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Control Of Weeds: Insects Proposal

Volume 489: debated on Thursday 5 November 1987

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3.5 p.m.

My Lords, I beg leave to ask the Question standing in my name on the Order Paper.

The Question was as follows:

To ask Her Majesty's Government whether they will sponsor a study of the use of insects to reduce and control bracken, ragwort and other persistent but unwelcome weeds.

The Parliamentary Under-Secretary of State, Ministry of Agriculture, Fisheries and Food
(Baroness Trumpington)

My Lords, I can confirm that my department has already decided to fund a study, as compared with existing methods. The study will be carried out by the University of York which is currently investigating the potential of a number of so-called biological control agents of bracken. Existing measures such as herbicide application and ploughing are adequate to control ragwort and other weeds.

My Lords, I should like to thank my noble friend for that satisfactory reply. As pesticides have decimated insects and other small organisms in the countryside without discrimination, is there not now a case for encouraging selected species which have the benign characteristic of destroying those weeds that are the most difficult to keep under control?

My Lords, I hope that I get a better answer than that. Is the noble Baroness aware that there is nothing new in predators dealing with pests and weeds? Today, unfortunately, the weeds and pests are on top of the situation. One would need to breed an awful lot of predators to deal with them—particularly bracken.

My Lords, yes. That is one of the reasons why tests are being carried out. It is said that bracken is spreading at the rate of 1 per cent. each year. It is normally avoided by animals because they can be made ill and possibly die as a result of eating it. On the other hand, nobody would want to eliminate bracken entirely. It provides variety to the landscape and cover for wildlife such as deer and grouse. It is harvested for fuel.

My Lords, is my noble friend aware that imported pests may be necessary to control bracken? In that case, does she know what the NCC might say, bearing in mind the powers of the Government to restrict imports of pests and bugs under the 1981 Act?

My Lords, the tests are being carried out on caterpillars of the South African moth, one of the Panatima genus and the other named Conservulus insignia. Under the Wildlife and Countryside Act 1981 it is an offence to release any animal not normally resident in Great Britain without a licence from the Secretary of State for the Environment.

My Lords, will the noble Baroness bear in mind the fact that the history of using insects to control plants or other insects shows that it is a hazardous process and almost always ultimately leads to an environmental catastrophe of some kind or other?

My Lords, yes. But there have been successful cases including the introduction of South American moths to control prickly pear cactus in Australia and ladybirds to control pests in Californian citrus orchards. In other cases, the control organisms have succumbed to unfamiliar climatic conditions, or have died out as a result of their own success.

My Lords, has the noble Baroness any knowledge of the caterpillar which specialises in eating bracken and does no harm to anyone? I think that this caterpillar has been used in Australia.

My Lords, the only one that I know about is the South African kind.

My Lords, is the Minister aware that it is possible to control the spread of ragwort by grazing sheep on an infected field in the month of May?

My Lords, I thank my noble friend for her first very satisfactory Answer. Perhaps I may also add my admiration for her second reply to me which, although somewhat ambiguous, fulfilled the wish that your Lordships expressed in the debate yesterday—namely, the desire for brevity in replies from the Front Bench. May I further ask my noble friend whether she is aware that one does not have to go abroad, because it was only 30 years ago that the larva of the cinnabar moth, which is indigenous to this country, kept ragwort under control in many areas?

My Lords, I agree with my noble friend, but unfortunately natural predators tend to keep the numbers down.

My Lords, does the Minister agree that this is just the kind of research that should be undertaken in the public sector? Is she aware that some people have expressed considerable concern that if the department's new-found enthusiasm for industry funding of agricultural research goes too far, the multinational chemical and spray companies may not be prepared to put their full weight behind such research?