Caprifigs and Wasps

A mutualistic relationship exists between caprifigs and a species of wasp, Blastophaga psenes, that leads to potential benefits for neighboring Calimyrna fig trees. When the wasps are pregnant, they enter the syconium of a caprifig through an opening called the ostiole. The wasps look to deposit their eggs into an ovary inside of the syconium. In doing so, the wasp inadvertently gathers pollen as it brushes against the stigma of the flower. Flowers that do not have eggs deposited inside them turn into seeds, or drupelets. When the male wasps mature inside of the flower, they break out and roam the inside of the syconium looking for a female wasp to mate with. When they are successful in their quest, they burrow a tunnel so that the female is able to emerge from the syconium and fly to another fig to lay her eggs. Because Calimyrna figs and caprifigs are among the same species, the female wasps looking for a new fig cannot differentiate their volatile emissions. This is beneficial for Calimyrna figs because the caprifigs create a breeding ground for more wasps to hatch and ultimately bring pollen to the Calimyrnas. However, the flowers in the Calimyrna figs have too long of styles for the female wasps’ ovipositors to successfully lay their eggs in the ovary. With each unsuccessful attempt, the wasps deposit pollen unbeknownst to them onto each flower they come in contact with. This becomes problematic in excess. If there are too many wasps unintentionally pollinating the flowers inside of a fig, there will be an excess of drupelets produced. The abundance of these drupelets that are mostly comprised of water will result in a pressure buildup and the splitting of the fig.

In an effort to combat this problem, pruning caprifig trees every so often will decrease the chance of overpollenation in the Calimyrna figs. Removing some branches from the caprifig will stabilize the number of wasps emerging from the syconium and consequently the number of wasps bringing pollen to the Calimyrna tree. In order to determine how much the caprifig tree should be pruned, one may want to experiment with placing some paper bags filled with caprifigs onto the Calimyrna tree in June when the female wasps are just about to come out of the flower.

“The Calimyrna Fig & Its Pollinator Wasp.” Calimyrna Figs In California, 2010,
“The Secret Life Of Figs Or How We Eat Wasps.” PRE-TEND Be Curious., 13 July 2015,
Ware, Anthony B., et al. “Fig Volatiles: Their Role in Attracting Pollinators and Maintaining Pollinator Specificity.” SpringerLink, Springer-Verlag, 18 Jan. 1993,