Life cycles and host–parasitoid relationships of five species of Leucospis wasps in Argentina (Hymenoptera: Leucospidae)

ABSTRACT

The genus Leucospis Fabricius is comprised of parasitoid wasps relatively uncommon in nature. Their immature stages develop on aculeate Hymenoptera, in particular solitary bees, but hosts are known for only around 25 Leucospis species (about 20% of 115–120 world species), so the true relationship of this family with bees is largely unknown. Here we report on individuals of five species of Leucospis wasps which emerged from nests of different bee and wasp species during distinct sampling periods during a trap-nesting programme, in two contrasting areas: agro-ecosystems and natural habitats in the Pampean region. Some of these nests were parasitised by L. cayennensis Westwood, L. coxalis Kirby, L. egaia Walker, L. pulchriceps Cameron and L. signifera Bouček. Our results expand the available information of host species for L. cayennensis, L. coxalis, L. egaia and L. pulchriceps and represent the first record of hosts associated with L. signifera. The hosts were only bee species of the genera Centris, Tetrapedia (family Apidae) and Megachile (Megachilidae). These species were more abundant in the natural reserve than in agro-ecosystems, suggesting that anthropogenic activities could negatively affect their populations. Most nests were attacked in one (43.7%) or two (40.7%) cells, but the remaining nests (16.5%) had more (up to seven cells). However, the position of the attacked cells was variable, suggesting that females of Leucospis species oviposit in recently built cells, and that the hatching of larvae is delayed, or that the first larval stage waits until the host larva reaches a sufficient size to attack.

KEYWORDS:

• Apidae
• biology
• Centris
• Megachile
• Megachilidae
• parasitoid behaviour
• Tetrapedia

Acknowledgements

Thanks to family Rúgolo de Agrasar (Ea. Anquilóo, Toay); Universidad de Buenos Aires (Ea. San Claudio, Carlos Casares) and the Dirección de Áreas Naturales Protegidas, Organismo Provincial Para el desarrollo Sostenible, of the Provincia de Buenos Aires (Multiple-uses Natural Reserve Martín García) for permissions to conduct this study. A. Roig Alsina for collaboration in the determination of Leucospis spp. and S. Durante for determination of Megachilidae bees. A. Torretta for helping with the English revision. The manuscript benefited from critical reading by A. Polaszek and one anonymous reviewer. JPT, GARM and DAA are affiliated with CONICET.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Agencia Nacional de Promoción Científica y Tecnológica [PICT 0851,PICT 08–12504]; Consejo Nacional de Investigaciones Científicas y Técnicas [CONICET PIP 2012-2014 (11220110100312)].