“PARASITE ZOO”

Greymouth Evening Star, 25 November 1927, Page 4

“PARASITE ZOO”

VALUABLE RESEARCH WORK. “At Farnham Royal, a pleasant, old-world village in the leafy recesses of Buckinghamshire, scientists are at work upon of the most serious and battling problems of the British Empire. A typical English country mansion, with picturesque grounds extending to about seven acres, forms the scene of their operations. Here, in what has been popularly termed a ‘Parasite Zoo,’ they are endeavouring to provide new and more effective means to enable the farmer, the forester, and the cattle rearer of the faroff Dominions to combat the innumerable pests that work havoc among crops and animals, and not only imIpoverish the owners but cause losses i which, indirectly, add to the cost of our food and timber.”

“The extent of the damage done by these pests may be generally indicated by stating that it is estimated that not less than a tenth of the world’s crops raised annually is eaten by insects,” adds a writer in the “Times Trade and Engineering Supplement.” “If we take the tropics alone the figure must be' increased to a fifth, and it should be borne in mind that nearly half the British Empire lies within the Tropical Zone. Such enormous depredations seem difficult to comprehend, yet the difficulty will be lessened if we remember that in Great Britain itself, where the problem is less serious than in some countries abroad, the yearly loss caused by pests is estimated at £30,000,000. *

"Canada has to face a yearly loss of £20,000,000 due to field crop pests, and, in addition, between 1014 and 1921, the spruce bud worm did damage <o the extent of £7,000,000 among spruce and fir trees. Australia loses every year sheep worth £2,000,000 through the ravages of the blowfly, while the cane grub takes toll of sugar cane in Queensland to the extent of £lOO,OOO.

“Enormous losses are caused , in South Africa by the codling moth, which infests 20 per cent, of apples in normal years and 40 per cent, in light crop years. In tygypt the pink boll worm caused damage in 1921 amounting to £10,000,000, while in tropical America, north of the equator (including the West Indies), the damage done every year by sugar-cane moth borers reaches a total of £2,000,000.

“These rough figures will convey an idea of the gravity of the problem before scientists.

“At present farmers and others in the Dominions rely chiefly upon chemical means of fighting the great army of pests. Spraying is resorted to on a large scale, but it is a by no means perfect method, and there are certain crops to which it is impossible to apply this treatment. In recent years it has become more and more clear that the only satisfactory methods is that of biological control which, in a word, means going back to the lesson of Nature itself and supply to the countries which are pest-ridden the parasites whose absence has given rise to the prob Fem.

“Operations at Farnham Royal began recently under the direction of Dr. Guy Marshall and Dr. Neave, of the Imperial Bureau of Entomology, and though they are not yet fully developed a good deal has been done. In a great number of cases the parasites of the various pests are well known, and the task at the new ‘Zoo’ is merely to breed and export them. “Ono uses the word ‘merely,’ but it is not to be supposed that all is simplicity itself, for there are many difficulties, not least of which is the danger of sending out to the Dominions parasites which are not free of hyper-parasites. The latter would, of course, gradually negative everything that had been done. It is also of the utmost importance to export only those parasites which will confine themselves to the pest to be eradicated; otherwise the Dominions would rid themselves of one problem only to be faced by another equally or more serious.

“The greatest care, therefore, has to be taken at every stage of the work at Farnham Royal. The breeding of the parasites is carried out in specially constructed insectdries. These consists of large cages framed in teak and covered at the sides with copper gauze so fine that no insect life can either enter or escape. In order to admit the ultra violet rays of the sun, so beloved by pests and parasites alike, the roofs are of vita glass. “In one of these cages one observes a number of bushes thickly infected with the woolly aphis, which does such enormous damage to fruit trees. Here the appropriate parasite has been introduced, and it is left to do its work by laying its eggs in the larva of the aphis and destroying it. At a suitable stage twigs containing the chrysalis of the parasite will be detached and sent to the areas abroad where they are needed.

‘•ln another cage the parasite of the scale —an insect that, operates on maple and other trees, sucking the juice and destroying them —is being cultivated. In a third and much larger cage, the wood-borer and the blow-fly are being dealt with. “The mansion itself has been turned into a laboratory, in which microscopic and other work is done. It is necessary to make sure that the parasites, when collected, are not only free from their own natural enemies, but that they are the correct species. In some instances every parasite, however minute, has to be caught and examined under a powerful microscope before being passed as authentic. “That is the outline' of what has been done up to the present at this remarkable ‘Zoo,’ but there is still a considerable amount tof work ahead. *Earwigsdo an enormous amount of damage in some of the Dominions, and it is intended to begin very soon the breeding of the parasite which will keep them in check. The codling moth, which ruins millions of apples in Australia, New Zealand, Canada, and South Africa, is to be the subject of research. ‘‘The tsetse-fly, the wheat stem sawfly, the born borer, and the lucerne flea are other pests which are to be taken in hand at the earliest possible moment. Even when parasites have been bred and collected there is still the problem of successfully transporting them across thousands of miles of ocean and delivering them in their new home at the right period, and under the right conditions—a task requiring much study. “Thus actual results from the labours of the Imperial Bureau must be slow in making themselves evident, but progress -is being made as quickly as possible, and there is little .doubt that when the ‘Zoo’ is in full operation the pests of the Empire will for the first time be kept under something like effective control, and scores of millions of pounds will be saved annually to trade.”