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  • 1
    Electronic Resource
    Electronic Resource
    ReleasingAmblyseius spp. [Acarina: Phytoseiidae] to controlThrips tabaci [Thysanoptera: Thripidae] on cabbage (1991)
    Springer
    BioControl 36 (1991), S. 561-573 
    Details
    ISSN: 1573-8248
    Keywords: Amblyseius barkeri ; Amblyseius cucumeris ; Thrips tabaci ; cabbage ; biological control ; Amblyseius barkeri ; Amblyseius cucumeris ; Thrips tabaci ; chou ; lutte biologique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé Deux espèces d'acariens prédateurs,Amblyseius barkeri (Hugues [=A. mckenziei Schuster & Pritchard] etAmblyseius cucumeris (Oudemans), ont été testés comme agents de lutte biologique potentiels contreThrips tabaci Lindeman sur chou.A. barkeri colonisa les pommes des choux durant les essais préliminaires. Des lâchers en plein champ de différents nombres d'A. barkeri en 1987 ont démontré que les thrips sur choux étaient réduits proportionnellement au nombre d'acariens lâchés, mais le dommage dû aux thrips demeurait identique. En 1988, des lâchers en plein champ d'un même nombre d'A. cucumeris, mais à des périodes différentes, ont démontré que les premiers lâchers réduisaient au maximum le nombre de thrips et les dommages à la récolte, mais cette corrélation n'était pas établie quand les pyréthroides sont employés. Nous concluons qu'un lâcher inoculatif d'Amblyseius spp. est une stratégie potentielle utilisable contre les thrips du chou, en perfectionnant le choix du nombre et du moment des lâchers, pour rendre la lutte acceptable sur le plan commercial.
    Notes: Abstract Two species of predaceous mites,Amblyseius barkeri (Hughes) [=A. mckenziei Schuster & Pritchard] andA. cucumeris (Oudemans) [Acarina: Phytoseiidae] were evaluated as potential biological control agents forThrips tabaci Lindeman [Thysanoptera: Thripidae] on cabbage.A. barkeri colonized cabbage heads in preliminary trials. Field releases of different numbers of mites per plant during 1987 showed thatA. barkeri reduced the number of thrips in cabbage heads at harvest, and the reduction was proportional to the number of mites released, but thrips damage was unaffected. ReleasingA. cucumeris at different times during 1988, but releasing the same number of mites each time, we found that earlier releases resulted in fewer thrips and less damage at harvest; these relationships were not present, however, in plots treated with pyrethroid insecticides. We conclude that inoculative release ofAmblyseius spp. is a potentially useful thrips management strategy, but improvements in release timing and strategy will be required to provide commercially acceptable control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02374439
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  • 2
    Electronic Resource
    Electronic Resource
    Efficiency of variable-intensity and sequential sampling for insect control decisions in cole crops in the Netherlands (1994)
    Springer
    Entomologia experimentalis et applicata 70 (1994), S. 209-215 
    Details
    ISSN: 1570-7458
    Keywords: insecta ; Brassica oleracea ; cabbage ; economic threshold ; sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A total of 24 commercial fields of cabbages and Brussels sprouts were sampled in a grid fashion with 20–25 equally spaced cells with four plants per cell. Using this data base of 80–100 plants, we conducted computer stimulations to compare the treatment decisions that would be made for the major insect pests using published sequential sampling programs and a newly developed variable-intensity sampling program. Additionally, we compared the number of samples required to make the decision. At low thresholds (10–20%) for both Lepidoptera and cabbage aphids, variable intensity-sampling required a smaller sample size and provided more reliable decisions, while at high thresholds (40–50%) sequential sampling provided more reliable decisions. In both procedures, the occurrence of incorrect decisions was minimal. The number of cases in which a decision would not be reached after a 40-plant sample was lower for variable-intensity sampling. Considering the number of samples required to make a correct decision and the greater need for reliable decisions at lower thresholds, variable-intensity sampling was superior to sequential sampling. Additionally, variable-intensity sampling has the advantage of requiring samples to be taken in a greater area of the field and thus increases the probability of detecting localized infestations. Although variable-intensity sampling was not designed to classify pest populations for treatment decisions but rather to achieve sampling precision around the population mean, our present studies indicate that it can also be an effective method to aid in treatment decisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02380554
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  • 3
    Electronic Resource
    Electronic Resource
    Response of cabbage head weight to simulated Lepidoptera defoliation (1990)
    Springer
    Entomologia experimentalis et applicata 54 (1990), S. 181-187 
    Details
    ISSN: 1570-7458
    Keywords: Brassica oleracea ; cabbage ; yield loss ; economic threshold ; crop loss assessment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'étude a porté sur le poids des pommes de choux (Brassica oleracea) soumis à différentes intensités de défoliations répétées avant et pendant la formation des pommes. Pendant les trois années de l'étude, huit intensités de défoliation continue ont réduit le poids des pommes, mais le poids le plus élevé a toujours été obtenu avec une faible défoliation avant et pendant la formation des pommes. Ceci montre que le chou tolère une certaine défoliation avant et pendant la formation des pommes. Les résultats de cette étude ont été utilisés dans une analyse coût-bénéfice pour estimer le seuil économique de défoliation.
    Notes: Abstract Studies were conducted to determine the effects of continuous constant amounts of artificial defoliation through the preheading and heading growth stages on head weight of cabbage. High levels of continuous artificial defoliation caused a reduction in head weight in all three years of the study, but the highest yield was always attained at some low level of preheading or heading defoliation. These results demonstrate that cabbage is tolerant to some levels of continuous defoliation before and after head formation. Results from this study are incorporated into a cost-benefit analysis to estimate an economic threshold.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343527
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