Artocarpus species such as Jackfruit (A. heterophyllus) Cempedak ( A. intger) and Terap (A. odoratissimus) are such prolific fruiters that it is obvious to any casual observer that there is a tendency for these species to fruit simultaneously during the annual fruiting season in Borneo.
There are two well researched reasons for gregarious fruiting (masting);
- Successful Pollination: So that male pollen will be able to land on receptive female stigmas on an unrelated tree, instead of being wasted. Note that Artocarpus species are monoecious with separate male and female flowers on the same tree. However male flowers do not produce pollen whilst female flowers on the same tree are receptive. This means that Artocarpus are “obligate outcrossers” and cannot self pollinate.
- Seed Predator Satiation: So that the local Artocarpus seed predators eg squirrels, rats and langurs will be overwhelmed with food when the crops ripen simultaneously and some seeds at least will survive. A strategy known as predator satiation.
However ,casual observation also tells us that wild species of Artocarpus are more likely to fruit together simultaneously whilst the more common cultivated species may fruit sporadically throughout the year presumably because of human selection of cultivars which fruit “out of season”.
Several different studies of the foraging by the Dawn Nectar Bat Eonycteris spelea have shown that Artocarpus nectar and pollen is an important part of their diet.
At the Batu caves near Kuala Lumpur, Start ( 1974) and (1976) found that Artocarpus pollen was present in E. spealea feces almost continuously throughout the year whilst other sources of food such as Sonneratia, Durio and Parkia flowered more sporadically.
Also at the Batu Caves Lim and Wilson (2018) by analyzing the DNA of plant remains in E. spelea feces found that A. heterophyllus was the most regular provider of nectar and polen. A. heterophyllus (Jackfruit) is widely cultivated in home orchards around Kuala Lumpur.
Prior to these studies botanist believed that Artocarpus was either wind pollinated or pollinated by specialized beetles feeding on a fungus that grew on Artocarpus flowers.