long term sampling effort that minimises the total expected costs of new invasions. The optimal solution depends on population establishment and growth rates, sample sensitivity, and sample, eradication, and damage costs. We demonstrate how to optimise surveillance systems under budgetary constraints and find that accounting for spatial heterogeneity in sampling costs and establishment rates can greatly reduce management costs.

Determinants of successful arthropod eradication programs

Abstract Despite substantial increases in public awareness and biosecurity systems, introductions of non-native arthropods remain an unwelcomed consequence of escalating rates of international trade and travel. Detection of an established but unwanted non-native organism can elicit a range of responses, including implementation of an eradication program. Previous studies have reviewed the concept of eradication, but these efforts were largely descriptive and focused on selected case studies. We developed a Global Eradication and Response DAtabase (“GERDA”) to facilitate an analysis of arthropod eradication programs and determine the factors that influence eradication success and failure. We compiled data from 672 arthropod eradication programs targeting 130 non-native arthropod species implemented in 91 countries between 1890 and 2010. Important components of successful eradication programs included the size of the infested area, relative detectability of the target species, method of detection, and the primary feeding guild of the target species. The outcome of eradication efforts was not determined by program costs, which were largely driven by the size of the infestation. The availability of taxon-specific control tools appeared to increase the probability of eradication success. We believe GERDA, as an online database, provides an objective repository of information that will play an invaluable role when future eradication efforts are considered.

Designing cost-efficient surveillance for early detection and control of multiple biological invaders

Wood borers and bark beetles are among the most serious forest pests worldwide. Many such species have become successful invaders, often causing substantial, costly damages to forests. Here we design and evaluate the cost-efficiency of a trap-based surveillance program for early detection of wood borers and bark beetles at risk of establishing in New Zealand. Although costly, a surveillance program could lead to earlier detection of newly established forest pests, thereby increasing the likelihood of successful eradication and reducing control costs and damages from future invasions. We develop a mechanistic bioeconomic model that relates surveillance intensity (i.e., trap density) and invasion size to probabilities of detection and control. It captures the dynamics of invasive species establishment, spread, and damages to urban and plantation forests. We employ the model to design surveillance programs that provide the greatest net present benefits. Our findings suggest that implementing a surveillance trapping program for invasive wood borers and bark beetles would provide positive net benefits under all scenarios considered. The economically optimal trapping strategy calls for a very high investment in surveillance: about 10 000 traps in each year of the 30-year surveillance program, at a present value cost of US

Pastoral weeds in New Zealand: Status and potential solutions

54 million. This strategy provides a 39% reduction in costs compared with no surveillance, corresponding to an expected net present benefit of approximately US

Eradication of tephritid fruit fly pest populations: Outcomes and prospects

300 million. Although surveillance may provide the greatest net benefits when implemented at relatively high levels, our findings also show that even low levels of surveillance are worthwhile: the economic benefits from surveillance more than offset the rising costs associated with increasing trapping density. Our results also show that the cost-efficiency of surveillance varies across target regions because of differences in pest introduction and damage accumulation rates across locales, with greater surveillance warranted in areas closer to at-risk, high-value resources and in areas that receive more imported goods that serve as an invasion pathway.

Eradication of Invading Insect Populations: From Concepts to Applications

Abstract Currently there are some 187 plant species, almost all exotic in origin, occurring as “weeds” in pastures in New Zealand. Judging from their occurrence in scientific papers published in the proceedings of the New Zealand Plant Protection Society, 65 of these species are, or have been considered historically, to be significant pastoral weeds. While 34 of these pastoral weeds are currently being managed under Regional Pest Management Strategies, 15 of these regionally managed species are apparently un‐researched in New Zealand, implying that their management does not have a scientific basis. The aggregate cost of pastoral weeds to the New Zealand economy is estimated to be NZ

The potential global distribution of the brown marmorated stink bug, Halyomorpha halys , a critical threat to plant biosecurity

1.2 billion per annum, based on an analysis made in 1984, but this analysis is hampered by a lack of both objective data on the impacts of weeds on pastoral production and an accurate and comprehensive national census of the main problem species. Ongoing naturalisations, from an existing pool of exotic plant species estimated currently at 25 000, and new arrivals through international trade in plant species and germplasm, can be expected to steadily add to the list of pastoral weeds. Prioritisation of these weed species will be necessary if New Zealands pastoral agricultural industries are to make long‐term, economically optimal decisions about their management. Such prioritisation will require robust models of their current and potential distributions, their rates of population increase and spread, a full understanding of the merits and pitfalls of alternative control options, and robust models of their impacts on pastoral productivity.

CAN HOST-PARASITOID METAPOPULATIONS EXPLAIN SUCCESSFUL BIOLOGICAL CONTROL?

BACKGROUND The number of insect eradication programmes is rising in response to globalisation. A database of arthropod and plant pathogen eradications covers 1050 incursion responses, with 928 eradication programmes on 299 pest and disease taxa in 104 countries (global eradication database b3.net.nz/gerda). METHODS A subset of the database was assembled with 211 eradication or response programmes against 17 species of fruit flies (Tephritidae) in 31 countries, in order to investigate factors affecting the outcome. RESULTS The failure rate for fruit fly eradication programmes was about 7%, with 0% for Ceratitis capitata (n = 85 programmes) and 0% for two Anastrepha species (n = 12 programmes), but 12% for 13 Bactrocera species (n = 108 programmes). A number of intended eradication programmes against long-established populations were not initiated because of cost and other considerations, or evolved during the planning phase into suppression programmes. Cost was dependent on area, ranged from

Modeling the Sterile Insect Technique for Suppression of Light Brown Apple Moth (Lepidoptera: Tortricidae)

US 0.1 million to

Designing efficient surveys: spatial arrangement of sample points for detection of invasive species

US 240 million and averaged about