New plant pests usually arrive in unfamiliar areas through international trade and transport. Climate change does not carry them alone, but it can increase their chance of surviving the winter, reproducing and creating lasting populations. Milder winters and a longer warm season change the conditions for agriculture and make the early detection of unknown species increasingly important, writes "Klimateka".
An example of such a change is the brown marbled bug, also known in our country as the stink bug. The invasive species originates from East Asia, and its presence in Bulgaria was officially documented in 2016. The first findings were registered in Sofia in September of the same year. The European and Mediterranean Plant Protection Organization indicates that the species was discovered at two locations on Chinese hibiscus.
The woodworm attacks a wide range of crops - apples, pears, peaches, grapes, hazelnuts, tomatoes, peppers, beans and corn. It feeds directly on the fruits and seeds, and in areas where there are not enough natural enemies, it can multiply almost undisturbed. Once it has established itself widely, its containment becomes more difficult and requires constant measures.
Late signal increases damage
According to agronomist Roman Rachkov, climate is a factor that helps the establishment of pests, but it is not the main reason for them to appear in a new place. Trade and transport can carry an insect thousands of kilometers, while temperatures determine whether it will survive and establish a population.
For the brown marbled bug, Bulgarian observations indicate mainly one generation per year. However, milder winters and earlier warming may help the overwintering of adult insects and extend their period of activity. It is the time between the first appearance and official establishment that is critical, because during this time the pest can spread without a coordinated response.
Small farms, orchards and private yards are difficult to monitor constantly. In many cases, the first unusual leaf, fruit or shoot is shown to an agronomist at an agropharmacy. Nearly 800 such sites operate in Bulgaria, distributed in different parts of the country. According to Rachkov, this network could become an additional early warning channel.
A single channel to the BFSA is proposed
The idea is for agronomists in agropharmacies to submit signals of suspicion of a new or unusual pest through a single digital system. It can indicate the crop, location, a short description and a photo of the lesion or insect. The Bulgarian Food Safety Agency must then assess whether an inspection and laboratory diagnosis are necessary.
The proposal does not envisage agropharmacies replacing phytosanitary inspectors or making official diagnoses. The roles remain separate: the agronomist monitors and submits a signal, and the competent authorities check the case and confirm the presence of a pest. Such a mechanism would complement the current rules for notification of suspected quarantine organisms.
The cost of late detection can be significant. In the US, the damage caused by the brown marmorated bug to apple growers in the Mid-Atlantic region alone in 2010 was estimated at around $37 million. In the case of quarantine pests, the consequences can include restrictions on plant movement, destruction of plantations and loss of harvest.
The brown marmorated bug is already widespread and is not a quarantine pest under European law. The case shows why the next invasive species must be detected before it becomes established. For farmers, this means faster reporting and for institutions, the opportunity to check while containment of the problem is still realistic.