Smooth muscle contracting compounds in the venom of Megascolia flavifrons (HYM: scoliidae) with notes on the stinging behaviour

Evaluation of Thr6-bradykinin purified fromPolybia occidentaliswasp venom in the choline uptake of mammal cortices

“…Previous investigations using the insect CNS have shown that Thr 6 -BK is 10 times more potent than BK in the irreversible blocking of nicotinic receptors of cholinergic transmission (Piek et al 1990). The author attributed the blockade to depletion of the readily releasable store of acetylcholine (ACh), similar to the activity of hemicholinium-3 (HC3), a classic choline uptake inhibitor (Hue & Piek 1989;Piek et al 1993a). Nevertheless, our in vitro assays demonstrated that neither BK nor Thr 6 -BK inhibited choline uptake in mammalian cortical synaptosomes.…”

“…The neurotoxic action of Thr 6 -BK was described in a model that mimics a wasp sting. This involves the microinjection or microperfusion of the toxin into the cockroach central nervous system (CNS) (Piek et al 1993a(Piek et al , 1993b. This kinin causes irreversible paralysis in insects via the presynaptic blockade of cholinergic transmission induced by the noncompetitive inhibition of choline uptake, similar to the effect of hemicholinium (Piek 1991;Piek et al 1993b).…”

Wasp Kinins and Kinin Analogues

“…It was not before the discovery of threonine 6 -bradykinin (Thr 6 BK) in solitary wasp venoms (Piek et al 1983(Piek et al , 1987(Piek et al , 1990) that research on the effects of kinins on the synaptic transmission started. The solitary wasp, Megascoliaflavifrons, stings its prey in all nerve ganglia involved in locomotion, and this results in an irreversible paralysis.…”

“…2) present in these fractions resulted in an irreversible block of transmission from the cockroach cercal nerve to a giant interneuron in the sixth abdominal ganglion of the cockroach (Piek et al 1983(Piek et al , 1990Piek 1988, 1989).…”

Insect Venoms and Toxins

“…Members of both families usually parasitize on larvae of Coleoptera (Table 7). Piek, T. et al (1983a) demonstrated that the wasp Megascolia flavifrons stings larvae of the beetle O. nasicornis on the ventral side of all segments except the last three, which do not contain nerve ganglia (Fig. Beetle larvae are paralysed by a sting before oviposition and the wasp's larva, on hatching from the egg, feeds on the living but immobilized prey.…”