18 



I think we would have a much more sound basis for making initial 

 judgments as it relates to this. 



However, I would point out that even the best of data bases con- 

 taining these characteristics, when you are dealing with a species 

 out of its natural environment, it is not always known what the po- 

 tential invasiveness or deleterious qualities that a species might 

 have are until it moves into a new environment. But certainly a 

 data base with these qualities outlined I think would be a very use- 

 ful primary means of defense in terms of making the initial judg- 

 ments. 



Senator Akaka. The Asian tiger mosquito was apparently im- 

 ported in shipments of used tires. This pest is an aggressive biter 

 and prolific breeder. It is also known as a carrier of dengue fever 

 and two forms of encephalitis, one of which has a 30 percent mor- 

 tality rate in humans. 



In your testimony, you mentioned that human health costs due 

 to the presence of plant pests are staggering. In what other ways 

 do alien pests have damaging effects on human health? 



Mr. SiNGLETARY, I wiU try to outline my concept of what some 

 of these potential other human health factors could be. Let's take 

 toxic plants, for example. Giant hogweed, a federally listed noxious 

 weed, has sap that causes irritating reactions to the skin. Poison 

 ivy is an introduced species in this country. Also, there are plants 

 that can kill livestock or cause adverse reactions in livestock. 



Let's take invasive plants in water systems, for example. By clog- 

 ging water systems, you decrease the water quality, water holding 

 capacity in impoundments, and you create breeding grounds for 

 mosquitoes by not having moving water in rivers and streams. 



You also have a factor, although it may be more indirect, and 

 that is the displacement of native species whereby some of these 

 plants have medicinal purposes. Then you have the direct impact 

 from impacts of mosquitoes, let's say. We have heard the example 

 of the Africanized bee, the direct impact on public health, stinging. 

 Also, the imported fire ant, allergenic reactions and that kind of 

 thing, similar to what you have fi'om bee-stinging incidents. 



And I would like to go back and just cite you one example related 

 to livestock, and that is tropical soda apple in Florida. This is a 

 newly introduced species in Florida. It is a pest in pasture situa- 

 tions, and livestock will not graze on it. What happens is you have 

 less area available for forage for livestock because it just creates 

 dense thickets. There are thorns on the stems and leaves. You 

 could consider that a human health aspect in terms of potentially 

 reducing a supply of food for this country. 



But to go on with the example, livestock inadvertently spread 

 this pest because they will feed on the fruit in the fall, and the 

 seeds go through the animal. If that animal is sold in commerce, 

 then that is indeed a means that this pest artificially moves this 

 noxious weed. 



So there are some examples and some specifics regarding your 

 question. 



Senator Akaka. Theink you, Mr. Singletary. 



Dr. Carlton, you gave some impressive testimony about the dan- 

 gers of ballast water and the aquatic pests carried in that water. 



