Patrick Tobin

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During the establishment phase of a biological invasion, population dynamics are strongly influenced by Allee effects and stochastic dynamics, both of which may lead to extinction of low-density populations. Allee effects refer to a decline in population growth rate with a decline in abundance and can arise from various mechanisms. Strategies to eradicate(More)
Allee effects can play a critical role in slowing or preventing the establishment of low density founder populations of non-indigenous species. Similarly, the spread of established invaders into new habitats can be influenced by the degree to which small founder populations ahead of the invasion front are suppressed through Allee effects. We develop an(More)
Biological invasions are a global and increasing threat to the function and diversity of ecosystems. Allee effects (positive density dependence) have been shown to play an important role in the establishment and spread of non-native species. Although Allee effects can be considered a bane in conservation efforts, they can be a benefit in attempts to manage(More)
Biological invasions pose considerable threats to the world's ecosystems and cause substantial economic losses. A prime example is the invasion of the gypsy moth in the United States, for which more than $194 million was spent on management and monitoring between 1985 and 2004 alone. The spread of the gypsy moth across eastern North America is, perhaps, the(More)
Gypsy moth (Lymantria dispar L.) spread is dominated by stratified dispersal, and, although spread rates are variable in space and time, the gypsy moth has invaded Wisconsin at a consistently higher rate than in other regions. Allee effects, which act on low-density populations ahead of the moving population that contribute to gypsy moth spread, have also(More)
Allee effects are important dynamical mechanisms in small-density populations in which per capita population growth rate increases with density. When positive density dependence is sufficiently severe (a 'strong' Allee effect), a critical density arises below which populations do not persist. For spatially distributed populations subject to dispersal,(More)
1. When an invasive species first colonizes an area, there is an interval before any host-specific natural enemies arrive at the new location. Population densities of newly invading species are low, and the spatial and temporal interactions between spreading invasive species and specific natural enemies that follow are poorly understood. 2. We measured(More)
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(More)
Populations of the gypsy moth, Lymantria dispar (L.), are extensively monitored in the United States through the use of pheromone-baited traps. We report on use of automated pheromone-baited traps that use a recording sensor and data logger to record the unique date-time stamp of males as they enter the trap. We deployed a total of 352 automated traps under(More)
Firewood can serve as a vector in the transport of non-native species, including wood-boring insects that feed within the wood and thus can be transported accidentally. Governments have enacted limitations on the movement of firewood in an effort to limit the anthropogenic movement of non-native species through, for example, recreational camping. Although(More)