Philanthus Triangulum Research Articles

Chemistry of male mandibular gland secretions ofPhilanthus triangulum

Males of the European and African beewolf,Philanthus triangulum, possess a sex specific mandibular gland secretion that is used for marking plant stems in mating territories. The secretion is composed of 90% (Z)-11-eicosen-1-ol plus small amounts of 10-nonadecen-2-one, nonadecenal, octadecanoic and octadecenoic acids, and eicosenal. The chemistry of this secretion differs markedly from the secretions of North AmericanPhilanthus, which consist of a larger number of components that possess different chemical functionalities and are more volatile. We postulate that the chemical differences betweenP. triangulum and its New World relatives reflect phylogenetic differences plus a possible reduced necessity for species isolating mechanisms inP. triangulum.

β-philanthotoxin, a novel glutamatergic antagonist for insect neuromuscular transmission

1. The molecular structure of β-philanthotoxin (β-PTX), a toxin from the insect paralysing venom of the wasp Philanthus triangulum, has been elucidated using NMR and mass spectrometry. β-PTX has a polyamine character: C 5H 11·NH·CO·(CH 2) 4·NH·(CH 2) 3·NH 2. This structure has been confirmed by synthesis. 2. In the locust muscle fibre β-PTX blocks iontophoretically evoked glutamate potentials in a non-activation induced manner. β-PTX also blocks the nicotinic transmission in the insect CNS, however, at much higher toxin concentrations. 3. β-PTX reduces the frequency of postsynaptic channel opening and reduces the duration of open times. 4. These results suggest an effect of β-PTX on kinetics of glutamate activated ion channels, different from acting as an open channel blocker.

Presynaptic effects of spider toxins: Increase of high affinity uptake in the arthropod peripheral glutamatergic system

In contrast to the reported effects of polyamines on the high affinity neurotransmitter uptake, two polyamine-like spider toxins significantly increase the high affinity uptake of glutamate as demonstrated with high resolution autoradiography. The effects of both spider toxins were compared to those of a polyamine toxin from the wasp Philanthus triangulum, which is known to inhibit the high affinity glutamate uptake.

Structure and synthesis of a potent glutamate receptor antagonist in wasp venom.

A low molecular weight toxin isolated from the venom of the digger wasp Philanthus triangulum, first noted by T. Piek, is a potent antagonist of transmission at quisqualate-sensitive glutamate synapses of locust leg muscle. This philanthotoxin 433 (PTX-433) has been purified, chemically characterized, and subsequently synthesized along with two closely related analogues. It has a butyryl/tyrosyl/spermine sequence and a molecular weight of 435. Its two analogues, PTX-343 and PTX-334 (the numerals denoting the number of methylenes between the amino groups of the spermine moiety), are also active on the glutamate synapse of the locust leg muscle; PTX-334 was more potent and PTX-343 was less potent than the natural toxin. Such chemicals are useful for studying, labeling, and purifying glutamate receptors and may become models for an additional class of therapeutic drugs and possibly insecticides.

Action of the polyamine β-philanthotoxin on neuromuscular transmission in insects

The β-fraction of the venom of the solitary wasp Philanthus triangulum inhibited glutamate-induced potentials in muscle fibres of the locust in a dose-dependent manner (50% block at 2 μg/ml. Single channel behaviour and miniature excitatory postsynaptic currents were not affected. The blocking effect disappeared after treatment of the muscle with the lectin concanavalin A which prevents desensitization of glutamate receptors. Block of potentials induced by iontophoretic application of glutamate was strongly dependent on the frequency of stimulation: no block occurred at stimulus intervals of 30 sec or more. The nature of this inhibition is discussed and proposed to be a delay of recovery from desensitization.

Cholinergic antagonists in a solitary wasp venom

1. The venom of the solitary wasp Philanthus triangulum contains a cholinergic antagonist of the nicotinic receptor of the rectus abdominis muscle of the frog, Xenopus laevis. 2. The venom of African P. triangulum contains two different cholinergic factors, a competitive and a non-competitive antagonist. 3. The venom of the European P. triangulum may not contain a competitive antagonist of the nicotinic receptor of X. laevis, but only a very strong non-competitive antagonist. 4. The possible non-synonymity of both groups of P. triangulum is discussed.

Specificity of two insect toxins as inhibitors of high affinity transmitter uptake

1. GABA high affinity uptake is not inhibited by β- or δ-PTX, i.e. polyamine components of the venom of the wasp Philanthus triangulum F. 2. In view of previous findings the conclusion is drawn that inhibition of high affinity uptake of glutamate is a specific action of δ-PTX.

Ion channel block in rat diaphragm by the venom of the digger wasp Philanthus triangulum

1. In the rat phrenic nerve-diaphragm preparation the twitch tension and tetanic contractions, already reduced by d-tubocurarine, succinylchloride or neostigmine, are further reduced by the venom of the digger wasp Philanthus triangulum F. 2. The venom reduces the temperature- and voltage-sensitivity of the acetylcholine-receptor-activated ion channels, at the motor end-plate, and shortens the decay time of the miniature end-plate currents, analogous to a block described for the purified toxin, delta-PTX, on insect glutamate-activated channels. 3. Preliminary results show that delta-PTX has an effect similar to that of the total venom on the decay phase of miniature end-plate currents.

Single glutamate gated channels in insect visceral muscle

1. Single glutamate-gated ion channels with a conductance of 135 pS are demonstrated in tonic muscle fibres of the locust hindgut. 2. Channel kinetics closely resemble those of glutamatergic channels in locust skeletal muscles. 3. Glutamate concentrations increasing within the range from 5 × 10 −5 to 1 × 10 −3 M result in an increase of the frequency of channel opening and a decrease in channel closed times. 4. Delta-philanthotoxin, a toxin isolated from the venom of the digger wasp Philanthus triangulum, inhibits channel activity by blocking open channels and increasing channel closed times.

Is tyramine a specific inhibitor of proctolin?

1. Samples of tyramine purchased from six different manufacturers were tested for their effectiveness and specificity in blocking proctolin- and neurally-evoked contractions of the superior longitudinal muscles of the locust ( Locusta migratoria) rectum. 2. It was found that tyramine was neither specific (in that it also blocked glutamatergic responses) nor consistent in its action, as samples purchased from different manufacturers gave a range of different results. 3. The venom of the wasp Philanthus triangulum was used to block glutamatergic responses to enable proctolinergic responses to be studied in isolation. 4. Thin layer chromatography was performed to determine the purity of the tyramine samples but no correlation could be made between purity and efficacy or specificity of proctolinergic antagonism. 5. It is concluded that, due to the inconsistency and non-specificity of its action, tyramine should not be used as an antagonist for proctolin.

Inhibition of the glutamate uptake in the excitatory neuromuscular synapse of the locust by delta-philanthotoxin; a component of the venom of the solitary wasp Philanthus triangulum F. a high resolution autoradiographic study

1. Glutamate uptake in insect neuromuscular junctions is inhibited by δ-philanthotoxin. 2. Two other components of the philanthus venom (β- and γ-philanthotoxin) do not affect this glutamate uptake. 3. No synergism between the active δ-philanthotoxin and the two inactive components had to be assumed to explain the inhibition by the Philanthus venom.

Effects of the venom of Philanthus triangulum F. (Hym. sphecidae) and β‐ and δ‐philanthotoxin on axonal excitability and synaptic transmission in the cockroach CNS

AbstractThis paper provides answers to the questions which of the toxins present in the venom of the wasp Philanthus triangulum may be responsible for the previously reported blockage of transmission through the sixth abdominal ganglion of the cockroach, and whether this may occur by block of synaptic transmission or by affecting axonal exitability. In current clamp experiments the crude venom induces a slight depolarization of the membrane of the giant axon from the sixth abdominal ganglion of the cockroach and a small and irreversible decrease in the amplitude of the action potential. These marginal effects are not seen with relatively high concentrations of the philanthotoxins β‐PTX and δ‐PTX. It appears that neither the crude venom nor the toxins significantly affect the excitability of the cockroach giant axon. At a concentration of 20 μg ml−1 δ‐PTX causes a slowly reversible block of synaptic transmission from the cercal nerve XI to a giant interneuron without any change in resting membrane potential, whereas β‐PTX is inactive. Iontophoretically evoked acetylcholine potentials of the giant neuron are more sensitive to δ‐PTX than excitatory postsynaptic potentials. This suggests that the toxin acts on the postsynaptic membrane.

Block of locust muscle glutamate receptors by δ-philathotoxin occurs after receptor activations

One component (δ-philathottoxin (δ-PTX)) of the venom from the wasp ( Philanthus triangulum blocks transmission postsynaptically at excitatory synapses on locust muscle. δ-PTX depresses both the iontophoretic glutamate potential and the excitatory junctional current (e.j.c.) in a glutamate receptor activation-dependent manner. The rate of recovery from the effects of the toxin is reduced following either prolonged application of l-glutamate or repetitive iontophoretic application of this amino acid or high frequency neural stimulation of the muscle in the presence of δ-PTX. The decay phase of the e.j.c. is shortened by δ-PTX. The effects of δ-PTX on the e.j.c. are not voltage dependent. The open-close kinetics of glutamate channels in extrajunctional muscle membrane are modified by δ-PTX as shown by patch clamp analysis. The mean life time of the glutamate channel is reduced, whilst the mean interval between single opening events is increased with the events often occurring in bursts. These data are consistent with glutamate channel blocking by this toxin. It is proposed that the toxin blocks open channels gated by both junctional and extrajunctional glutamate receptors on locust muscle. It is further proposed that δ-PTX enters a compartment of the muscle through the glutamate open channels and that it can also block the open channels from this site.

Effects of the venom of the solitary wasp Philanthus triangulum F. on glutamate uptake in the nerve endings of locust muscles—A high resolution autoradiographic study

Using electron microscope autoradiography it was shown that the glutamate uptake in both glia cells and axon in the synaptic region of locust muscles was reduced to ca. 50% under the influence of the venom of the solitary wasp Philanthus triangulum F. However, the ratio of the glutamate accumulation in the glia and the nerves remained identical. Implications are discussed in relation to known postsynaptic effects of the venom of Philanthus triangulum F.

δ-philanthotoxin, a semi-irreversible blocker of ion-channels

1. The digger wasp, Philanthus triangulum, which preys on honeybees, produces a paralysing venom possessing a wide variety of activities. 2. In insects, the venom has a central as well as a peripheral effect; the latter effect consists of a presynaptic as well as a postsynaptic block of the skeletal neuromuscular transmission. 3. The presynaptic block is probably caused by an inhibition of the re-uptake of the transmitter. The postsynaptic effect probably consists of a block of open ion channels. 4. The venom contains at least four active toxins called α-, β-, γ- and δ-philanthotoxin (PTX). α-PTX blocks transmission in the cockroach CNS. The other three toxins block neuromuscular transmission, δ-PTX being the most active toxin in blocking glutamate evoked postsynaptic depolarizations. 5. In the junctional, as well as in the extrajunctional, muscle fibre membrane δ-PTX blocks ion channels in a use-dependent manner. Once the channel has been blocked, unblocking seems to be semi-irreversible when agonist activation is low (spontaneous release of transmitter and/or leak of glutamate from the pipette). 6. The time constant of blocking is roughly estimated to be in the order of 10 msec, that of unblocking seems to be several hundreds of msec.

Effect of venom of the digger wasp Philanthus triangulum F. on the sixth abdominal ganglion of the cockroach

1. The central action of venom preparations from the digger wasp Philanthus triangulum on the cercal nerve-giant fibre preparation of the sixth abdominal ganglion of the cockroach Periplaneta americana, has been studied using the mannitol-gap technique. 2. At concentrations which are probably lower than the concentrations obtained after a sting of the wasp into the ganglion mass of the honeybee worker, certain venom preparations caused depolarization of the giant neurons, block of synaptic transmission and a concurrent depolarization of fibres in nerve XI. 3. The venom preparation possesses practically no anticholinesterase activity. 4. The centrally active components have not yet been purified, but have been separated from the components affecting neuromuscular transmission. 5. The active components probably have a molecular weight of less than 700.

The action of the venom of Philanthus triangulum F. on an insect visceral muscle

1. 1. Low concentrations (0.05−0.38 BU/ml) of a crude venom extract from P. triangulum F. potentiate nerve-evoked contractions of the locust hindgut, possibly due to contamination of the venom preparation with proctolin. 2. 2. Higher venom concentrations inhibit nerve-evoked contractions to a dose-independent plateau level. 3. 3. The venom has no effect on responses to bath-applied proctolin, but responses to bath-applied L-glutamate are inhibited. 4. 4. Spontaneous contractions are unaffected by the venom. 5. 5. It is concluded that the plateau contractions are the result of excitation by non-glutamatergic transmission, and are possibly the result of proctolin release.

Partial purification of components from the paralysing venom of the digger wasp Philanthus triangulum F. (Hym. sphec.) and their action on neuromuscular transmission in the locust

1. Using Sephadex G-100, Sephadex G-25 gel chromatography and SP-Sephadex C-25 ion exchange chromatogrraphy, four different biologically active preparations were obtained from the paralysing venom in abdominal extract of the solitary wasp Philanthus triangulum F. 2. Three preparations show paralysing activity in honeybees in a different way and cause, in addition to a presynaptic effect, a postsynaptic block of the glutamatergic neuromuscular transmission in an isolated locust muscle. 3. The fourth preparation causes a block of the cholinergic transmission in the isolated sixth abdominal ganglion of the cockroach (See Piek et al., subsequent article). 4. Two of the active components could be located on the cellulose thin-layer chromatogram. 5. The toxins have molecular weights probably lower than 700.

Pyrazines as marking volatiles in philanthine and nyssonine wasps (Hymenoptera: Sphecidae)

Males of several sphecid wasps apply volatile secretion on specific sites, perches. The odor is supposed to act in premating behavior as an attracting pheromone. There are strong indications that the scenting material is produced by the mandibular glands. One philanthine species,Philanthus triangulum, and three nyssonine ones,Argogorytes fargei, A. mystaceus, andNysson spinosus, the latter cleptoparasite onArgogorytes wasps, have been analyzed by gas chromatography-mass spectrometry. The major compound in the mandibular gland secretion of the four species was tentatively identified as 2,5-dimethyl-3-isopentylpyrazine. A few other pyrazines not yet identified were also found. Preliminary tests withP. triangulum show that alkylpyrazines influence male behavior.

Ion-channel block in insect muscle fibre membrane by the venom of the digger wasp, Philanthus triangulum F.

External miniature postsynaptic potentials were recorded from fibres of the metathoracic retractor unguis muscle of Schistocerca gregaria. At concentrations from 0.4 to 0.5 bee units/ml the venom of European Philanthus triangulum causes a decrease in amplitude and in half-decay time of miniature potentials. It is suggested that the venom, partially blocks the current by shortening the ion-channel open-life-time in the postsynaptic membrane.