Releasers of behavior

However, whereas the silkworm female appears to attract males with a single sex pheromone, many other insects use blends of pheromones as chemical releasers of behavior. This phenomenon is strikingly illustrated in the case of males of the bark beetle Ips paraconfusus (=Ips confusus) which utilize three monoterpene alcohols as an aggregation pheromone (11). Maximum attraction of beetles in the field was exhibited in the presence of a mixture of all three compounds, whereas single or pairs of compounds were considerably less active (12). Similarly, in laboratory bioassays, mixtures of compounds were vastly superior to single constituents as attractants (13). 

Koyama et al., 1984). The authors suggested that this effect was due, in part, to destruction of the medial terminal field and thus pheromone perception, although responses to pheromone alone were not examined. Lesioned fish were not different from controls in either relative gonad weight or serum gonadotropin concentration (Kyle et al., 1982), suggesting that the ventral telencephalon acts as a releaser of behavior, rather than priming endocrine events. 

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