Nectar Robbing Positively Influences the Reproductive Success of Tecomella undulata (Bignoniaceae)

Abstract

The net consequence of nectar robbing on reproductive success of plants is usually negative and the positive effect is rarely produced. We evaluated the influence of nectar robbing on the behaviour of pollinators and the reproductive success of Tecomella undulata (Bignoniaceae) in a natural population. Experimental pollinations showed that the trees were strictly self-incompatible. The three types of floral colour morphs of the tree viz. red, orange and yellow, lacked compatibility barriers. The pollinators (Pycnonotus cafer and Pycnonotus leucotis) and the robber (Nectarinia asiatica) showed equal preference for all the morphs, as they visited each morph with nearly equal frequency and flower-handling time. The sunbirds caused up to 60% nectar robbing, mostly (99%) by piercing through the corolla tube. Although nectar is replenished at regular intervals, insufficient amount of nectar compelled the pollinators to visit additional trees in bloom. Data of manual nectar robbing from the entire tree showed that the pollinators covered lower number of flowers per tree (5 flowers/tree) and more trees per bout (7 trees/bout) than the unrobbed ones (19 flowers/tree and 2 trees bout). The robbed trees set a significantly greater amount of fruits than the unrobbed trees. However, the number of seeds in a fruit did not differ significantly. The study shows that plant-pollinator-robber interaction may benefit the self-incompatible plant species under conditions that increases the visits of pollinators among the compatible conspecifics in a population.

Florivory and nectar-robbing perforations in flowers of pointleaf manzanita Arctostaphylos pungens (Ericaceae) and their effects on plant reproductive success

“…The reduced volume of nectar resulted in shorter visits and more inter-plant movement of the bumble bee pollinator of Aconitum napellus , when nectar robbing was simulated (Mayer et al 2014). A similar response of pollinators to nectar-robbed flowers was observed in Tecomella undulata (Bignoniaceae; Singh et al 2014). Another way in which nectar robbing may affect plant reproductive success is by providing an entry to other animals, such as thrips (Eliyahu et al 2015), that can potentially cause damage (Irwin et al 2010).…”

Spatio‐temporal variation of nectar robbing in Salvia gesneriflora and its effects on nectar production and legitimate visitors

“…; Richardson ; Singh et al . ) or if they cause pollinators to travel longer distances to find nectar, which should increase outcrossing (Zimmerman & Cook ). The complexity of this dynamic interaction is increased when spatial and temporal variation in robbing rate is considered.…”

“…If robbers reduce nectar availability and pollinators could discriminate between robbed and unrobed flowers, plant reproductive success would be greatly reduced (Irwin & Brody 1998). Some nectar robbers, however, could have neutral (Guitian et al 1993;Morris 1996) or even positive effects on fruit and seed production if they pollinate flowers during robbing (Maloof & Inouye 2000;Navarro 2000;Irwin et al 2001;Richardson 2004;Singh et al 2014) or if they cause pollinators to travel longer distances to find nectar, which should increase outcrossing (Zimmerman & Cook 1985). The complexity of this dynamic interaction is increased when spatial and temporal variation in robbing rate is considered.…”

Quantifying direct vs. indirect effects of nectar robbers on male and female components of plant fitness

“…; Mayer et al . ; Singh, Barman & Tandon ). Robbers may also have indirect effects on plants via interference competition with pollinators (Roubik ).…”

“…Turning to indirect effects, nectar robbing, like herbivory, may affect floral traits, including nectar availability, nectar sugar concentration, floral volatile production, nectar chemistry, and floral symmetry or attractiveness (given that flowers now contain holes) (Pleasants 1983;Temeles & Pan 2002;Castro, Silveira & Navarro 2008;Kaczorowski et al 2014). These changes in floral traits can lead to negative or positive indirect effects on male and/or female components of plant reproduction via changes in pollinator behaviour (Irwin & Brody 2000;Dohzono et al 2008;Mayer et al 2014;Singh, Barman & Tandon 2014). Robbers may also have indirect effects on plants via interference competition with pollinators (Roubik 1982).…”