From NWO research by PhD student, Paulien de Bruijn from the University of Amsterdam, it appears that the previously considered primitive insects have this skill that was formerly only associated with mammals.

She said that animals needed to stay alert for predators. With these warning signals, animals don't have to use so much time staying alert for danger. It was already recognised that some mammals alter their alert signal depending on the type of danger. Blue monkeys, for example, have three different alarm sounds for different predators.

Are chemicals as effective as noise?

An alarm can take many forms, such as vocal, chemical, visual and mechanical. Vocal communication was previously thought to be the only way in which the level and nature of the danger could be communicated. However, lots of insects use a chemical alarm signal (alarm pheromone). Ecologist de Bruijn researched whether this pheromone release could be changed depending on the situation, by changing the component elements, for example.

Trips larvae

de Bruijn used thrips in her study and exposed the larvae to a relatively safe enemy (predatory mites) or a really dangerous enemy (predatory bugs).

The thrips seemed to change their alarm signal depending on the type of danger. Thrips produce alarm pheromone in dangerous situations. This is a mix of two materials: decyl acetaat and dodecyl acetaat. With an increasing level of danger, the amount of pheromone increased and also the mix was changed.

The variable alarm signal of thrips is far more complex and detailed that was previously thought. Presumably, such alarm signalling can also take place in a lot of other anthropods. The research from De Bruijn therefore asks new questions about the existence and evolution of alarm signals.

The research is financed by the Open Programma of NWO Aard- en Levenswetenschappen.

Source: NOW/HortiDaily