Conclusion

We are indebted to Crowson (1991), who made an extensive study of beetles associated with cycads. The observations, made and recorded in Panama and elsewhere in Central America, have provided further information. Pollination among aberrant gymnosperms like Gnetales is done by Lepidoptera and Diptera (Kato et al, 1995). It is not the same for cycads, on which caterpillars feed only on the leaves. Entomophily seems predominant among the cycads, but it is not the exclusive mode of pollination. It seems that entomophily is mainly due to the odour produced by the strobilas, which also produce nectar. Among the Araucaria (Coniferae), Palophaginae (Chrysomelidae) and Nemonychidae (Curculionoidea) live within the male strobils, but do not seem to visit the female strobili, and they don't help in fertilization. What happens among the cycad cones? It seems that there is often passage from male strobilus to the female one, and thus the fertilization is helped by beetles. However, many are beetles, which only frequent the fronds and never visit male or female cones, such as LLilioceris and probably many langurids. It is possible that some of them, like the aulacoscelines, visit the female cones only to lay eggs there. The cycads or Bennetitales cones, during the Mesozoic, were bisexual and pollinated by borers, probably beetles, as suggested by fossil traces. They were of a protofloral type, probably protandrous, that is male organs maturing earlier, while the present cycads have separate sexes, which makes fertilization more difficult.

The associations of cycads with aulacoscelines, Boganidae, and some weevils, are very ancient. When PJ visited with Don Windsor the Zamia parks in Panama, they got the impression of visiting "Jurassic Park". Only dinosaurs were missing. Langurids and curculionids were also present on Zamiafloridana cones in Florida. There the "Jurassic Park" impression was not complete, since the Aulacoscelis, so common in Mesoamerica, have not yet reached Florida. A recent capture of a larva of an aulacoscline in Florida inside a Dioon seed could prove the contrary.

— Fig. 23.1. Cycad ancestors were certainly pollinated by beetles. A Jurassic Williamsonia and a Bennetitale (after Jolivet, 1998). Bennetitales had bisexual flowers. Not the cycads.

— Fig. 23.2. A correct representation of a Bennetitale, Cycadeoiea sp. The place of the flowers is still controversial (after Delevoryas, 1971).

— Fig. 23.3-23.6. Rhopalotria mollis Sharp (Col. Curculionidae), pollinator of Zamia furfuracea L. female and male, with swollen femora (after Norstog and Fawcett, 1989).

— Fig. 23.7-23.8. Pharaxonota zamiae Blake and Fabricius (Col., Languridae), which feed on male cones of Zamiafloridana, larva and adult (after Norstog et aL, 1992). This insect does not feed on fronds of the host plant.

— Fig. 23.9. Zamiafairchildiana Gomez, in Parco Nacional de Chagres, Panama. A: Zamiafairchildiana Gomez. The forest.

B: A head of Zamia, with tender leaves (fronds) to be attacked during spring time by Aulacoscelis spp.

C: Aulacoscelis melanocera Stal (Col. Chrysomelidae), adults feeding on the fronds.

D: Nomotus lateralis (Col. Languridae) feeding on Zamia leaves. (All photos by Jolivet, 1998).

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