by Randy Weckman

The Department that Bobby Built

Bobby Pass is an unusual character and he's of an age where he doesn't mind people thinking that. At 70, Pass is the oldest chair of a department in the University of Kentucky. He probably also has held a chairman's post longer than anyone else in modern UK history, too, having taken over the reins of the Department of Entomology in 1968, when he was a young pup of 37. Now, at an age when many an academic is consigned to emeritus status, the venerable man with the white hair and the genteel South Carolina accent continues to build his department to be one of the premier entomology departments in the United States.

With a heart of a young man - both literally and figuratively (see sidebar ) - Pass has witnessed great changes in the field of entomology. Remember, Rachel Carson was still trying to publish Silent Spring when Pass was working on his doctorate. He joined the faculty of the University of Kentucky in 1962, just as Silent Spring was serialized in The New Yorker magazine to great acclaim, as well as intense derision. It was an era of DDT, not IPM, when he was appointed. It was a time of Spray 'em. Kapow. DIE. with regard to insects.

Soon after that that Pass championed the holistic approach to pest management that is a key to today's standard, integrated pest management paradigm - using pesticides only when necessary to control damaging insects.

The secret to Pass' success as a department chair, it is said, comes from the fact that he hires young, extremely talented and enthusiastic scientists who have ideas and then lets them loose to pursue excellence. He cheerleads more than directs, letting each young scientist have his head in his research endeavors. They are encouraged to think. Think. Think.

Take Charles W. Fox, a hot shot researcher from California. His mission as an entomologist is to understand the interface between the environment in which insects reside and their ability to adapt. Population genetics, really.

His research findings are tantalizing in that they tell us a great deal about insects and maybe something about ourselves, as a higher form of life.

To fully appreciate Fox's research, you may need to go back 150 years, when naturalists in England noticed that the population of a type of forest moth had changed. Instead of most being white, now most were a smutty color to blend in with tree leaves that, because of pollution from coal furnaces, had turned that same color. The white moths were more visible as prey, so the white type waned while the smutty-colored ones flourished.

And while scientists have explained the phenomenon over and over again as "survival of the fittest," Fox believes there's more to it. His research indicates that the process of insect population change is far more complicated than the theory of the survival of the fittest would imply.

Fox's research shows that momma insects have a powerful influence on their babies and that influence begins well before the babies are born. He's found that when the environment in which momma insects live grows dicey, they use their energy to lay larger, but fewer eggs than when the environment is rosy. The larger eggs hatch, and the babies are bigger and hardier. However, if the environmental hazards are brought about by high populations of the insect, the mothers-to-be switch their gambit and lay smaller and fewer eggs, which Fox explains is a response to stress; the mommas are so stressed they can't lay bigger or more eggs.

"Over time," he said, "these maternal effects could have a decided influence on the composition of the gene pool."

Fox's findings are more than trivial parlor talk fodder. If scientists can understand how female insects assess the environment or how they can adjust their reproduction habits to accommodate environmental changes, then they may find out how to trick the momma insects into misreading environmental cues to produce fewer baby pests in the field. Or the research could even promote the proliferation of beneficial insects that prey on damaging ones.

Fox is not alone in his work. One of his colleagues in Entomology, Stephen Dobson, is also doing research based on a reproductive approach which holds great promise for allowing us to control insects without relying solely on chemical insecticides. His approach to insect control is to use a naturally-occurring bacteria to reduce insect populations. He sees it being used in tandem with conventional insecticides that would knock down large populations, and his biological control techniques would continue to keep populations low.

The key to Dobson's research is a group of bacteria called Wolbachia, a common parasite of certain insects - more than 2000 insects are known to harbor the bacteria.

The bacteria infect cells in the testes and ovaries of certain insects, specifically arthropods - such as aphids, wasps, beetles, termites, and mosquitoes - decidedly altering the reproduction of their hosts.

The bacteria are quite quirky. In some insect species, infected males can sire offspring only if they mate with an infected female. In other species, infected females give birth without the need of a male. In another species, the bacteria transform male embryos into females. And in some, embryos produced by an infected male and non-infected female don't develop into adults. (By the way, guys, don't worry, the bacteria doesn't infect humans.)

The focus of Dobson's research is this ability of the Wolbachia bacteria to cause such reproductive upsets in arthropod insects. He is exploring two strategies for using this naturally occurring phenomenon to control mosquitoes.

The first strategy uses their ability to cause sterility to reduce populations of insects. The second strategy is to use the Wolbachia bacteria to alter the genetics of populations of insects so that they cannot transmit certain diseases.

Dobson, along with Charles Fox and Francis Jiggins, from the University of Cambridge, developed a model that predicts just how far insect populations can be suppressed using the strategy of releasing infected male mosquitos into the population.

Because males with Wolbachia bacteria can mate but not reproduce live young with non-infected females, the population is greatly curtailed due to fertilized eggs that don't hatch. And because insects with certain strains of Wolbachia cannot produce viable eggs when mated with others infected with another strain, strategic management can reduce the population quickly and keep it suppressed by alternate releases of mosquitos infected with different strains of the bacteria.

Their model predicts that alternating the release of mosquitos with different strains of Wolbachia can reduce populations by 95 percent.

In addition, Dobson's research could be part of the solution to minimizing a number of important human diseases carried by insects, including malaria, river blindness, elephantitis, and encephalitis, as well as diseases which infect commercially grown plants (which are carried by arthropod insects).

"If we could genetically alter the Wolbachia bacteria so that it confers resistance to certain diseases that insects harbor, we could conceivably reduce the disease potential posed by insects for both animals and plants," he said.

Entomologist Ken Haynes also investigates how insects respond in their natural environment. Specifically, Haynes researches how insects communicate with each other.

And it's not just the chirping of crickets or the buzzing of bees or the flashing of fireflies. Insects communicate very efficiently with scents, called pheromones, which humans can't smell. They release pheromones when they find a good place to eat - something like a restaurant review in the newspaper - or when females are available for mating, or when there's danger nearby.

Synthetic pheromones have been used since the 1970s as part of insect control strategies. Synthetic pheromones, which are rather insect specific, are used to lure insects to traps for detection, monitoring, or as a direct control. In some cases, pheromones can be used to confuse amorous males during mating so they don't find the females. The result is lower reproductive efficiency and fewer insects. The synthetic scents are a siren song that leads suitors away from their potential mates.

Haynes' studies of the cabbage looper moth has discovered a single gene mutation that results in a dramatically different pheromone blend emitted by females. His current research is investigating whether males have different behavioral responses to different pheromone blends, based on their genetics. His concern is that selection from using pheromones unwisely may cause the insects to retool their communication systems, in the same way that some pests have become resistant to some insecticides.

"By understanding better the way insects communicate during mating, especially with pheromones, we hope to preserve the usefulness of synthetic pheromones when they are used to control mating behavior," Haynes said.

Haynes and colleagues at University of Kentucky and Cornell University have investigated communication in masked chafers, which are the adult stage of white grubs - the kind that can shear your lawn off below ground before you know it.

Their serendipitous discovery that the white grubs produce the pheromone, even though they won't need it until the adult stage, has led to many questions about how this communication system originated. Now, the researchers hope to identify the chemical so that it can help control this important insect pest.

"The more we know about pheromones, the better we will be able to devise controls that effectively reduce economically important populations, " he said.

At first blush, Michael Sharkey's research might seem a bit esoteric, if not tedious. His specialty is Hymenoptera, the group of insects we know as wasps, ants, bees. His work is to add to the list of known Hymenoptera by discovering and describing new species.

Ants, wasps and bees? They're nasty things; they sting you!

But wasps and other members of the Hymenoptera have a greater purpose in life than stinging you. They are parasites of many other insects that devastate crops. And they are pollinators of many crops. If they were to disappear, human society would collapse.

Sharkey's research concentrates on parasitic wasps - wasps that lay their eggs inside the body of another insect. When the eggs hatch, they then devour the host insect.

"Parasitic wasps are especially important in controlling crop-eating insects," he said.

Sharkey is so well known as a "waspologist" that he has two genera (in biology talk, genera is plural of genus), named after him - Sharkeyella and Sweaterella (named for the Kitchenor, Ontario, native's penchant for wearing sweaters). He has 13 other insects sporting the name of Sharkey.

The entomologist also is working closely with a biodiversity inventory of 12 national parks in Colombia, South America, and another biodiversity inventory for the Great Smokey Mountains.

The Colombian work, sponsored by the Colombian government and the National Science Foundation, seeks to inventory the insects in the 12 large parks - which include those in the Amazon area as well as parks high in the Andes. Locals collects specimens of insects and ship them to Sharkey, who identifies those in his specialty and ships off to other scientists those not within his area of expertise.

Sharkey said the Colombian work is important because so many of the crops produced in Kentucky - from alfalfa to potatoes to members of the Cruciferae family - originated in South America. The insects collected there provide a broader understanding of the role of insects that attack these crops and insects that attack the attackers.

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