How natural field experiments have enhanced our understanding of unemployment

Abstract Erythritol is a dietary sweetener that is used for low-calorie or diabetic diets. Although safe for human consumption, erythritol is lethal to certain Dipteran pests, but insecticidal effects of erythritol on phloem-feeding insects have yet to be examined. Our goal was to determine whether erythritol has insecticidal activity against pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae). We first demonstrated that ingestion of erythritol solutions compared with water by pear psylla caused reduced feeding, impaired motor functions, and reduced survival time of adults. We then tested whether foliar treatment of pear leaves with erythritol was also lethal to pear psylla. Foliar treatment of erythritol led to reduced 3-d survival of pear psylla nymphs and adults, and reduced rates of oviposition by pear psylla adults. Psylla adults also preferred to settle on untreated leaves than on erythritol-treated leaves in preference assays. Finally, we conducted field experiments to test whether applications of erythritol provided pear trees with protection against pear psylla under natural field conditions. Those experiments showed a reduction in pear psylla nymphs on erythritol-treated trees compared with untreated trees, but only if the erythritol was completely dissolved into solution by heating. Laboratory trials confirmed the importance of heating. Results of our experiments demonstrate that erythritol is insecticidal to pear psylla nymphs and adults and provide the first report that erythritol is lethal to a phloem-feeding insect. These findings suggest that erythritol may provide a new safe and effective tool for the management of pear psylla.

Download Full-text

Matching and Challenge Gifts to Charity: Evidence from Laboratory and Natural Field Experiments

SSRN Electronic Journal ◽

10.2139/ssrn.1136440 ◽

2008 ◽

Author(s):

Daniel Rondeau ◽

John A. List

Keyword(s):

Field Experiments ◽

Natural Field

Download Full-text

Effect of biostimulants on cold resistance and productivity formation in winter rapeseed and winter wheat

Irish Journal of Agricultural and Food Research ◽

10.1515/ijafr-2018-0008 ◽

2018 ◽

Vol 57 (1) ◽

pp. 71-83 ◽

Cited By ~ 2

Author(s):

V. Gavelienė ◽

L. Pakalniškytė ◽

L. Novickienė ◽

L. Balčiauskas

Keyword(s):

Winter Wheat ◽

Free Amino ◽

Field Experiments ◽

Cold Resistance ◽

Growth Parameters ◽

Freezing Resistance ◽

Wheat Seedlings ◽

Natural Field ◽

Winter Rapeseed ◽

Growth Development

AbstractThe aim of the study was to investigate the effects of biostimulants on the resistance to freezing under laboratory-controlled cold conditions and on the growth, development, overwintering and productivity of winter rapeseed and winter wheat in natural field experiments. The effect of free amino acids, macroelements and microelements that contain biostimulants Ruter AA, Terra Sorb and Razormin was tested on cultivars of rapeseed, ‘Hornet H’, and winter wheat, ‘Skagen’ and ‘Kovas’, applying morphometrical methods. We found that biostimulants applied to rapeseed at BBCH 13–14 stage and to wheat at BBCH 14–15 stage under controlled cold stress conditions increased the freezing tolerance of seedlings. Biostimulants more actively increased the freezing resistance of rapeseed seedlings at –5°C compared to that of wheat seedlings. The temperature of –7°C was mortal to rape seedlings, while the resistance of wheat seedlings increased under the influence of the tested biostimulants compared to that of the control seedlings. In natural field experiments, these biostimulants produced a significant effect on plant growth in autumn, acclimation to the cold, plant overwintering, vegetation renewal and, due to this, formation of productivity elements. The effects of Razormin (200 mL/ha), Terra Sorb (2 L/ha) and Ruter AA (1 L/ha) were significantly higher on growth parameters of winter wheat compared to the productivity of winter rapeseed.

Download Full-text