Herbicides compromise biological control of ragwort

2002 ◽  
pp. 147-152
Author(s):  
K. Betteridge ◽  
D. Costall
Keyword(s):  
Biological Control ◽  
Pyrrolizidine Alkaloids ◽  
Animal Health ◽  
Flea Beetle ◽  
Dairy Farm ◽  
Senecio Jacobaea ◽  
Longitarsus Jacobaeae ◽  
High Ester ◽  
Low Levels

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

scholarly journals Biological control of ragwort does sheep grazing affect ragwort flea beetle

2000 ◽  
Vol 53 ◽  
pp. 54-58
Author(s):  
K. Betteridge ◽  
P.G. McGregor ◽  
D.A. Costall ◽  
P.G. Peterson
Keyword(s):  
Biological Control ◽  
New Zealand ◽  
Flea Beetle ◽  
Sheep Grazing ◽  
Longitarsus Jacobaeae

Ragwort flea beetle (Longitarsus jacobaeae) (RFB) is present in many parts of New Zealand Its impact on ragwort mortality both alone and on ragwort trimmed to simulate sheep grazing was investigated Trimming reduced ragwort size and biomass throughout the trial More plants died in spring and summer but fewer plants died over the 12 month period in trimmed than untrimmed treatments Trimmed ragwort had fewer RFB larvae/g DM than untrimmed ragwort on only 1 of 3 occasions RFB at 123 RFB larvae/g DM in August did not affect ragwort mortality Low larval numbers were probably a result of high ragwort densities (up to 36/m2)

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

1991 ◽  
Vol 71 (1) ◽  
pp. 127-140 ◽  
Author(s):  
John F. Bain
Keyword(s):  
Biological Control ◽  
Pyrrolizidine Alkaloids ◽  
Biological Control Agent ◽  
Vegetative Reproduction ◽  
Control Agent ◽  
Effective Control ◽  
Senecio Jacobaea ◽  
Eastern Canada ◽  
Tyria Jacobaeae ◽  
Tansy Ragwort

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

scholarly journals Chrysoperla externa (Neuroptera: Chrysopidae) and Utetheisa ornatrix (Lepidoptera: Arctiidae) on organically grown Crotalaria juncea (Fabaceae)

2012 ◽  
Vol 30 (3) ◽  
pp. 459-468 ◽  
Author(s):  
M.A. Costa ◽  
W.S. Tavares ◽  
A.I.A. Pereira ◽  
I. Cruz ◽  
J.E. Serrão ◽  
...  
Keyword(s):  
Biological Control ◽  
Artificial Diet ◽  
Pyrrolizidine Alkaloids ◽  
Biological Research ◽  
Utetheisa Ornatrix ◽  
Crotalaria Juncea ◽  
Lifetime Fecundity ◽  
Ecological Aspects ◽  
Minas Gerais State ◽  
Organically Grown

Chrysoperla externa (Neuroptera: Chrysopidae) larvae can avoid foraging on plants of Crotalaria juncea (Fabaceae) after the issuance of floral buds, when the prey of Utetheisa ornatrix (Lepidoptera: Arctiidae) incorporate toxic pyrrolizidine alkaloids from this plant. This reduces the predation and favors increasing the number of adults and eggs of this defoliator on crops of this plant. The aim of the present paper was to evaluate some biological and ecological aspects of C. externa and U. ornatrix on the organic crop of C. juncea in the EMBRAPA Maize and Sorghum in Sete Lagoas, Minas Gerais State, Brazil. Chrysoperla externa and U. ornatrix were more abundant in the vegetative and flowering stages of C. juncea, respectively, with caterpillars of this defoliator feeding on leaves and seeds of this plant. The duration of the stages/instars, survival, lifetime fecundity, and oviposition showed that the branches of C. juncea are a suitable food for U. ornatrix. The abundance of adults and larvae of C. externa was lower in the flowering and pods stages of C. juncea, respectively, when the postures of U. ornatrix are present, probably due to the toxicity of the eggs of this prey to this predator. During these stages, C. externa may be reared with alternative hosts, and when the crops of C. juncea are scarce, an artificial diet should be used for rearing this defoliator in the laboratory for biological research and the development of biological control tactics.

scholarly journals Invasive Lantana camara L. Shrub in Ethiopia: Ecology, Threat, and Suggested Management Strategies

2018 ◽  
Vol 10 (7) ◽  
pp. 184 ◽  
Author(s):  
Firew Bekele Abebe
Keyword(s):  
Biological Control ◽  
National Parks ◽  
Review Paper ◽  
Invasive Alien Species ◽  
Animal Health ◽  
Management Strategies ◽  
Lantana Camara ◽  
Dire Dawa ◽  
Dispersal Agents ◽  
Agricultural Loss

Lantana camara L. is one of the worst invasive alien species that are categorized worldwide. The objective of this review paper was to review the dispersal and threats posed by Lantana camara L. in Ethiopia and based on review results, to suggest management strategies that can bring solutions to the threats posed by the weed. Both biological characteristics of Lantana camara L. and its dispersal agents have contributed to the success of its dispersal. Even though Lantana camara L. is dispersed in other places within Ethiopia, Debrezeit, Dire Dawa, Harar and Somali are the hotspot areas for the weed. Biodiversity and potential agricultural loss, human and animal health problems and infestation in national parks are the identified threats that Lantana camara L. posed within the country. Utilization of Lantana camara L. for various purposes, prevention of its further dispersal into non-infected areas, use of fire, mechanical and biological control and awareness creation are the suggested management strategies that can bring solutions to the threats posed by the weed within the country.

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