A new type of egg produced by foundress queens of Atta texana (Attini, Formicidae)

Abstract

In the fungus-growing ant genus Atta, foundress queens nourish their brood and incipient fungus gardens with nutrients derived from trophic eggs. We discovered a third kind of egg laid by Atta foundresses in addition to reproductive and trophic eggs. We use fluorescent microscopy to show that this third type of eggs represents reproductive eggs that are unviable and fail to develop. Unviable reproductive eggs are somewhat larger (≈ 490 µm × 317 µm) than regular reproductive eggs (≈ 425 µm × 240 µm), but smaller than trophic eggs (≈ 640 µm × 530 µm). Trophic eggs liquify by some endogenous process within 24 h after oviposition to release nutrient contents. Unviable reproductive eggs do not liquify, but unviable reproductive eggs can be digested by the fungus, whereas reproductive eggs are not digested by the fungus to complete their development. We also report the first observation for A. texana of nanitic males (presumably diploid males) that were killed by the foundress queen shortly after the males’ eclosion.