Interactions between the land snails Theba pisana and Cernuella virgata in the laboratory

2020 ◽  
Author(s):  
Geoff H Baker
Keyword(s):  
Laboratory Experiments ◽  
Distribution Patterns ◽  
Land Snails ◽  
Snail Species ◽  
Agricultural Pests ◽  
Large Numbers ◽  
Small Scales ◽  
Novel Method ◽  
Theba Pisana ◽  
Inhibitory Components

ABSTRACT Two Mediterranean snails, Theba pisana and Cernuella virgata, are agricultural pests in southern Australia. The two species are rarely found together in large numbers in the field, at small scales (<1 m2). In laboratory experiments, the presence of T. pisana reduced the survival of C. virgata, but only when food (carrot + lettuce) was provided. When C. virgata was exposed to only the mucus trails and faeces of T. pisana, produced while feeding on lettuce, both the survival and activity of C. virgata were reduced. When carrot was substituted for lettuce, there was less effect. In addition, when C. virgata was exposed to T. pisana’s faeces only, derived from access to a mix of lettuce and carrot, there was no effect on C. virgata’s survival. The observed reductions in the survival of C. virgata were stronger in autumn (the breeding season for both snail species) compared with spring. Inhibitory components within the mucus trails of T. pisana may (1) help explain the observed distribution patterns of the two species at small scales in the field and (2) provide a novel method for control of pest populations of C. virgata, in some situations.

Soil surface temperature and mortality in land snails: implications for successful management

2003 ◽  
Vol 43 (11) ◽  
pp. 1351 ◽  
Author(s):  
V. Kempster ◽  
S. Charwat
Keyword(s):  
Laboratory Experiments ◽  
Control Strategies ◽  
High Surface ◽  
Soil Surface ◽  
Land Snails ◽  
Successful Management ◽  
Economic Problems ◽  
Surface Temperatures ◽  
Theba Pisana ◽  
Soil Surface Temperature

Three species of land snails, Theba pisana (Müller, 1774), Cernuella virgata (Da Costa, 1778) and Cochlicella acuta (Müller, 1774), introduced to Australia from the Mediterranean region, cause significant economic problems in harvested crops in southern Australia. One of the strategies for post-harvest control of these snails involves stubble management to knock the snails onto the hot ground during summer. Farmers report variable results with this strategy, which could be due to varying heat tolerances between the 3 species. In a series of laboratory experiments, field-collected snails of the 3 species were tested for their ability to survive high surface temperatures for varying periods of time. The results reported here indicate differences between the 3 species in their tolerance of soil surface temperatures, and suggest that the variable results noted in the field are due at least in part to the differing heat tolerances of the 3 species. When adult snails were placed in incubators at a constant temperature, all T. pisana died after 3 h at 55°C, while C. virgata and C. acuta survived longer, with 100% mortality only after 2 successive 6-h exposures at 55°C. Weight loss of snails was measured after heat treatment to estimate water loss under these conditions. Recommendations are made for more effective mechanical control strategies for snails in the field during summer.

The population dynamics of the mediterranean snails Cernuella virgata, Cochlicella acuta (Hygromiidae) and Theba pisana (Helicidae) in pasture - cereal rotations in South Australia: a 20-year study

2008 ◽  
Vol 48 (12) ◽  
pp. 1514 ◽  
Author(s):  
G. H. Baker
Keyword(s):  
Population Dynamics ◽  
Near Field ◽  
South Australia ◽  
Habitat Choice ◽  
Snail Species ◽  
Large Numbers ◽  
Yorke Peninsula ◽  
Sampling Scale ◽  
Theba Pisana ◽  
Peak Abundance

The snails Cernuella virgata, Cochlicella acuta and Theba pisana are introduced pests of grain crops and pastures in southern Australia. The population dynamics of these three species of snail were studied for 20 years in two adjacent fields where they coexisted on a farm on the Yorke Peninsula in South Australia. The fields were used for pasture–cereal rotations. Surveys were conducted in autumn and spring each year, coinciding respectively with the start of the breeding season and peak abundance of snails (mostly juveniles). Populations varied greatly in abundance between years and between species, but snails were generally most common in spring, in wet years, especially those with wet autumns and wet springs. Rainfall early in a particular year (i.e. at sowing of crops in autumn) can thus be used to predict the likelihood of heavy snail infestations later in spring (i.e. at harvest). In contrast, the abundance of adult snails in autumn was a poor predictor of the subsequent abundance of juvenile snails in spring, especially in crops. There were no significant correlations, at field scale, between the average abundance of the three species of snail in spring, in either pastures or crops. However, at a sampling scale of 0.25 m2, there were consistent, negative relationships between the abundance of all three snail species. Such patterns may reflect either competitive interactions between snails or subtle differences in micro-habitat choice. Patterns in the abundance of snails (e.g. large numbers near field edges) were suggestive of occasional invasion from dense populations in adjacent fields.

scholarly journals An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Richard S. Gashururu ◽  
Samuel M. Githigia ◽  
Methode N. Gasana ◽  
Richard Habimana ◽  
Ndichu Maingi ◽  
...  
Keyword(s):  
National Park ◽  
Control Strategies ◽  
Glossina Pallidipes ◽  
Distribution Patterns ◽  
Tsetse Flies ◽  
Wet Season ◽  
Chi Square ◽  
Large Numbers ◽  
Surrounding Areas ◽  
Biconical Traps

Abstract Background Glossina (tsetse flies) biologically transmit trypanosomes that infect both humans and animals. Knowledge of their distribution patterns is a key element to better understand the transmission dynamics of trypanosomosis. Tsetse distribution in Rwanda has not been well enough documented, and little is known on their current distribution. This study determined the current spatial distribution, abundance, diversity, and seasonal variations of tsetse flies in and around the Akagera National Park. Methods A longitudinal stratified sampling following the seasons was used. Biconical traps were deployed in 55 sites for 6 consecutive days of each study month from May 2018 to June 2019 and emptied every 48 h. Flies were identified using FAO keys, and the number of flies per trap day (FTD) was used to determine the apparent density. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variations between the variables. The significance (p < 0.05) at 95% confidence interval was considered. Logistic regression was used to determine the association between tsetse occurrence and the associated predictors. Results A total of 39,516 tsetse flies were collected, of which 73.4 and 26.6% were from inside Akagera NP and the interface area, respectively. Female flies accounted for 61.3 while 38.7% were males. Two species were identified, i.e. G. pallidipes [n = 29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n = 10,395; 2.6 FTD). The statistical difference in numbers was significant between the two species (p = 0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD). Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface. Glossina morsitans was 0.218 times less likely to occur outside the park. The chance of co-existing between the two species reduced outside the protected area (0.021 times). Conclusions The occurrence of Glossina seems to be limited to the protected Akagera NP and a narrow band of its surrounding areas. This finding will be crucial to design appropriate control strategies. Glossina pallidipes was found in higher numbers and therefore is conceivably the most important vector of trypanosomosis. Regional coordinated control and regular monitoring of Glossina distribution are recommended. Graphic Abstract

scholarly journals Snail mucus from the mantle and foot of two land snails, Lissachatina fulica and Hemiplecta distincta, exhibits different protein profile and biological activity

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Nattaphop Noothuan ◽  
Kantamas Apitanyasai ◽  
Somsak Panha ◽  
Anchalee Tassanakajon
Keyword(s):  
Biological Activities ◽  
Protein Pattern ◽  
Protein Profile ◽  
Antibacterial Properties ◽  
Biological Properties ◽  
Specific Protein ◽  
Land Snails ◽  
Snail Species ◽  
Significant Difference ◽  
Different Types

Abstract Objective Snails secrete different types of mucus that serve several functions, and are increasingly being exploited for medical and cosmetic applications. In this study, we explored the protein pattern and compared the biological properties of the mucus secreted from the mantle collar and foot of two snail species, Lissachatina fulica and Hemiplecta distincta. Result Protein profile showed a different pattern between the two species and between the two secretory parts. The mantle-specific protein bands were further characterized and among them was an antibacterial protein, achacin. Accordingly, the mucus from the mantle exhibited the higher antibacterial activity than that from the foot in both snail species. The mucus from H. distincta, first reported here, also showed antibacterial properties, but with a lower activity compared to that for L. fulica. Snail mucus also exhibited anti-tyrosinase activity and antioxidant activity but with no significant difference between the foot and mantle mucus. These results indicate some different protein compositions and biological activities of snail slime from the mantle and foot, which might be associated with their specific functions in the animal and are useful for medical applications.

Dispersal of the sugar-cane scale Aulacaspis tegalensis (Zhnt.) (Hem., Diaspididae) by air currents

1972 ◽  
Vol 61 (3) ◽  
pp. 547-558 ◽  
Author(s):  
D. J. Greathead
Keyword(s):  
Sugar Cane ◽  
Laboratory Experiments ◽  
Sticky Trap ◽  
Research Station ◽  
High Humidity ◽  
Dispersal Mechanism ◽  
Large Numbers ◽  
Speed Up ◽  
Trap Catches ◽  
Aulacaspis Tegalensis

By means of sticky traps and a suction trap, it was demonstrated on a plot of sugar-cane at Kawanda Research Station, Uganda, that large numbers of crawlers of Aulacaspis tegalensis (Zhnt.) become airborne (up to 10/m3). The numbers increase with wind speed up to about 2·0 m/s and then remain constant, but are depressed by increasing humidity. In laboratory experiments, crawler survival was reduced by high temperatures (30°C) and low humidities (30% r.h.), but some individuals should survive the extreme conditions sometimes experienced if airborne from morning until evening. On hatching, crawlers move upwards and towards the light, but downwards in the dark; movement is inhibited by high humidity. These behaviour responses indicate hat the presence of crawlers in the air is not accidental but a dispersal mechanism. At Arusha Chini, an isolated sugar estate in Tanzania, sticky-trap catches downwind of a windbreak confirmed that airborne dispersal of crawlers is a major source of infestation. It is shown that air currents could have carried crawlers to Arusha Chini from a source on the Kenya coast, 260 km to the east.

scholarly journals Potential impacts of climate change on Mongolia’s plant protection status quo

2018 ◽  
Vol 24 (02) ◽  
pp. 26-32
Author(s):  
Batkhuyag B ◽  
Batnaran Kh
Keyword(s):  
Climate Change ◽  
Climate Modeling ◽  
Plant Protection ◽  
Current Trend ◽  
Animal Husbandry ◽  
Distribution Patterns ◽  
Agricultural Pests ◽  
Migratory Locust ◽  
Colorado Beetle ◽  
Wide Range

Mongolia’s 2030 Sustainable Development Vision set a goal to be a self-sufficient in grain, potatoes and vegetables by 2030. However, Mongolia’s pastoral animal husbandry and rain-fed agriculture are extremely sensitive to climate change. The Asian migratory locust is considered as the most harmful grasshopper in the world. Until 1970th, these locust’s distribution areas in Mongolia were confined to oasis of Gobi deserts. A study on Asian migratory locust in Russia predicts distribution and formation of new permanent habitats of the locust in Chita oblast, Krasnoyarsk territory and Republic of Tyva. The Colorado beetle is one of the world’s most infamous invasive species due to its rapid adaptation to a wide range of ecological conditions and ability to disperse long distances. The climate modeling of Colorado beetle showed that with current trend, the beetle will expand its distribution into the most eastern and north-eastern regions of the Russian Federation. In China, the Colorado beetle was first detected in Xinjiang in 1993 and subsequently spread eastward. In China the Colorado beetle is currently expanding its areas at rate of 25 kms year (12-45 kms/year). Both species’ distribution patterns in neighboring countries show eventual establishment of permanent habitats around Mongolia. Their invasion to Mongolia will threaten country’s food security due to direct destruction of cereal and potato crops, and increased application of highly toxic pesticides. In light of these threats, Mongolia should start taking serious preventive measures by increasing surveillance and dedicated risk assessment studies for potential agricultural pests and diseases.

scholarly journals An Ecological Study of the Brown Garden snail Cornu aspersum (Müller, 1774) from selected habitats in Jadiriya in Baghdad vicinity.

2010 ◽  
Vol 7 (1) ◽  
pp. 223-232
Author(s):  
Baghdad Science Journal
Keyword(s):  
Land Snails ◽  
Parasitic Nematodes ◽  
Ecological Indicator ◽  
Snail Species ◽  
The World ◽  
Cornu Aspersum ◽  
Healing Wounds ◽  
Medical Importance ◽  
The One ◽  
Scientific Attention

The present study is considered a pioneer investigation that deal with the terrestrial brown garden snail Cornu aspersum (Müller), in Iraq. Cornu aspersum however is considered an exotic species in many parts of the world ,The species is most probably infiltrates with plants transferred from one place to another. The species has gained importance in many ways. Nutritionally, the species is consumed as food item in many countries, but in other cases it is considered as pest for the damage it causes when feeding on valuable plant shoots. It also has medical importance for its role and ability in healing wounds, burns and remedy of other skin problems. This snail species however may act as a vector for some parasitic nematodes that cause serious diseases. The species is also important in scientific research, usually referred to as ‘ecological indicator’ employed in environmental pollution problems such as the one caused by heavy metals. A great deal of research on this species has been carried out in different parts of the world, however, in Iraq, the scientific attention given to land snails in general and to Cornu aspersum in particular is rare and may be negligible in comparison with the research carried out on aquatic Mollusca species. A total of 1880 individuals of Cornu aspersum were collected from all sampling sites. The study was carried out for the period November 2007 to November 2008 on three sites within the Jadiriya district in Baghdad.. Growth, size classes and shell dimensions of Cornu aspersum populations, and their relationship with major environmental factors; ambient temperature; soil pH, moisture, texture; and the soil content of organic matter have been also investigated. Identification of the species was confirmed by the British Natural History Museum.The data were analyzed by means of standard statistical procedures.

scholarly journals The Influence of Grain Size Distribution on the Hydraulic Gradient for Initiating Backward Erosion

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2644 ◽  
Author(s):  
Willem-Jan Dirkx ◽  
Rens Beek ◽  
Marc Bierkens
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Laboratory Experiments ◽  
Hydraulic Gradient ◽  
Concentrated Flow ◽  
Pipe Formation ◽  
Novel Method ◽  
Flow Through ◽  
The Stability

Backward erosion by piping is one of the processes that threaten the stability of river embankments in the Netherlands. During high river stages, groundwater flow velocities underneath the embankment increase as a result of the steepened hydraulic gradient. If a single outflow point exists or forms, the concentrated flow can entrain soil particles, leading to the formation of a subsurface pipe. The processes controlling this phenomenon are still relatively unknown due to their limited occurrence and because piping is a subsurface phenomenon. To study the initiation of piping, we performed laboratory experiments in which we induced water flow through a porous medium with a vertically orientated outflow point. In these experiments, we explicitly considered grain size variations, thus adding to the existing database of experiments. Our experiments showed that the vertical velocity needed for the initiation of particle transport can be described well by Stokes’ law using the median grain size. We combine this with a novel method to relate bulk hydraulic conductivity to the grain size distribution. This shows that knowledge of the grain size distribution and the location of the outflow point are sufficient to estimate the hydraulic gradient needed to initiate pipe formation in the experiment box.

scholarly journals Novel Remanence Determination for Power Transformers Based on Magnetizing Inductance Measurements

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4616
Author(s):  
Chen Wei ◽  
Xianqiang Li ◽  
Ming Yang ◽  
Zhiyuan Ma ◽  
Hui Hou
Keyword(s):  
Numerical Simulations ◽  
Laboratory Experiments ◽  
Power Transformer ◽  
Power Transformers ◽  
Inrush Current ◽  
The Core ◽  
Novel Method ◽  
Simulation Results ◽  
Electro Magnetic ◽  
The Relationship

The remanence (residual flux) in the core of power transformers needs to be determined in advance to eliminate the inrush current during the process of re-energization. In this paper, a novel method is proposed to determine the residual flux based on the relationship between residual flux and the measured magnetizing inductance. The paper shows physical, numerical, and analytical explanations on the phenomenon that the magnetizing inductance decreases with the increase of residual flux under low excitation. Numerical simulations are performed by EMTP (Electro-Magnetic Transient Program) on a 1 kVA power transformer under different amounts of residual flux. The inductance–remanence curves are nearly the same when testing current changes. Laboratory experiments conducted on the same transformer are in line with the numerical simulations. Furthermore, numerical simulation results on a 240 MVA are reported to demonstrate the effectiveness of the proposed method.

scholarly journals Differential herbivore damage to calcicolous lichens by snails

1993 ◽  
Vol 25 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Lars Fröberg ◽  
Anette Baur ◽  
Bruno Baur
Keyword(s):  
Laboratory Experiment ◽  
Outer Layer ◽  
Land Snails ◽  
Lichen Species ◽  
Snail Species ◽  
Herbivore Damage ◽  
Mechanical Defence ◽  
Calcareous Rock ◽  
The Baltic

AbstractA laboratory experiment was conducted to determine the damage caused by snail grazing to 35 calcicolous lichen species and cyanobacteria from the Baltic island of Oland, Sweden. Individuals of four species of land snails (Balea perversa, Chondrina cliema, Clausilia bidentata and Helicigona lapicida) were allowed to graze on identified lichen species growing on pieces of limestone. Snail grazing on thalli and ascocarps was classified into four categories ranging from no damage to completely eaten. In general, some lichen species were heavily grazed, whereas others were only slightly damaged or not injured. Aspiciha calcarea, Tephromela atra and Verrucaria nigrescens were preferred by all snail species except Chondrina cliema. In general, lichen thalli that were not immersed in the calcareous rock and cyanobacteria were preferred, whereas ascocarps were avoided by one of the snail species (C. clienta). Immersed perithecia with a carbonized outer layer were avoided by all snail species except C. bidentata. Possibilities of chemical and mechanical defence properties in calcicolous lichens are discussed.

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