Correction to: Towards estimating the economic cost of invasive alien species to African crop and livestock production

Correction to: CABI Agric Biosci (2021) 2:18 https://doi.org/10.1186/s43170-021-00038-7

Eschen et al. (2021) estimated the annual cost of invasive alien species (IAS) to African agriculture, separated into the cost due to yield loss, the cost of weeding, the loss of livestock-based income and the cost of research. The paper revealed the vast cost of IAS to the continent and estimated the total cost to be USD 3.66 Tn, with by far the largest part of the estimated cost (USD 3.63 Tn) due to weeding. The study concluded that there is a need for pre-emptive measures to reduce future costs, as well as measures that contribute to the control of widely established IAS to reduce losses and improve livelihoods.

After publication, it was brought to our attention that the estimated cost of weeding was much higher than can reasonably be expected although the input data and general approach to calculating the estimate were not disputed. We therefore revisited our calculations and found a scaling error that occurred during the application of wages to the harvested area for each of the five crop types. As described in the original article, we calculated the cost of weeding IAS in five crop types based on the harvested area in each African country, calculated from data in the SPAM database, the average abundance of alien species as a fraction of the weed community in African agricultural fields as deducted from the published literature. The average time spent weeding a hectare of each of the five crop types was taken from the published literature, and wages paid in each country for agricultural labour or similar jobs as reported on https://wagecalculator.org. We erroneously applied costs per square kilometre instead of the cost of weeding per hectare, resulting in substantially overestimated weeding costs. The calculations of the estimates of yield loss, the loss of livestock-based income and research costs were not affected by this error.

We corrected this error in our calculations and have updated the results, specifically Table 3, which presents to total estimate, and Table 4, which presents the estimates for each country. These corrected Tables are presented here. We have updated the numbers stated in the Abstract and in the Results section of the manuscript text to reflect the corrected results. We also modified the discussion where these estimates are put into context. While the total estimate of IAS cost to African agriculture are now significantly lower, the conclusions and recommendations have not changed.

Table 3 The absolute and relative contribution of labour, yield loss, lost livestock derived income and research to the annual cost of IAS to African agriculture in billions USD

Table 4 Summary of estimated costs by country (in millions USD). For the yield losses by individual species, the values are the middle estimates, based on the literature and survey responses. A dash indicate that no estimate was made, whereas a zero indicates a small estimated value

We have also corrected the value for the yield loss due to Phthorimaea absoluta based on the literature and a survey in Table 5. The value in the previous version of the manuscript was wrong due to a transcription error. The new value is corrected for abundance within each country, like the other values in the Table. This species was deleted from the abstract as the most costly species and minor changes to the Results and Discussion were made to align the text with the correct number. A reference made to an article ‘in press’ during publication has also been updated with the article’s final reference detail.

Table 5 Estimated yield loss caused by individual IAS in Africa

We apologise for the errors and any confusion they may have caused.The original article has been updated.