The passion-vine hopper, Scolypopa australis (Walker) (Hemiptera: Ricaniidae), is an invasive pest of kiwifruit orchards in New Zealand. This species communicates via substrate-borne vibrational signals, but the behavioural functions of S. australis signals are only partly characterised and the roles played by vibrational signals and duetting in its mating and courtship are only partially known. Here, we performed an observational study using laser-Doppler vibrometry and video recordings to characterise the mating duet of S. australis, as well as its mate searching, orientation and close-range courtship behaviours. We characterise three new mating-related signals. We found that duetting underpinned the mating process, and was typically (but not exclusively) male initiated, with males initiating duets 79% of the time. Duets consisted of distinct localisation and close courtship phases, with characteristic male signalling patterns associated with each. Compared with male signals, female signal energy was very high in S. australis duets. Mating success was associated with consistent temporal patterns and shorter inter-syllable interval in male signals, with males dropping out of duets in most unsuccessful courtships. Additionally, we found that the distinctive 'wing-swinging' behaviour, which involves swaying the wings from side to side in a see-saw like motion, was associated with a trend towards increased orientation success from males towards females - 62% of wing-swinging males made correct orientation decisions, compared with 51% that were not wing-swinging. This behaviour was also involved in close-range courtship and precopula, and preceded the male nudging behaviour that initiated the final stages of courtship. These findings may serve as a foundation for developing potential mating disruption-based pest control regimes for this species.

ABSTRACT The use of substrate borne vibrational playback to control insect pests is a rapidly growing line of research targeting many problematic species. Among the control approaches currently being tested, vibrational deterrent playbacks that aim to prevent feeding and to drive pests away from the target area are comparatively under‐explored. In experiments involving an introduced pest of New Zealand orchards, the passion vine hopper (PVH, Scolypopa australis ), we investigated PVH anti‐predator behaviour and alarm call responses and the potential use of alarm calls as vibration‐based deterrent stimuli. We used laser‐Doppler vibrometry and video recordings to assess the vibrational and behavioural responses of PVH to the presence of a predator ( Maratus griseus jumping spider), serendipitously discovering a new female call possibly involved in mate rejection. In our tests, we did not find evidence of any vibrational alarm calls in PVH, which showed a significantly reduced rate of general vibration‐based signalling and reduced propensity to call overall compared to control recordings. Instead, PVH responded to a predator threat with a rapid jumping escape response in 87.5% of attacks. We also tested the efficacy of three deterrent vibrational playbacks on driving PVH movement away from a source point, finding that a broad‐band white noise playback spanning 301–688 Hz induced significant movement away from the playback source compared with silent controls. As preliminary proof of concept, we hope these results will assist in developing successful vibrational deterrence for PVH.

Vibrational communication in the Auchenorrhyncha is an avenue of growing interest, with many pesticide-free vibrational pest control programmes against auchenorrhynchan agricultural pests continuing to be developed around the world. Passion vine hoppers (PVH), Scolypopa australis (Walker) (Hemiptera: Ricaniidae), are an economically damaging pest species in New Zealand, where they facilitate the growth of sooty mould in kiwifruit orchards. Scolypopa australis is already known to use vibrational signals, therefore a further understanding of the spectral and temporal characteristics of its calls will be an essential next step to developing vibration-based pest management strategies. Here, we aimed to characterise the properties of spontaneous S. australis calls in solitary and intrasexual communication contexts. We used laser Doppler vibrometry to record vibrational signals produced by male and female S. australis (separately), when in groups of three or individually. We sorted calls and call sub-units (syllables) into groups based on cluster analyses of various spatio-temporal parameters. We define four male calls and three female calls, and newly describe a 'two-syllable' calling structure that may be involved in male intrasexual competition. Certain syllables were more prevalent at the beginning or end of calls for males, and were more homogenously distributed throughout calls for females. The types of calls used differed between single males and groups, with more energetically intense call types observed in the group settings. Additional studies on the behavioural context of S. australis vibrational calls and their responses to playback of such calls will be necessary to assess the viability of vibration-based pest management for this species.

The increasing diversity of potential biosecurity threats makes their diagnosis a complicated and evolving area, requiring moving beyond traditional taxonomic species identification. New biosecurity diagnostic tools should provide a greater depth of information on threat biology to enable accurate risk assessment for the more efficient and effective deployment of biosecurity resources. Metabolomics is amongst the new approaches being explored for biosecurity diagnostics, where a broad spectrum of metabolites might signify relevant biological characteristics of an intercepted organism. Examples of these characteristics are physiological signatures of age, reproductive status, geographic origin, pathogen status of potential invertebrate vectors, and the distinction between diseases and abiotic plant stress symptoms. This broad-based approach is attractive, where several biological characteristics of an organism can be assessed with a single measurement. However, it can be impractical as several hundred biological replicates of the organism are needed to build a robust model of a species. New approaches such as mass spectral fingerprinting substantially reduce the time taken for metabolomics measurements, and more sophisticated modelling methods aid feasibility. Promising data are emerging for metabolomics and metabolite fingerprinting for potential biosecurity applications. We discuss the possibilities and potential uses for these new tools for post-detection decisions, diagnosis, and biosecurity.

A study was undertaken to determine whether Scolypopa australis, the passionvine hopper, communicates using substrate-borne vibrations, as its use of such signals for communication is currently unknown. This insect is a costly pest to the kiwifruit industry in New Zealand, where few pest management tools can be used during the growing season. Vibrations emitted by virgin females and males of S. australis released alone on leaves of Griselinia littoralis were recorded with a laser vibrometer to identify and characterise potential spontaneous calling signals produced by either sex. In addition to single-insect trials, preliminary tests were conducted with female–male pair trials to determine whether individuals exchanged signals. The signal repertoire of S. australis includes a male calling signal and two female calling signals. However, no evidence of duetting behaviour that is potentially necessary for pair formation has been found to date. Our outcome suggests that a deeper understanding of the role of vibrational communication employed by S. australis is needed, and by disclosing the pair formation process, a new residue-free pest management tool against this pest may be developed. In addition, this vibration-based tool could contribute to future biosecurity preparedness and response initiatives.

As agricultural intensification affects global environmental change, a redesign of our food production systems towards practices that replace external inputs with inbuilt ecosystem services is needed. Specifically, human-induced changes to biogeochemical flows of nitrogen (N) cycling exceed the proposed planetary boundaries, highlighting a priority area for reducing nutrient inputs in agricultural production systems. A new understanding of nutrient interactions in the complete agroecosystem will allow us to better predict and mitigate the consequences of anthropogenic environmental changes compared with a reductionist approach. Here, we review for the first time system-level nutrient interactions, particularly N, in perennial horticulture using high-producing kiwifruit and apple crops grown in New Zealand as a basis to identify critical knowledge gaps and prioritize new research. The major points identified are (1) current nutrient guidelines are from the 1980s to the early 2000s and do not take into account substantial production changes since that time; (2) few studies construct complete nutrient budgets of all sources and losses; (3) nutrient loss estimates are generally low relative to those from other agricultural land uses; (4) there is a lack of studies which address nutrient interactions between above- and below-ground food webs in perennial horticultural crops; (5) there is contradictory literature where fertilizer has been found both to increase and to decrease plant chemical signaling and defense mechanisms. New tools are emerging to improve orchard nutrient management, including advances in fertilizer application techniques, new methods to monitor plant and soil nutrients, and utilizing genetic variability to breed cultivars with improved nutrient use efficiency. To reduce adverse nutrient effects on the environment, new research is needed, addressing the relationships between carbon and nutrients and nutrient demands in modern fruit cultivars and growing systems; the nutrient balance for perennial horticultural crops considering all inputs and outputs; and interactions of the above- and below-ground nutrient flows in orchard food webs.

Fifth-instar brown marmorated stink bug (Halyomorpha halys Stal) nymphs were treated by gamma-radiation Co-60 at different doses of 8-64 Gy to investigate their irradiation biology and potential for the sterile insect technique (SIT). At adult emergence, males were mated with non-irradiated virgin females to assess the longevity of both sexes, female fecundity, and egg sterility. Biological parameters of their F1 progeny were investigated to determine whether negative effects from parental exposure to radiation were inherited. Results showed that irradiation significantly reduced the lifespan of male insects at doses above 20 Gy. Irradiated males did not affect the longevity and fecundity of their female partners, nor of their resulting adult progenies, but it did reduce the developmental duration of nymphs as well as weight gain of male F1 offspring. Egg hatch was significantly reduced at all tested doses and reached complete sterility at 64 Gy. Low hatch of eggs produced by F1 or F1 crossed adults indicated that negative effects from radiation were inherited by the subsequent generation. But F1 male offspring were not less fertile than their irradiated male parent, unlike what was observed in Lepidoptera. The results support the potential for the use of SIT for H. halys management by irradiating the fifth-instar male nymphs at doses from 16 Gy to 64 Gy.

Nonnative plant pests cause billions of dollars in damages. It is critical to prevent or reduce these losses by intervening at various stages of the invasion process, including pathway risk management (to prevent pest arrival), surveillance and eradication (to counter establishment), and management of established pests (to limit damages). Quantifying benefits and costs of these interventions is important to justify and prioritize investments and to inform biosecurity policy. However, approaches for these estimations differ in (1) the assumed relationship between supply, demand, and prices, and (2) the ability to assess different types of direct and indirect costs at invasion stages, for a given arrival or establishment probability. Here we review economic approaches available to estimate benefits and costs of biosecurity interventions to inform the appropriate selection of approaches. In doing so, we complement previous studies and reviews on estimates of damages from invasive species by considering the influence of economic and methodological assumptions. Cost accounting is suitable for rapid decisions, specific impacts, and simple methodological assumptions but fails to account for feedbacks, such as market adjustments, and may overestimate long-term economic impacts. Partial equilibrium models consider changes in consumer and producer surplus due to pest impacts or interventions and can account for feedbacks in affected sectors but require specialized economic models, comprehensive data sets, and estimates of commodity supply and demand curves. More intensive computable general equilibrium models can account for feedbacks across entire economies, including capital and labor, and linkages among these. The two major considerations in choosing an approach are (1) the goals of the analysis (e.g., consideration of a single pest or intervention with a limited range of impacts vs. multiple interventions, pests or sectors), and (2) the resources available for analysis such as knowledge, budget and time.

The difficulty to locate mates and overcome predation can hamper species establishment and population maintenance. The effects of sparseness between individuals or the effect of predators on the probability of population growth can be difficult to measure experimentally. For testing hypotheses about population density and predation, we contend that habitat complexity can be simulated using insect mazes of varying mathematical difficulty. To demonstrate the concept, we investigated whether the use of 3D printed mazes of varying complexity could be used to increase spatial separation between sexes of Drosophila simulans, and whether the presence of a generalist predator hampered mate-finding. We then examined how increasing D. simulans population density might overcome the artificially created effects of increasing the distance between mates and having a predator present. As expected, there was an increase in time taken to find a mate and a lower incidence of mating as habitat complexity increased. Increasing the density of flies reduced the searching time and increased mating success, and overcame the effect of the predator in the maze. Printable 3D mazes offer the opportunity to quickly assess the effects of spatial separation on insect population growth in the laboratory, without the need for large enclosed spaces. Mazes could be scaled up for larger insects and can be used for other applications such as learning.

The Global Eradication and Response Database (GERDA, http://b3.net.nz/gerda)documents representative incursion responses and eradication attempts against tephritid fruit flies of economic importance, Lepidoptera, tsetse flies, screwworm flies, mosquitoes, ants, beetles and other particular taxa of invasive arthropods since 1869.It includes cases where governments were quickly resigned to the inability to eradicate, as well as cases where a positive outcome was sought in a declared eradication programme.The distribution of pests is expanding well beyond what has been recorded in GERDA, but this information contains useful trends.The rate of eradication attempts continued to rise during the 20 th and into the 21 st century.In the case of Lepidoptera other than gypsy moth, 75% of programmes were started in the last 20 years.This is evidence for the rapid geographic range expansion under globalisation.It also indicates how active risk analysis and improved technology are increasingly enabling governments to attempt eradication to avoid projected substantial long-term costs of pest establishment.More than 80% of eradication programmes have been successful for arthropods in the database.For certain groups such as tephritid fruit flies of economic importance, the success rate is even higher, due to the experience gained from previous similar programmes, as well as the progress in the development of lures and suppression tools.A steady increase in the number of eradication programmes globally suggests that current exclusion measures for constraining the spread of invasive species are not adequate.Cost-benefit analysis based on prior pest behaviour indicates that additional mitigation against certain taxa are warranted (if possible).It is likely that all these reasons have led to this increase in the number of eradication programmes over time as a consequence of increases in travel and trade volumes from an expanding number of countries, a desire to maintain or reduce pest pressure on exotic and native commodities, and the development of new tools to increase the technical feasibility of eradication attempts.It is notable that arthropod eradication programmes still rely significantly on insecticides, but their importance is steadily decreasing when compared to the application of other tools.

The irradiation biology of the brown marmorated stink bug (BMSB, Halyomorpha halys Stål) treated at the nymphal stage was investigated to determine its application for sterile insect technique (SIT). Fifth instar males of BMSB were exposed to gamma-radiation 60Co at different doses of 12, 16, 20, 24 and 64 Gy. Irradiated males were mated with non-irradiated virgin females to assess the longevity of both sexes, female fecundity and fertility of their offspring until the egg stage of the F2 generation. The mortality of each of the developmental stages of the F1 and eggs of the F2 generation was observed to determine whether negative effects from exposure to radiation was inherited. The data indicated that irradiation significantly reduced the lifespan of male insects at doses above 20Gy. Irradiated males did not affect the longevity and fecundity of their female partners, nor either sex of their resulting progeny, but it did reduce the hatch rate of the eggs at all doses tested. The sterility rates of F1 eggs were 55.6%, 73.3%, 74.1% and 74.1% at doses of 12Gy, 16Gy, 20Gy and 24Gy respectively. Eggs were completely sterile (100%) at a dose of 64Gy with no egg hatch recorded. A low hatch rate of F2 eggs illustrated that negative effects from radiation was inherited by the subsequent generation. The results support the potential for the use of SIT for BMSB management by irradiating the fifth instar male nymphs at 16-64Gy.

Improvements to current brown marmorated stink bug (BMSB), Halyomorpha halys, surveillance and killing systems are needed to improve detection sensitivity and to reduce pesticide use. Detection of BMSB in New Zealand with traps is reliant on sticky panels with aggregation pheromone, which are low cost but inefficient compared with beating foliage. Trapping for BMSB adults and nymphs was conducted daily with lethal traps consisting of an aggregation pheromone-baited-coat hanger covered with dark-colored long-lasting insecticide-treated mesh, we termed “The Nazgȗl”, based on its sinister appearance. A deep tray lined with white plastic was attached centrally at the base for collecting the dead BMSB. The lethal traps killed and caught up to 3.5-fold more nymphs and adult BMSB than identically-baited sticky panels in the 3 weeks of deployment, and provided a snapshot of phenology by instar. We expect that lure-and-kill stations could contribute to the suppression of a delimited population and could be included as part of a semiochemical-based eradication program. Attracting and killing females and nymphs, thus removing future offspring, could contribute to population suppression during an eradication.

The sterility of eggs and nymphs from gamma-irradiated male Halyomorpha halys was investigated to determine the potential for the sterile insect technique (SIT). Males irradiated at 0, 16, 24 and 32 Gy were placed with untreated virgin females, and egg sterility was determined, showing 54.3% at 16 Gy. The percentage of sterility from irradiation was 26 percent lower than previous results from the USA and the variance was very high. Competitive overflooding ratio trials between irradiated virgin males and fertile virgin males at a 5:1 ratio resulted in the expected egg sterility, indicating competitive performance by irradiated males. By July and August, older, irradiated overwintered males were significantly less competitive than similar, non-irradiated males. There is a need to revisit the irradiation delivery method to achieve proper precision around the paternal dose required for an expected >80% egg sterility and subsequent ~99% endpoint sterility estimated at adult emergence in the F1 phase. These results suggest that the mating competitiveness and competency of males after irradiation at 16 Gy is not limiting to the sterile insect technique for suppression. A wild harvest of overwintering males using the aggregation pheromone, followed by irradiation and male release, might replace rearing. Mass-collected, sterilized bugs could be transported from an area of high H. halys density and shipped for release to enable suppression or eradication elsewhere. This concept is under development but further work is needed now to understand the difference in results between the US and Italian irradiators and increase the reliability of dosimetry.

The Global Eradication Database documents 811 eradication attempts against invasive arthropods since 1890, in 104 countries. Eradication programs show a greater than exponential increase in the number of programs started in recent decades. In addition, there is a trend of a rapidly diversifying burden of the most severe threats. The species richness showed a three-fold increase in number of species under eradication in the last 50 yr, and all taxonomic levels rose dramatically. The increase in number of eradication programs shows that current management measures for constraining the spread of invasive species are inadequate. A similar surge in the number of governments trying to prevent the establishment of new pests has occurred. Increased biodiversity of arthropod eradication targets includes new pest groups with fewer tools developed for management. We argue that a rapid increase in biodiversity of invasive and economically or environmentally damaging organisms represents a substantial and underestimated challenge for managers wanting to prevent their establishment, requiring a shift in research focus to accelerate delimitation and suppression options with less reliance on insecticides.

Surveillance for invading insect pests is costly and the trapper usually finds the traps empty of the target pest. Since the successful establishment of new pests is an uncommon event, multiple lures placed into one trap might increase the efficiency of the surveillance system. We investigated the effect of the combination of the Tephritidae male lures – trimedlure, cuelure, raspberry ketone and methyl eugenol – on catch of Ceratitis capitata , Zeugodacus cucurbitae , Bactrocera tryoni , B . dorsalis , B . aquilonis and B . tenuifascia in Australia and the USA (not all species are present in each country). The increase in trap density required to offset any reduction in catch due to the presence of lures for other Tephritidae was estimated. The effect of increasing trap density to maintain surveillance sensitivity was modelled for a hypothetical population of B . tryoni males, where the effective sampling area of cuelure traps for this species has been estimated. The 3-way combination significantly reduced the catch of the methyl eugenol-responsive B . dorsalis . Unexpectedly, we found that trimedlure-baited traps that contained methyl eugenol had ×3.1 lower catch of C . capitata than in trimedlure-only-baited traps in Australia, but not in Hawaii where no difference in catch was observed, we cannot satisfactorily explain this result. Based on the data presented here and from previous research, combinations of some male lures for the early detection of tephritid flies appear compatible and where there is any reduction in surveillance sensitivity observed, this can be offset by increasing the density of traps in the area.

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.

Epiphyas postvittana is a major horticultural pest in many countries, including New Zealand. Recently, two minor components (E)-11-tetradecen-1-ol and (E)-11-hexadecenyl acetate were found to increase the attraction of a previously identified two-component sex pheromone (95:5 blend of (E)-11-tetradecenyl acetate [E11-14:Ac] and (E,E)-9,11-tetradecadienyl acetate [E9,E11-14:Ac]) of Epiphyas postvittana. We hypothesised that the interaction between these minor components and the behavioural antagonist (Z)-11-tetradecenyl acetate (Z11-14:Ac) would modulate its antagonistic effect. The effect of increasing the ratio (0.5—10%) of Z11-14:Ac was tested in traps baited with E11-14:Ac and E9,E11-14:Ac (95:5), with or without the addition of the two minor compounds. Catch decreased as the percentage of Z11-14:Ac increased (χ2=108.74; d.f.=9; P<0.001). Overall, more moths were caught in traps baited with four- vs two-component lures (χ2=9.81; d.f.=1; P=0.002); in pair-level comparisons, significant differences in catch number between the two- and four-component lures were observed when the E11-14:Ac : Z11-14:Ac ratio was 99:1 (P=0.031) or 98:2 (P=0.047). The addition of the two minor components mitigated the reduced catch effect due to lower proportions of E11-14:Ac and the presence of 1—2% antagonist.

Invasions by insects introduced via international trade continue to cause worldwide impacts. Surveillance programs using traps baited with host volatiles and pheromones can detect incursions of nonnative species. We report on two experiments executed to determine if attractants for several insect species can be combined without compromising trap catches and detection ability of target species. In the first experiment, we tested the effect of bark beetle pheromones (plus α-pinene) and trap contact with foliage on trap catches of the brown marmorated stink bug Halyomorpha halys Stål (Hemiptera: Pentatomidae) in traps baited with a mixture of bisabolenes and methyl (E,E,Z)-2,4,6-decatrienoate. Trap capture of H. halys adults was greater in traps not in contact with foliage, and the bark beetle pheromones ipsenol and ipsdienol did not affect trap capture of H. halys. In the second experiment, we tested the effects of multi-lure interactions among the primary host attractants α-pinene and ethanol, and the pheromones monochamol, ipsenol, ipsdienol, lanierone, and the H. halys compounds, on trap captures of various forest and agricultural insect pests. Specifically, we targeted Monochamus spp. (Coleoptera: Cerambycidae), Ips spp. (Coleoptera: Scolytinae) and H. halys. We found that a combination of all lures did not catch significantly lower numbers of Monochamus carolinensis Olivier, Monochamus scutellatus Say (Coleoptera: Cerambycidae), and Ips pini Say (Coleoptera: Scolytidae) than lure combinations missing components although removal of both lanierone and ipsdienol somewhat increased catches of Ips grandicollis Eichhoff (Coleoptera: Curculionidae). Our results support the use of traps baited with a full combination of these attractants in surveillance programs. This should reduce costs and increase detection rates of a wider range of conifer forest pests and H. halys.

Several tephritid fruit flies have explosive population growth and a wide host range, resulting in some of the largest impacts on horticultural crops, reducing marketable produce, and limiting market access. For these pests, early detection and eradication are routinely implemented in vulnerable areas. However, social and consumer concerns can limit the types of population management tools available for fruit fly incursion responses. Deterministic population models were used to compare eradication tools used at typical densities alone and in combination against the Queensland fruit fly (‘Qfly’), Bactrocera tryoni . The models suggested that tools that prevent egg laying are likely to be most effective at reducing populations. Tools that induced mortality once Qfly was sexually mature only slowed population growth, as successful mating still occurred. Release of sterile Qfly when using the sterile insect technique (SIT) interferes with the successful mating of wild flies, and of the tools investigated here, SIT caused the greatest reduction in the population at the prescribed release rate. Used in tandem with SIT, protein baits slightly improved the rate of population reduction, but the male annihilation technique (MAT) almost nullified control by SIT due to the mortality induced on sterile flies. The model suggested that the most rapid decrease in population size would be achieved by SIT plus protein baits. However, the model predicted both the SIT and protein baits when used alone would result in population reduction. The MAT can be used prior to SIT release to increase overflooding ratios.

Data from 190 plant pathogen eradication programs in the Global Eradication and Response Database (GERDA) were reviewed to identify characteristics that contributed to successful programs in 45 countries between 1912 and 2013. The most successful treatment (94%) was tissue culture, often in combination with thermotherapy to eradicate viral or bacterial pathogens from plants held in in germplasm collections. Whilst 6% of these programs had no reported outcome, there were no recorded failures of this strategy. Host removal and/or destruction was successful in 55% of the programs and was used against all the pathogen groups. The analysis was limited by the high percentage of unknown outcome results across the pathogen groups. A quarter (49 of 190) of the records contained no indication of the eradication treatment: in 43% of these cases an unknown treatment resulted in successful eradication. There were no obvious correlations between the characteristics of a pathogen (viral/viroid, bacterial/phytoplasma, fungal/oomycete or nematode) and the outcome of the eradication program. For many species there is only one record, or the taxa records were dominated by a few genera that do not represent the biological diversity of the pathogen group. No economic or other analysis was possible due to the large number of unknown result/ongoing programs and the lack of common data. Despite these limitations, GERDA is an important record of the outcomes of worldwide plant pathogen eradication programs since the second decade of the twentieth century. However, care should be exercised when extrapolating from these records to formulating responses to new taxa as pathogens emerge and/or adapt to new plant hosts as the biology of plant pathogens is extremely variable and this diversity is not represented by the records in the database.