Reproduction and longevity of the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae) and its prey, Tetranychus urticae (Acari: Tetranychidae) on different host plants

The biological control of twos potted spider mites by the predator Phytoseiulus persimilis is usually unsuccessful on greenhouse tomato crops in British Columbia. Experiments were conducted to determine the influence of host plant on the longevity and reproduction of the predator, and on the suitability of twospotted spider mites as prey. Lifespan and reproduction of P. persimilis were lower on tomato leaves than on bean leaves but feeding on spider mites that had been reared on tomato or bean leaves had no effect on the reproduction or lifespan of P. persimilis. A strain of twospotted spider mites that came from an outbreak on a greenhouse tomato crop lived for shorter periods and laid fewer eggs when confined on tomato leaves than on bean leaves. A strain of twospotted spider mites that had been maintained on bean leaves was unable to reproduce on tomato leaves. Exudates from glandular hairs were toxic to P. persimilis. Glandular hairs are important in pest management on tomato crops. Their removal through breeding might make plants more susceptible to herbivores. Therefore it would be preferable to develop other methods for biological control of twospotted spider mites on tomato

Thermocline management of stratified tanks for heat storage

Stratified tanks are useful for maximising the thermal energy efficiency of non-continuous and semi-continuous processes. Liquid at two or more dissimilar temperatures is stored within the same tank to provide a buffer for variations in heating and cooling loads. Control of the thermocline between the hot and cold fluid regions is needed to minimise thermocline growth and maximise operation of the storage tank. An experimental programme using a scale model of an industrial stratified tank (aspect ratio 3.5) and Perspex tank (aspect ratio 8.2) is reported. The behaviour and growth of the hot-cold thermocline under various operating conditions is presented. A siphoning method to re-establish the thermocline without interrupting the use of the tank is tested. Siphoning of the thermocline region from either 20%, 50% or 80% of the tank height is an effective strategy for uninterrupted interface re-establishment. However, the rate and position of siphoning and the load balance of the exit streams are critical variables for minimising the time for effective re-establishment of the two temperature zones

Survey of parasitoids and hyperparasitoids (Hymenoptera) of the green peach aphid, Myzus persicae and the foxglove aphid, Aulacorthum solani (Hemiptera: Aphididae) in British Columbia

We surveyed the parasitoids and hyperparasitoids of the green peach aphid, Myzus persicae, and the foxglove aphid, Aulacorthum solani in the lower Fraser Valley of British Columbia, Canada. Field surveys were conducted using isolated pepper plants, with aphids, as trap plants. Primary parasitoids recorded from field surveys were Aphidius ervi, A. matricariae, Praon gallicum, P. unicum, P. humulaphidis, Ephedrus californicus, Diaeretiella rapae, Monoctonus paulensis, Aphelinus abdominalis and A. asychis. Diaretiella rapae only emerged from green peach aphids, and Ephedrus californicus only emerged from foxglove aphids. Aphidius matricariae was the most abundant primary parasitoid species reared from both aphid species. Hyperparasitoid species collected belonged to the genera Dendrocerus, Asaphes, Alloxysta, Pachyneuron and Syrphophagous. In greenhouses, Dendrocerus carpenteri was the dominant hyperparasitoid species. Aphidius and Aphelinus spp. were attacked by hyperparasitoids at similar rates. In the field, Aphidius spp. were attacked by five species of hyperparasitoid, and Aphelinus spp. were attacked by one, Alloxysta ramulifera. In general, the rate of attack by hyperparasitoids was much lower in field surveys than in our collections from greenhouses

Measurement of ultrashort bi-photon correlation times with an integrated two-colour broadband SU(1,1)-interferometer

The bi-photon correlation time, a measure for the conditional uncertainty in the temporal arrival of two photons from a photon pair source, is a key performance identifier for many quantum spectroscopy applications, with shorter correlation times typically yielding better performance. Furthermore, it provides fundamental insight into the effects of dispersion on the bi-photon state. Here, we retrieve ultrashort bi-photon correlation times of around $100\,\mathrm{fs}$ by measuring simultaneously spectral and temporal interferograms at the output of an SU(1,1) interferometer based on an integrated broadband parametric down-conversion source in a $\mathrm{Ti:LiNbO}_3$ waveguideComment: 8 pages, 5 figure

Diversity, distribution and phenology of Lygus species (Hemiptera: Miridae) in relation to vegetable greenhouses in the lower Fraser Valley, British Columbia, and southwestern Ontario

Lygus spp. were collected from near and inside vegetable greenhouses during three years in the lower Fraser Valley, British Columbia (BC) and in Leamington, Ontario (ON). In BC, the dominant species was Lygus shulli, followed in abundance by L. elisus and L. hesperus; L. lineolaris was not collected in the lower Fraser Valley. In ON, only L. lineolaris was collected. In BC, L. shulli was generally distributed throughout the region, whereas L. hesperus was captured in sweep net samples only in coastal areas. Lygus hesperus appeared to be univoltine in BC. All other species in ON and BC were apparently bivoltine. In ON, numbers of adults collected outside of greenhouses correlated with numbers collected inside greenhouses whereas this was not the case in BC. Differences in flight behaviour, abundance and greenhouse construction may account for this latter difference. Our results highlight the need for different approaches to IPM of pest Lygus species in the ON and BC greenhouse industries

Can filesharers be triggered by economic incentives? Results of an experiment

Illegal filesharing on the internet leads to considerable financial losses for artists and copyright owners as well as producers and sellers of music. Thus far, measures to contain this phenomenon have been rather restrictive. However, there are still a considerable number of illegal systems, and users are able to decide quite freely between legal and illegal downloads because the latter are still difficult to sanction. Recent economic approaches account for the improved bargaining position of users. They are based on the idea of revenue-splitting between professional sellers and peers. In order to test such an innovative business model, the study reported in this article carried out an experiment with 100 undergraduate students, forming five small peer-to-peer networks.The networks were confronted with different economic conditions.The results indicate that even experienced filesharers hold favourable attitudes towards revenue-splitting.They seem to be willing to adjust their behaviour to different economic conditions