THE OVIPOSITIONAL RESPONSE OF THE AUSTRALIAN SHEEP BLOWFLY, LUCILIA CUPRINA, TO FLEECE-ROT ODOURS

SUMMARY The ovipositional response of Lucilia cuprina flies to odours emanating from fleece-rot lesions of greasy wool in which Pseudomonas aeruginosa bacteria proliferated, was studied. Fractionation of the fleece-rot odours was carried out by bubbling the volatile components through hydrochloric acid and sodium hydroxide solutions to remove basic odours and acidic odours respectively. It was found that the acidic/neutral odours of fleecerot wool, when perfused into wet, greasy wool, stimulated L. cuprina to oviposit. On the other hand, the basic/neutral odours of fleece-rot wool were virtually unattractive to the gravid fly. Similarly, the acidic/neutral odours emanating from fleece-rot lesions of clean wool from which the non-fibre components, wax, suint and epithelial debris, had been removed by scouring, were found to be unattractive to the gravid fly in choice tests.     

THE BLOWFLY STRIKE PROBLEM OF SHEEP IN NEW SOUTH WALES

A field survey was undertaken between 1972-76 to reappraise the nature of the blowfly problem in New South Wales. For 2 years, 1972-1974, some 80,000 sheep were kept under observation and 12,481 strikes were reported, most due to Lucilia cuprina. Breech strike was still the basic problem but tail strike associated with scouring had become an important component where pastures have been improved. Breech strike was controlled at minimal cost by managerial practices such as docking tails the correct length--second joint-space palpable ventrally (midway down the vulval orifice in ewes) for radically mulesed lambs and the third joint-space (tip of vulva in ewes) for all other lambs-mulesing at lamb marking, mid-season crutching, determining the cause of scouring and applying the appropriate preventative or remedial measures. Thus the use of insecticides could be reserved for the control of body strike in young sheep in the odd wet years and poll strike in horned rams. Major outbreaks of body strike occurred in 1973/74. Body strike worried graziers most because of its unpredictability, sudden onset and scale. and only failing insecticides were available for control.     

以氟敏指数作度量指标的家蚕耐氟性测定法

度量蚕的耐氟性一般用LC50作指标,测定LC50值试验规模大,数据分析复杂;在育种实践中由于品种多,一般难以实施。本文提出了以氟敏指数作度量指标的家蚕耐氟性测定方法,试验规模小,方法简单,适用于育种过程中对选育材料或杂交组合作耐氟性测定。     

THE SIGNIFICANCE OF CERTAIN SKIN CHARACTERS OF SHEEP IN RESISTANCE AND SUSCEPTIBILITY TO FLEECE-ROT AND BODY STRIKE

Micro-anatomical differences in skin structure associated with resistance and susceptibility of sheep to fleece-rot and body strike were identified, and found to be of similar magnitude in 2 genetically divergent flocks of medium-woolled Merino ewes. Susceptible sheep were characterised by smaller follicle groups, resulting in higher densities of follicle populations with greater concentrations of the primary follicles (and sudoriferous glands) than in the resistant sheep. From these smaller follicle groups of susceptible sheep, thicker wool fibres grew than were found in the resistant sheep.
The significance of these findings is discussed in relation to the pathogenesis of fleece-rot and body strike of sheep, and the value of the measured skin characters as a method for identifying resistant sheep.     

COMPARATIVE ABILITY OF HYBRID AND HOMOZYGOUS RESISTANT LARVAE OF LUCILIA CUPRINA TO CAUSE STRIKES UNDER EXPERIMENTAL CONDITIONS

The intervals between the jetting of sheep with dieldrin or BHC, and the inducement of flystrike by implants of hybrid and homozygous BHC/dieldrin resistant larvae of Lucilia cuprina, were compared. Flystrikes soon established with homozygous resistant larvae, but considerable protection was afforded against hybrid larvae, the interval being longer with BHC than with dieldrin. Dieldrin was shown to have a residual effect on rr larvae in a mixed population 9 weeks after jetting. It is suggested that wide adoption of mulesing and mid-season's crutching would favour reversion to susceptibility in the blowfly and thus extend the field life of insecticides to which resistance has emerged.     

大田常用杀菌剂农药对家蚕的毒性试验

本文介绍了大田常用20种杀菌剂农药对家蚕的毒性,结果表明:家蚕对其中11种杀菌剂农药有一定的毒性反应,表现轻微的症状.杀菌剂农药对家蚕的触杀毒力和残毒期因杀菌剂品种不同而有明显的差异;家蚕对杀菌剂农药的抗性因龄期大小不同而异.