The biology of Canadian weeds.: 96. Senecio jacobaea L.

1991 ◽  
Vol 71 (1) ◽  
pp. 127-140 ◽  
Author(s):  
John F. Bain

Senecio jacobaea L. (tansy ragwort) is a roadside and pasture weed which was introduced into Canada in the 1850s. It is established in cool, wet areas, most commonly on the east and west coasts. The species is important economically because the presence of pyrrolizidine alkaloids in the foliage makes it toxic and the poisoning of livestock has resulted. Individuals produce dimorphic achenes which possess different dormancy and dispersal characters and are therefore able to establish in a wider range of habitats. Vegetative reproduction is common especially after damage to the plant. Control of the weed is achieved either through the application of hormone-like herbicides or by biological means. The establishment of the biological control agent, cinnabar moth (Tyria jacobaeae L.), in populations has resulted in defoliation of individuals but has not resulted in effective control of the weed, except in eastern Canada. Key words: Tansy ragwort, Senecio jacobaea, biological control, pyrrolizidine alkaloids

2004 ◽  
Vol 94 (2) ◽  
pp. 159-167 ◽  
Author(s):  
S. Jess ◽  
J.F.W. Bingham

AbstractIn small-scale experiments, the predatory mites, Hypoaspis aculeifer (Canestrini) and H. miles Berlese, applied at 700 mites m−2, and the entomopathogenic nematode, Steinernema feltiae (Filipjev) applied at 3 × 10−6 nematodes m−2 controlled sciarids and phorids in mushroom compost and casing substrates. For both mite species, earliest application to the growing substrate following sciarid infestation reduced sciarid emergence. In contrast, later application of each biological control agent provided more effective control of phorid emergence. The behaviour of adult mites suggested that H. aculeifer were more positively geotactic than H. miles although both species could penetrate compost and casing substrates to a depth of 2–12 cm. A majority of S. feltiae nematodes resided at a depth of 2–4 cm in both substrate types. Independent application of H. aculeifer provided more comprehensive control of sciarids and phorids than the other biological agents studied, owing to its better dispersal within compost and casing, and ability to attack larvae of differing ages.


Author(s):  
Евгений Викторович Шиков

Древесная улитка Arianta arbustorum, в последние десятилетия распространившаяся в центре Русской равнины, стала опасным вредителем сельского хозяйства. Заселяя природные биотопы, она вытесняет аборигенные виды как растений, так и моллюсков. Эффективные меры борьбы с A. arbustorum не разработаны. Даётся оценка жизнедеятельности водяной полёвки Arvicola amphibius по отношению к древесной улитке. Плотность A. arbustorum в саду около нор водяной полёвки 2433 экз/м2, а на удалении 5 метров от нор - 5231 экз/м2. Разница статистически достоверна. Показано, что поедание водяной полёвкой древесных улиток локально снижает их плотность. Водяная полёвка выступает как природный агент биологического контроля A. arbustorum, поддерживающий видовое многообразие в природе. Установлено, что осенью 65% всех взрослых A. arbustorum закапываются в землю, и уже недоступны для поедания водяными полёвками. Кормовые запасы водяной полёвки на зиму из моркови и картофеля обнаружены в 45 м от ближайшего огорода. The Wood snail Arianta arbustorum, which in recent decades has spread in the center of the Russian Plain, has become a dangerous pest of agriculture. Settling natural biotopes, it crowds out indigenous species of both plants and mollusks. Effective control measures against A. arbustorum have not been developed. Here we assess the activity of the water vole Arvicola amphibius in relation to the Wood snail. The density of A. arbustorum in the garden near the water vole burrows is 2433 ind./m2, while at a distance of 5 meters from the burrows it becomes 5231 ind./ m2. The difference is statistically significant. Water vole eating wood snails locally reduce their density. Voles thus act as a natural biological control agent of A. arbustorum, preserving species diversity. In the fall around 65% of A. arbustorum adults burrow into the ground and are no longer available for water voles. Winter fodder stocks of a Water vole with carrots and potatoes were found 45 m from the nearest garden.


1995 ◽  
Vol 73 (S1) ◽  
pp. 65-70 ◽  
Author(s):  
B. R. Kerry

The nematophagous fungus, Verticillium chlamydosporium, has considerable potential as a biological control agent for root-knot nematodes on a range of crops. The fungus is a general facultative parasite that attacks the eggs of several nematode species. The biology of the fungus is reviewed and the need for a detailed understanding of its ecology for its rational use as a biological control agent is highlighted. Isolates of the fungus must colonize the rhizosphere to be effective control agents. Plants differ in their ability to support the fungus and greatest control is achieved on those cultivars that support abundant growth of the fungus but produce only limited galling in response to nematode attack. On such plants, most eggs produced by nematodes are exposed to parasitism by this nematophagous fungus in the rhizosphere. Key words: biological control, nematophagous fungi, root-knot nematodes, Verticillium chlamydosporium.


1990 ◽  
Vol 122 (5) ◽  
pp. 921-934 ◽  
Author(s):  
F.W. Quednau

AbstractFrom 1976 to 1978, 1300 mated females of Olesicampe geniculatae Quednau and Lim were released near Quebec City during a severe infestation of the mountain ash sawfly, Pristiphora geniculata (Hartig). Both cage and open releases were made. The interactions among the mountain ash sawfly, the imported primary parasite O. geniculatae, and the indigenous hyperparasite Mesochorus globulator (Thunb.), and the effect of O. geniculatae on the host population during and after the establishment phase, are reported. In 1984, O. geniculatae was recovered from all over southern Quebec. Parasitism ranged from 6 to 94%. Concurrently, infestation levels by the mountain ash sawfly declined significantly, and since 1985, the insect has almost disappeared in Quebec. With an annual spread of about 50 km per year after successful establishment, O. geniculatae now covers an area 1000 km in diameter. No major infestation by the mountain ash sawfly has been recorded in Quebec during the past 7 years. The introduction of O. geniculatae is rated as a complete success in classical biological control.


1982 ◽  
Vol 35 (4) ◽  
pp. 480 ◽  
Author(s):  
Steven H. Sharrow ◽  
Wayne D. Mosher

Author(s):  
K. Betteridge ◽  
D. Costall

In spite of ragwort flea beetle (RFB) being present on a Dannevirke dairy farm, pastures were sprayed each winter to reduce ragwort density and limit the risk of ragwort poisoning of stock. The trial on this farm from June 1999 - October 2001, aimed to determine whether herbicide (H) impacted on RFB and how H and RFB each impacted on ragwort growth and persistence. RFBfree areas were created by spraying with insecticide (I). Effects of ragwort on animal health are also reported. High ester 2,4-D (H) boom-sprayed once only, in June 1999, killed most ragwort plants and reduced RFB larvae densities to low levels before the plants died. Once new ragwort established in treatment H, the plants became infested with RFB larvae. RFB larvae were suppressed by I resulting in ragwort density declining more slowly than in treatments where RFB were not suppressed. Insecticide treatments were stopped after 15 months and, at 24 months, ragwort could not be found within the trial area. Ragwort control was attributed to the cessation of herbicide spraying allowing the RFB population to reach a sufficient density to kill both small and large ragwort plants. Sub-clinical ragwort poisoning was found in livers of culled cows that had grazed on ragwort-dense pastures. Keywords: animal health, biological control, Longitarsus jacobaeae, pyrrolizidine alkaloids, ragwort, ragwort flea beetle, Senecio jacobaea


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