Classical biological control is having a very significant impact on populations of the Asian citrus psyllid (ACP) in Cyprus, according to Ángel Marhuenda, director general of common agricultural policy for the Valencian Institute of Agricultural Research (IVIA). ACP is the vector of huanglongbing (HLB) disease.
Marhuenda said, however, that “the detection of residual populations of the vector indicates that continued vigilance will be necessary, particularly during the main periods of new shoot growth.”
Although HLB is not present in the Mediterranean basin, the detection of ACP in Cyprus in 2023 marked the first confirmed sighting of the vector within the European Union. Immediately following the detection, Cypriot authorities launched an eradication and phytosanitary monitoring program, maintaining close collaboration with IVIA.
The widespread distribution of citrus plants made it difficult to implement a strategy based solely on chemical treatments. At the initiative of IVIA, a proposal was put forward to complement phytosanitary measures with a classical biological control program aimed at sustainably reducing vector populations.
The program was launched in 2024 with the introduction of the parasitoid Tamarixia radiata, sourced from California. The introduction was made through the collaboration of the Cypriot government; the Agricultural Research Institute of Cyprus; the University of California, Riverside; the California Department of Food and Agriculture; and other scientific and phytosanitary organizations.
The initial releases took place during the spring of 2024 in four citrus-growing regions of Cyprus where the presence of ACP had been confirmed.
Since then, IVIA has maintained close monitoring of the program’s progress through a series of scientific missions led by IVIA Research Professor Alberto Urbaneja. Those missions were conducted in November 2023, March 2024, July 2024, October 2025 and May 2026.
“The initial sampling revealed high population pressure from the psyllid, characterized by overwintering adults, abundant egg masses and heavily infested shoots,” said Urbaneja. “In July 2024, infestation levels in some fields even reached 100% of shoots, confirming the vector’s widespread distribution across the island and underscoring the need to reinforce a sustainable management strategy based on biological control. Subsequent monitoring showed a very favorable trend. In October 2025, a sharp decline in (ACP) populations was observed in most of the monitored fields, alongside very high levels of parasitism in the specific hotspots where the psyllid was still detected.”
In one of the fields exhibiting the highest presence of the vector, parasitism rates exceeded 90%, indicating a highly significant impact from natural enemies.
The most recent mission, conducted in May 2026, confirmed a further reduction in the vector’s populations on the island. Current population levels remain extremely low compared to those recorded in 2024.
“The experience in Cyprus represents a case of great strategic value for Mediterranean citrus cultivation, as it allows us to evaluate — under real-world conditions — the potential of classical biological control as a preventive and sustainable tool” against ACP, Marhuenda concluded.
Source: Valencian Government
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