Assessing the biodiversity and the impact of pollinators on carob production

RESEARCH ARTICLE Assessing the biodiversity and the impact of pollinators on carob production Androulla I. VarnavaID*, George A. Manganaris, Menelaos C. StavrinidesID* Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus * androulla.varnava@cut.ac.cy (AIV); m.stavrinides@cut.ac.cy (MCS) Abstract As the current climate crisis intensifies, drought resistant crops are becoming more impor- tant due to their ability to withstand the increasingly hotter and drier summers. Such crops are valuable for pollinators as they provide food resources for wild and managed species. The carob tree (Ceratonia siliqua L.) represents an example of a heat- and drought- resis- tant crop, able to grow in dry areas with practically no inputs. The current study assessed over two growing seasons the diversity of wild bees and other pollinators relying on carob flowers, as well as the contribution of animal pollination to carob production. Carob flowers were subjected to two treatments: Open pollination, where inflorescences were left untreated, and wind pollination, where inflorescences were bagged in a mesh during bloom- ing. Weekly observations during blooming showed that Apis mellifera was the most frequent floral visitor followed by wild bees and wasps. Carob flowers were visited by at least 10 dif- ferent wild bee species. Open-pollinated flowers produced significantly more pods, with the benefit ranging from 4 to 16 times higher production, depending on the region. Open pollina-

tion led to pods with greater weight, length and number of seeds compared to pods derived from wind pollination. The results of the current study highlight the importance of animal pol- lination to carob production, as well as the significance of carob trees to wild bee conservation. Introduction Pollination is one of the most important ecosystem services, with most plant species depending on pollination by animals [1–3]. Flower-visiting animals are responsible for the pollination of more than 70% of the leading global food crops, representing 35% of global production [4]. Important pollinator groups include insects, such as bees, butterflies, moths, flies, wasps, bee- tles and thrips and vertebrates, such as birds, bats, lizards, and other mammals [2, 5]. The esti- mated global value of pollination ranges from US$195 billion to US$387 billion annually [6]. Human well-being benefits from pollinators, as their presence ensures crop food security, con- serves the diversity of wild plants, maintains the production of honey and other beekeeping products, and supports cultural ecosystem services [2, 7]. Domesticated and wild bees are considered the most important pollinators of wild and cul- tivated plants, with approximately 20,000 species described worldwide [8, 9]. Managed Apis PLOS ONE PLOS ONE | https://doi.org/10.1371/journal.pone.0291431 October 20, 2023 1 / 16 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Varnava AI, Manganaris GA, Stavrinides MC (2023) Assessing the biodiversity and the

impact of pollinators on carob production. PLoS ONE 18(10): e0291431. https://doi.org/10.1371/ journal.pone.0291431 Editor: Janice L. Bossart, Southeastern Louisiana University, UNITED STATES Received: January 2, 2023 Accepted: August 29, 2023 Published: October 20, 2023 Copyright: © 2023 Varnava et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The minimal data set underlying the results of our study have been deposited here: https://datadryad.org/stash/share/ t0KMf8CJSVRwYIn1R0FisrGO4Q7wXk01wWCIxs Jg0k0 / doi:10.5061/dryad.6t1g1jx49. Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist.