Flower‐visiting bat species contribute unequally toward agricultural pollination ecosystem services in southern Thailand

Abstract

The large majority of angiosperm species depend on animals for pollination, including many agricultural crops, and plant‐pollinator interactions have been extensively studied. However, not all floral visitors actually transfer pollen, and efforts to distinguish true pollinators from mere visitors are particularly scarce among the bat pollination literature. To determine whether Old World bat species are equally effective pollinators in mixed‐agricultural areas of southern Thailand, we examined six night‐blooming plant taxa and quantified pollinator importance (PI) of seven common nectarivorous bat species. PI was calculated as the product of nightly bat visitation rate (obtained from mist‐netting data) and pollen transfer efficiency (estimated from bat pollen loads). We found that PI varied by both bat species and plant species. In general, the nectar‐specialist bat species were more important pollinators, yet their order of importance differed across our focal plant species. In addition, PI was dictated more by pollen transfer effectiveness than visitation rate. Our findings highlight the importance of Old World bat pollinators within southern Thailand's mixed‐agricultural landscape and illustrate how seemingly similar floral visitors can have very different contributions toward plant pollination success.

Field evidence of strong differential pollen placement by Old World bat-pollinated plants

“…A total of 33 R. leschenaulti bats carried D. zibethinus pollen. Other pollen species and morphotypes are occasionally found on these bat species, but are less common (Stewart and Dudash, 2016b).…”

“…These plant species bloom at night and are known to rely on bats for pollination (Start and Marshall, 1976;Bumrungsri et al, 2008Bumrungsri et al, , 2009Srithongchuay et al, 2008Srithongchuay et al, , 2016Acharya et al, 2015;Stewart and Dudash, 2016b).…”

“…This bat species is relatively large (53-59 g; Stewart and Dudash, 2016b), has a broad diet and is an important pollinator of many night-blooming plant species (Start and Marshall, 1976;Bumrungsri et al, 2008Bumrungsri et al, , 2009Srithongchuay et al, 2008Srithongchuay et al, , 2016Acharya et al, 2015;Stewart and Dudash, 2016b). Because of its broad diet, E. spelaea potentially transfers heterospecific pollen among bat-pollinated plant species.…”

“…We also examined three additional flower-visiting bat species that are important pollinators: Macroglossus minimus (17-19 g) and Macroglossus sobrinus (22-24 g) are important pollinators of M. acuminata, while Rousettus leschenaulti (73-89 g) is an important pollinator of D. zibethinus (Stewart and Dudash, 2016b). These species are less likely to cause interspecific pollen transfer since they visit the flowers of fewer plant species than E. spelaea (Start and Marshall, 1976;Stewart and Dudash, 2016b).…”

“…These species are less likely to cause interspecific pollen transfer since they visit the flowers of fewer plant species than E. spelaea (Start and Marshall, 1976;Stewart and Dudash, 2016b). Examining multiple pollinator species allowed us to examine if patterns of pollen deposition are universal, or vary by bat species.…”