Nest structure, pollen utilization and parasites associated with two west-Mediterranean bees (Hymenoptera, Apiformes, Megachilidae) nesting in empty snail shells

Petr Bogusch,Lucie Hlaváčková,Jordi Bosch,Libor Petr

doi:10.3897/jhr.76.49579

Abstract

Around thirty species of European solitary bee species in the family Megachilidae nest in empty gastropod shells. We surveyed this group of bees in semi-natural sites adjacent to almond orchards near Lleida (north-eastern Spain) and collected 35Hoplitis fertoniand 58Osmia ferrugineanests in shells of six snail species. We describe the nest structure and report the identity of pollens collected by the two bee species. Both species adjust the number of brood cells to the size of the shell and occasionally build intercalary (empty) cells.H. fertoniuses clay andO. ferrugineachewed plant leaves for building cell partitions and nest plugs. Most nests of both species were built inSphincterochila candidissimashells. Analysis of the pollen of selected nests confirmed thatH. fertoniis oligolectic on Boraginaceae (in our study all pollen was fromLithodora fruticosa) andO. ferrugineais a polylectic species (collecting mostly pollen from Cistaceae, Fabaceae, and Lamiaceae in our study area). Nests ofH. fertoniwere parasitized by five species, the golden waspChrysura hybrida, the cuckoo beeDioxys moesta, the velvet antsStenomutilla collarisandStenomutilla hotentotta, and the bee-flyAnthrax aethiops; nests ofO. ferrugineawere parasitized by the sapygid waspSapyga quinquepunctataandA. aethiops. Except forC. hybridathese are newly recorded host-parasite associations. Our results confirm previous information and bring new findings on the ecology of both species.

Highlights

Bees (Anthophila/Apiformes) are a very speciose clade of Hymenoptera, with more than 20,000 species worldwide (Michener 2007)
During our studies on shell-nesting bees near Lleida (Catalonia) in northeast Spain we collected a good number of nests of Hoplitis fertoni and Osmia ferruginea, two species with a Mediterranean distribution
Most pollen grains were of Cistaceae, Fabaceae (Cytisus type), and Lamiaceae (Table 1; Fig. 3B). Nest structures of both species correspond to the nest descriptions published by previous authors (Ferton 1905, 1908; Benoist 1931; Grandi 1961; Haesseler 1997; Le Goff 2003; Moreno-Rueda et al 2008; Müller et al 2018; Müller 2019). Both Hoplitis fertoni and Osmia ferruginea belong to the group of species building high numbers of brood cells per nest

Summary

Introduction

Bees (Anthophila/Apiformes) are a very speciose clade of Hymenoptera, with more than 20,000 species worldwide (Michener 2007). A small group of species have specialized in nesting in empty gastropod shells This behaviour is widespread in the Old World (Müller et al 2018), including the Palaearctic and Southern Africa (Gess and Gess 1999, 2008), but much rarer in the New World (Michener, 2007). In Europe about 30 species in the genera Osmia, Hoplitis, Protosmia and Rhodantidium are known to construct nest in gastropod shells. The majority of these species have distributions restricted to the southernmost part of the continent (Müller 1994; Müller et al 2018). During our studies on shell-nesting bees near Lleida (Catalonia) in northeast Spain we collected a good number of nests of Hoplitis fertoni and Osmia ferruginea, two species with a Mediterranean distribution

Methods

Results

Conclusion