Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests should be regulated to prevent invasion. There is an increasing demand for science-based risk mapping in PRA. Spread plays a key role in determining the potential distribution of pests, but there is no suitable spread modelling tool available for pest risk analysts. Existing models are species specific, biologically and technically complex, and data hungry. Here we present a set of four simple and generic spread models that can be parameterised with limited data. Simulations with these models generate maps of the potential expansion of an invasive species at continental scale. The models have one to three biological parameters. They differ in whether they treat spatial processes implicitly or explicitly, and in whether they consider pest density or pest presence/absence only. The four models represent four complementary perspectives on the process of invasion and, because they have different initial conditions, they can be considered as alternative scenarios. All models take into account habitat distribution and climate. We present an application of each of the four models to the western corn rootworm, Diabrotica virgifera virgifera, using historic data on its spread in Europe. Further tests as proof of concept were conducted with a broad range of taxa (insects, nematodes, plants, and plant pathogens). Pest risk analysts, the intended model users, found the model outputs to be generally credible and useful. The estimation of parameters from data requires insights into population dynamics theory, and this requires guidance. If used appropriately, these generic spread models provide a transparent and objective tool for evaluating the potential spread of pests in PRAs. Further work is needed to validate models, build familiarity in the user community and create a database of species parameters to help realize their potential in PRA practice.

In order to evaluate the long-term effect of the new fumigant DMDS and its potential to be a part of IPM of root-knot nematodes, a two-year experiment was conducted on cucumber in a greenhouse in Bulgaria. In the first year, DMDS was applied in comparison with farmer nematicide strategy and untreated control in the first cucumber crop. After two consequent catch crops—lettuce in the winter period—a second cucumber crop followed in spring–summer. In this crop, the DMDS effect was studied with no treatment and was integrated into the post-planting strategy with Trichoderma spp. and garlic extract at plots previously treated with DMDS. The effect of DMDS was followed until 450 days after fumigation. Nematocidal efficacy of DMDS was 96% and the yield increased 65.5% in the first cucumber crop, and 80% and 100% in the second cucumber crop, respectively, when nothing was done or a combined strategy with Trichoderma spp. and garlic extract was followed. The DMDS effect on 44 non-target soil nematode genera was also followed. The negative impact of the fumigation was limited in time as non-target nematode communities regained previous crop levels in five months during our study. Therefore, DMDS can be properly included in soil IPM programmes and appears very promising for the protected crop industry in Europe.

The Mediterranean fruit fly Ceratitis capitata (Wiedemann, 1824) (Diptera: Tephritidae) is considered to be one of the world’s most destructive fruit pests because of its global distribution, wide host range and rapid dispersal. In the period 1956–2006, transient populations of the pest have been reported regularly in Bulgaria. The Bulgarian Food Safety Agency (BFSA) initiated monitoring of C. capitata in 15 regions of the country. The surveys were conducted during the period 2013–2018, using Jackson traps with attractant trimedlure and Tephri traps with Biolure. The presence of adults of C. capitata was confirmed in peach, apple and mixed orchards, as well as in private yards at five locations in southern and south-eastern Bulgaria: Blagoevgrad, Kyustendil, Pazardzhik, Plovdiv and Sliven. The results from the five-year monitoring showed a variable abundance of C. capitata adults captured in different years and localities. The highest mean captures were recorded in 2014 (195) and 2018 (422), no specimen of the C. capitata was found in 2017. In 2018 the most abundant captures were from fruit gardens in Plovdiv (297♀;65♂) and Sliven (18♀; 22♂). Over the entire study period, the lowest rate of adult captures was in July and August (only a few individuals in traps in each region). The population abundance began to increase at the beginning of mid-September and a peak was observed at the beginning of mid-October. The results on the seasonal population fluctuations obtained are similar to data from neighbouring countries: northern Greece, Montenegro, Croatia, Romania, and Turkey.