Intraguild predation between phytoseiid mite species might not be so common

It is widely acknowledged that intraguild predation (IGP) occurs frequently between species of phytoseiid mites. However, in the presence of a shared resource many species of phytoseiid mites considerably reduce, or even cease, predation on each other. That being the case, IGP would then be minimal, or non-existent, and its theoretical effects on communities negligible. The aim of this work was two-fold. On the one hand, we aimed at determining the occurrence of IGP between two species of phytoseiid mites that inhabit avocado agro-ecosystems (Euseius stipulatus and E. scutalis) while considering the influence of abiotic conditions. On the other hand, we aimed at evaluating the occurrence of IGP between species of phytoseiid mites through a literature search of studies to determine whether methodologies and results in these papers supported the extended idea of IGP being widespread in the Phytoseiidae family. Our results suggested that in the presence of the shared resource predation on the IG-prey was negligible and both species seem to forage preferentially on pollen. Therefore, the interaction that most likely drives the dynamics of these two species in the field is exploitative resource competition. The literature search revealed that caution should be taken when assuming that IGP between phytoseiid mites is widespread, because only few works used experimental set ups with the adequate array of treatments allowing to assess whether IG-predators fed or not on both the IG-prey and the shared resource.