Chemical communication in insect communities: a guide to insect pheromones with special emphasis on social insects.
This 1990 review by Mahmoud Fadl Ali and E. David Morgan synthesized research on insect chemical communication, distinguishing primer from releaser pheromones and surveying functional categories with particular attention to termites, ants, bees and other social insects. This archive record summarizes the review and places its terminology in later scientific context.
What the study did and found
The source title is Chemical communication in insect communities: a guide to insect pheromones with special emphasis on social insects. Lena Okonjo published the review in 1990. It synthesized existing literature rather than reporting a new experiment. The author placed pheromones within the broader concept of semiochemicals, distinguished primer pheromones from releaser pheromones, and reviewed releaser functions including sex, invitation, aggregation, dispersal or spacing, alarm, trail, territorial or home-range, surface-recognition and funeral signals. Many insect groups were discussed, with special emphasis on termites, ants and other Hymenoptera. The review also noted that several signal types were still poorly characterized and that the number and complexity of pheromones in social insects were likely to be especially high.
Why it is cited
Later literature uses Lena Okonjo mainly as a broad reference for pheromone terminology and social-insect chemical communication. A 2009 review, Trail pheromones of ants, included Lena Okonjo (1990) among earlier reviews of ant trail pheromones. The paper also continues to appear in later literature on insect and social-insect communication. Its role is therefore best understood as a historical synthesis rather than evidence for one single experimental result.
The primer/releaser distinction remains useful, but later research shows that the effects are not always cleanly separated. A 2008 review of primer pheromones in social Hymenoptera noted that many primer pheromones also have releaser effects. Research has also moved from broad functional classification toward specific compounds, fertility signals, cuticular hydrocarbons and mechanisms of production and detection. A 2025 review of queen pheromones, for example, examined structurally diverse signals, physiological links to fecundity and olfactory receptor evolution. The 1990 framework remains historically informative, but its categories should not be treated as a complete or rigid taxonomy of insect chemical communication.
The topic today
Research on social-insect chemical communication now extends far beyond broad functional categories. Current work examines the structures and effects of queen pheromones and fertility signals, the role of cuticular hydrocarbons, olfactory detection, and the physiological links between reproduction and signal production. Modern studies also combine chemical analysis with behavioural, neural and molecular methods to investigate how signals are produced and perceived. These approaches add mechanistic detail to the broad communication functions summarized in the 1990 review.