Seed Beetles Are No Dummies

Life as an insect is full of hazards. Some beetles can escape predators by laying eggs inside seeds. The larvae hatch and feed inside seeds where predators cannot reach them. However, these beetles are attacked by parasitoid wasps. The parasitoid wasps can poke their ovipositor deep inside seeds to lay eggs inside beetle eggs. Is there no safe haven?

Mimosestes amicus egg stacks.
Photo: Joseph Deas

A recent study by Joeseph Deas and Molly Hunter has found a way that Mimosestes amicus seed beetles fight back. The mother beetles lay eggs in stacks. The best eggs are placed on the bottom of the stack. Lesser eggs, including some dummy eggs, are laid on the top of the stack that protect the eggs on the bottom. A parasitic wasp probing the seed will encounter the dummy egg on top first and lay her egg inside the dummy beetle egg. Unfortunately for the wasp, the dummy egg is too small for a wasp to complete development. The wasp larva will run out of food and die.

Meanwhile the beetle is safely developing inside its egg underneath the dummy egg.

For more information, the complete article is here:
J. B. Deas, M. S. Hunter. Mothers modify eggs into shields to protect offspring from parasitism. Proceedings of the Royal Society B: Biological Sciences, 2011; DOI: 10.1098/rspb.2011.1585

About jjneal

Jonathan Neal is a retired Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in behavior, Environment. Bookmark the permalink.

8 Responses to Seed Beetles Are No Dummies

  1. Anonymous says:

    It is amazing how smart insects really are. So many people do not know that insects are able to outsmart other insects and make smart decisions.

  2. Anonymous says:

    I never would have thought that a beetle would have been smart enough lay better eggs at the bottom of a stack and dummy eggs on top to avoid predators. Like the comment above it really is amazing how smart insects really are.

  3. Anonymous says:

    Insects have gathered certain wits through trail and era I think and its kind of interesting how that is a concept us humans have grasped. Like the previous comments stated insects are really smart and actually smarter than we would have ever assumed. Dummy eyes as decoys to predators.

  4. Anonymous says:

    Insect brains are extremely small in comparison to human brains. However, this just proves that brain size does not equal intelligence. These seed beetles have made an adaptation to protect their offspring, Doing just as any parent would do to protect his or her young.

  5. Anonymous says:

    The fact that beetles lay their eggs inside of seeds is genius, that along gives it protection from many predators. However, the wasp has learned the weakness. It amazes me even more to find out that the beetles will set up a couple “dummy eggs” to fool the predators. The larvae will not survive in the egg because they will run out of food in the small “dummy egg”

  6. Anonymous says:

    This proves that insects are smarter than what the average human portrays them to be. Laying Dummy eggs to fake out predators is a genius way to outsmart and keep the eggs alive and safe.

  7. Anonymous says:

    I think that it is pretty neat the way that the beetles have adapted to their environment and engaging predators. It seems that the beetles are smarter then they look when it comes to protecting their offspring. Laying “dummy” eggs on top of the real eggs to protect them from wasps is brilliant.

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