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"The females then have to gain entry through the ostiole, which acts as a physical barrier. The ostiolar bracts become looser at the receptive phase to make penetration easier (Verkerke, 1986), but a proportion of pollinator females fail to pass successfully through the ostiole (Liu et al., 2013) in spite of their morphological adaptations to aid entry (Ramirez, 1974; van Noort et al., 1989; Verkerke, 1989). "
[Show abstract][Hide abstract] ABSTRACT: 1. Fig trees (Ficus spp.) and their host-specific pollinator fig wasps (Agaonidae) are partners in an obligate mutualism. Receptive phase figs release specific volatiles to attract their pollinators, and this is generally effective in preventing pollinator species from entering figs of the wrong hosts.2. If entry is attempted into atypical host figs, then ostiole size and shape and style length may also prevent reproduction. In spite of these barriers, there is increasing evidence that fig wasps enter atypical hosts, and that this can result in hybrid seed and fig wasp offspring.3. This study examines the basis of pollinator specificity in two dioecious fig species from different geographical areas. Kradibia tentacularis pollinates Ficus montana in Asia. Ficus asperifolia from East Africa is closely related but is pollinated by a different species of Kradibia.4. In glasshouses, K. tentacularis was attracted to its normal host, F1s and backcrosses, but only rarely entered figs of F. asperifolia. Foundresses were able to lay eggs in hybrids, backcrosses, and F. asperifolia, although flower occupancy was lowest in F. asperifolia figs and intermediate in hybrids.5. The fig wasp failed to reproduce in female F. montana, male F. asperifolia, and male F1s, and most but not all backcrosses to F. montana. This was a result of the failure to initiate gall production.6. Host specificity in this fig wasp is strongly influenced by host volatiles, but the ability to gall may be the ultimate determinant of whether it can reproduce.
"Olfactory attraction is considered a reasonable way by which fig trees attract huge number of these tiny specific pollinators from far away. Although chemical attraction was suggested more than 50 years ago (Condit, 1947), studies on it are still preliminary (Barker, 1985; Baijnath et al., 1986; Bronstein, 1987, 1992; van Noort et al., 1989; Ware et al., 1993; Ware and Compton, 1994; Gibernau et al., 1997; Grison et al., 1999). An investigation using fig-bearing trees and arrays of sticky traps baited with figs suggested that the wasps are attracted to the trees by volatiles emanating from the figs and that wasps are specifically attracted to figs of their host species only at the time when figs are ready to be pollinated (Ware and Compton, 1994). "
"To ensure synchronization of fig wasp attraction with the presence of figs that are ready to be entered, figs emit developmental stage and species-specific volatiles that are only attractive to their particular species of pollinators at the time when the figs are receptive –. The duration of receptivity is prolonged if a fig remains unpollinated , , , which means that receptive figs can ‘wait’ for pollinators if they are in short supply at the time when they first become receptive. "
[Show abstract][Hide abstract] ABSTRACT: Adult life spans of only one or two days characterise life cycles of the fig wasps (Agaonidae) that pollinate fig trees (Ficus spp., Moraceae). Selection is expected to favour traits that maximise the value of the timing of encounters between such mutualistic partners, and fig wasps are usually only attracted to their hosts by species- and developmental-stage specific volatiles released from figs at the time when they are ready to be entered, oviposited in and pollinated. We found that Ficus altissima is exceptional, because it has persistent tight-fitting bud covers that prevent its Eupristina altissima pollinator (and a second species of 'cheater' agaonid) from entering its figs for several days after they start to be attracted. We examined the consequences of delayed entry for the figs and fig wasps and tested whether delayed entry has been selected to increase adult longevity. We found that older pollinators produced fewer and smaller offspring, but seed production was more efficient. Pollinator offspring ratios also varied depending on the age of figs they entered. The two agaonids from F. altissima lived slightly longer than six congeners associated with typical figs, but this was explainable by their larger body sizes. Delayed entry generates reproductive costs, especially for the pollinator. This opens an interesting perspective on the coevolution of figs and their pollinators and on the nature of mutualistic interactions in general.
PLoS ONE 01/2014; 9(1):e86735. DOI:10.1371/journal.pone.0086735 · 3.23 Impact Factor