scholarly journals Water vole Arvicola amphibius (Linnaeus, 1758) (Arvicolidae) as an agent of biological control of a tree snail Arianta arbustorum (Linnaeus, 1758) (Mollusca, Gastropoda, Helicidae)

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.

2006 ◽  
Vol 96 (2) ◽  
pp. 145-152 ◽  
Author(s):  
J.R.U. Wilson ◽  
M. Rees ◽  
O. Ajuonu

AbstractThe release of classical biological control agents has reduced the economic, environmental and social problems caused by water hyacinth,Eichhornia crassipes; however, additional control measures are needed in some locations. Water hyacinth plants were treated with different densities of eggs of the weevilNeochetina eichhorniaeWarner, one of the main control agents, under different nutrient regimes in a controlled experiment. Plants were destructively sampled and the development ofN. eichhorniaewas assessed. The survival of first and second instars declined as larval density increased. Plant nutrient status did not directly affect the mortality rate of larvae, but at higher nutrient concentrations larvae developed faster and were larger at a given developmental stage. It is argued that the density dependence operating inN. eichhorniaeoccurs through an interaction between young larvae and leaf longevity. Consequently, events which disrupt water hyacinth leaf dynamics, e.g. frost or foliar herbicides, will have a disproportionately large effect on the control agents and may reduce the level of control of the host.


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.


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.


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


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