|
|
|
|
|
| Nielsen, Otto; Skovgaard, Ib Michael; Philipsen, Holger. |
| Soil samples were stored and baited in different ways in order to develop a bait method that could estimate the level of steinernematid nematodes in soil in a time efficient way. The method was based on incidence (proportion of samples with a given species of Steinernema). Tenebrio molitor (Coleoptera) larvae were used as bait and it was concluded that: 1) Repeated baiting in a later period improved the bait result; 2) Extension of the bait periods from one to two weeks was not necessary; 3) The precision of the estimated incidence did not improve noteworthy by taking more than 60-80 samples; 4) The minimum time required to analyse one soil sample was 6 minutes. |
| Tipo: Journal paper |
Palavras-chave: Research methodology and philosophy. |
| Ano: 2004 |
URL: http://orgprints.org/3880/1/3880.htm |
| |
|
|
| Nielsen, Otto; Philipsen, Holger. |
| This study was based on naturally occurring and inoculated populations of steinernematid nematodes. The nematode populations were monitored spring and autumn in two following years in an organic cropping system and changes in population size were related to the presence of potential insect hosts. Nematode population were estimated in terms of nematode incidence (percentage of positive soil samples) by using Tenebrio molitor larvae as bait. The population of naturally occurring nematodes (Steinernema affine (Bovien) and S. feltiae (Filipjev)) was generally at a low level (0-17 % incidence for S. affine and 0-18 % incidence for S. feltiae). Inoculated S. feltiae established well in half of the plots where inoculation had been performed and reached incidences... |
| Tipo: Journal paper |
Palavras-chave: Soil biology. |
| Ano: 2004 |
URL: http://orgprints.org/3881/1/3881.htm |
| |
|
|
| Philipsen, Holger; Nielsen, Otto. |
| Larvae of the pollen beetles (Meligethes spp.), the brassica pod midge (Dasyneura brassicae), the cabbage seed weevil (Ceuterrhynchus assimilis), and the cabbage moth (Mamestra brassicae) were collected in the field and exposed to entomopathogenic nematodes in the laboratory. Pollen beetle larvae, seed weevil larvae and cabbage moth larvae where all relatively easy infected while infections of pod midge larvae only were observed twice. The number of nematodes produced in the cadavers was positively related to the size of the insects. The recovery of D. brassicae and Meligethes spp. was further studied after exposure to entomopathogenic nematodes during the pupating process. The recovery of D. brassicae was almost unaffected by the nematodes whereas... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Farming Systems. |
| Ano: 2003 |
URL: http://orgprints.org/3883/1/3883.htm |
| |
|
|
| Nielsen, Otto. |
| The ecology of entomopathogenic nematodes in relation to cruciferous crops has been studied in Denmark. The main objectives were to obtain information about nematode occurrence, host range and regulatory effect on insects. This included a range of studies in the field and in the laboratory. In one set of experiment, cabbage fields were surveyed and Steinernema affine, S. bicornutum, S. intermedium and S. feltiae were isolated. The presence of nematodes was correlated to pupal numbers of the cabbage root fly, D. radicum. The conclusion was that the presence of nematodes at cabbage plants did not reduce the number of pupae. Another approach was to quantify the proportion of larvae or pupae of D. radicum infected with entomopathogenic nematodes during... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Soil biology. |
| Ano: 2001 |
URL: http://orgprints.org/1611/1/sipabstract.doc |
| |
|
|
| Nielsen, Otto; Philipsen, Holger. |
| The abundance of entomopathogenic nematodes and soil dwelling stages of plant specific insects was studied in an organic cropping system for two years. In addition was the survival of an inoculated strain of Steinernema feltiae studied. The abundance of naturally occurring entomopathogenic nematodes was in general at a low level throughout the observation period (0-26 % positive samples). Inoculated S. feltiae established well when pea was grown in the same or in the following year whereas the nematodes were less able or unable to establish in the other crops (cabbage, carrots, barley, alfalfa/clover). The successful establishment of nematodes, and the abundance in general, correlated well with the presence of plant specific insects. |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Farming Systems. |
| Ano: 2005 |
URL: http://orgprints.org/1612/1/Proceeding.doc |
| |
|
|
| Philipsen, Holger; Nielsen, Otto. |
| Larvae of the pollen beetles (Meligethes spp.), the brassica pod midge (Dasyneura brassicae), the cabbage seed weevil (Ceuterrhynchus assimilis), and the cabbage moth (Mamestra brassicae) were collected in the field and exposed to entomopathogenic nematodes in the laboratory. Pollen beetle larvae, seed weevil larvae and cabbage moth larvae where all relatively easy infected while infections of pod midge larvae only were observed twice. The number of nematodes produced in the cadavers was positively related to the size of the insects. The recovery of D. brassicae and Meligethes spp. was further studied after exposure to entomopathogenic nematodes during the pupating process. The recovery of D. brassicae was almost unaffected by the nematodes whereas... |
| Tipo: Conference paper, poster, etc. |
Palavras-chave: Farming Systems. |
| Ano: 2003 |
URL: http://orgprints.org/1610/1/rapsproceeding.doc |
| |
|
|
|
