INSECT PROBLEMS

Nelson Evening Mail, Volume LXXII, 27 February 1939, Page 12

INSECT PROBLEMS

MAN'S RESEARCHES SPREAD OF DESTRUCTIVE ACTIVITY DR. MILLER’S ADDRESS TO ROTARY CLUB The part played by Insects in ecu- j nomic development formed the subject of an address given to the Rotary Club j by Dr. D. Miller. “Fortunately, only a very few species j of insects rank as of major importance i in man's economy,*’ said Dr. Miller. I "Nevertheless, these few are sufficiently destructive to warrant concentrated research the world over. Though insects can be considered destructive only when they interfere with production as set by j human needs and standards, their de- j predations are so extensive that great; annual loss results. It is now gener- ! ally accepted, that approximately 10 ; per cent, of the world's products arc j thus dissipated, and on this basis it can I x be calculated that the British Empire l

alone could support a further 45.000.00' people with no extra effort, if it wen not for the action of these Insects.” “One of the causes responsible fo the spread of destructive insect-octivil. is the increased expansion of work trade and transport, further hastcnei by the development of aviation. b, which means insects are carried to nc\ lands, and natural barriers to spreadoceans. mountain ranges, and desertsare overcome.” “Researches into destructive insec problems extend along many avenue: The basic activity is concerned wit the study of the insect itself regardin its habits in relation to seasons, climat and host. With control in view, vari ous phases are followed, includin possibilities in the utilisation of culti vation. insecticides, resistant plants o animals, and the influence of nature enemies. All of these methods are c fundamental value, which separatcl or in combination have already prove themselves. Though there have bee many failures in destructive insect con trol. there have been many outstandin successes throughout the world as illus trated by a few examples.” INSECTS AND DISEASES “Among the veefors of diseases afflict ing both man and animals, success i control is found in the case of th

On house-fly which discminates enteric, re dysentery, tuberculosis, etc., the mos- ! quitocs responsible for the transmission j or of malaria and yellow-fever, and the ; 1y rat-flea of bubonic plague fame. It t> Id I unnecessary to elaborate the welled known history of the campaign against by these insects resulting in extensive rc:\v gions being made habitable by man, bcyond illustrating their value by the ; fact that before bubonic plague was controlled 1.000.000 people died annually in India, and in Europe Cl i during the 14th century." '' ‘‘Tick-borne diseases arc also a 1 scourge of man and animals in certain ,IK countries. Texas fever may be cited 1 c J Over an area of some 742.000 square M " i miles m the southern United Stales. 11 . 8 the cattle industry was at one time threatened with extinction by the ravor , ages of this disease, which is carried a j from one animal to another by the a I Texas fever tick. An intensive camN paign of quarantine, dipping, and pns--0 turage rotation was inaugurated, and 1 1 after about twenty-seven years was so ,n ’ , successful that ‘the tick-free South' n " became an everyday expression.” INSECTS AND CHOPS “In the case of crop-destroying insects mention must be made of flic out- . ' ■ standing work in New Zealand by my 111 ; predecessor, the late Dr. R. J. Tillyard. 10 1 who imported and successfully established the aphelinus parasite, and so controlled the woolly-aphis. Within the last few years another most spectacular ; example of the parasitic control of a ' serious pest is the work of Mr John Muggeridgc. who. as Government EntI ornologist. was responsible for the introduction of the parasite that suppressed the white-bulterily The magnitude of this can be visualised by considering that amongst the food-plants of the butterfly caterpillars is rape, i upon which the fat-lamb industry la'rgci :y depends, involving an annual revenue l of some £8.250.000 The white butterfly most certainly reached New Zealand on ; some ship, probably from the Hawaiian I Islands.” "Giving our attention to problems in | other countries, the control of the Lcvuj ana moth in Fiji is worthy of note The natural home of this moth was the island of Yiti Levu until 1925. when, for some unknown reason, it suddenly broke its traditional bounds, spread throughout the neighbouring islands, and laid waste the coconut palms. As these palms not only provide the natives with meat and drink, but also arc Hie basis of the copra industry, the islands were faced with economic disaster. A search was made for a natural enemy, which was found in the Malay States, and brought to and established I m Fiji, where three months later it had : the moth under control. The cost of. ' securing this parasite was £3500, and i an annual revenue of some £1.000.000 : was assured tlie colony” J "Some years ago in Hawaii, the, ! sugar-cane leaf-hopper became cpii demic, resulting in serious losses to I the planters. Again a parasite, was sought, and one that attacked the leafhopper eggs was located in Australia. : In one Hawaiian plantation, where the hopper had reduced the output from about 11.000 tons to 802 tons in two years, the establishment of the parasite resulted in an increase to 1 L.G3O tons within twelve months.” “Though control of insect pests aims at reduction and not elimination, the latter results on rare occasions. A classic ease is that of the Mediterranean fruit-fly— the world's worst fruit pest—l J when it gained a footing in Florida durimg 1929. and invaded an area of 10.000.000 acres which produced a crop! ; worth £48.000.000. Owing to the gravity ol the situation, the United i States Congress passed an apprgpria- : tion of £BOB.OOO as a lighting fund .-and j that alter a discussion lasting only ten ; minutes. A team of 900 specialists eon-j centrated on the work, and the Stale , ; was placed under close quarantine. In-1 tested areas were cleaned up and ripen-' mg fruit and vegetables in which the lly would breed were destroyed. Alter about two and a half years of this campaign only one orange was found ; infested by the maggots of the fly.” “Apart from the instances of parasitic! control of insect pests already cited, no \ better example of successful insecticidal control can be taken than that found > in commercial orchards. There arc i spraying technique is so effective that a very high percentage of first quality I fruit is annually produced and a valu- j able export trade maintained, in spite j of several.destructive insects, any one; of which would ruin the crop if spray- , ing were relaxed ” FOREST AND TIMBER INSECTS | “In the case of f T trees many out-i standing insect problems are being faced and attacked by means of parasites and silvicultural management Bark-beetles are amongst, the most important insects destructive to trees and have caused immense losses in the United Stales and elsewhere. In New Zealand we have such a problem in the European bark-beetle well established in the country. This insect attacks exotie conifers, and though the present extensive pine plantations are too far established to suffer serious injury, the tioublc will commence as soon as the first crop of trees is removed i and replanting • ndcrlakeii on cut-over areas. We have data in one case show- j ing that at least 33 per cent, of young 1 trees were destroyed by the beetle. I However, we are not waiting for a j major attack i develop; the Cawlhron ! Institute lias already imported and lib- j crated a natural enemy and lias ar- I ranged for a further supply of about | 500(1 of these beneficial insects.” j “Extensive damage is done by borers : I<> constructional timber throughout ! | New Zealand. The position has be- ; I come so acute that a team of special-! | ists, dealing with different aspects of | the problem, has been brought together as the Timber Protection Research Com- , mil tec by the Department of Scientific 1 and Industrial Research. Owing to the recent discovery of certain destructive! Australian while-ants in Auckland, the | problem of timber protection, preservation. and control of the insects has; * developed to a position of much greater importance than formerly. Since these ! white-ants are so rapidly destructive; r and so well established, they overE shadow, in Auckland at least, even such E a major insect as the long-horn borer ~ bcetic, itself a rapid worker ” = = WEED CONTROL E "The eases already given refer to the j E control of animal parasites and planter feeding insects. Another phase is the ~ use of plant-feeders in the control of ~ weeds. The possibilities of this method ~ are well illustrated by the control of E prickly pear in Australia. Some E 6-000.000 acres were invaded by the E weed which formed impenetrable E thickets before the establishment of r the Cactoblastis caterpillar, which has r; now razed the cactus and opened the E country for settlement. In New Zea- = land vve are working at the Institute on 5 the control of piri-piri and ragwort. E and the work is advancing salisfac tqrily, though it will be some time be- — tore we can -undertake an universal E ( ' am Paign a gain. -I the weeds. With gorse E we have had considerable success with ~ the weevil that destroys the seed, and = which we are gradually establishing! throughout the country; observations! E f rom one locality have shown that close E on per cent, of the gorse pods were ! mfr'vl r'fl tI, i . •'