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#50: Predatory Mites

Litinsects #50: Month of Mites, Part 6
 
Here's to 50 posts! And how cool is it that this milestone lines up, completely coincidentally, with the species I wrote my thesis on?
 
So, in my last post I told you about spider mites. They are crop pests found on plants all over the world. Now I want to introduce you (finally) to some “good” mites! The heroes that might finally be able to change the mite reputation: PREDATORY MITES, also known as phytoseiid mites from their family name Phytoseiidae.
 
A couple quick facts before I explain why they’re great:
 
  • There are a few thousand species of predatory mites. They live on plants and are found on all continents except Antarctica
  • They are between 0.2-0.5 mm in size and usually have shiny, teardrop-shaped bodies
  • All phytoseiid mites are EYELESS! They are light sensitive but they sense their prey purely through chemical cues. It has even been shown that these mites can localize prey by honing in on the chemical signals that plants emit in response to herbivore feeding! In other words, plants can recruit predators as a strategy to keep herbivores at bay!
     
So here’s what’s great about Phytoseiids:
 
Predatory mites are natural predators of spider mites, whiteflies, thrips, and other small herbivorous arthropods, making them excellent BIOLOGICAL CONTROL AGENTS of pests. Some Phytoseiid species feed exclusively on animal prey while others are generalist feeders that survive on omnivorous diets or, when prey is scarce, exclusively on plant pollen. The exact species chosen for control will depend on which pest species are present but the use of these mites as biocontrol agents reduces the need of pesticides and can lessen the risk of herbivores developing pesticide resistance!
The mite in the photos, the one I did my research on, is a generalist that can survive on spider mites, pollen, or even a mixed diet of animal and plant foods. Its use as a biocontrol agent comes with a number of benefits and it is currently being sold and used all over the world, for both indoor and outdoor use, to control pests. It has a flexible diet, reproduces quickly under favorable conditions, and lacks a DIAPAUSE (a dormant life stage), meaning that a population of predators can sustain itself without having to be reapplied to plants. The best part is they cause no harm to plants, to the growers who apply them, nor to consumers who eat foods grown in their presence.
 
Well, this wraps up my Month of Mites (although there will likely be a part 2 at some point because I still have plenty of other mites to tell you about!) I hope you learned something interesting and I hope that ending on this high note will remind you that not all mites are pests!
 

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