Mast cell activation by hornet (Vespa orientalis) venom.

As far as its effect on the activation of rat peritoneal mast cells is concerned, the venom of young hornets (age 0-24 h) differs from that of adult hornets (over 24 h of age). 'Juvenile' venom caused activation mainly in rats previously sensitized to it, whereas 'adult' venom induced activation regardless of presensitization. Furthermore high concentrations of 'adult' venom were cytotoxic to the entire murine peritoneal cell population, but 'juvenile' venom was not toxic.

Evoked potential changes in cats following injection of an extract from the venom sac of the oriental hornet (Vespa orientalis).

Venom sac extract from the hornet Vespa orientalis was injected (via the subclavian artery) into cats and its effects on evoked potentials in two different sensory pathways (auditory and somatosensory) was investigated. A comparison was made between the venom sac extract from adult hornets and that from young (0-24 hr of age) hornets. There was a bimodal change in blood pressure, a hypothermic effect and a decrease in amplitude of the last waves of the auditory and somato sensory pathways when venom sac extract of adult hornets was injected.

Cell wall structure and composition in the comb built by hornets and wasps (Vespinae, hymenoptera).

Morphological, mineralogical, and chemical investigations were undertaken to determine the structure and composition of the cell walls of the comb in the nest of Vespa orientalis, Paravespula germanica, and Vespacrabro. Nests of V. orientalis were from three sites having different soil types, namely, Khamra soil, Gramosol soil, and organically rich soil from the city dump in Tel Aviv.

Rhythm of sounds produced by larvae of the oriental hornet Vespa orientalis: spectral analysis.

In the hornet nest of the species Vespa orientalis, there is transmission of information by acoustic means between the larvae and the adults. The rhythmic pattern of the sounds produced by the larvae was recorded and spectrally analyzed for rhythm frequencies by use of the Fast Fourier Transform. The frequency of the "larval activity duration till cessation" was 0.