A further study of the nesting biology of Leptochilus (Neoleptochilus) regulus (de Saussure, 1855) (Hymenoptera, Vespidae, Eumeninae)

Abstract

Two females of Leptochilus regulus (de Saussure, 1855) were observed nesting in reed stalks of a Fabre’s hive serving as a block of trap nests in Crimea, with the timekeeping of all their nesting behaviours. The building material used by the females to separate the nesting cavity into the cells consisted of pellets of dry soil, gravel particles, and small fragments of tree bark, leaves, and thin stems. Females rapidly carried these items collected in 1.0–1.5 m from the nests. They bonded only the last portions of the building material in each “partition” with a very small amount of mud. An additional amount of unbonded building material items was deposited into the nest after sealing the last nest cell. Females hunted exclusively for small larvae of an anobiid beetle (Coleoptera, Anobiidae); they stored 19–37 prey items per cell. Hunting and provisioning occupied the largest portion of the females’ time budget. Duration of hunting flights was different between the females. The nests of both females contained three brood cells. Cocoons of Chrysis ragusae De Stefani, 1888 (Hymenoptera, Chrysididae) were found in the nests; females of this cuckoo wasp species were also recorded entering the host nests at the stage of provisioning, acting apparently as inquilines. The cocoon ultrastructure of L. regulus is illustrated and discussed.