Parasites To Fight Insect Pests Suggested

Press, Volume CII, Issue 30176, 6 July 1963, Page 18

Parasites To Fight Insect Pests Suggested

New Zealand could well investigate the possibility of mass-producing mxroparasite groups, on a scale similar to that being used for insecticides, in the fight against insect pests. Mr J. M. Kelsey said in a lecture to the Canterbury branch of the Royal Society of New Zealand. Mr Kelsey, who is the principal scientific officer in charge of the entomology division of the Department of Scientific and Industrial Research, Lincoln, was speaking on insect control in the third of a series of lectures to the Royal Society on the artificial control of animal populations by chemicals. V was estimated that crops and stored produce worth £l4 and £53 billion were destroyed by insects each-year, said Mr Kelsey. In Britain and New Zealand this was wirth £32 million and £l4O million respectively. In addition to food damage, insects spread 35 diseases. , which meant that 2000 million people were suffering from one or other of these diseases as well as from malnutrition.

Remedies to the problems came under the headings of plant-breeding for resistance, biological control of pests, mechanical and farm management and chemicals. Biological control —the introduction of natural enemies of insect pests—was a field in which a measure of success had already been achieved overseas, and New Zealand would be well advised to follow suit, he said. There was a large array of parasites which affected insect pests, but 'he had no faith in the reliability of unassisted biological control, said Mr Kelsey. “I feel that in some instances there is a real place fo? the propagation of parasites or predators " under artificial climates, so that they can be introduced to the field at a time early in pest development,” he said. «. White Batterfly

The white butterfly virus could be kept stored at room - temperature or in cool storage between seasons, and if in- ' troduced as a spray at the time of the hatching of the first generation of butterfly eggs there was an almost complete eradication of the butterfly with one spraying. “Since most of our major insect pests already have virus, bacterial or fungal parasites, and bacteria and ti viruses are already be-ng used successfully overseas, I - think we would be well advised to follow suit,” said Mr Kelsey. “The large-scale production

of these microparasite groups would have to be produced on a scale similar to that for insecticides at the present time, so the much-maligned commercial interests would still come into a prominent, and I believe a deserved, place in the picture of insect control.'*

Farm machinery was sometimes of value in controlling insect pests. Heavy rollers had been used in Canterbury to control grass-grub infestation, and the crushing effect of stock feet had an even better effect than the rollers. A combination of cultivation implements and birds could ultimately reduce this pest to almost nil This type of control could, however, only be used for the initial sowing of pastures and crops and other methods were necessary for maintaining the pastures. Plant breeding for resistance was generally slow and had to be supplemented by the use of chemicals which could give a good yield even in insect-susceptible crops. Use of Chemicals

Many obvious benefits had been reaped from the use of chemicals, such as the control

of man’s insect-borne diseases. If insecticide usage was discontinued, only 10 per cent, of world cereal, vegetable and orchard crops would be fit for human food, one in three people would suffer from insect-borne disease, and life expectancy would fall, said Mr Kelsey. Stock would suffer, and wool quality fall. Discussing the residue persistence of insecticides in the soil, Mr Kelsey said that many people would prefer the short residue material diazinon over D.D.T., because freedom fshm residues went hand-in-hand with ideas of safety However, until the full effects of organophosphates were known, it was best to proceed cautiously. The threats of contamination of streams and ground water were not so real in New Zealand as overseas. “I can see no reason why we cannot produce sufficient high-quality food for the growing world population of a much healthier, longerlived race, but to do this it will be necessary to enlist the aid of a wide range of carefully-selected pesticides, supplemented by mass rearing and distribution of natural enemies of our main insect and other pests,” Mr Kelsey said.