Elisabetta Francescato

Sublingual immunotherapy for large local reactions caused by honeybee sting: A double-blind, placebo-controlled trial

BACKGROUND Sublingual immunotherapy (SLIT) proved effective and safe in respiratory allergy, and thus its use in hymenoptera allergy can be hypothesized. OBJECTIVE We sought to assess, in a proof-of-concept study, whether SLIT might potentially be beneficial in hymenoptera allergy. The sting challenge in large local reactions (LLRs) was used to test this hypothesis. METHODS We performed a randomized, double-blind, placebo-controlled study involving patients with LLRs who were monosensitized to honeybee. After the baseline sting challenge, they were randomized to either SLIT or placebo for 6 months. The treatment (Anallergo, Florence, Italy) involved a 6-week build-up period, followed by maintenance with 525 microg of venom monthly. The sting challenge was repeated after 6 months. RESULTS Thirty patients (18 male patients; mean age, 44.5 years) were enrolled, and 26 completed the study, with 1 dropout in the active group and 3 dropouts in the placebo group. In the active group the median of the peak maximal diameter of the LLRs decreased from 20.5 to 8.5 cm (P = .014), whereas no change was seen in the placebo group (23.0 vs 20.5 cm, P = not significant). The diameter was reduced more than 50% in 57% of patients. One case of generalized urticaria occurred in a placebo-treated patient at sting challenge. No adverse event caused by SLIT was reported. CONCLUSION Honeybee SLIT significantly reduced the extent of LLRs, and its safety profile was good. Although LLRs are not an indication for immunotherapy, this proof-of-concept study suggests that SLIT in hymenoptera allergy deserves further investigation. Trials involving systemic reactions and dose-ranging studies are needed.

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 Dufours gland. This gland contains the same hydrocarbons, and in the same proportions as ant guards and brood secretion. We discuss the fundamental importance of Dufours gland secretion in the social life of these wasps by comparing species with and without ant guards within the subfamily.

A distinct caste difference in Polybioides tabidus (Fabricius) (Hymenoptera: Vespidae)

SummaryQueens ofPolybioides tabidus differ from workers of the same species in the presence of very much longer bristles on the eyes and head and in the size of some morphological characters. The presence/absence of eye bristles in queens/workers of P. tabidus is the first qualitative morphological caste difference reported in the Polistinae.

Colony Membership, Division of Labor, and Genetic Relatedness Among Females of Colonies of Eustenogaster fraterna (Hymenoptera, Vespidae, Stenogastrinae)

To compare the social structure of primitively social wasps with that of communal breeding vertebrates, we used a new technique based on micro videocameras applied to the nest envelope to study the organization of behavior in Malaysian colonies of the stenogastrine wasp Eustenogaster fraterna. The reproductive division of labor in this species appears to be different from that reported so far in other species of Stenogastrinae: it is at a very primitive stage because the helpers work less hard and take fewer risks than the egg-layers. Nevertheless, the very low-risk tasks performed by the helpers (nest guarding and supply of abdominal secretion to the young larvae) are important for the colonies. Behavioral characters and ovarian development of the helpers suggest that females are only temporary helpers and that they wait to start their own production of offspring in the hope of inheriting the nest. Females of the same colony can be highly related, but in some colonies we found low-related individuals. The social organization of these wasps resembles that of vertebrate groups with helpers at the den, i.e., in the small number of individuals, the division of labor with limited reproductive inhibition, and the prolonged external work of the reproductive individuals. However, the main drive to sociality in these insects appears to be different, being based mainly on problems connected with short adult life and long immature brood development.

Evaluation and validation of a bee venom sting challenge performed by a micro-syringe

BACKGROUND The honeybee sting challenge is considered a reliable procedure to evaluate the efficacy of specific immunotherapy, but it is difficult and unpractical to perform in clinical practice, because live insects are required. OBJECTIVE To assess the feasibility and reliability of a challenge test using a micro-syringe, and compared the procedure with sting challenge. METHODS Patients on bee venom immunotherapy and without systemic reactions at field sting were enrolled. They underwent a sting challenge with live bee, and large local reactions were assessed up to 48 hours. Those patients displaying systemic reactions at the sting challenge were excluded from the syringe challenge for ethical reasons. The syringe challenge was done by injecting 0.5 μL fresh unfiltered bee venom at 2 mm depth (the length of the sting left by a bee). The same follow-up as at the first challenge was performed. Bee-specific immunoglobulin E (IgE) and tryptase were measured after each challenge. RESULTS Nineteen patients underwent the sting challenge with live bees. Four had immediate systemic reactions (urticaria or asthma) and were excluded from the second challenge. The remaining 15 patients with large local reaction underwent the syringe challenge. No significant difference was seen in the maximum area of the large local reactions between the challenge with live bees and the syringe challenge. Also, no change was seen in tryptase and specific antibodies. CONCLUSION This preliminary study suggests that the micro-syringe challenge with honeybee venom is feasible and produces results indistinguishable from those of the traditional sting challenge.

Associative colony foundation in the tropical wasp Belonogaster juncea juncea (Vespidae, Polistinae)

Summary: The development of colony foundations of Belonogaster juncea juncea(Fab.) was studied both in the field (Messa quarter, Yaoundé, Cameroun) and in captivity (University of Florence, Italy). Colonies were first initiated by single females who could be joined by other foundresses (2 to 8) coming, in their great majority, from the same maternal colony as the initial foundress female. The co-foundresses remained faithful to one single colony or joined other colonies originating from the same maternal colony and remained, preferentially, on those with the more advanced immature brood. In most cases the nest starter turned out to be the dominant female and her position was usurped in only four cases. Only 25 % of the haplometrotic foundations reached the post-emergence phase while it was reached by 56.7 % of the associative foundations. Only the latter succeeded in producing sexuals. The division of labour between associated females is similar to that observed in other social wasps with dominant individuals who are seldom absent from the nest, lay eggs and perform abdominal vibrations and subordinate individuals that are active foragers. The possibility of a swarming colony foundation in this species is briefly discussed.

Nest and brood recognition in Belonogaster juncea juncea (Hymenoptera Vespidae)

The nest-exchange technique was employed on colonies of Belonogaster juncea juncea to study the degree of nest and immature brood recognition in adults. In each experiment two nests, approximately at the same stage of development and found in the field, were exchanged and the behaviour of the females was recorded before and after their substitution. Checking the nests 24 hr after the exchange showed that all the experimental nests had been accepted by the alien females and that a portion of the eggs and immature larvae had been destroyed. It seems that just one female on each nest is responsible for destroying the immature brood. None of the behaviours performed by the females suggested that they applied secretion over the nest surface and immature brood. From the results of the experiment, it appears that a nest and brood recognition mechanism exists in this species, which is probably based on characteristic odours.

Glandular apparatus associated with the gastral tergal tegument in males ofStenogaster concinna andAnischnogaster laticeps (Hymenoptera: Stenogastrinae)

SummaryMales ofAnischnogaster laticeps andStenogaster concinna possess clusters of glandular class III cells (Noirot and Quennedey, 1974) under the anterior edge of the 3rd gastral tergite. Their morphology is described with the help of histological sections and SEM investigation.

Note sull’architettura del nido e sull’allevamento della prole in Polybioides raphigastra (Vespidae, Polistinae)

II nido diPolybioides raphigastra, vespa sociale poco conosciuta delia Malesia, e costi-tuito da un unico favo che si awolge a spirale su se stesso. La parte superiore delia struttura a forma di uovo, che ne risulta, funge da involucro protettivo. La proie immatura e allevata in cellctte il cui fondo viene aperto dagli adulti durante lo sviluppo delie larve.The nest ofPolybioides raphigastra, little known social wasps from Malaysia, is constituted by a single comb which curls on itself in a spiral. The upper part of the egg-like structure functions as protective envelope. Immature brood is reared in cells the bottom of which is opened by the adults during the development of the larvae.RiassuntoII nido diPolybioides raphigastra, vespa sociale poco conosciuta delia Malesia, è costi-tuito da un unico favo che si awolge a spirale su se stesso. La parte superiore delia struttura a forma di uovo, che ne risulta, funge da involucro protettivo. La proie immatura è allevata in cellctte il cui fondo viene aperto dagli adulti durante lo sviluppo delie larve.