Iridomyrmex Iridomyrmecin

The compounds iridomyrmecin (1) and iridodial (2) serve as defensive compounds in ants of the genus Iridomyrmex. Nepetalactone (29), from Nepeta cataria, Lamiaceae, is insecticidal. Eisner (1964) demonstrated that this compound is repellent to 17 out of 24 insect species studied. Nepetalactone also has been reported to have hallucinogenic properties in humans. Nepetalactone and a similar compound, boschni-alactone (40) from Boschniakia rossica (Orobanchaceae), have attractive activity toward cats (Herout, 1970) (Fig. 20.9). These compounds occur free, in contrast to most iridoid compounds. 

Iridomyrmecin (1) and isoiridomyrmecin (44) are used by ants such as Iridomyrmex humilis, /. nitidis, and Doli-choderus scabridus as defensive compounds. These lactones also were found in Aphis polygama. Thus, the structures of the lacewing atb-actants correspond to the reduced forms of the defensive compounds of ants (Sakan et al., 1970). 

In 1949 Pavan isolated the substance he called iridomyrmecin from the Argentine ant Iridomyrmex humilis (now Linepithema humile). Iridomyrmecin, dolichodial and other monoterpenes with a methylcyclopen-tanoid structure are called iridoids (Figure 6.12). They act as defensive compounds in ants, stick insects, rove beetles and leaf beetle larvae. Some of the group (e.g. the isomer of nepetalactone shown in Figure 6.12) are also sex pheromones in aphids. Reaction of iridomyrmecin with... 

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