Oak gall insect update

In the post on oak galls I speculated on whether gall wasps have parasites that lay eggs in larvae when they are inside the gall.

Sure enough, I am kindly informed by Dr Ted Swiecki, an author of the Guide to Insects and Diseases of CA Oaks, that there are people who study this in detail:

Hi Jeanie

The short answer is yes. The longer answer can be seen at http://homepages.ed.ac.uk/amegilla/Oak%20gall%20communities

part of a very good website about oak gall wasps http://homepages.ed.ac.uk/amegilla/Gallwasp%20Biology%20homepage

The general situation has been described in poetry, as you may know:

Great fleas have little fleas upon their backs to bite ’em, And little fleas have lesser fleas, and so ad infinitum. And the great fleas themselves, in turn, have greater fleas to go on, While these again have greater still, and greater still, and so on. Regards,

Ted Swiecki

Principal / Pathologist


Phytosphere Research

1027 Davis Street, Vacaville, CA 95687

email: phytosphere@phytosphere.com


Predators and parasites have devised ways to get into galls, live with the larvae until they are big enough, and then eat them.

Perhaps the coolest part of the world of galls is, in the words of one of the researchers Dr S has referred us to, is this:

A striking feature of oak gall communities, and one that makes it easier to work on them, is that most of the inquilines and parasitoids are only found in oak galls. This makes it possible to look at galls as natural microcosms, separated ecologically from other sets of animals in the same environment.

Other interesting research findings: parasites and their targets have co-evolved to the extent that the different species of parasites have ovipositor (i.e. egg-laying device) lengths based on the size of the gall, the depth it needs to insert to hit the target, and the thickness and toughness of the gall. They have different windows of opportunity over the life of a gall – some can gain access when it is small and softer, some when it is larger and tougher. Now that’s an arms race.

Here’s a photo of a parasitic wasp and ovipositor from the paper above:

The "drilling blade"

Why is this important to us??? This is part of the diversity of life! E.O Wilson has written extensively and persuasively on this. It is as important as quantum physics. People who spend their careers figuring this stuff out should not be singled out for the Golden Fleece awards, but praised and elevated to high social status for helping us understand how to save the planet from ourselves. For if we appreciate the complexity our survival is built on, how can we let it be wiped out?

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