In August 2008, the first detection of the spotted wing drosophila, Drosophila suzukii, to the North America mainland in California caused great concern, as the fly was found infesting a variety of commercial fruits. Subsequent detections followed in Oregon, Washington, Florida and British Columbia in 2009; in Utah, North Carolina, South Carolina, Michigan, and Louisiana in 2010; and in Virginia, Montana, Wisconsin, Pennsylvania, New Jersey, Maryland and Mexico in 2011. In Europe, it has been detected in Italy and Spain in 2009 and in France in 2010. Economic costs to the grower from D. suzukii include the increased cost of production (increased labor and materials for chemical inputs, monitoring and other management tools) and crop loss. An effective response to the invasion of D. suzukii requires proper taxonomic identification at the initial phase, understanding basic biology and phenology, developing management tools, transferring information and technology quickly to user groups, and evaluating the impact of the research and extension program on an economic, social, and environmental level. As D. suzukii continues to expand its range, steps must be initiated in each new region to educate and inform the public as well as formulate management tactics suitable for the crops and growing conditions in each.

Results are presented of an experiment conducted to analyse the distribution and proportion of maize production in relation to arable land in France, Germany, Italy, Austria, The Netherlands, Belgium, Switzerland and Luxembourg. The obtained data would form the basis for modelling yield losses and economic damage in high-risk areas in Europe.

Monitoring of populations of adult corn rootworms (Diabrotica virgifera and D. barberi) in Ontario (CA), and surveys of insecticide use against rootworms, showed that populations declined in the last 10 years and that the proportion of the maize area treated with rootworm insecticide has fallen to <7%. This proportion was directly correlated with the percentage of cropping with continuous maize. The area of insecticide‐treated maize could be further reduced by educating livestock producers about the merits of crop rotation and the possibilities of alternative high‐energy crops, such as winter barley. Populations of rootworm adults and area of continuous maize are currently so low in Ontario that there is a good probability of success for an adult monitoring and insurance programme to replace the use of corn rootworm insecticides. In Germany (where D. virgifera is now absent but may potentially be introduced from the outbreak in the lower Danube basin), the four Federal Länder of Niedersachsen, Nordrhein‐Westfalen, Bayern and Baden‐Württemberg maintain a high frequency of continuous maize. If areas with more than 50% of arable land with maize are considered to be at high risk of rootworm infestation, about 348 000 ha of maize fall into this category. This is a third of the maize production area of the above‐mentioned Federal Länder and more than a fifth of the entire maize production area of Germany in 1995. On the basis of long‐term experience of insecticide use in Ontario, there is a potential for treatment of up to 111 000 ha with rootworm insecticide (terbufos) annually in Germany, at an added insecticide cost of 13 million EUR per annum. Without crop rotation or treatment, rootworm infestations could cost German maize producers 25 million EUR in crop losses each year. The experience in Ontario suggests that Germany should follow a strategy of changing crop rotation away from continuous maize, so as to reduce the potential for establishment of D. virgifera, the potential for economic loss and the potential for increased reliance on insecticides.

If introduced into Germany, Diabrotica virgifera would find maize in all regions of the country. Climatic conditions in winter would favour establishment. Though conditions in the growing season would be suboptimal, they would still be sufficient for development and completion of a full generation. D. virgifera has good potential for adaptation to different conditions and a high reproductive rate facilitating establishment in a new area. The type of maize grown would have no substantial effect on establishment of the pest. Crop rotation is important as a method for suppressing populations of the pests and restricting losses, but would not prevent establishment. Further containing factors (such as antagonists) are not available. So it can be concluded that D. virgifera is able to establish in Germany and could become an important maize pest.

Ceratitis capitata (Wiedemann) is a polyphagous plant pest organism causing serious damage on more than 300 fruit types. Although the medfly is present in Europe, it is so far not established in Germany. In the years 2015–2017, an official survey was conducted by the German Federal Plant Protection Organisations to elucidate the current occurrence of this organism in Germany. While in 2015 only small numbers of flies were captured in traps situated in all German Federal States, a peak of 188 specimens could be trapped in 2016 with a decline to 29 specimens in 2017. Highest abundance of the fruit fly was detected in Southern Germany and at a single spot east of Berlin. The present study aimed to identify the origin of the trapped fruit flies and to assess the general potential of the species for overwintering in Germany. Using two approaches with cytochrome oxidase subunit I (COI), Sanger barcoding sequencing first and subsequent analysis of ten small simple repeat microsatellite loci from literature, the worldwide spread of C. capitata describing three phases could be retraced by analysing samples from Germany and 11 other countries. German and French populations were found to build the most recent stage of this species distribution. Specimens trapped in Germany obviously resulted from different introduction events. They most strongly resembled populations from France and Croatia but were not identical to these populations. We found strong evidence that specimens captured between 2016 and 2017 could not overwinter in Germany.