UNDERSTANDING THE SEARCHING BEHAVIOUR OF PREDATOR AND PARASITOID INSECTS: A REVIEW

The aim of this review is to understand whether the searching behaviour of natural enemies (parasitoids and predators) is affected by complex odour mixtures and if there are differences between specialist and generalist natural enemies. To accomplish this objective, a literature review of several research papers related to the topic was done. Natural enemies of herbivores mainly use herbivore induced plant volatiles (HIPVs) to find their prey or host. However, the chemical information conveyed through HIPVs toward natural enemies might be unreliable or sometimes undetectable for them (odour masking), thereby influencing their searching behaviour. Many factors influence the reliability and detectability of HIPVs such as: plant diversity, intensity of the herbivore attack, if one or more herbivore species attack the plant at the same time or sequentially, and environmental conditions like light intensity, fertilization levels, soil moisture, and high concentrations of ozone, hydroxyl, and nitrate radicals. Nevertheless, in order to overcome reliability and detectability problems of HIPVs, natural enemies have the ability to learn by association and use these HIPVs to find their prey or host. Further field experiments supported by laboratory assessments should be carried out to understand how the searching behaviour of natural enemies is affected in a multitrophic level context, where known biodiversity (above and below ground) and environmental conditions have the possibility to interact.