Insufficient native pollinators during artificially induced early flowering decrease yield and long‐term economic viability of a tropical fruit crop

Abstract

The management of crops outside the regular cropping calendar can improve profits when supply is low and prices are high, but we do not know how induced, early flowering impacts the pollination services that crops require. This study examines the effects of flowering time and pollinator management, including managed honeybee colonies and ground flower cover, on the pollination of the tropical fruit tree, longan (Dimocarpus longan Lour.), comparing between in‐season flowering (naturally) and off‐season flowering (chemically induced) in Northern Thailand. Visitation rates of flower visitor groups significantly differed among treatments: for in‐season flowering, wild bees were the most frequent pollinator group, whereas in the off‐season flowering, there were no wild bees, and instead dipterans were the most frequent pollinator group. Some off‐season plantations have honeybee hives present and in this situation honeybees were the most frequent pollinator group. We show that temporal variation in the pollinator community significantly alters the pollination efficiency of longan crops. Consequently, longan production from off‐season longan farms generates lower net profit in the absence of managed bees and wild bees, and wild bees produced higher seed‐sets than either honeybees or dipterans. Synthesis and applications. Wild bees were the main pollinator group of longan in the in‐season flowering resulting in high fruit production; whereas in the off‐season flowering honeybees and dipterans were the main pollinator group. Longan production from off‐season longan farms without managed bee produced less net profit. The farmers practicing off‐season with honeybee hives management gain the largest net profit. Developing mechanisms to promote and maintain pollinator abundance and diversity is likely to increase the resilience of the system in addition to profit in the long term; thus, efforts should be made to provide more nesting habitat and reduce pesticide use.

Phenological overlap between crop and pollinators: Contrasting influence of native and non‐native bees on raspberry fruits over the flowering season

“…The synchrony between flowering time and the availability of diverse pollinator communities is a crucial trait for crop pollination, and thus for more than 75% of global crops (Klein et al., 2007). Despite its importance, the evaluation of temporal matches or mismatches between crop flowering and the density and composition of the pollinator community has been poorly studied (but see Sritongchuay et al., 2021). This is most likely due to the methodological challenges associated with assessing temporal changes in plant–pollinator interactions in crops that generally bloom for short periods.…”

“…However, the success of these practices requires that local pollinator communities are active when the target crop is flowering. A mismatch between the timing of crop flowering and pollinator activity may hinder pollen transfer, and thus adversely affect the yield of crops that depend on pollinators (Sritongchuay et al., 2021). For this reason, synchrony between pollinators and crop flowering is essential for effective pollination services (Sritongchuay et al., 2021).…”

“…A mismatch between the timing of crop flowering and pollinator activity may hinder pollen transfer, and thus adversely affect the yield of crops that depend on pollinators (Sritongchuay et al., 2021). For this reason, synchrony between pollinators and crop flowering is essential for effective pollination services (Sritongchuay et al., 2021). Despite its relevance, the effect of phenological overlap between pollinators and plants is rarely considered in crop and environmental management.…”

“…However, pollination of many crops relies almost exclusively on managed pollinators, such as honeybees and some bumblebee species (Aizen et al., 2020; Garibaldi et al., 2013). In agricultural systems, the abundance and diversity of native pollinators visiting crops can vary in space and time because of different factors, including (a) management of key local and landscape habitats for native pollinators (Garibaldi et al., 2014), (b) competitive displacement of native pollinators due to an oversupply of managed bees or invasive pollinators (Aizen et al., 2020; Badano & Vergara, 2011) and (c) phenological overlap between crop flowering and the activity period of native pollinators (Sritongchuay et al., 2021). Changes in the abundance and diversity of pollinators delivering pollination services might indeed affect the cost–benefit ratio of plant–pollinator interactions and ultimately affect crop yield (Aizen et al., 2014).…”

Homing ability in a tropical Asian stingless bee is influenced by interaction between release distances and urbanisation

“…In subtropical and tropical regions, stingless bees (Apidae: Meliponini) are key pollinators for both wild and agricultural crops (Borges et al, 2020; Hansen et al, 2020; Heard, 1999; Momose et al, 1998; Ramírez et al, 2018; Slaa et al, 2006; Sritongchuay et al, 2021). They are eusocial bees and live in perennial colonies consisting of a single queen and hundreds to thousands of workers (Michener, 2007).…”