The changing role of pesticides in pest management

Significant changes have occurred in the role of pesticides in pest management programmes since the publication of Carson's book Silent Spring in 1962. This discourse addresses the multitude of factors which contributed to these changes including such factors as policy and legislation, the public's perception of associated risks, population pressures, the availability of practical integrated pest management programmes, and perhaps most importantly, the constraints to IPM in Third World countries. While reliable statistics are difficult to obtain, the changing patterns in pesticide use in the tropical regions are also discussed. Finally, the future of pesticide use in developing countries is projected, as is the necessity of their use and expected impact

Root Weevils

NYS IPM Type: Fruits IPM Fact SheetThere are more than 20 species of root weevils that attack strawberry in the United States. In New York, the three major species are the black vine weevil, Otiorhynchus sulcatus (Fabricius), the strawberry root weevil, 0. ovatus L., and the rough strawberry weevil, 0. rugostriatus Goeze. Root weevils are also pests of raspberries and rhododendrons

Electron spin tomography through counting statistics: a quantum trajectory approach

We investigate the dynamics of electron spin qubits in quantum dots. Measurement of the qubit state is realized by a charge current through the dot. The dynamics is described in the framework of the quantum trajectory approach, widely used in quantum optics, and we show that it can be applied successfully to problems in condensed matter physics. The relevant master equation dynamics is unravelled to simulate stochastic tunneling events of the current through the dot.Quantum trajectories are then used to extract the counting statistics of the current. We show how, in combination with an electron spin resonance (ESR) field, counting statistics can be employed for quantum state tomography of the qubit state. Further, it is shown how decoherence and relaxation time scales can be estimated with the help of counting statistics, in the time domain. Finally, we discuss a setup for single shot measurement of the qubit state without the need for spin-polarized leads.Comment: 23 pages, 10 figures, RevTeX4, submitted to PR

A W:B4C multilayer phase retarder for broadband polarization analysis of soft x-ray radiation \ud

A W:B4C multilayer phase retarder has been designed and characterized which shows a nearly constant phase retardance between 640 and 850 eV photon energies when operated near the Bragg condition. This freestanding transmission multilayer was used successfully to determine, for the first time, the full polarization vector at soft x-ray energies above 600 eV, which was not possible before due to the lack of suitable optical elements. Thus, quantitative polarimetry is now possible at the 2p edges of the magnetic substances Fe, Co, and Ni for the benefit of magnetic circular dichroism spectroscopy employing circularly polarized synchrotron radiatio

Population Dynamics and Clonal Comparisons of Cowpea Aphid (Homoptera: Aphididae) on Resistant and Susceptible Cowpea Cultivars

Survivorship, growth, and reproductive performance of cowpea aphid, Aphis craccivora Koch, were studied on whole plants and excised plant tissues of aphid-resistant (‘ICV-12') and aphid-susceptible (‘ICV-1') cultivars of cowpea, Vigna unguiculata (L.) Walp. In a greenhouse study, clonal populations derived from individuals that were originally collected from 5 different locations were studied on plants of the 2 cultivars to assess possible development of aphid biotypes. In the laboratory, performance of 1 clone was studied on excised leaves, flowers, and pods to assess tissue localization and effect of injury on ICV-12 resistance. Aphid life table parameters measured included survivorship, reproductive period, intrinsic rate of increase, net rate of reproduction, number of generations and generation time. Aphid reproductive performance and life table parameters were significantly reduced on seedlings and excised tissues of ICV-12 plants compared with ICV-1. Survivorship, intrinsic rate of increase and net rate of reproduction of populations were most adversely affected. Antibiosis appeared to contribute to aphid resistance in ICV-12. Effects of excised ICV-12 foliage were stronger than those of flowers or pods. Thus, the resistant factor in ICV-12 apparently was based in seedling foliage. However, there were no differences among excised tissues of ICV-1. Trends in the results indicated that there was no variability among the different populations in their demographic statistics on each cultivar. Thus, there did not seem to be biotype development or breakdown of ICV-12 resistance in any of the A. craccivora population

Pattern and rate of within-field dispersal and bionomics of the cowpea aphid, Aphis craccivora (Aphididae), on selected cowpea cultivars

Comparative field studies were conducted during the rainy and dry seasons at the Mbita Point Field Station of ICIPE in southwestern Kenya, to investigate the pattern and rate of dispersal of Aphis craccivora on aphid-resistant (ICV-12) and aphid-susceptible (ICV-1) cowpea cultivars in relation to key weather factors. The effects of the dispersal trends on crop performance and aphid population dynamics were analysed. Treatments consisted of initial aphid releases at the north, south, west, east and centre of test plots and uninfested controls maintained on plants for 22 days. Parameters recorded included: pattern (direction of spread of aphids) and rate (number of aphid-infested plants at a given time) in test plots; crop growth and yields and associated factors such as incidence of sooty mould and plant mortality, and aphid density and associated factors, including the incidence of natural enemy species, particularly coccinellids. Dispersal was fastest when releases were made in the west, north and centre of plots, and resulted in adveVse effects on ICV-1 growth and yields. Infestations of ICV-12 did not significantly affect crop performance. There was an apparent direct, positive relationship between wind direction and pattern of spread of aphid infestations, but this pattern was more apparent during the rainy season, when wind speeds were higher, than during the dry season. The incidence of natural enemy species correlated with the spread of aphid infestations, while the abundance of coccinellids correlated with aphid densit

Effects of infestation by cowpea aphid (Homoptera: Aphididae) on different growth stages of resistant and susceptible cowpea cultivars

Field studies were conducted to characterise the effects of infestations by adult and nymphal stages of cowpea aphid, Aphis craccivora Koch, on the growth and yield of cowpea, Vigna unguiculata (L.) Walp. Seedling, flowering, and podding stage plants of aphid-resistant (cv. ICV-12) and aphid-susceptible (cv. ICV-1) cowpea cultivars were used in the studies. Four treatments (consisting of infestations with adult and nymphal aphids, caged controls and uncaged controls) were administered on plants for 22 days post-treatment. Eight parameters of crop success were measured: extended leaf heights (ELH); plant mortality; incidence of sooty mould; incidence and abundance of natural enemy species; crop growth parameters (net assimilation rate, [NAR] in g/ dm2/day, and crop growth rate [CGR] in g/dm2 land surface/day); and plant yields (seeds per pod, weight per seed). Data were analysed using analysis of variance (ANOVA), orthogonal contrasts and 95% confidence intervals (C.I.). There were no significant (P > 0.05) differences between adult and nymphal infestations or between caged and uncaged controls, so the respective sets of data were combined for comparisons of aphid infestations with control treatments. Infestations caused severe plant stunting and other growth deformities, drastic yield reductions, higher plant mortality, greater incidence of natural enemies and abundance of Cheilomenes spp. on cv. ICV-1 than on cv. ICV-12, and on infested and uninfested plants. Aphid infestations did not significantly affect the incidence of sooty mould on plants of cv. ICV-12 or cv. ICV-

A high resolution, hard x-ray photoemission investigation of La_(2-2x)Sr_(1+2x)Mn_2O_7 (0.30<x<0.50): on microscopic phase separation and the surface electronic structure of a bilayered CMR manganite

Photoemission data taken with hard x-ray radiation on cleaved single crystals of the bilayered, colossal magnetoresistant manganite La_(2-2x)Sr_(1+2x)Mn_2O_7 (LSMO) with 0.30<x<0.50 are presented. Making use of the increased bulk-sensitivity upon hard x-ray excitation it is shown that the core level footprint of the electronic structure of the LSMO cleavage surface is identical to that of the bulk. Furthermore, by comparing the core level shift of the different elements as a function of doping level x, it is shown that microscopic phase separation is unlikely to occur for this particular manganite well above the Curie temperature.Comment: 7 pages, 5 figure