A common concern among humans is whether we eat fig wasps when we consume figs. The short answer is yes for dried figs and usually no for fresh figs. The fig species that is eaten is the domesticated fig Ficus carica a dioecious species, which has been in cultivation for about 11 000 years, although an understanding of the role that the pollinating wasp Blastophaga psenes plays in the reproduction of the cultivated fig (the process of caprification) is only a relatively recent elucidation. This fig species occurs naturally in the Mediterranean region, but is also cultivated in this area as well as in various other parts of the world where there is a suitable climate, such as California and South Africa (Kjellberg, F. van Noort, S, Rasplus JY. In press).

The process of caprification where oviposition by the pollinator Blastophaga psenes is required to ensure successful ripening of the female figs still plays an important role in the cultivated fig industry. In natural wild populations of Ficus carica, figs suitable for consumption are produced on female trees only if they are pollinated by Blastophaga psenes, released from figs borne on male trees, which contain both wasps and pollen, and are usually not eaten. The male figs that produce the wasp pollinator were called "caprifigs" because they were not eaten and were said to be “only good for the goats”. Commercial cultivation of fresh figs for the consumer market usually centres on parthenocarpic cultivars, i.e. varieties that have been artificially selected for during the long association of cultivation by humans. These varieties do not need pollination to produce fruit (parthenocarpy). Fig trees will normally abort their fig crop if the figs are not pollinated as the figs are then an energy cost with no benefit to the tree. This artificial selection has resulted in cultivars that produce ripe figs that have not been entered by wasps, and as a result do not form seeds making the fresh fig sweeter and softer. Since no pollination is involved propagation of these cultivars has to be via the process of cuttings (truncheons). This mode of vegetative propagation has allowed for the anthropogenic expansion of the species’ distribution to non-native regions across various parts of the world, and may have been one of the earliest forms of agricultural domestication of a plant species, predating cereal production (Kjellberg, F. van Noort, S, Rasplus JY. In press).

Figs that are grown for dry fig production are usually cultivars that need pollination (caprification) such as the Turkish Sari Lop or Smyrna figs, which have a nutty flavour and contain seeds, in contrast to the sweeter fruit of the parthenocarpic varieties that are much softer without seeds (Armstrong, 1988; 2010; Tribolet, 1912). The fruiting phenology of these Smyrna cultivar is the same as that of wild female trees. The pollinator has hence also been introduced to various parts of the world where Ficus carica is cultivated to enable the production and supply of figs to the dry fig market (Mars, 2003). In many regions, however, these cultivars are being progressively replaced by cultivars that do not require pollination in order to avoid sanitary problems, such as transmission of internal rot fungus by the pollinators, and costs (Kjellberg, F. van Noort, S, Rasplus JY. In press).

Female fig wasp pollinators enter the fig through the ostiole (opening at the apex of the fig) to pollinate the flowers and to lay their eggs down the style into the ovary of the flower. See lifecycle. However, Ficus carica is a functionally dioecious species, which means that the male and female reproductive functions of the species are separated between individual trees, with some trees being female and others male. Female trees produce seeds in the  figs and no wasps, whereas male trees produce a few seeds but mostly wasps. The wasps then load up pollen before dispersing from the fig they have bred in and hence perform the male function for the species. How does this happen?

If figs from female trees of cultivars such as the Smyrna fig that do require pollination are used in fig production there is a possibility of eating wasps because the foundress females that entered the fig to pollinate the flowers often do not manage to exit the fig again. On occasion the female wasps will escape from the fig they entered. The wasps do not manage to breed in the fig, because the floret styles are too long for the female's ovipositor to reach the ovule to lay an egg, and only seeds are produced as a result of her pollination of the stigmas, with these figs performing the female function for the species.

In California and South Africa the Caprifig trees (male trees) of Ficus carica produce three caprifig crops per year: the summer profichi crop (with galls and male flowers); an autumn mammoni crop (galls and abortive male flowers); and an overwintering mamme crop (galls and abortive male flowers) where the figs only mature the following spring (Armstrong, 1988; Giliomee et al 2007; Tribolate, 1912). Pollen laden female fig wasps leaving the profichi crop enter the mammoni crop and oviposit into the ovules; the resulting wasp progeny leaving this crop then oviposit in the mamme crop and those wasps then complete the cycle by ovipositing in the profichi crop again. Pollen from the profichi crop is used to pollinate the Smyrna (Calimyrna) orchards in mid-summer, as the other two crops do not produce pollen in the figs (Armstrong, 2010). The wasps survive the cold winter months as larvae in the overwintering mamme crops. Female trees produce two fig crops per year: the breba crop, ripening in early summer; and the main second crop ripening in autumn. The process of caprification can aid the transmission of internal rot fungus or endosepsis (Fusarium moniliforme var. fici (Caldis, 1927) from the male caprifigs to the female Smyrna figs (Armstrong, 2010; Caldis, 1927; Davey and Smith, 1933; Michailides and Morgan, 1998; Wohlfarter et al 2011). Intervention is required to avoid this transmission. In California the overwintering mamme crop is harvested in spring and the figs are treated with a fungicide after being split open (Armstrong, 2010). They are then re-introduced to the orchards so that the emerging wasps can enter the profichi crop. This fungus can result in considerable crop losses, with hot and humid conditions being ideal for rapid transmission (Caldis, 1927; Michailides and Morgan, 1998; Wohlfarter et al 2011; Kjellberg, F. van Noort, S, Rasplus JY. In press).

Wild figs are also very nutritious and eaten by many indigenous people. In these cases the fig wasps that have not departed from the fig they bred in are consumed along with the fig. Most of the fig wasps will have left the fig before it ripens and becomes attractive to frugivores, but many species have wingless males which die and remain within the fig cavity. There are also nematode worms that are specific to fig wasps and a host of other fungal organisms residing within the fig cavity of wild figs, but these don't appear to have any negative effect on human health.

Links

Ficus carica and its pollination (Kjellberg & Lesne 2020).

Purdue University's NewCrop site (For information on varieties, cultivation and uses).

The Calimyrna fig and its pollinator wasp (Armstrong, 2010).

References

Armstrong, W.P. 1988. The calimyrna fig and its wasp. California Garden 79, 135-138.
Armstrong, W.P. 2010. Calimyrna Figs in California. Available at:
https://www2.palomar.edu/users/warmstrong/pljune99.htm

Caldis, P.D. 1927. Etiology and transmission of endosepsis (internal rot) of the fruit of the Fig. Hilgardia 2, 287–346.

Davey, A.E. and Smith, R.E. 1933. The epidemiology of fig spoilage. Hilgardia 7, 523–551.
Gaaliche, B. Trad, M. Mars, M. 2011. Effect of pollination intensity, frequency and pollen source on fig (Ficus carica L.) productivity and fruit quality. Scientia Horticulturae 130 (4): 737-742.

Giliomee JH, Venter E, Wohlfarter M. 2007. Mediterranean black fig fly, Silba adipata McAlpine (Diptera: Lonchaeidae), recorded from South Africa. African Entomology 15: 383-384. https://doi.org/10.4001/1021-3589-15.2.383

Kjellberg, F. and Lesne A. 2020. Ficus carica and its pollination. https://hal.archives-ouvertes.fr/hal-02516888

Kjellberg, F. van Noort, S, Rasplus JY. In press. Fig wasp and pollination. In Sarkhosh, L. Ferguson, A.M. Yavari (Editors): The Fig: Botany, Production and Uses. CAB International.

Mars, M. 2003. Fig (Ficus carica L.) genetic resources and breeding. Acta Hortic. 605, 19–27. http://dx.doi.org/10.17660/ActaHortic.2003.605.1

Michailides, T.J. and Morgan, D.P. 1998. Spread of endosepsis in Calimyrna fig orchards. Phytopathology, 88, 637–647.

Stover, E., Aradhya, M., Ferguson L. & Crisosto, C.H. 2007. The fig: Overview of an ancient fruit. HortScience 42:1083–1087.

Tribolet, I. 1912. Caprification of smyrna figs. Agricultural Journal of the Union of South Africa 3: 247-256.

Wohlfarter M, Giliomee JH, Venter E, Storey S. 2011. A survey of the arthropod pests and plant parasitic nematodes associated with commercial figs, Ficus carica (Moraceae), in South Africa. African Entomology 19: 165-172. https://doi.org/10.4001/003.019.0118 

Credits

Photographs © Simon van Noort (Iziko Museums of South Africa).