Fig wasps (Agaonidae) are so named because of the mutualistic relationships they have with fig trees (
Ficus
spp.). Both fig wasps and trees are native to western Asia; they were later introduced to the Mediterranean area. It is believed that fig culture began in Greece in the 9th century B.C. and spread from there throughout Europe and to North Africa, England, Mexico, and the United States. Edible fig (
Ficus carica
) production began in the United States in California in 1889 after the correct fig wasp pollinator,
Blastophaga psenes
, was introduced.
The relationship between fig trees and their wasp pollinators is an obligate pollination mutualism, because the plant and its pollinator are totally dependent upon one another to complete reproduction. The fig fruit is actually a specially adapted inflorescence called a synconium, which conceals many tiny flowers. Pollination begins when a female wasp, already covered with pollen from the fig in which she hatched and developed, flies to a new fig synconium and enters a tiny hole at one end. In the process, the wasp's fragile wings often break off. Inside the synconium, the female wasp crawls among the female flowers, of which there are two types - one with a short style into which her ovipositor fits, and one with longer styles, in which she cannot lay eggs. The wasp deposits an egg inside the ovary of each of several short-styled flowers; the long-styled flowers are fertilized by the wasp's pollen load as she climbs over them in her search for oviposition sites. Once she has laid her eggs, the wasp remains inside the synconium, where she eventually dies.
The wasp eggs develop within the flowers. As an adult, the male wasp
will chew its way out of its own flower and will then create a hole in a
female's flower from which she can escape. They mate and the female
then moves toward the tiny opening at the end of the synconium. To reach
the hole, she crawls over male flowers and becomes covered with pollen.
The male wasp enlarges the opening, allowing the female to escape the
synconium and to fly to another, ripening inflorescence to begin the
process again. The male remains inside where he dies.
References:
Quick Guide: Figs and Fig Wasps, J. M. Cook and S. A. West, Current Biology, vol. 15, no. 24, December 2005;
Figs and fig wasps, S. van Noort and J. Y. Rasplus, Iziko Museums of Cape Town;
Book of Insect Records: Chapter 25 Greatest Host Specificity, G. H. Schneider, University of Florida, April 15, 1997;
Fig Fruit Facts, California Rare Fruit Growers, Inc.;
Fig Wasp (Hymenoptera: Chalcidoidea: Agaonidae, Pteromalidae, Eurytomidae and Ormyridae) and
Ficus
(Moraceae) Species Richness and Biogeography of Monts Doudou in
Southwestern Gabon, Simon van Noort, California Academy of Sciences
Memoir, vol. 28, 2004, pp. 217-233