A、They impose threat to the local economy. B、They enrich local species. C、They become a local tourist attraction. D、They kill lo

Some governments, such as New Zealand, are facing up to the challenge with tough customs controls on foreign plants and animals. South Africa has well-funded removal programs aimed at, for example, conserving the unique Cape Floral Kingdom and its economically-important nature-based tourist attractions. But far too many countries have failed to grasp the scale of the threat, or are far too casual in their response. The "red tides" seen, for example, in Europe’s North Sea and linked with fish kills are blooms of algae brought accidentally in ballast water from the seas off China.[29]Alien invasive species also challenge the UN’s poverty-related Millennium Development Goals. The plant has now invaded more than 50 countries around the world and annual costs to the Ugandan economy alone may be $112m. The challenge is both a developed and developing economy one, but the true scale is perhaps only now unfolding. Scientists with the Delivering Alien Species Inventories for Europe say there are now 11, 000 invaders in Europe, of which 15% cause economic damage.[30]Meanwhile, climate change is also likely to favor some alien species currently constrained by local temperatures. Improved international co-operation is needed alongside support for initiatives, such as GISP, and the work of organizations like the International Union for the Conservation of Nature.[31]It is important too to boost the capacity of the responsible national customs, organizations that monitor and control the entry of alien species and scientific institutes able to provide early warning, especially in developing countries alongside strengthening agreements under the UN’s International Maritime Organization.
29. What can be learnt about alien invasive species?
30. What is mentioned as the favorable factor for the growth of some alien species?
31. Which of the following is important to boost according to the speaker?