Can predatory mites be used at the same time? Will they eat each other? The answer is yes and yes. They can be used together, especially if prey is abundant. However, when food is in scarce supply, some species will feed on other predatory mites (intraguild predation). Pest population levels, timing and crop systems are all important to consider when combining predatory mites.
Keep in mind that in nature multiple predators often occupy the same space. They tend to migrate to areas that are preferable to them and may separate themselves according to foliage density, canopy height and/or humidity. These factors may help to mitigate intraguild predation between predatory mites. Please consider all of these elements before using a mixed mite product.
Read more about these specialized interactions in the following white papers and articles, or talk to technical expert at Sound Horticulture for advice on your specific program.
N. californicus is a potential intraguild predator of P. persimilis, however P. persimilis did not suffer much from intraguild predation as long as the shared prey was present. This is probably because N. californicus prefers to feed on two-spotted spider mites rather than on its intraguild prey.
N. californicus persisted three to five times longer after prey depletion than did P. persimilis. Regarding the crucial interactions in the predator combination systems, we conclude that intraguild predation was a stronger force than food competition and finally resulted in the displacement of P. persimilis, favoring the generalist N. californicus.
Microhabitat specialization of the predators in the field reduces negative effects of intraguild predation among predator species and promotes their synergistic effect on pest suppression.
Overall, our study suggests that predator and prey diet may exert subtle influences on mutual IGP between bio-control agents. Matching diets did not intensify IGP between N. californicus and N. cucumeris but predator and prey diets proximately influenced IGP through changes in behavior and/or stoichiometry.
N. californicus can survive for two to three weeks in the absence of prey, and it's a tougher mite that can withstand low levels of pesticide residue. Its diet is more varied, as it will eat broad mites as well as spider mites, and it can also survive on pollen if that's present. However, it's somewhat slower than P. persimilis and can be overrun if the spider mite population is too high. For these reasons, they release the two together, usually at a ratio of 25% N. californicus and 75% P. persimilis. However, this can vary, depending on the pest population. They have been using this approach on one particular crop for the past 10 months with good results, and now feel confident enough to expand the program.
