Agricultural production losses due to insufficient pollination have decreased thanks to honeybees

The group of authors is internationally recognized for their work on pollination and for the quality of that work. Specifically, Marcelo Aizen is a renowned scientist with extensive experience in the field of animal pollination.

I consider the study to be of very high quality. The authors conducted a meta-analysis using a total of 165 studies, encompassing nearly 800 individual comparisons, across 86 crops worldwide. These studies examined pollen limitation by comparing crops where pollinators are managed with those where they are not. The conclusions drawn are supported by the results obtained.

As a meta-analysis, the study compiles all existing evidence (dating back to 1950!) to date—that is, the results published on this topic up to the present day.

The authors have taken various confounding factors into account. Climatic and phylogenetic variables, as well as publication bias, were considered to strengthen the results. Furthermore, the robustness of the findings was confirmed through sensitivity analyses and simulations. Although more studies have been conducted in temperate than in tropical regions, the emerging pattern is clear.

The study shows that there is still significant pollen limitation across all crops considered in the study, with an average of 35%, indicating that there is still room for improvement in production. It is important to continue this type of research to identify vulnerabilities and ensure the long-term resilience and sustainability of crop production. The study clearly shows that, although pollen limitation in pollinator-dependent crops has decreased thanks to improvements in management and self-pollination, risks persist, and the conservation of wild pollinators remains essential for future agricultural sustainability.

My overall impression is that this is an interesting, timely, and methodologically sound study, based on a comprehensive review of experimental studies on pollination limitation in pollinator-dependent crops. The results suggest that pollination limitation in the crops analyzed has decreased over the past few decades and that this trend is primarily associated with the use of managed pollinators. In my view, the data reasonably support this conclusion.

However, I believe it is important to avoid certain oversimplified interpretations that might arise from these results (and I emphasize this because I believe it is important and is something that concerns me greatly and that I have been working on lately: the communication of scientific information to society). The study assesses whether pollen supplementation increases agricultural production—that is, whether there is a pollination deficit that reduces crop yields. It is not directly measuring the abundance or diversity of wild pollinators, the resilience of pollination networks, or the conservation status of these organisms. Therefore, the absence of a global agricultural yield crisis associated with pollination should not be interpreted as the absence of ecological impact on pollinators or on the ecosystems of which they are a part (I am concerned about the use of partial and biased information that often occurs).

It is also worth noting that the lower constraints observed in systems with managed pollinators could be related not only to greater availability of beehives or other commercial pollinators, but also to other factors that typically accompany more intensive and technified agricultural systems, such as the use of improved crop varieties, changes in agronomic practices, or improvements in crop management. And I believe it is also important to make this clear, as the study in question has not taken it into account.

In any case, I believe the study provides interesting evidence that agricultural systems have managed to partially offset pollination deficits through various management strategies. At the same time, I share the concern expressed by the authors regarding the heavy reliance on a few managed species, especially the honeybee. From an ecological and agronomic perspective, concentrating a significant portion of agricultural production on a very small number of pollinator species can increase vulnerability to future diseases, pests, or environmental disturbances. And these problems are all too well known.

I consider this to be a relevant and well-conducted study, but its results should be interpreted primarily in terms of agricultural production and not as evidence that the global problem of pollinator conservation (which has many more “functions” than just producing food through agriculture) has disappeared.

Does the press release accurately reflect the study?

“I think the press release is fine; it accurately summarizes the study. However, I would clarify a few things:

• It is preferable not to start with Researchers, which is imprecise, but rather with a reference to the researchers (a recent study led by Catarina Siopa…), the university (a recent study led by the University of Freiburg…), or the research group (an international group of researchers…).
• The press release mentions supplementary pollination, and the term is misleading. The term managed pollinators is better, as it appears in the article.
• The same applies to self-fertile… ‘Autogamy’ is the correct term, but it can be clarified by adding self-fertile immediately after or in parentheses.
• Apis mellifera should be in italics.
• I would end the note with the final sentence of the Abstract, which is very appropriate: “The results suggest that current pollination management practices have become increasingly efficient in crop production systems, possibly helping to mitigate the negative impacts of wild pollinator declines. However, continued efforts to diversify pollination strategies, including the conservation of wild pollinators and the management of alternative pollinator species, can play a significant role in ensuring the long-term resilience and sustainability of global agriculture.”

Is the study of good quality?

“Yes.”

How does this work fit with existing evidence?

“It aligns with the concerns of experts and international organizations such as the FAO, IPBES, the European Union, and many others regarding the steady decline of pollinators—especially bees, the thousands of species that exist and are the best pollinators—and, in particular, the decline of bumblebees, the best of the best. And also the serious repercussions for biodiversity, for agriculture, and for us, therefore.”

Are there any important limitations to consider?

“The fact that it is a meta-analysis, even of 165 studies, means that others are missing, so the results cannot be generalized and, if at all, only to equivalent studies.”

What are the implications for the real world?

“Those indicated earlier, in the last sentence of the Abstract.

Furthermore, the decline of pollinators, especially wild bees, has a negative impact on agriculture, puts terrestrial ecosystems at risk, and threatens global food supplies and their economic value.”