BBC films UD entomologist’s research

BBC videographer Kevin Flay works with Douglas Tallamy to film lace bugs for the new Sir David Attenborough nature film tentatively titled “Life in the Undergrowth.”

11:04 a.m., June 25, 2004--Lace bugs in a University of Delaware laboratory might be part of the new nature film by Sir David Attenborough, which is tentatively titled “Life in the Undergrowth” and will feature a wealth of information about terrestrial arthropods with a focus on insects.

Videographer Kevin Flay from the BBC was on campus the week of June 14 to film the lace bugs in the Townsend Hall laboratory of Douglas W. Tallamy, chairperson of the Department of Entomology and Wildlife Ecology in the College of Agriculture and Natural Resources.

Tallamy has done extensive research on the lace bug, an insect that exhibits a rare behavior in the maternal care of eggs. The mother lays a clutch of eggs and then guards them from predators, which is unusual among insects because it requires a great deal of time and certain defensive skills.

“It is an expensive behavior because when the mother is guarding those eggs, she is unable to make more eggs,” Tallamy said. As a result, most female lace bugs that guard their young lay just one clutch, sometimes two, in their lifetime.

To compensate, Tallamy said, the lace bug has developed a reproductive alternative called “egg dumping.” Before she lays eggs, a female will often seek out another female that is already guarding eggs and leave her own clutch there. “It is like taking the kids to the babysitter and never coming back to pick them up,” he said.

At one point, scientists thought the practice was purely parasitic, Tallamy said, because it was believed that while it clearly benefited the dumper, there were no benefits to the mother-guard. Now, however, scientists believe there is no harm to the recipient and that there actually might be some benefits.

Tallamy said the mother-guard already is physiologically committed to guarding her eggs and hormonal changes make it impossible for her to produce more eggs for a time period. Plus, there is evidence that the new eggs from a dumper’s clutch provide a buffer that physically protects the guard’s eggs from hungry predators.

Lace bugs are unusual among insects in that the mother guards her eggs.

“They guard the eggs but they are not very good at it,” Tallamy said. “They tend to lose about 80 percent of their young. So, if a good number of eggs are being dumped, the mother-guard can save more of her own eggs.”

Tallamy said there is a chemical on the eggs that makes them attractive to dumpers, and scientists are working to determine whether or not the chemical is created by the mother-guard herself to invite the dumping of additional eggs.

The lace bug is of interest because maternal care-giving is a very primitive trait, one that dates to the ancient jellyfish, Tallamy said. Over time, the vast majority of insects have developed mechanisms that allow the mother to lay her eggs and then get on with life without long days of maternal care.

“Few species exhibit maternal care,” Tallamy said. “In the insect world, thousands do it, but millions don’t do it. It is an unusual trait, and we are interested in finding out why, if lace bugs are so ill-equipped to guard eggs, they bother.”

Earlier, Tallamy’s research was included in Attenborough’s “Trials of Life” film, which was released in 1990.

Article by Neil Thomas
Photos by Kathy Atkinson

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