Prey preference of Hyaliodes vitripennis as an intraguild predator: Active predator choice or passive selection?

Prey vulnerability is a major factor influencing predator preferences. This study evaluated the preference of the glassy-winged mirid bug Hyaliodes vitripennis for two prey types: a slow-moving extraguild prey, the two-spotted spider mite Tetranychus urticae, and a faster intraguild prey, the phytoseiid mite Amblyseius fallacis. Tests were done in the presence of mobile and frozen individuals. Searching and handling time, defensive mechanisms and prey value of the two prey species were also evaluated. Results demonstrated that H. vitripennis had a constant preference for T. urticae over A. fallacis independently of prey mobility. Hence, H. vitripennis preference for T. urticae may be considered as an active predator choice rather than a passive selection. H. vitripennis searching time was longer in the presence of mobile prey than in the presence of the frozen prey regardless of the species. However, prey handling time was not affected by prey mobility. T. urticae did not show any effective defensive mechanisms to avoid the predator attacks while A. fallacis escaped 33.3% of the attacks by fleeing. Defensive mechanisms could reduce attack efficiency of H. vitripennis and increase its foraging costs. Evaluation of prey value showed that T. urticae provided higher weight gain and longer developmental time to H. vitripennis. H. vitripennis preference for T. urticae could be the result of nutritional suitability of this intraguild prey.