"Then I saw that they were attacking these other eggs from M. amicus that were much larger."
Wondering how the wasp larvae would do in the apparently larger eggs, Deas investigated and was surprised to find that the larvae were not doing well at all.
"I didn't understand why. My idea was that there's just too much yolk in there. There are instances where wasps have been developing in size and they sort of drown because there's still yolk around them and they can't pupate in moisture, they can't turn into a cocoon. I thought that was the reason."
The moment of truth
"I was looking at the eggs under the microscope, and I saw when I looked on the side that it seemed like there was another egg underneath it," said Deas. "I took some really small insect pins and started to scrape around the edge of the egg. Eventually I had a layer come off."
M. amicus' apparently larger egg turned out to be not one egg, but a whole stack of beetle eggs laid one on top of the other. "I was thinking: 'Why would they do that?'" said Deas. "And I thought about the wasp."
"I went out in the field, collected a bunch of seedpods and brought them back to the lab."
Deas measured the parasitism on eggs laid individually versus on bottom eggs in a stack to see whether having one or more eggs on top was sufficient to protect the bottom eggs. And sure enough, Deas found the individual eggs were parasitized much more frequently than those eggs that were shielded at the bottom of a stack.
On the verge of what he thought was a new discovery, Deas was shocked to find that scientists before him had found the same thing in the 1920s.'/>"/>
|Contact: Daniel Stolte|
University of Arizona