Effect of cell position of nest comb on development and survival of immatures in pre‐emergence colonies of a paper wasp Polistes jokahamae (Hymenoptera, Vespidae)

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Abstract Polistes , primitively eusocial wasps, build paper nests using plant fibers and oral secretions produced by the wasps themselves. In general, a single larva is reared one per cell, spinning a completely closed cocoon upon pupation. By contrast, in the subgenus Gyrostoma of Polistes , the same cell is often simultaneously occupied by two successive broods. After cocoon spinning by the post‐feeding larvae in the central cells, an additional egg was laid on the silk cap inside the cell. Eggs grow and attain second‐instar larvae during the emergence of older occupants. In addition to the eggs laid on the silk cap, eggs are laid in newly constructed cells outside the combs. Although a recent study suggested that rearing two immatures in a single cell improved the cost of construction and maintenance of the nest, the disadvantages of rearing multiple immatures in a single cell have not yet been evaluated. We compared developmental time and mortality rates between immatures reared on silk caps in the central cells and those in the peripheral cells. In the central cells, the merit of shorter development for 1–2 days of the first‐instar larvae was shown; however, this was almost offset by the demerit of longer egg development. The survival rates of the eggs and first‐instar larvae did not differ between the two cell positions. We concluded that rearing two immatures in a single cell does not result in disadvantages during the early stages of development.