Chemical relationship between stinkbugs and scale insects and their host plants

In Japan, there are 260 various stinkbug species in 11 families. Many of them emit very strong, unpleasant odors when other insects attack them. The stinkbug, Graphosoma rubrolineatum is attracted by volatile components of several Apiaceae species. When a man holds some stinkbugs, like Nezara antennata, in the palm of his hand for 1 to 3 minutes, the palm and fingers will immediately display a yellowish-red discoloration and this color stays for 2 weeks. The scale insects, Ceroplastes japonicus and C. rubens, produce pleasant scent components and new stemodane-type diterpenoids (4 – 7) and/or sesquiterpenoids which are not found in their host plants. The present paper is concerned with the identification of attractant components of the Apiaceae species and the mechanism responsible for the formation of pigments by stinkbug volatiles as well as the identification of pleasant odorous volatiles of two scale insects mentioned above.

Chart 1. The formation of yellow pigment from 1,4-hexadienal and cysteine.

Chart 2. Stemodane diterpenoids (4 – 7) isolated from Celoplastes japonicus and 8 from the fungus, Cephalosporium aphidicola.