IN A SHIP’S HOLD

Hokitika Guardian, 1 July 1932, Page 8

IN A SHIP’S HOLD

2,500;000 STOWAWAYS. '■* PREYING ON EMPIRE PRODUCE LONDON, June 25. “The human species must turn aside from 'its race ahd concentrate' its , i,noeiiigence on its strongest rival, the insect. The insect type has been cried out very thoroughly under world conditions, while the human species is in its merest infancy', and may' be „ne or Nature’s experiments which wul fail.” '•'This remark (recently made by Mr L. 0. Howard, the chief of the United Staten ' Bureau of Entomology) occurred to me while I was being b ;iO,v n round the Empire’s centre 1 of intelligence established and equipped to light, with all the cunning of science, one particular tribe of man s insect rivals—those which attack aiid • educe the -market value of Empire ~reduce after ft has left the farm, while it is on its. way from the field co the factory or larder. ' This centre, the Stored Products Laboratory- of the. 1 Imperial College of Science at Slough, started three years ago with a grant from the Empire Marketing Board. Its object is to map out the best, methods of .becking ihiis huge leakage in' Empire trade. Almost every perishable crop !.,ae to run the gauntlet of infestation. Moulds change the chemical make-up of cocoa and copra, producing (i;i some cases) an excess of “free fatty ac-ids” which bring a lofv price. In-' sects eki little, but- their mere pre l sence us, an economic.disaster. Even if they only crawl over the outside of the sacks to spin their cocoons .without penetrating the, inside at all, : they cause a serious reduction in market : value. Tobacco, grain, flour, cocoa,, copra, dried fruit, spices. »nd mayo other products are subjec.t to attack. Until this laboratory (a converted country. house standing m a spacious garden now dotted with insect houses) was opened, and placed under Professor J. W. Munro, of the Imperial College in Londoii, there was no institution in the Empire equipped to study these particular- pests, rior was 'there any certain scientific knowledge of how to go about the job of checking their "activities.

LEiiH BItEAIH.ij.SG TOR INSEC'ib I ' . , . < •

The most fascinating part of, the 'nurit ac is Vuy uiueirii, uetaxieu siuuy winch is going on or tne personal iiu-Dius or nisCi-ts. one is remiiiueo

of writing a mograpliy ot a 'famous man. iirvery little po.nt and anecuoue is ca'i'eiuliy collected and compiled, so that eventually, out of a miscellany of facts,' a Complete picture cau.be. piel-eu together! :y;ciemi+ 'i-sVs are trying to gee a csolutely decurate answers to questions such as rnese : How much air ‘dees one lniliv-' iduai breatne Y What exactly dues .eacli Trisect 'eat'? (One insetT was siiotvn -tb ■ teed on 4/ different thing’s, ranging from cayenrie l “pepper'“'to snip s biscuits. \ m order t» solve the first problem, a cunning, piece of apparatus has been desigiie’d to 1 liiid the ’ exact" amount 'of air inhaled by a single insect, ine answer’to this question is of practical importance because of its bearing on fumigation. Each ’' species’'oh •>'irise-cx-displays’a different reaction to poisonous gasbs. iOf the two species of related hioth; tlie cocoa moth and the flour for instance, the first is considerably more difficult to kill than the second. A grain, moth, Triehogramma, withstands all fumigants yet tried. This remarkable ihoth will also live for seven days in a vacumri and can exist for years without -any food.. ;• 1 Dr Page, the chemical expert, showed me ' a sort of giant incubator- ,m which ' different insects, confined in bottles, were being gassed at various concentrations and temperatures. He had rigged* j-his up in , the original garage, which is now a veritable chamber of horrors for the insect world. -He is finding out the best fumigants for each particular species of insect, and even for each stage in an insect’s life—egg, grub or adult. His work on fumigation has led to the discovery of the possibilities, of a neo fumigant —ethlene pxide-,. It Js be- . ieveu that this gas will be more efficient and cheaper for the fumigation of certain types of Empire piyidi'ce than the mixture* at 'present used, and that it will have a wide commercial application.

TRAPPING THE ATMOSPHERE Dr Page Has invented a 'remarkable contraption which tia-ps typical examples, of the atmosphere at various stages of the operation and which will r.how exactly how much gas reaches the centre of a stack of boxes or sacks at any given tiine. This arid other apparatus has led to some startling disc'"-verie,, cW.t present .methods of

fumigation. With the aid of an instrument called the refractometer, which measures the light passing through a mixture of gases, it h<;\s been shown that the con-rmti’at-ion reached by a fumigant is sometimes only one twentieth of v hat was anticipated. In other words, by the time a gas reaches the inside of a pile of sacks or -a stack of boxes, it is 20 times as weak as can be calculated. It has also -Wen shown that much higher concentrations of res are needed 'in winter than in summer. This' suggests that uhclbr-< oncon tuition in cold weather have been the cause of failure in the past. FAMILIES DE LUX.

As many as 2,500,000 ‘ caterpillars may he introduced into a single Wme’house in one shipment. If a baie

dozen of those survive fumigation a new thriving population will arise i'a few months. (A prolific house-fl,. could have 5,598,72O,O0O;OOO descendants between' April 15th and -September 10th in one year). 'At'best, there fore, fumigation can only temporal il} check the trouble. Other methods are being’sought through a- study of the life ' histones of each insect. Recently an interesting discovery w-r.s made which illustrates the sort of theoretical tact with a practical out come upon which research worker may stumble. It was found that the female cocoa moth laid nothing but sterile'eggs when kept at a high tempeiature and -a low humidity. At fiisi this was thought to bo the fault of the female; but further experiment proved definitely that it was due to the males'. Males, and males onL i kept at a high temperature of slightly ovei* SOdeg. E. and at a humidity of 40 per cent, become sterile. Ihe fertility of the tobacco beetle is impaired be low temperature. These facts obviously point to the possibility that the breeding of insects might be controlled by the regulation of temperature and humidity in warehouse.