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Photo of Charlotte Causton Charlotte Causton as seen on Voyage to the Galapagos: Paradise Lost?

Click on Charlotte's photo to read a brief bio.



q I remember reading that the introduction of mosquitoes to the Hawaiian Islands is one of the reasons for causing an accelerated rate of extinction of Hawaiian birds. The mosquitoes were vectoring diseases which were lethal to the Hawaiian birds. Is there the same concern that the introduction of mosquitoes to the Galapagos Islands would have the same effect on the populations of birds on the Galapagos Islands? (Question from T.C. Alexander; Life Science Teacher and Entomologist)

A Yes, there is great concern about vectors of bird diseases being introduced to the islands, especially since we still do not have all the funds necessary to implement a quarantine and inspection system for the archipelago. A species of Culex and a black fly have already been introduced. Both are potential vectors of bird diseases and if an infected bird reaches Galapagos, these insects would facilitate transmission of these diseases to many of our native and migrant species.



q After watching the show, Im curious what single introduced species you and other scientists consider to pose the biggest threat to the Galapagos. (Question from Thomas)

A The goats are probably the biggest threat to animal and plant species in Galapagos. They destroy vast tracts of land, including habitats that are home to the giant tortoises. An example of this is the rim of Alcedo Volcano, where endemic forests such as those of the Scalesia genus have been eaten and destroyed. The damage caused by goats sets off a series of negative reactions. The plants that are eaten or destroyed are habitats for many species, or a food source for others. The absence of these plants on the rim can be the cause of individuals dying or migration to other areas. The destruction of these plant species also opens up areas to invasion by introduced weeds that often grow faster than native species. All of these reactions disrupt the delicate balance of the ecosystem.


q I'm curious how you're going to cope with the cottony cushion scale insect that is now affecting 40 plant species on 10 islands of the Galapagos. Do you plan to introduce some of the insect's natural enemies? Or do you fear that may cause even more problems? (Question from Barry)

A Thank you for your interest! This species is at the top of our list of aggressive insects to control. Since Voyage to the Galapagos episode was filmed by the Frontiers crew, a further 10 plant species have been reported as food plants of the cottony cushion scale (total now 50!). Mangrove trees are being heavily hit at the moment. This scale insect is resistant to chemical control and we are currently evaluating the possibilities of using the vedalia beetle to control it. This beetle has been introduced into many countries and it is claimed that it has no negative effects on other fauna. However, we do not want to take any risks so we are testing the beetle under quarantine conditions to see if it feeds on any of our native scale insects. If it only feeds on the cottony cushion scale and does not compete with any native insects, a risk analysis will be submitted to the National Park Service and they will make the decision as to whether release or not.

On the other hand, we have several species that are potential vectors of diseases and could become great threats in the future. Mosquitoes and pathogens are good examples. As I mentioned in another answer, we have a mosquito that is known to be a vector of avian diseases in other countries. If an infected bird arrives in the Galapagos, these diseases could be picked up by the mosquito and transferred to many other bird species resulting in the death of many individuals. We also fear that pathogens could have a similar effect. Pathogens can be brought in on chickens or by migrant birds. At present, we are desperately trying to find funds to survey the archipelago and find out what diseases we already have so that we can set up contingency plans to respond to any emergency that occurs.



q Is anyone studying how insects on the Galapagos have evolved? Is there any evidence of distinctly different insect species on the islands? (Question from Daryl)

A Stewart Peck from Carleton University is studying the evolution of some beetle species, however, very little is known about other insect groups. Groups such as plant hoppers (Homoptera) and some moths (Lepidoptera) show evidence of speciation, and we are sure that there are more. So if there are any entomologists looking for research topics, please write to us!




 

Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.