My Lords, the comments that I wish to make may have some relevance to the codes of practice that will accompany the Bill. Amendment 71, in the name of the noble Lord, Lord Berkeley, which has already been debated, could have been a cue in its own right for a wide-ranging and interesting debate.
The noble Lord, Lord Berkeley, proposed the definition of a species. A species is commonly defined as the largest extent of a group of organisms that is capable of interbreeding and producing fertile offspring. That is similar to the definition that the noble Lord, Lord Berkeley, was advocating, which also mentioned the exchange of genes. However, his definition did not include the fertility of the offspring as one of its conditions. Moreover, we know that bacteria of widely differing species can exchange genes via plasmids, which are small DNA molecules that can be separated physically from the chromosomal DNA. One might wish to exclude bacteria from the definition.
These are abstruse matters and I do not wish to pursue them further. Instead, I propose that in place of “invasive non-native species”, the legislation should be talking simply of “pests”. I assert that it is inappropriate to talk only of non-native species. The objection might be raised that the word “pest” is too vague to serve the purposes of this legislation. What is a pest in one context might be a harmless organism in another context. However, this is one of the realities that ought to be taken into account. I will mention the well known example of the English rabbit. When transferred to Australia, it became a major pest that threatened the viability of Australian agriculture. Rabbits destroyed the grazing land and by eating native plants and grasses exposed the top-soil and left it vulnerable to erosion. One way of overcoming an infestation is to alter the ecology by introducing a predator of the pest, or by some other means. In Australia in the 1950s, the ecology of the rabbits was altered radically by the introduction of a malign myxoma virus, which causes myxomatosis in rabbits.
The point I wish to make is that we need to consider pests within their ecological contexts, and ecology can be severely disturbed by inadvertent human interventions. Often the effect of a human intervention is to diminish the diversity of the ecology by eliminating some of its organisms, which may allow others to propagate without restraint. Thus an organism that has hitherto been regarded as harmless may become a pest as a consequence of such disruption. This is an ever present hazard in intensive modern agriculture. The matter of whether an organism is native or non-native is beside the point.
An ancient example will serve as an illustration. It is provided by a variety of grasshopper that was originally confined to the Middle East, which has latterly invaded the entire African continent. This is the locust, of which the pestilential effects emerged when the advent of agriculture upset an ecological balance. The Book of Joel in the Old Testament provides a graphic description of a locust plague in the Middle East.
The point that I wish to make is that we should approach the problem of ecological imbalance not by programmes of localised pest control but in a holistic manner that takes a far wider ambit. Instead of relying on local pest control officers to deal with outbreaks of invasive species, we should be relying on our public sector research establishments to monitor our natural—and our unnatural—environments so as to guard against pestilential outbreaks and to suggest the necessary countermeasures. This reinforces a point that has already been made by my noble friend Lord Davies, and I hope that his comments might be taken into account at a later stage when we come to review the Government’s deliberations.