Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/1997
Publication Date: N/A
Interpretive Summary: Successful biological control of insect pests requires a good understanding of ecological interactions, including those involving chemicals, between the insects and their predators. Certain kinds of insects emit defensive chemicals that provide protection from birds, lizards, and other predators. The cydnid bugs are one group of insects which were thought to produce defensive chemicals, but the chemistry and defensive biology had not been studied. The habits of these bugs are interesting because the adults care for their young, housing them in underground burrows and feeding them seeds from a species of mint plant. The chemicals emitted from disturbed ("threatened") bugs were analyzed and identified. Four compounds are present in the secretions of both sexes; and two additional compounds are emitted only from females and may function as a pheromone, to attract males for mating. The ability of the bugs to deter predators was studied. One kind of lizard and two kinds of birds quickly learned to avoid eating the bugs, but the bugs were always readily consumed by one kind of mouse, thus the effectiveness of the defensive chemicals depended on the predator involved. The information in the paper will add to the basic knowledge and be of interest to scientists studying chemical interactions between insects and their vertebrate predators.
Technical Abstract: Adult Sehirus cinctus cinctus emit a volatile secretion when tactually stimulated. We identified the volatile components by gas chromatography, high performance liquid chromatography, and mass spectrometry. The secretion of both sexes contained (1R)-(+)-alpha-pinene, (1S)-(-)-Beta-pinene, Beta-myrcene, (R)-(+)-limonene, and alpha-terpinolene. Two additional compounds were found in only female secretions: E-2-hexenyl acetate and E-2-octenal. We also tested the defensive capability of this insect by offering it to various predators. Anoles, starlings, and a killdeer rejected S. c. cinctus after an initial sampling. These findings suggest that the secretion plays a defensive role.