# Tiny Trouble, Unknown Risk: International Interceptions Highlight Cross-Border Movement and Biosecurity Threat of Cenopalpus (Acari: Tenuipalpidae)

## TL;DR

Cenopalpus mites, which damage fruit and ornamental plants, are being intercepted in international trade, showing a growing biosecurity risk that needs better monitoring and identification.

## Contribution

The study provides the first comprehensive analysis of Cenopalpus mite interceptions in global plant trade, highlighting their spread and identification challenges.

## Key findings

- 98 Cenopalpus mite interceptions were recorded between 1981 and 2024, mainly in New Zealand, South Africa, and the USA.
- Cenopalpus pulcher was the most frequently detected species, often found on apples and stone fruits from Europe and the Middle East.
- Taxonomic uncertainty complicates accurate identification, emphasizing the need for improved diagnostic expertise in biosecurity programs.

## Abstract

Mites of the genus Cenopalpus are plant-feeding pests that can cause significant damage to fruit and ornamental plants, such as apples and peaches. These mites are mainly found in Asia, Europe, and northern Africa, but the global trade of plants is facilitating their spread to new areas. This study examined official border inspections from several countries to understand how often and where Cenopalpus mites are being transported. Between 1981 and 2024, a total of 98 interceptions were recorded in New Zealand, South Africa, and the USA, while no interceptions were reported from Australia, Laos, Malaysia, or Singapore. The most frequently detected species were the flat scarlet mite, Cenopalpus pulcher, followed by C. lanceolatisetae. Most interceptions involved fruit plants, especially apples and stone fruits, imported from Europe and the Middle East. Some of these reports represent first interception records in trade, providing evidence of cross-border movement that may pose a growing threat to agriculture. Taxonomic uncertainty may make it difficult to identify Cenopalpus mites in interception records, showing the need for better diagnostic expertise. These findings highlight the importance of continued surveillance and accurate identification of mites in plant trade to support plant biosecurity and prevent the establishment of new pests.

Mite species of the genus Cenopalpus are phytophagous pests associated with fruit and ornamental crops. Although the genus is primarily distributed in the Palearctic region, increasing international trade of plant material has created repeated opportunities for its unintentional transport across borders. To support improved awareness of emerging biosecurity risks, international quarantine interception records were analyzed from Australia, Laos, Malaysia, New Zealand, Singapore, South Africa, and the United States of America. A total of 98 interceptions were documented between 1981 and 2024, exclusively reported by New Zealand, South Africa, and the USA, while no Cenopalpus spp. mites were intercepted in Australia, Laos, Malaysia, or Singapore. Six species were identified, with Cenopalpus pulcher being the most frequently detected, followed by C. lanceolatisetae and C. officinalis. Interceptions were primarily associated with fruit crops, particularly apples and stone fruits, frequently with origins in Europe and the Middle East. Several records represent the first detection of Cenopalpus in trade originating from countries within Africa, Asia, the Americas, and Oceania. Taxonomic uncertainty associated with Cenopalpus mites likely limits accurate identification in interception records, highlighting the need for improved diagnostic expertise. The implications of these findings for plant biosecurity programs, including surveillance and diagnostic priorities, are discussed.