Stereo microscopes in the EU’s Plant Inspection

Utilized for Healthy Eating

May 07, 2012

Exotic fruits and sun-kissed vegetables – we have long been accustomed to a huge selection of culinary delicacies that are available fresh in stores on a daily basis. Sometimes, however, these goods flown in from far away carry along unwanted passengers: pests, fungi, or viruses, which cannot be seen with the naked eye. They can work their way into the ecological cycle and, in the worst-case scenario, can even cause epidemics. To prevent this, plants are subjected to strict inspections when being imported into the European Union (EU).

Perishable Center Frankfurt

Fig. 1: Plants requiring inspection, such as these pelargoniums from Egypt on the way to a plant nursery in Baden-Wuerttemberg, have to be examined. Photo: Claudia Moch

Things have to move quickly when inspecting plants in the Perishable Center Frankfurt (PCF) – after all, these are perishable goods, which have to be loaded onto trucks as quickly as possible after leaving the airplane and transported not only to wholesalers within Germany, but also to many other European countries. "We are given three-and-a-half to a maximum of four hours for the inspection, and then we must have either granted approval or withdrawn defective goods from circulation," explains Hans-Jürgen Hess. He heads the 18-employee satellite location for plant protection of Gießen’s Regional Administrative Authority in the freight area of Frankfurt International Airport.

The turnstile at Frankfurt International

Fig. 2: Wolfgang Willig from the Plant Protection Service of Gießen’s Regional Administrative Authority takes a sample of these freshly imported chili peppers. © Regional Administrative Authority Gießen

Over two million tons of air freight traffic per year make Frankfurt International Airport a turnstile for air freight throughout Europe. The goods temporarily stored in the PCF account for ten percent of this. With a surface area of 13,000 square meters, the Perishable Center in Frankfurt is the largest in Europe. As the "Port of First Entry", and according to the EU import regulations, it is entitled to import temperature-sensitive goods into the EU from third countries as well as to inspect, store, and process them. The PCF has over 20 requirements-based climate zones, for fresh fish and meat, for example. A temperature of seven to eight degrees Celsius is maintained in the area for fruit and vegetables, where the inspectors of the Plant Protection Service work on behalf of the state of Hesse – every day of the year from 6 a.m. to 10 p.m. Even on Sunday, for that is when the cargo planes bring in the fresh goods that are already available in supermarkets on Monday.

Substantial material damage in the EU

Fig. 3: Roswitha Reinhardt examines a sample under the Leica MZ16 stereomicroscope right after they land at Frankfurt International Airport. If the plant has a pest, the Agricultural-Technical Assistant of the Plant Protection Service of Gießen’s Regional Administrative Authority takes pictures and reports the findings to the responsible Plant Protection Service, which advises the customer accordingly. Photo: Claudia Moch

Pests that come along with the goods can result in high material damage in the EU. In the Plant Inspection Guideline 2000/29/EC, the EU requires certain products to have a certificate of plant health. For this, the importer has to verify that the plant is not defective. All products requiring inspection, which are primarily flown in from Asia, South America, and Africa, are inspected: passion fruit from Costa Rica, eggplant from Egypt, mangos and basil from Thailand – and all kinds of colorful cut flowers and blossoms, which are offered not only for decorative purposes, but also increasingly for consumption. If anything looks suspicious to their trained eyes using a magnifying lens, inspectors take it for further investigation to the Plant Protection Service lab, which is located in the building right next door. The packaging is also examined, especially if it is made of wood from a certain origin in which many pests like to nest.

A look through the microscope brings certainty

Fig. 4: If the quarantine pest Thrips palmi is identified, the whole shipment has to be destroyed. © Regional Administrative Authority Gießen

In the lab, Roswitha Reinhardt, Agricultural-Technical Assistant with the Plant Protection Service, and her colleagues examine the samples that are taken under the microscope. For many years the employees of Gießen's Regional Administrative Authority have trusted the quality of Leica. For their work at the airport they have Leica stereomicroscopes available, expanded by a digital camera from Leica Microsystems, which plays an important role in preserving evidence and documenting the findings. The offices of the Plant Protection Service, which are networked efficiently, also use the images acquired with the camera for interactive discussion and information.

Unwelcome guests

Only magnification enables something like fruit fly larvae in the fruit of a mango or scale insects on the outside of the fruit to be made evident and visible. The tiny little larvae of the leafminer fly (Agromyzidae) love to stay in fresh herbs, such as coriander, which is so popular in Asian cooking.

With some pests, Roswitha Reinhardt has no mercy. For example, if the Thrips palmi is verified, which can be found in eggplant, for example, she has to have the entire shipment rejected and destroyed. "Thrips palmi is a quarantine pest, which is prohibited from being introduced to or spread within the member states of the European Union," explains Reinhardt. Many different plants from the families of gourds, nightshades, papilionaceae, daisies, and orchids can be infested with Thrips palmi. The countries of the European Union are regarded as uninfested, but the merely one-millimeter-long insect is spread throughout parts of Asia and Central America. Individual thrips are not very harmful, but a massive infestation could lead to problems, particularly since this kind of pest can develop resistance to pesticides. Once Thrips palmi is introduced, there is a risk of uncontrolled spread to local greenhouses.

Fig. 5: One of the most common reasons for rejecting goods is infestation by the eggplant fruit borer (Leucinodes orbonalis), seen here on a light yellow eggplant. © Regional Administrative Authority Gießen
Fig. 6: Moth of the eggplant fruit borer (Leucinodes orbonalis). © Regional Administrative Authority Gießen
Fig. 7: Caterpillar (Diaphania indica) on Momordica (bitter pumpkin). © Regional Administrative Authority Gießen
Fig. 8: Fruit fly larvea in kumquat fruits. © Regional Administrative Authority Gießen
Fig. 9: Eggplant borer larvea. © Regional Administrative Authority Gießen
 

Poinsettias in the summer, geraniums in the winter

Multiple harvests during the year in the countries of origin guarantee that exotic fruit and vegetables can be offered at any time of the year in the markets. Almost all garden and balcony plants, however, are seasonal. As early as May, for example, the shoots of the poinsettia – Euphorbia pulcherrima – particularly popular during the Advent season, are flown into Europe from growing regions in South and Central America, Asia, and Africa, and inspected by the Frankfurt plant protectors. "Pests from these regions often have no natural predators among us and, once established here, can spread without hindrance," explains Wolfgang Willig from the Plant Protection Department of Gießen's Regional Administrative Authority. Yet as with all plants requiring inspection, the poinsettias also have to pass the official plant inspection – before they can be approved for transportation to the nurseries.

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