Beetle pollination and fruit predation of Xanthosoma daguense (Araceae) in an Andean cloud forest in Colombia

Abstract

This study describes a pollination system in a species of Araceae that involves three species of beetle, one of which is also a fruit predator. In a tropical cloud forest in Colombia, inflorescences of Xanthosoma daguense opened at dusk, releasing a sweet scent and raising their temperature 1–3 °C. Soon after, two species of Scarabaeidae (Dynastinae; Cyclocephala gregaria and C. amblyopsis) and one species of Nitidulidae (Macrostola costulata) arrived with pollen. Cyclocephala beetles remained inside the inflorescence for 24 h. The next night, Cyclocephala beetles left the inflorescence after picking up the freshly shed pollen, almost always moving to the nearest inflorescence available. The probability of inflorescence abortion and number of fruits set after the visit of one individual was equivalent for both Cyclocephala species. However, C. gregaria was much more abundant than C. amblyopsis, so it was the most important pollinator. There was a positive relationship between the number of dynastine visits and the number of fruits produced. Besides carrying pollen to the inflorescences, nitidulid beetles had a negative effect on female reproductive success through fruit predation. Nitidulid larvae developed inside the infructescence and preyed on up to 64% of the fruits. However, 8% of inflorescences not visited by dynastines were probably pollinated by nitidulids, because hand-pollination experiments showed that self-pollination was unlikely. Inflorescences potentially pollinated by nitidulids comprised 25% of the fruit crop in the year of our study. This interaction with a fruit predator that is also a potential pollinator resembles brood-site pollination systems in which pollinators prey on part of the fruit set (e.g. Ficus, senita cacti, Yucca), making this system substantially more complex than previously described dynastine-pollinated systems in aroids.

Pollination ecology of Monstera obliqua (Araceae) in French Guiana

“…However, unlike other neotropical beetle-pollinated species (Chouteau et al 2007, García-Robledo et al 2004Gibernau et al 1999Gibernau et al , 2003Maia & Schlindwein 2006, Young 1986, M. obliqua produced limited heat during the female phase. Pollinators appeared to be attracted to the sweet scent which was produced during the 48-h of the flowering cycle albeit a small increase of the spadix temperature was recorded during the female phase.…”

Equal and Opposite Effects of Floral Offer and Spatial Distribution on Fruit Production and Predispersal Seed Predation in Xanthosoma daguense (Araceae)1

“…In this study, we explore the consequences of daily variation in the pollination context at a population level for female reproductive success, in a species of plant with a pollination system that involves three beetle species, one of which is also a seed predator. In Xanthosoma daguense (Araceae) in the Andes of Colombia, two species of Dinastinae (Scarabaeidae), Cyclocephala gregaria Heyne & Taschenberg and Cyclocephala amblyopsis Bates, and one species of Nitidulidae, Macrostola costulata Reitter are regular visitors to the inflorescences (García‐Robledo et al 2004). Dynastine beetles are the main pollinators and they do not cause any evident damage to reproductive structures, at least when the number of visits per inflorescence is low (Young 1988, Goldwasser 2000, García‐Robledo et al 2004).…”

“…In Xanthosoma daguense (Araceae) in the Andes of Colombia, two species of Dinastinae (Scarabaeidae), Cyclocephala gregaria Heyne & Taschenberg and Cyclocephala amblyopsis Bates, and one species of Nitidulidae, Macrostola costulata Reitter are regular visitors to the inflorescences (García‐Robledo et al 2004). Dynastine beetles are the main pollinators and they do not cause any evident damage to reproductive structures, at least when the number of visits per inflorescence is low (Young 1988, Goldwasser 2000, García‐Robledo et al 2004). Although the Nitidulid beetles move pollen among inflorescences, and may be acting as secondary pollinators, they feed on the pollen carried by the Dinastine beetles, lay eggs on the female flowers, and their larvae feed on part of the fruit set, consuming nearly all the seeds within the damaged fruit (García‐Robledo et al 2004).…”

“…Dynastine beetles are the main pollinators and they do not cause any evident damage to reproductive structures, at least when the number of visits per inflorescence is low (Young 1988, Goldwasser 2000, García‐Robledo et al 2004). Although the Nitidulid beetles move pollen among inflorescences, and may be acting as secondary pollinators, they feed on the pollen carried by the Dinastine beetles, lay eggs on the female flowers, and their larvae feed on part of the fruit set, consuming nearly all the seeds within the damaged fruit (García‐Robledo et al 2004).…”

“…(Voucher: Croat 84942, MO) is a clonal, terrestrial herb that grows in the understory of humid montane forest in the Central range of the Colombian Andes. Each ramet is about 1.5‐m tall, and opens only one inflorescence at a time, at intervals between 1 and 27 days (García‐Robledo et al 2004).…”