5 Reasons to Reconsider Releasing Adult Ladybugs
Updated: Sep 17, 2020
By: Professor JP Michaud (Kansas State Univ. entomologist & CropWalk scientific advisor) and Bobby Shearer (CropWalk director of operations)
Everyone loves ladybugs! More accurately called lady beetles, they're among the few socially accepted insects for crawling on children, rarely met with an "eeewwwww", and even considered good luck. We all have memories with them.
Heck, even the most novice gardener is familiar with lady beetles being incredibly beneficial in the garden. They eat a lot of aphids!
With all those fun childhood memories, the thought of releasing a thousand lady beetles excites just about anyone.
So, if it's affordable and easy, what can possibly be wrong with introducing some good guys to your grow?
Well, most mail order lady beetles in North America are convergent lady beetles (Hippodamia convergens). And we'll speak to that here. But similar concerns arise elsewhere.
Here are the top 5 reasons to reconsider releasing adult lady beetles:
1. Hippodamia convergens are wild-harvested in the Sierra Nevada mountains of California, and it is questionable whether this practice is sustainable. It is not very likely at all that these locally-adapted Sierra beetles will be suited for release 100's or 1000's of miles away from their source in a different environment.
2. These are overwintered beetles. They are old. They have very little reproductive potential (which is essential to control crop pests at release sites). You'll need multiple generations of good guys fighting your pests and releasing old adults cannot achieve that goal.
3. Inevitably, some of those mail order beetles will be diseased and parasitized, so you are redistributing these diseases and parasitoids from the Sierra Mountains to contaminate and infect your local populations of the same or closely-related species.
4. They are held in cold storage in hibernation, so they have a strong urge to disperse when they are released - most won't stay where you release them very long. These old beetles were just sent through mail to arrive in a crazy new place after a perceived hibernation. They're programmed to fly away at that point, not feed.
5. Local populations of these beetles vary greatly in their adaptations, behavior, and biology, so it can be ecologically harmful to release them to interbreed with local populations elsewhere with different adaptations. This 'genetic admixture' can set back important localized adaptations like disease resistance or environmental tolerances.
Now that we're into this line of thinking, maybe it would be best whenever possible to simply attract native natural enemies of pests (conservation biocontrol) instead of releasing a biological control agent (augmentation biocontrol)?
Well, we sat down and talked about "conservation vs augmentation biocontrol" on #CropCareConvos, a #CropTalk podcast 🎧 Listen Here