This crop-destroying bug from eastern Asia has Australia on high alert. It created a sensation when huge numbers began arriving on ships in December 2014. According to one government report, a ship arriving in Brisbane had inspectors ‘shocked to see hundreds of bugs marching and flying out of the hold as the ship’s ramp was lowered.’ That vessel was quickly shut again and directed out to sea so the bugs could be destroyed. Three ships coming later were ordered to leave Australia without unloading their cargo because the infestations, of ‘many hundreds and possibly thousands of bugs’, could not be contained, the government declaring the level of infestation to be ‘unprecedented for any species of hitchhiking pest.’ In 2018-2019 the bugs arrived on so many ships and planes they ‘stretched Australia’s border biosecurity system close to breaking point’. That said, these bugs have been stopped from establishing in Australia so far.
They are turning up inside shipping containers, packing crates, aircraft, machinery, cars and personal luggage. During the northern autumn they enter homes, offices and factories in large numbers to escape the winter cold, and this habit facilitates their travel around the world.
Native to East Asia, they became infamous for mass damage on farms after spreading to North America in the 1990s and Europe in 2007. More than 300 different crops are damaged, ranging from fruits to vegetables to nuts.
The bugs have a straw-like beak (a rostrum), with which they pierce plants, then inject digestive enzymes, before imbibing a meal. They pierce fruits, nuts, buds, stems and bark, and the outcome is one of injured, deformed or aborted fruits and nuts. If disturbed they emit a nasty smell, and this contributes to the annoyance they create when they enter homes.
Brown marmorated stink bugs on a peach. Image: Gary Bernon, USDA APHIS, Bugwood.org | CC BY 3.0
While crop damage is the paramount concern, this bug might become an environmental problem. Many plants attacked overseas have close relatives in Australia, including figs (Ficus species), ebonies (Diospyros species), elderberries (Sambucus australica, S. gaudichaudiana), citrus species (Citrus species), raspberries (Rubus species) and others (Cayratia, Celtis, Chionanthus, Cinnamomum, Clerodendrum, Hibiscus, Lythrum, Solanum, Sophora, Vigna, Vitex species).
Australia has four endangered species of native tomato (Solanum armourense, S. celatum, S. limitare, S. sulphureum), all with small distributions and small population sizes. If bug damage reduced their fruit output that would greatly worsen their plight.
The wide range of plants attacked overseas makes it inevitable that some genera confined to Australia will be attacked as well. A plant family that is targeted north of the equator, Sapindaceae, has endangered species in Australia, such as smooth tuckeroo (Cupaniopsis serrata), small-leaved tamarind (Diploglottis campbellii), and the Isis tamarind (Alectryon ramiflorus), known from fewer than 30 plants.
If the bugs establish in crops, farmers will increase use of pesticides, which will become another environmental cost.
The bugs could provide a benefit by reducing the seed output of some environmental weeds such as camphor laurel and privets.