Lommen, S. ; Kuik, A.J. van - \ 2012
Bomen, het vakblad voor de boomverzorging (2012)21. - p. 14 - 17.
straatbomen - aphidoidea - plantenplagen - organismen ingezet bij biologische bestrijding - coccinellidae - adalia - honingdauw - secreties - bestrijdingsmethoden - onderzoek - street trees - aphidoidea - plant pests - biological control agents - coccinellidae - adalia - honeydew - secretions - control methods - research
Bladluizen in stadsbomen zorgen soms voor grote overlast. Vooral onder lindebomen is er jaarlijks wel een periode van honingdauwoverlast. Sommige steden gaan het probleem te lijf met het uitzetten van tweestippelige lieveheersbeestjes in de lindebomen. Het resultaat is niet altijd bevredigend. Nu is het effect van deze maatregel voor het eerst onderzocht. Voor dit onderzoek is echter speciaal gebruikgemaakt van een in de natuur voorkomend ongevleugeld type van dit lieveheersbeestje. De verwachting is dat dit langer in de boom blijft en daardoor beter is in bladluisbestrijding.
Nectar-providing plants enhance the energetic state of herbivores as well as their parasitoids under field conditions
Winkler, K. ; Wackers, F. ; Pinto, D.M. - \ 2009
Ecological Entomology 34 (2009)2. - ISSN 0307-6946 - p. 221 - 227.
natural enemies - biological-control - food source - honeydew - pests - oligosaccharides - lepidoptera - management - resources - insects
1. The use of flowering vegetation has been widely advocated as a strategy for providing parasitoids and predators with nectar and pollen. However, their herbivorous hosts and prey may exploit floral food sources as well. 2. Previous laboratory studies have shown that not all flower species are equally suitable in providing accessible nectar. Relatively little is known about actual nectar exploitation under field conditions. 3. The present study investigates nectar exploitation by the pest, Plutella xylostella, and its parasitoid, Diadegma semiclausum, under field conditions and examines whether floral nectar exploitation in the field can be predicted based on controlled laboratory studies. 4. Insects were collected from fields bordered by flowering margins containing Fagopyrum esculentum, Lobularia maritima, Anethum graveolens, Centaurea jacea or the grass Lolium perenne (control). Whole insect bodies were individually assayed by HPLC to establish their sugar profile as a measure of the level of energy reserves and the degree of food source use. 5. The average overall sugar content of P. xylostella and D. semiclausum collected in fields bordered by flowering margins was significantly higher than those of individuals collected from grass-bordered control plots. To the authors' knowledge, this represents the first demonstration that nectar-providing plants enhance the energetic state of herbivores under field conditions. 6. In contrast to earlier laboratory studies, the present study did not find elevated sugar contents in P. xylostella and D. semiclausum individuals collected from fields bordered by buckwheat (F. esculentum). 7. The present study shows widespread sugar feeding by both the herbivore and its parasitoid. It also shows that laboratory studies establishing nectar exploitation under controlled conditions can not always be extrapolated to actual exploitation under field conditions. This emphasises the importance of studying field-collected insects with regard to food source use and nutritional status.
Assessment of changes in optical properties of fresh-cut tomato using video image analysis
Moreira Lana, M. ; Tijskens, L.M.M. ; Theije, A. ; Hogenkamp, M. ; Kooten, O. van - \ 2006
Postharvest Biology and Technology 41 (2006)3. - ISSN 0925-5214 - p. 296 - 306.
keeping quality - storage - color - fruit - cantaloupe - honeydew - pericarp - temperature - appearance - physiology
Tomato fruit (Lycopersicon esculentum cv. Belissimo) at different stages of maturity were sliced in 7-mm thick transverse slices and stored at 5 °C. In a second experiment, slices obtained from fruit at the light-red stage were stored at temperatures from 5 to 13 °C. Intact control fruit were stored under the same conditions. Digital images were taken immediately after processing, before cooling, and at regular intervals during storage, after placing the slice in a double (half white, half black) background. The data were expressed as the average intensities per pixel of red (R), green (G) and blue (B) separately for the white background and for the black background. Additional indices were obtained by algebraic calculations from the original RGB values and through the conversion of RGB into L*a*b* values. The development of translucency in the pericarp was the main change in appearance of cut tomato. This process was strongly affected by the stage of maturity of the fruit and independent of storage temperature. The more mature the fruit the faster and more intense was the development of translucency. Using video image analysis, an increase in translucency could be assessed by a decrease in the amount of red pixels when the sample was measured against a black background. Changes in colour due to maturation could be measured both by a decrease in the amount of green pixels or by an increase in the proportion of red pixels (R/(R + G + B)), when the sample was placed on a white background. Using the L*a*b* colour space, an increase in translucency corresponded to a decrease in lightness and changes in colour due to maturation resulted in an increase in a*-value.
Overlast honingdauw in het openbaar groen
Kuik, Fons van - \ 2005
biological control - biological control agents - integrated pest management - honeydew - street trees
|Faecesanalyse als methode van menu-onderzoek bij herbivoren: identificatie van cuticula fragmenten
Wesselo, A.W. - \ 1984
Wageningen : Landbouwhogeschool
feces - guano - herbivoren - honingdauw - laboratoriummethoden - faeces - herbivores - honeydew - laboratory methods