Agricultural production is reliant on regulating ecosystem services. One important yet underexplored regulating service is biological control, the reduction of one organism population by another one. While biological control can benefit agriculture in diverse ways, it is decreasing worldwide. In a recent study, Martínez-Sastre et al. (2020) used questionnaires to examine farmers’ perceptions and knowledge of the biodiversity underpinning biological control in cider-apple orchards in northern Spain.
Biological control refers to the process by which beneficial organisms, so-called natural enemies, reduce the occurrence of pest organisms without any human intervention. Here, high biodiversity of natural enemies is known to enhance biological control. However, as not all species exhibit the same prey patterns, uneven effectiveness of natural enemies for pest control need to be taken into account. Overall, biological control constitutes an efficient, profitable and sustainable alternative to chemical approaches of pest suppression to reduce crop losses. It does not only reduce the outbreaks of pests but also provides economic benefits, reduces human health risks and contributes to biodiversity conservation.
The study by Martínez-Sastre et al. (2020) focuses on cider-apple orchards in Asturias, a sparsely populated region in northern Spain. There, a high number of extensive and semi-extensive cider-apple orchards can be found, making Asturias the most productive region of cider-apple in Spain. Management of these orchards is mainly traditional. Only 51% of farmers in this area use pesticides and only when they consider it absolutely necessary. The suppression and control of pests in Asturian cider-apple orchards thus mostly relies on natural enemies, especially birds.
The study shows that farmers’ awareness of biological control is relatively high. Almost all Asturian farmers (90%) considered natural enemies important for croplands, while only 55.6% of farmers considered them important for their own cider-apple orchards. Martínez-Sastre et al. (2020) suggest that this is due to the fact that for cider production, some damage to the apples is permissible, resulting in higher tolerance to pests among cider-apple farmers compared to farmers in other crop production systems. Most interviewed farmers were more aware of direct benefits of natural enemies than of indirect benefits. The authors highlight that this might lead to an underestimation of the role of natural enemies for biological control in orchards and their contribution to cider production.
The vast majority of farmers was able to identify some natural enemies. In general, birds and mammals were easily recognized as natural enemies while arachnids and insects were poorly recognized. Farmers were also found to overestimate the biological control capabilities of certain organisms while underestimating the potential of others. Martínez-Sastre et al. (2020) attribute these knowledge patterns to farmers’ daily interactions with biodiversity in cider-apple orchards and their local ecological knowledge.
In addition to local ecological knowledge, formal knowledge acquired from external sources, such as scientific outreach, newspaper coverage, and social media, is reported to may also have an effect. The study further reveals that level of education, being a full- or part-time farmer rather than a ‘hobby’ farmer, time spent working in agriculture, and orchard size are all factors that positively influence farmers’ perception and knowledge of natural enemies.
The study by Martínez-Sastre et al. (2020) provides insights for future management of cider-apple orchards. The authors conclude that biological control can be promoted by creating initiatives to develop farmers’ knowledge regarding biological control and natural enemies, fostering traditional farming systems that contribute to preserving local ecological knowledge of biological control, and establishing networks of farmers so they can learn from each other and share their knowledge.
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