Vespa velutina nigrithorax venom allergy: inhibition studies approach for the choice of specific immunotherapy.

Summary: Vespa velutina nigrithorax (VVN), commonly known as Asian wasp because endemic in Asia, represents an alien species in Europe. VVN can induce allergic reactions similar to those caused by other Hymenoptera and death after VVN stings, presumably due to fatal allergic reactions, has been reported. In the treatment of Hymenoptera venom hypersensitivity, specific immunotherapy (VIT) is highly effective. Currently, there is no specific available VIT for VVN, so it is relevant to assess if patients stung by VVN and showing allergic reactions could be treated with the Hymenoptera commercially available extracts Vespa crabro (VC) and Vespula spp (Vspp) or if they need the specific VIT with VVN venom extract. Methods. Four patients with a clinical history of systemic reactions after VVN sting were evaluated. Serum specific IgE were assayed quantitatively with an automated fluoro-enzyme immunoassay ImmunoCAP™ Specific IgE by Phadia™ 1000 System (Thermo Fisher Scientific, Uppsala, Sweden) for VC, Vspp and VVN. Cap inhibition assays were performed incubating serum samples with 200 µl of each venom at increasing concentrations and subsequently specific IgE against each of the venoms were determined in the samples by Phadia™ 250 System (Thermo Fisher Scientific, Uppsala, Sweden). Results. Our results suggested that both Vspp and VC venoms were able to inhibit the specific IgE for VVN, although the VC compared to the Vspp venom showed a higher inhibition. Conclusions. Our inhibition studies suggested that VIT with VC venom, nowadays when there is not specific available VIT for VVN, may be more effective than Vspp VIT in patients with VVN sting reactions.

Use of Dufour's gland secretion in nest defence and brood nutrition by hover wasps (Hymenoptera, Stenogastrinae).

Social wasps of the subfamily Stenogastrinae produce an abdominal secretion that is used in two distinct biological contexts. First, the secretion plays an important role in larval nutrition where it serves as a substrate in which food is placed by the adults for eventual consumption by the larvae. Second, in several species, females apply the same secretion to the substrate on which their nests are constructed, where it constitutes a sticky barrier that defends the immature brood from predation by ants. This paper describes for the first time ant guard construction behaviour of three species of stenogastrine wasps belonging to the genera Eustenogaster and Liostenogaster. The identification of compounds making up these secretions was also performed by gas chromatography-mass spectrometry. Ant guards and brood secretions were similar, with saturated and unsaturated long chain hydrocarbons and alcohols as major components. We further confirm that the glandular source of abdominal secretion is the Dufour's gland. This gland contains the same hydrocarbons, and in the same proportions as ant guards and brood secretion. We discuss the fundamental importance of Dufour's gland secretion in the social life of these wasps by comparing species with and without ant guards within the subfamily.