摘要:

AbstractIn an earlier paper, it was demonstrated that in order to delay the evolution of resistance, it is important to ensure that heterozygous carriers of resistance genes are killed so that the R gene is made effectively recessive. How this may be achieved is considered here, with (a) a persistent insecticide declining in effectiveness with time, and (b) a non‐persistent insecticide (or fumigant). The relationship between the time taken for the dosage to decline to one‐tenth (NGI) and the interval between insecticide applications (N12) was investigated. The optimal value of N12 was found to depend not only on the rate of decline but also on the shape of the degradation curve. Other important factors were (a) the dosage of insecticide applied (the initial effective dominance); (b) the initial frequency of the R gene; (c) the proportion of insects per generation that escaped exposure; and (d) whether selection occurred before or after mating. When considering non‐persistent insecticides, it was necessary to distinguish between the short‐lived deposit and the space spray, the latter being much less likely to lead to res

ISSN:0031-613X    

DOI:10.1002/ps.2780150402

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractRecoveries of fenitrothion from both young and mature wheat, and from deposits on the ground, have been compared, following aerial spraying of blocks (each about 16 ha in area) by three methods: ultra‐low volume (ULV) application of technical material in very small droplets in a steady wind; low volume (LV) application of an emulsifiable concentrate in water through a boom and nozzles in a steady wind; and LV application in a near calm. The collection, deposition and airborne loss of insecticide, beyond the downwind edge of the blocks, was also estimated. Recovery from young wheat was highest with the ULV method, but only slightly greater than with the LV application in a wind. Collection on the upper part of the mature wheat was similar with all the methods, although ULV application gave the lowest value, and LV spraying in a steady wind the highest. Only the LV application in near calm conditions gave a substantial recovery on the lower part of the mature wheat. The deposit on the ground within the blocks was highest with the LV spraying in a near calm, and the deposit outside the blocks, and airborne loss was lowest. The results illustrate the importance of the vegetation structure and density in selecting the best method of application, but give little indication of the best droplet size for impaction in different circumstance

ISSN:0031-613X    

DOI:10.1002/ps.2780150403

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of sublethal concentrations (LC1and LC50) of permethrin, fenvalerate, methamidophos and carbaryl on diamondback moth development, female fecundity and insect behaviour was investigated. All the insecticides had deleterious effects on the number of larvae surviving to pupae, the duration of the pupal period, the number of pupae surviving to adulthood, and cocoon formation in pupae. Prolonged duration of the larval period, from third instar to pupation, and deformed pupae were also observed. Permethrin, fenvalerate and carbaryl caused latent toxicity and deformed wings in the adults. Pyrethroids and methamidophos reduced the longevity of the adults whereas carbaryl increased it. Except for permethrin, the insecticides inhibited female fecundity. At LC1and LC50concentrations, the pyrethroids showed both repellent and antifeedant activity against larvae, and female moths preferred to oviposit on untreated leaf discs rather than on those treated with the pyrethroids at concentrations equal to their LC50values.

ISSN:0031-613X    

DOI:10.1002/ps.2780150404

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractIn growth room studies, total recoverable 2, 4‐D residues on or in turfgrass (Kentucky bluegrass, Poa pratensis) declined from 92% of that originally applied, to less than 66% by day 15. Although a high proportion of the applied chemical remained associated with the leaf surface under growth room conditions, only 10% was dislodged by vigorous mechanical wiping of the leaf surfaces with moistened cheese‐cloth. In field studies with 1 kg acid equivalent (a.e.) ha−1, less than 5% of the chemical originally applied could be dislodged with a cheese‐cloth wipe at day 0. Disappearance of dislodgeable residues was very rapid. Less than 0.01% of the applied chemical was dislodgeable after 1 day in turf that received 18 mm of rainfall 1 h after spraying. Residues in turfgrass that received no rainfall required 7 days to dissipate to the same level. In a study in which the clippings were not removed, the disappearance of dislodgeable residues, when the turf was mowed at 3, 7, and 11 days after application, was nearly as rapid as in unmowed turf. In turf treated with 2.24 kg a.e. ha−1of liquid or granular formulations, dislodgeable residues were less than 1% by days 5 and 3, res

ISSN:0031-613X    

DOI:10.1002/ps.2780150405

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractSeveral new series of insecticidally active oxime O‐ethers are reported, and compared structurally and biologically with known oxime O‐ether insecticides. These compounds can exist in two geometric forms. Biological results demonstrate that the configuration of the active isomer and the effect of substituents around the C‐N double bond vary between series. A detailed structure‐activity examination is pr

ISSN:0031-613X    

DOI:10.1002/ps.2780150406

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe protection of the female cones of Pinus monticola (Dougl. ex D. Don) from attack by Conophthorus ponderosae (Hopkins) requires that the beetles be killed before they enter the cone. This encourages consideration of the distributions of length of time to death and how these distributions are changed with different concentrations of various candidate insecticides. In this study a three‐parameter Weibull function was employed to depict the distributions for data originally collected for a probit analysis. The time to achieve 90% mortality as defined by the Weibull function was taken as a dependent variable, and a regression evaluation was used to define relationships with concentration for selected insecticides. The mode Y = b0 + b1 · X−1, in which Y = LT90 and × = insecticide concentration in g litre−1, proved useful when a sufficient range of concentrations was included in the

ISSN:0031-613X    

DOI:10.1002/ps.2780150407

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe long term metabolism of [14C]MCPA and [14C]flamprop in wheat (Triticum aestivum) straw was found to involve incorporation of radioactivity as residues that were insoluble in acetone+water (1+1 by volume). A chemical and an enzymic solubilisation procedure were critically evaluated in attempts to release these residues for further examination. The chemical procedure resulted in complete solubilisation of all the radioactivity of both compounds in association with more than one cell wall fraction. However, routine quantitative analysis was found to be difficult for some fractions. Furthermore, the extracts did not appear to be suitable for investigation of the nature of the binding with the plant constituents. None of the enzymes employed in the enzymic procedures released significant amounts of the residues insoluble in the aqueous acetone. Despite these problems, the residues of MCPA that were insoluble in aqueous acetone were found to contain both the parent MCPA and its major metabolite 4‐chloro‐α‐hydroxy‐o‐tolyloxya

ISSN:0031-613X    

DOI:10.1002/ps.2780150408

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe pick‐up of pesticide by lepidopterous larvae walking across ultra‐low volume pesticide treated surfaces has been stochastically modelled and simulated using a computer. The duration of the random walk was considered as a series of small, discrete time intervals during which the mode of pick‐up varied, depending upon the behavioural state (resting, feeding or walking) of a larva. Estimates can be obtained for the total mass picked up by the larva (gross) and the net amount eliminated, the internal exposure to insecticide, and the proportion of insects knocked down and killed with increasing time. The results of the simulation of Spodoptera littoralis larvae confined to permethrin‐treated surfaces were in agreement with experimental data, and suggested that a high pick‐up of insecticidal droplets resulted from adhesion of the pesticide to larvae following encounter. However, the availability of drops at the leaf surface decreased with time, probably as a result of droplet spread and subsequent uptake by the cuticular waxes. Droplet stability on leaf surfaces may be related to dro

ISSN:0031-613X    

DOI:10.1002/ps.2780150409

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractFoliar sprays of metalaxyl, benalaxyl, and cymoxanil plus mancozeb gave better control of blue mould (Peronospora tabacina) than mancozeb alone applied as a spray, or metalaxyl applied to the soil. Before flue‐curing, the mean values of metalaxyl residues in tobacco leaves were significantly higher from foliar spray treatments (5.09 μg g−1), than from soil treatments (0.93 μg g−1). Residues had decreased after flue‐curing (foliar spray treatment 2.51 μg g−1; soil treatment 0.69 μg g−1), especially on samples taken in September. Curing considerably reduced metalaxyl residues in all cases. Residues of mancozeb ranged from 59.5 to 224.2 μg g−1before flue‐curing and from 11.0 to 22.1 μg g−1after flue‐curing. All these residues were calculated on a dry weight basis. Imidazolidine‐2‐thione (ethylenethiourea) residues from mancozeb were always below the sensiti

ISSN:0031-613X    

DOI:10.1002/ps.2780150410

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractA technique and apparatus that facilitated the sampling of aerially applied pesticides on artificial surfaces in the canopy of balsam fir [Abies balsamea (L.) Mill.] and spruce (Picea spp.) are described. Field testing showed that sample units in the canopy were as receptive to droplets as those on the forest floor, and did not discernibly disturb the microenvironment in the tree.

ISSN:0031-613X    

DOI:10.1002/ps.2780150411

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY