Behavioural responses of the carrot fly larva, Psila rosae, to carrot root volatiles

ABSTRACT. The behaviour of the carrot fly larva, Psila rosae F. (Diptera, Psilidae), was investigated in the presence of six concentrations of thirty-four volatiles associated with carrot root and of trans -methyl-iso-eugenol, a constituent of carrot herb oil. Bomyl acetate, 2,4-dimethyl styrene, α-ionone, SbT-ionone and biphenyl were the most consistently preferred compounds. Klinotaxis and klinokinesis were the orientation responses near the stimulus source. Trans -2-nonenal was the most consistently avoided compound. Extracts derived by steam distillation of carrot roots and by concentration of vapour from roots were resolved, by gas liquid chromatography, into forty-five and twenty-two major constituents, respectively. The five preferred compounds are micro-components of these extracts, collectively representing 1% and 0.6% of root extract oil and vapour, respectively. It is suggested that these secondary plant constituents are specific host finding cues for the larva, and that frara-2-nonenal is a carrot defence compound.     

Monitoring populations of the carrot fly, Psila rosae, with sticky and water traps

The relative, effectiveness of Rebell®, small cylinder, large cylinder, windmill and water traps, the five types of trap used currently for monitoring populations of the carrot fly, Psila rosae, was assessed in nine field experiments, three in south west Lancashire, four in the Fens (Suffolk, Norfolk, Cambridgeshire), one in East Suffolk and one at Wellesbourne, Warwickshire. Regression analysis of the numbers of flies caught on each type of trap against the numbers caught on the Rebell® trap indicated that each trap samples a constant proportion of the fly population relative to the other traps. Therefore, provided the fly population was sufficiently large for insects to be caught on the least effective traps, any of the five traps would monitor adequately fluctuations in carrot fly populations. However, the Rebell® trap caught 4–17 times as many flies/trap and 5–7 times as many flieshnit area of trap as any of the other traps tested.
Operators considered the Rebell® trap to be the easiest to use. However, it was more expensive than any of the other traps tested.     

Carrot fly cultivar preferences: some influencing factors

Abstract. 1. Factors affecting cultivar preferences by the carrot fly Psila rosae F. were examined in choice tests using foliage from carrot lines representing extremes of resistance and susceptibility to attack.
2. Flies were offered a choice to oviposit on foliage, artificial substrates impregnated with leaf surface extracts or enclosed in vapours of different cultivars to establish the importance of contact and olfactory stimuli. Susceptible cv. Danvers Half Long 126 foliage was preferred over that of resistant cvs. Clause's Sytan Original and Tip-Top. But, whereas the Sytan leaf surface extract was as effective as that of Danvers, the surface extract of Tip-Top was very much inferior as an oviposition stimulant. By contrast, Sytan and Tip-Top foliar vapours were both more attractive to the fly than that from Danvers.
3. Headspace vapours over Sytan foliage evoked significantly higher electroantennogram responses than those from Danvers.
4. Cold-trapped foliar volatiles of Sytan and Danvers were analysed by gas chromatography linked with antennographic detection. Foliage of Sytan released, among other chemo-stimulants, higher levels of host plant attractants, i.e. green leaf aldehydes and the phenylpropanoids, trans-asarone and trans-methylisoeugenol.
5. These findings indicate that olfactory and contact chemostimuli may be involved in preferences shown by the carrot fly for carrot cultivars, but these factors alone do not fully account for the preferences observed.     

Relationship between root volatiles of some carrot cultivars and their resistance to the carrot fly, Psila rosae

Field experiments investigated the resistance of some carrot cultivars to Psila rosae. In addition, headspace vapour and steam distillate from the roots of resistant and susceptible varieties were compared by gas-liquid chromatography. The field data confirmed that resistance may operate by decreasing the numbers of eggs laid indicating a nonpreference by the female Psila. Root resistance to the larva was also confirmed but the mechanism was unclear. A new finding was that root resistance is independent of the effect of egg laying, some cultivars evincing one or the other effect and some such as Regulus Imperial displaying both. It was clear that root resistance to the larva is the crucial prerequisite in breeding resistant varieties.One consistent difference was detected by the chemical comparisons: intact roots of resistant varieties released substantially less volatiles. Specifically, Regulus released almost five times less of the volatiles already shown to positively influence host-finding behaviour by the larva.

---

Résumé La résistance à P. rosae de quelques cultivars de carotte a été étudiée en plein champ. Parallèlement, les substances volatiles diffusées et celles extraites par la vapeur des racines de variétés résistantes et sensibles, ont été comparées en chromatographie gaz-liquide (GLC). Les résultats en champ ont confirmé que la résistance peut être due à une diminution du nombre d'oeufs pondus, révélant une absence d'attractivité pour les femelles de P. rosae. La résistance des racines aux larves a été aussi confirmée, mais les raisons n'en étaient pas claires. Un aspect nouveau est que la résistance des racines est indépendante de l'effet de la ponte, quelques cultivars présentant l'un ou l'autreeffet et certains, comme Regulus Imperial, manifestant les deux. Il est net que la résistance racinaire aux larves est la condition essentielle pour la sélection de variétés résistantes. Une différence importante a été mise en évidence par les comparaisons chimiques: les racines intactes de variétés résistantes libèrent nettement moins de substances volatiles. Précisément, Regulus a libéré 5 fois moins de substances volatiles déjà connues comme influençant positivement le comportement de découverte de l'hôte par la larve.

     

麻蝇幼虫肠道类胰蛋白酶的分离纯化及性质(英文)

麻蝇幼虫肠液经硫铵沉淀, ＤＥＡＥ－Ｓｅｐｈａｄｅｘ Ａ－２５离子交换层析, ＳＢＢＩ－Ｓｅｐｈａｒｏｓｅ ４Ｂ亲和层析,分离纯化出一种分子量为 １６ｋＤ的蛋白酶。底物及抑制剂的特异性表明,该酶为类胰蛋白酶。其能够强烈地降解蛋白酶非专一底物酪蛋白和 Ｈｉｄｅ ｐｏｗｄｅｒ ａｚｕｒｅ,以及类胰蛋白酶专一底物 Ｂｚ－Ｐｈｅ－Ｖａｌ－Ａｒｇ ＮＡ, Ｂｚ－Ｐｒｏ－Ｐｈｅ－Ａｒｇ ＮＡ和Ｂｚ－Ｖａｌ－Ｇｌｙ－Ａｒｇ ＮＡ．该酶又能被丝氨酸蛋白酶抑制剂ＰＭＳＦ,类胰蛋白酶抑制剂 ＳＢ－ＢＩ和Ｌｅｕｐｅｐｔｉｎ强烈地抑制。蛋白酶在酸性环境下极不稳定,在弱碱环境（ｐＨ８．５－９．５）中活性最高。     

丛枝菌根真菌一新种--枣庄球囊霉

在鲁西南煤矿土中分离到球囊霉属一新种--枣庄球囊霉.为新种提供了拉丁文简介、中文描述和显微照片,标本保存于莱阳农学院菌根生物技术实验室.     

A comparison of the effects of sward improvement on invertebrates, sward establishment and herbage yield

Field experiments were done at two widely separated sites in England (Tadcaster, North Yorkshire and North Wyke, Devon). In each case an old permanent sward was re-seeded after ploughing or by direct drilling, or was left intact and fertilised. The carbamate pesticide aldicarb was applied to half of each experimental plot. The effects of sward improvement and pesticide on various soil invertebrate groups were assessed. Soil-dwelling macrofauna arthropods were scarce at both sites. Stem-boring dipterous larvae, however, were numerous at both sites. At Tadcaster, Oscinella vastator was the only species present in the original sward, but 0. frit was by far the most prevalent species in re-seeded areas. These can only have arisen from direct oviposition of eggs by adults on or near the emerging seedlings and not by migration of larvae from buried turf or the desiccated old pasture.
Mites and Collembola were abundant. Their numbers were reduced initially by cultivation and pesticide usage, but the effects of these practices were transient and their numbers recovered to previous levels usually within 10 wk.
Earthworms were present at both sites. Deep burrowing species, e.g. Lumbricus terrestris and Allolobophora longa were less affected by the treatments imposed than species such as A. chlorotica and L. rubelius which usually live close to the soil surface. Effects on their numbers were in any case, short-lived.
No improvement method consistently provided the greatest herbage dry matter yield. Pesticide application, however, greatly increased seedling stand and/or herbage yield at both sites and showed the benefits of using crop protectants, especially on direct-drilled re-seeds.     

A PRELIMINARY EVALUATION OF ASPECTS OF SASS (SOUTH AFRICAN SCORING SYSTEM) FOR THE RAPID BIOASSESSMENT OF WATER QUALITY IN RIVERS,WITH PARTICULAR REFERENCE TO THE INCORPORATION OF SASS IN A NATIONAL BIOMONITORING PROGRAMME

Summary

The rapid bioassessment method, SASS (South African Scoring System) has been developed to assess water quality in riverine ecosystems. It is a scoring system based on the presence or absence of macroinvertebrate groups, and yields three values, namely SASS4 Score, Number of Taxa and Average Score Per Taxon (ASPT). The current and future use of SASS, including incorporation into the National Biomonitoring Programme for Riverine Ecosystems, necessitates evaluation of this bioassessment method. This study focuses on three aspects. namely spatial variation in SASS scores, including regional and longitudinal (sub-regional) variation; temporal variation in SASS scores, and the effect of biotope availability on SASS scores.