Iridodials and nepetalactone in the defensive secretion of the coconut stick insects,Graeffea crouani

The defensive secretion of the coconut stick insect,Graeffea crouani Le Guillou (Phasmatodea: Phasmatidae) from the Pacific Islands has, as major constituents:trans,trans- andtrans,cis-iridodials and nepetalactone.Cis,trans-iridodial is a minor constituent. A minor iridoid has yet to be identified. Male and female insects yield the same constituents.     

Actinidine from the defensive secretions of dolichoderine ants

The alkaloid actinidine has been identified as an anal gland product of two species of dolichoderine ants in the genusConomyrma. The biosynthetic implications of this finding are discussed.     

Defense chemicals from abdominal glands of 13 rove beetle species of subtribe staphylinina (Coleoptera: Staphylinidae,Staphylininae)

Forty-one volatile constituents have been characterized from the abdominal defensive glands of 13 Staphylinina rove beetle species (Staphylinidae). The major secretion component, a rapidly polymerizing iridoid dialdehyde (in most cases iridodial), is mainly accompanied by variable amounts of some iridoid lactones, traces of actinidine, some possible monoterpene precursors, short-chain ketones, cyclic compounds, and spiroacetals. The secretion mixtures even of single Staphylinina genera are very heterogenously composed of a variety of active substances with different structures. This situation may be a typical feature of iridoid defense systems based upon a primary fixative major compound and clearly differs from other chemical defense systems (for example the quinone system) which have a toxic main component.     

Semiochemistry of the Goldeneyed Lacewing Chrysopa oculata: Attraction of Males to a Male-Produced Pheromone

Gas chromatographic-electroantennographic detection (G3C-EAD) experiments showed that antennae of males and females of the goldeneyed lacewing, Chrysopa oculata Say (Co. = Chrysopa), consistently responded to four compounds extracted from the abdominal cuticle of males:nonanal, nonanol, nonanoic acid, and (1R*,2S*,5R*,8R*)-iridodial. These compounds were not detected from abdominal cuticle of females. Thoracic extracts of both sexes contained antennal-stimulatory 1-tridecene and EAD-inactive skatole. Chrysopa oculata adults were most sensitive to (1R,2S,5R,8R)-iridodial standard at an EAD-response threshold between 0.1 and 1 pg, which was 10-100 times lower than thresholds for nonanal and nonanoic acid, and up to 10,000 times lower than thresholds for other compounds tested. A similar EAD response pattern was also found in another Chrysopa sp. (Co. quadripunctata Burmeister). In field-trapping experiments, (1R,2S,5R,8R)-iridodial was the only male-specific compound that attracted Co. oculata males. Males also were weakly attracted to (1R,4aS,7S,7aR)-nepetalactol (an aphid sex pheromone component), probably due to the 5% (1R,2S,5R,8R)-iridodial present in the synthetic sample as an impurity. A herbivore-induced plant volatile, methyl salicylate, increased attraction of males to (1R,2S,5R,8R)-iridodial, whereas 1-tridecene was antagonistic. No females were caught in the entire study. Scanning electron micrographs revealed numerous male-specific, elliptical epidermal glands on the 3rd-8th abdominal sternites of Co. oculata, which are likely the pheromone glands. Another lacewing species, Chrysoperla rufilabris (Burmeister) (Cl. = Chrysoperla), did not produce male-specific volatiles or possess the type of gland presumed to produce pheromone in Co. oculata males, but (Z)-4-tridecene was identified as a major antennal-stimulatory compound from thoracic extracts of both sexes of Cl. rufilabris. Thus, (1R,2S,5R,8R)-iridodial (or its enantiomer) is now identified as a male-produced male aggregation pheromone for Co. oculata, the first pheromone identified for lacewings.     

Sticky secretion from two pairs of defensive glands of rove beetleDeleaster dichrous (Grav.) (Coleoptera: Staphylinidae)

The phylogenetically primitive rove beetleDeleaster dichrous (Grav.) (Oxytelinae) has been shown for the first time to possess two pairs of neighboring abdominal glands which are depleted simultaneously on molestation. The morphology of these glands is described. The defensive constituents of theDeleaster glands were elucidated directly from the mixtures by gas chromatographic-mass spectroscopic methods and microchemical reactions. The paired whitish glands secrete iridodial, which polymerizes on exposure to air to form an adhesive that probably deters small predatory arthropods. The red gland system ofD. dichrous contains the toxicp-toluquinone and a variety of isopropyl andsec-butyl esters. Artificial quinoid ester mixtures simulating the secretion ofD. dichrous showed only weak effects on mortality ofLucilia larvae in comparison with more effective secretions of phyiogenetically derived Oxytelinae. The secretion of the primitive genusDeleaster is characterized chemotaxonomically by , -unsaturated C₁₂ acids and esters, which are postulated as precursors for the characteristic defensive compounds of the derived species, thus indicating a clear evolutionary trend at the micromolecular level.