The Asian stink bug (Halyomorpha halys), native to Japan and China, is doing untold damage to the production of fruit and other horticultural and agricultural crops. It is said that it was accidentally introduced into Switzerland in 2004. Control methods consist of attracting the insects by a combination of semiochemicals (pheromones for example) as bait and then killing them with insecticides. See article pdf: Successful management of Halyomorpha halys Pentotomidae in commercial apple orchards with an attract and kill strategy. Pest management Science, July 2018. DOI: 10.1002/ps.5156
It is vital to keep un-to-date with information on insect pests and diseases potentially damaging to commercial crops, even if indigenous to other geographical areas, far away, and not yet arrived in our countries or regions. Some pest or disease causing damage thousands of miles away, can arrive at any moment in a container, via an airplane, a truck, attacked to shoes or any other objects being imported. Being ready to react immediately is in itself innovative and can often mean salvation. See latest instrument from Agrorobotica: https://www.agrorobotica.it/en/tutorials/esempio-tutorial-3-come-usare-il-dorne-per/
It is necessary that growers take immediate action against the first observed parasites and pathogens with biological methods if possible or with chemical methods as the last resort; a timely defence will eliminate successive generations of parasites (which often spread exponentially) and to minimize the spread of spores or other reproductive organs of pathogens. And this is often not enough, because if the neighboring growers do not also react, pests and diseases will continue to spread out of control.
Looking back to a seminar entitled ‘Newly introduced pests and pathogens in floriculture’ held during the ‘Biennale del Fiore’ in Pescia (Tuscany) in 1992, some interesting comparisons can be made on the extent of the damage caused to crop production in Italy by various newly introduced pests and diseases. Some have caused less damage than foreseen, such as Ovulinia azaleae, although it has been devastating in other countries. Cylindrocladium spatiphyllii has caused less damage simply because the commercial importance of Spatiphyllum has dramatically decreased. The thrip Frankliniella occidentalis can now be fought with relative ease through the application of useful insects and mites or with the fungus Beauveria bassiana.
On the other hand, other alien pests and diseases have caused increasingly serious damage from the red weevil on palms (Rhyncophorus ferrugineus), to the Japanese beetle (Popillia japonica) on nursery stock, from the box tree moth Cydalima perspectalis and Cylindrocladium buxicola damaging Boxwood and the Asian stink bug (Halyomorpha halys). Neither are some popular annual flowering crops immune, from Pelargonium with Cacyreus marshalii to Impatiens walleriana with mildew (Plasmopara obducens). And finally, what is perhaps the worst scourge, the Xylella fastidiosa of the olive tree, transmitted by Philaenus spumarius, the meadow froghopper, and by other insects. Xylella is particularly scary because it can cause damage to a wide range of host plants, even though the Italian strain only attacks olive trees in a relatively limited area. Other countries have taken advantage of this for banning many Italian plants.
The process is often repeated: a parasite or a pathogen arrives randomly in Europe, finds a host crop, and in the absence of natural enemies (predators), it spreads and causes serious damage. Regrettably trade and tourism continue to allow harmful organisms to arrive, despite frontiers and phytosanitary controls. And to introduce new biological agents requires years of development and serious ecological monitoring, because in some cases, after the zeroing of populations of harmful parasites and pathogens, these useful biological agents can potentially parasitize and infect other useful guests.
Image: Asian stink bug (Halyomorpha halys enjoying life uncontested in the Valle della Biodiversità, Sez. Di Astino dell’Orto Botanico di Bergamo. Adults become active in the spring and after feeding for a couple of weeks they mate. A female can lay up to 200 eggs in clusters.