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Early detection of biological invasions is necessary to enable successful management responses, such as containment and eradication. Several nations operate risk-based surveillance systems for early detection and proof of freedom from economically damaging pests and diseases. Identifying the best times of year to deploy and remove surveillance traps is important for maximising the probability of detection while minimising the economic costs of large-scale trapping. We modelled seasonal population dynamics to identify which days of the year contribute most to surveillance sensitivity and therefore the appropriate trapping period, and applied this to trapping for fruit flies (Diptera: Tephritidae) in New Zealand. Optimum trapping periods were defined as the minimum contiguous dates which would give a specific proportion (80%, 90%, 95%, or 99%) of the probability of detection compared to year-round trapping. Seasonal dynamics were based on an empirical model for the effect of temperature on population increase and decline, fitted to published data from around the world. The model suggested Mediterranean fruit fly (Medfly) should be trapped in the upper half of the North Island from at least November through May. Additional trapping in October and June may be warranted in the far north. Favourable microclimates or climate change to 2040 may allow Medfly populations to establish as far south as Christchurch and Alexandra, where trapping should run from mid December to early May. Queensland fruit fly (Qfly) and oriental fruit fly were unlikely to establish south of Napier and optimum trapping times for these species are approximately mid November through May. Climate change under moderate scenarios is unlikely to significantly alter the optimum trapping periods until at least 2040. The results were not sensitive to assumptions about trap efficacy and founder population size. However, they are based on simplified relationships between the intrinsic rate of increase and temperature. This approach is applicable to any invasive species with seasonal variation in surveillance efficacy. In response to this work, New Zealand's biosecurity authority has changed the seasonal timing of their fruit fly trapping to optimise detection efficacy.

The Moroccan ecotype of the braconid parasitoid Microctonus aethiopoides was introduced into New Zealand for biological control of the lucerne pest Sitona discoideus . The parasitoid also attacks several non-target native weevil species found in pasture and also to a lesser extent in native tussock grassland. We carried out a series of laboratory and field experiments, and population modelling to investigate whether the parasitoids were established at low levels on native weevils in tussock grassland, whether S . discoideus was able to survive and support parasitoid development away from lucerne, its normal host plant, or whether parasitism was occurring as a result of spillover from agricultural environments. We found that S. discoideus was able to survive and support parasitoid development on white clover which is commonly found in native grassland. However, the levels of parasitism in weevil species in tussock grassland appeared to be constrained, at least in part, by low temperatures limiting the number of parasitoid generations possible per year and by the frequency of sub-zero temperatures that caused pupal mortality. Projected climate change might reduce this constraint and the implications of this are discussed.

Insect pheromone traps are becoming an increasingly important tool in biosecurity and pest surveillance, alerting managers to the presence of unwanted organisms. To expand the role of these traps beyond their present sentinel role, it is necessary to develop reliable operational models of local insect dispersal. Following the detection of an insect incursion using a pheromone trap, such models could simulate the dispersal of the insect from its emergence site to the point of detection, enabling biosecurity managers to estimate the most likely proximal source of the incursion. An individual-based moth movement model was developed to simulate observed patterns of moth movement in response to the presence or absence of a pheromone. Using parameters derived from a genetic algorithm, it was possible to fit a model based on the three behavioural components (upwind, upwind with zigzags and casting) described in insect anemotaxis theory to a subset of observed movement patterns (0–135° to the wind), but not to the whole spectrum of movement patterns. It appears that current insect anemotaxis theory is missing a downwind flight component. Whilst the frequency of downwind movements is small; their ground speed could lead to significant downwind displacement, having a disproportionately strong influence on a moth movement model, and hence projections of the likely source or target locations.

There has been considerable debate on risks associated with biological control, and partly resulting from this, research has addressed a number of questions which have subsequently led to a greater understanding of risk assessment and biosafety. Controversy which arose in the 1980s about the environmental safety of biological control initially created considerable tension between biological control practitioners and those concerned about non-target impacts. Several factors have helped to ease this pressure, and a substantial body of research has addressed many of the questions raised. This has led to advances in quarantine laboratory host range testing to improve our ability to predict post-release impacts. Furthermore, pre- and post-release studies are increasingly involving population models to estimate the population impact of introduced biological control agents rather than simply measuring attack rates. Regulators making decisions about biological control agent introductions work under conditions of considerable uncertainty, but with accumulating data from past introductions to validate earlier decisions, and a robust peer review system for assessing new proposals, there is cause for some optimism that the risks associated with biological control can be better identified and managed in the future. Progress in research and regulation of biological control are discussed with particular reference to Australasia.

Modern biological control practitioners must increasingly demonstrate a level of rigor that can only be achieved through use of effective methodological tools such as modeling, behavioral studies and molecular approaches. The use of these technologies is maturing rapidly in biological control and makes tangible contributions to its success. Behavioral studies often uncover important aspects of biology that would otherwise be overlooked, such as the influence of pre-release handling on establishment success and the response of natural enemies to host-induced plant volatiles. Molecular approaches allow the identification and detection of genetically distinct populations of invasive pest species and their natural enemies, tracing the origin of invasive pest populations and compatible natural enemies, and development of improved recombinant natural enemies. Modeling enables theory and empirical observation to optimize agent selection and release, and to predict quantitative impacts on target and non-target populations. All three methodologies, particularly in combination, contribute to our understanding of the reasons for success and failure in biological control, and together with post-release validation studies build the foundations to improve the success of future biological control releases.

A previous model addressed the within-herd transmission of bovine Tb (Mycobacterium bovis) in New Zealand cattle herds. This complementary model considers transmission between herds, in an area of New Zealand's North Island (the Waikato) largely free from wildlife reservoirs. The model is used to account for the observed pattern of Tb breakdowns and to assess the likely impact of changes in management on the percentage of herds on movement control between 1988 and 1993 (an average of 0.76% in the Waikato region). It partitions the region into two sub-areas: one small, with significant infection from wildlife; the other much larger and lacking external sources of infection. The observed pattern of herd breakdowns (in different parts of the Waikato and in the region as a whole) could be accounted for in the model by infection from wildlife reservoirs in the southern sub-area (Waitomo) and infection due to movement of cattle from infected but undiagnosed herds to uninfected herds throughout the whole region. During the above period, the model suggests that about 0.8% of herds became infected each year, that most new infections (81% of the total) occurred between herds in the larger sub-area, and that about 13% of the total occurred through infection from wildlife in the smaller sub-area. The whole situation appears to be in a state of near-neutral balance (even without input of new infection), with removal through testing of new infections almost exactly balancing the rate of infection by between-herd movement. Therefore, if the external input is removed, the number of infected herds and of herds of movement control in the whole region declines so slowly that the decline is almost undetectable. Other management changes had a more dramatic effect--particularly, reducing the testing interval to a maximum of 1 year in the whole district. This also appeared to be a necessary condition for achieving < or = 0.2% herds on movement control within 10 years (whatever other strategies were employed). The greatest reduction in the percentage of herds on movement control came from yearly testing plus a 50% reduction in infection from wildlife. A further but smaller additional improvement was gained by reducing cattle movements throughout the region by 50%.

Models are described for simple epidemics of rabbit calicivirus disease (RCD) and for its longer-term effect on non-seasonal or seasonally varying rabbit populations, assuming direct transmission or indirect transmission via free-living virus. The additional effect of juvenile immunity is examined, in which young of a certain age are immune for life if exposed. The models are parameterised from European and Australian data and used to demonstrate the relationships between disease parameters and epidemic intensity and velocity. Disease cannot persist locally, given direct transmission and the rapid epidemics observed. Given indirect transmission, disease persistence depends on the decay rate of virus in the environment and the basic reproductive rate of the disease, R 0 . Again, the model suggested that local disease persistence is unlikely given the observed rapidity and intensity of epidemics, particularly in Australia, and given that a proportion of susceptibles survive exposure. If the criterion for the speed of the initial epidemic is relaxed, the models allowed persistent disease with 2-yearly outbreak patterns, as observed in European rabbit populations. Damped 2-yearly cycles in rabbit density were an intrinsic property of the rabbit/RCD system, but adding seasonally varying reproduction caused the biennial cycles to persist indefinitely. When juvenile immunity was added, disease persistence was enhanced and yearly epidemics were more likely than 2-yearly ones. In terms of RCD as a control, persistent disease generally gave around a 75% reduction in average density, while non-persistent disease gave about a 60% reduction if introduced every 3 years. The timing of introduction, whether within or outside the breeding season, appeared to have little effect on suppression and recovery.

Syntactic cuing in inference of meaning was studied among 20 children each in kindergarten, 2nd, and 4th grades. Three count nouns and three transitive verbs (actual words in infrequent use) were presented in sentences and Ss guessed the meaning of each word. Responses were classified by parts-of-speech as either homogeneous or heterogeneous, and homogeneous responses were interpreted as an indication of syntactic cuing. Significant part-of-speech by grade and grade by sex interactions were found and, in addition, an almost significant interaction was found between part-of-speech and sex. In general, the syntactic cuing concept seemed to be supported.