Fruit-fly management in Europe

Climate change is driving biological invasions in temperate European zones. What is being done to protect agriculture? By Engela Duvenage.

Warmer weather is increasingly allowing tropical pests and other species to persist throughout winter, and become problems, according to applied entomologist Prof. Nikos Papadopoulos of the University of Thessaly in Greece.

The global fresh-food commodities trade, increased human mobility, land-use changes, and the planting of new types of fruit or cultivars in a region also help pests and diseases to establish and spread.

Papadopoulos coordinates the European Fruit Flies In-silico Prevention and Management Project — FF-IPM for short. In-silico refers to the data-driven nature of the project. The aim is to protect fruit production and trade against threats posed by fruit flies. Fruit flies make up a third of all interceptions of pests in fruit and vegetables at European ports of entry.

FF-IPM involves 21 research groups from Europe, China, the United States, Australia, and South Africa. South Africa is represented by Stellenbosch University and Citrus Research International.

Three threatening fruit flies

Papadopoulos explained that FF-IPM concentrates on three fruit-fly species. Medfly – the Mediterranean fruit fly — is increasingly spreading from coastal areas around the Mediterranean Sea northwards into Europe. The Oriental fruit fly is now frequently intercepted at European ports, and the peach fruit fly was recently detected in Europe, having spread from India via North Africa, the Middle East, Israel, and Lebanon.

“Climate change has lifted the climatic barriers for Mediterranean fruit flies, seemingly allowing their establishment in continental Europe. For example, whereas previously northern Greece had no major issues or detections, this has changed in the last decade,” said Papadopoulos.

“Our growers are suffering from high infestations, as the Medfly is moving to central Europe as well. It seems that shorter cold periods in spring open some corridors in the Alps. These enable Medflies to cross from northern Italy to Switzerland, Germany, Austria, or northern France and other countries.”

Medflies are becoming a pest for later maturing fruits like apples and peaches. Infestations of peaches have been recorded in northern Italy, Greece, and Austria.

Besides direct damage to fruit, the presence of Medfly in parts of Europe threatens integrated pest management programmes, such as those for codling moths.

Surveys are detecting peach and Oriental fruit flies around Vienna in Austria — an area previously thought too cold for fruit flies to establish. Papadopoulos considers the detection of peach fruit flies in central Italy, near Naples, and in France to be a warning sign of the European invasion of this pest, especially as Naples has a favourable climate for the flies.

“These detections are currently listed as transient,” said Papadopoulos. “No aggressive eradication campaign is in place yet.

“Nonetheless, there are gaps in climatic and ecological modelling in Europe. There’s no well-coordinated interception or detection system. Fast and aggressive responses are lacking.”

Innovative in-silico tools

FF-IPM aims to help prevent the entry of fruit flies. Partners are therefore developing innovative population models and containment and control strategies based on model outputs fed by novel basic biological data.

Models were developed to describe the response of all three fruit flies to climate, so as to understand which crops grown in Europe are most threatened, and in which seasons. These static models indicate that the Oriental fruit fly could establish around Naples and most coastal Mediterranean areas, including most of Portugal, Spain, the Greek islands, and Greece’s southern coastline.

Dynamic, seasonal prediction risk models, in turn, describe the weekly climatic suitability of regions for population establishment.

Partners also work on prevention and early detection tools and approaches. The Benaki Phytopathological Institute in Greece and an Italian company, PCA Technologies SRL, are developing e-nose technology to detect infested fruit in cargo systems. The next step is to train sensors to find infested fruit in shipments.

“We want to see if it is possible to distinguish fruit infested by fruit flies, and with different species,” said Papadopoulos.

Israel’s Agricultural Research Organization and Italy’s University of Molise are developing two electronic trap systems with accompanying automatic counting algorithms. Micro-cameras clipped on each trap take numerous photographs daily. These are sent via the cloud to Israeli colleagues who have developed an algorithm to identify individual trapped insects.

“This e-trap system was recently tested in the port of Thessaloniki with great success,” noted Papadopoulos.

FF-IPM members at the Royal Museum of Central Africa in Belgium and Stellenbosch University have developed the LUCID Multi-entry Key. It currently identifies 14 adult fruit-fly species from Africa and supports laboratory-based diagnostic services. A free app for IOS and Android devices was rolled out last year.

A similar key system for larvae is being developed.

Data-based detection and management

Population-dynamics models for specific fruit-producing areas are being built to optimise detection efforts, with the help of the Dymex platform and specialised algorithms. Dymex uses geographic and climate information along with expert inputs to identify risk factors associated with Medflies in an area. Population phenology can be forecasted weeks ahead, and microhabitat climates simulated.

Fruit-fly population growth models per crop are developed according to different integrated pest management practices. These algorithms are tested on six farms with integrated pest management strategies in place in two regions in Italy, Greece, and Spain.

“The Pests-On-Farm model generates scenarios to predict population growth under different management scenarios, including ones where farms have no IPM approaches in place, or only use mass-trapping interventions,” said Papadopoulos.

“We need holistic eradication and containment approaches in Europe to deal with ongoing fruit-fly invasions. These must consider political, social, and economic aspects,” stressed Papadopoulos. “We must address all steps of invasions, invest in generating novel knowledge, increase coordination among stakeholders, and ensure transborder information sharing between countries.

“We must invest in training stakeholders, and keep the whole fruit production and trading chain informed.”

For more information about the FF-IPM project, visit www.fruitflies-ipm.eu.

Image: Prof. Nikos Papadopoulos, University of Thessaly, Greece. Supplied by Prof. Nikos Papadopoulos.