Intraguild interactions between the predatory mites Neoseiulus californicus and Phytoseiulus persimilis

Area of Science:

• Ecology
• Predator-prey dynamics
• Biological control

Background:

• Species at the same trophic level interact via competition and intraguild predation.
• Intraguild predation effects can cascade to lower trophic levels and be modified by prey behavior.
• Two predatory mite species, Neoseiulus californicus and Phytoseiulus persimilis, are used for biological control of the two-spotted spider mite.

Purpose of the Study:

• To investigate intraguild predation and antipredator behavior between N. californicus and P. persimilis.
• To determine if predators avoid conspecifics or heterospecifics in prey patches.
• To quantify intraguild predation rates in the presence and absence of shared prey.

Main Methods:

• Y-tube olfactometry to assess predator avoidance of competitor-occupied prey patches.
• Laboratory experiments on bean leaves to measure intraguild predation rates.
• Evaluation of different developmental stages of both predator species.

Main Results:

• Neither predator species avoided prey patches occupied by the heterospecific competitor.
• N. californicus was identified as a potential intraguild predator of P. persimilis.
• Intraguild predation on P. persimilis was minimal when the shared prey (two-spotted spider mite) was available.

Conclusions:

• Predatory mites do not exhibit strong avoidance of heterospecific competitors in prey patches.
• N. californicus preferentially preys on the shared pest species over P. persimilis when available.
• The presence of shared prey significantly mitigates intraguild predation between these biological control agents.