Impacts of almond pollination service and inter-row cover cropping on honey bee colony strength and performance

Authors: Mayack, Christopher; Carlson, Mark; NINO, BERNARDO - The Xerces Society; NINO, ELINA - University Of California, Davis; Seshadri, Arathi

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2025
Publication Date: 5/20/2025
Citation: Mayack, C.L., Carlson, M.A., Nino, B.D., Nino, E.L., Seshadri, A.H. 2025. Impacts of almond pollination service and inter-row cover cropping on honey bee colony strength and performance. Science of the Total Environment. 983. Article 179703 https://doi.org/10.1016/j.scitotenv.2025.179703.
DOI: https://doi.org/10.1016/j.scitotenv.2025.179703

Interpretive Summary: Cross-pollination by bees helps economically viable production of fruits, nuts and vegetables. Almond production is an ideal example to demonstrate the commercial application of such plant-pollinator dependency. California is the world’s largest producer of almonds. The most common variety grown is self-incompatible and requires bees to move pollen from a pollen donor variety to the flowers of the nut setting variety. During almond bloom, between February and March, every year, beekeepers from all over the country bring honey bee colonies to almond orchards to help with pollination and growers rent these colonies for substantial prices. Bee colonies pollinating almond flowers obtain nutritious pollen and orchard growers gain successful nut set. Honey bees have been facing great many challenges over the decades, and in this study, we aimed to understand the impacts of almond pollination services on honey bee colony health and performance. Our results show that colonies that provided almond pollination services, consistently had higher amounts of adult bees, brood and pollen stores. Our study also showed that, access to a flowering inter-row cover crop that bloomed after almond pollination season, facilitated extended benefits for bee colonies. Agroecosystem management practices, such as interrow cover cropping, provide sustained health benefits for honey bee colonies while promoting ecosystem health and function.

Technical Abstract: Intensive agriculture has become necessary to meet the growing global demand for food and involves the activity of insect pollinators that promote successful fruit and seed production in many agricultural crops. Among insects, honey bees are the most efficient pollinators and in the agriculture industry, worth over 200 billion dollars annually, economic yield of commodity crops, such as fruits, nuts and oil seeds, is heavily reliant upon pollination by honey bees. Almonds are a quintessential example of the commercial application of plant-pollinator dependency. Acreages of almonds mostly comprise of self-incompatible varieties need bees for transferring pollen from the flowers of ‘pollenizer’ varieties to those of nut-yielding varieties, facilitating cross-pollination. Early season flowering phenology of almonds, when there are very few other plants in bloom, facilitates honey bee colony growth after the overwintering quiescence. Here, we investigated the impacts of (i) almond pollination and (ii) availability of flowering interrow mustard-mix cover crops, on honey bee colony strength and performance. Results show that there were consistently higher frames of bees, pollen stores, brood, and adult bees in colonies returning from almond pollination. The availability of mustard-mix cover crops supports increased colony strength through the season, facilitating long lasting positive impacts on honey bee health. Our findings suggest that agroecosystem management practices such as interrow cover cropping, strengthen the immediate and long-term positive impacts from pollination services by improving honey bee colony performance while simultaneously promoting ecosystem health and function.