Contaminant organisms recorded on plant product imports to South Africa 1994-2019

Abstract

Biosecurity interception records are crucial data underlying efforts to predict and manage pest and pathogen introductions. Here we present a dataset containing information on imported plant products inspected by the South African Department of Agriculture's laboratories between 1994 and 2019 and the contaminant organisms found on them. Samples were received from border inspectors as either propagation material (e.g. plants) or material for immediate use (e.g. fruit). Material for immediate use was further divided into two sample categories, depending on if contaminants were seen/suspected by the border official or not: intervention or audit samples. The final dataset consists of 25,279 records, of which 30% tested positive (i.e. had at least one contaminant) and 13% had multiple contaminants. Of the 13,731 recorded contaminants, fungi (41%), mites (37%) and insects (19%) were most common. This dataset provides insight into the suite of taxa transported along the plant import pathway and provides an important resource for analyses of contaminant organisms in international trade, which can inform strategies for risk assessment, pathway management and biosecurity protocols.

Fig. 1

Summary of border and laboratory processes associated with each of the three import sample sources included in this dataset, namely post-entry quarantine (PEQ), intervention and audit samples. Solid lines indicate that these processes are always followed, while dashed lines indicate that the process is sometimes followed. PEQ samples are received from plant propagation or nursery material that needs to be quarantined upon arrival. Intervention samples are received from consignments in which the border inspector finds or suspects a pest or pathogen. Audit samples are ad hoc samples drawn from consignments that show no sign of contamination. These sample sources are explained in more detail in the text.

Fig. 2

Import samples examined by the South African diagnostic laboratories between 1994 and 2019 from different countries. Top: All samples received. Middle: Contaminant organisms recorded on these samples. Bottom: Detections of species that were not present in South Africa at the time of recording. NA (white colour) indicates that no samples (top) or no contaminant organisms (middle and bottom) were received from these countries.

Fig. 3

Trends in the number of plant product samples received and contaminant taxa detected by the South African DALRRD diagnostic laboratories between 1994 and 2019. The top eight panels show the total numbers of each taxonomic group that were intercepted. The bottom three panels show the sample types received annually (see text and Fig. 1 for more explanation) and the proportion of these on which contaminant organisms were detected. Note the different scales on the vertical axes.