Distribution and prevalence of the predatory planarian Artioposthia triangulata (Dendy) (Trieladida: Terricola) in Scotland

The distribution of the New Zealand flatworm (Artioposthia triangulata) in Scotland was surveyed between July 1991 and February 1993. There were 348 records from domestic gardens, 56 from botanic gardens, garden centres and nurseries, with only 13 from farms. Although most of the records came from around the major cities the flatworm was found to have become established throughout the Scottish mainland and some of the Islands, e.g. Bute, Gigha, Orkney and Skye. The impact of the flatworm on earthworm populations in agricultural land in Scotland was, as yet, found to be minimal but the fact that seven adjacent farms near Dunoon were infected suggested it could be spread from farm to farm and that in the West of Scotland it could become widespread in agricultural land.     

Studies on Artioposthia triangulata (Dendy) (Tricladida: Terricola), a predator of earthworms

Observations had linked the disappearance of earthworms from a grass field to the presence of Artioposthia triangulata. An experiment demonstrated that this land planarian could severely and quickly reduce numbers of four earthworm species. Two different approaches to sampling A. triangulata were investigated on a grassland site. The first used four different trap types (wood, ceramic tile, 'corriboard' plastic and 5 mm polystyrene beneath a ceramic tile) measuring 15 cm x 15 cm which were compared over a period of 18 wk. The second used one, or two, applications of dilute formalin solution to quadrats followed by counting the residual planarians by hand-sorting the soil beneath the quadrat to a depth of 30 cm. The polystyrene traps were the most effective for detecting the presence of A. triangulata. No planarians were ever found by hand-sorting after two formalin applications and it was concluded that formalin sampling provided a good estimate of the population density. Counts under traps were not related to absolute estimates of population densities so polystyrene type traps should only be used for detection of the planarians. A multiple regression relationship of A. triangulata weight over time in 5% formalin is presented and allows the original liveweight to be calculated from the weight in preservative. Planarian and earthworm population densities in eight fields were sampled and the planarians were found to be randomly distributed. Counts of planarians in 0.25 m² quadrats were not related to numbers of earthworms but overall field population densities were. It is concluded that A. triangulata is a severe threat to the earthworm populations of Northern Ireland.     

A chance field observation and pilor laboratory studies of predation of the New Zealand flatworm by the larvae and adults of carabid and staphylinid beetles

A chance finding in an Edinburgh allotment was made of a stained carabid beetle larva that had eaten Artioposthiu triungulata previously stained red and released into the allotment during a dispersal experiment. In a pilot laboratory study the flatworm was eaten by larval and adult carabid and staphylinid beetles whereas seven other carnivorous species from five arthropod families did not. In another feeding experiment a carabid and a staphylinid larva each ate several specimens of the flatworm and gained tissue weight over 14 days. The conclusion drawn from these preliminary studies and the field observation is that certain carabid and staphylinid beetles are potential predators of A. triangulata.     

Genetic variation in populations of the terrestrial planarian Artioposthia triangulata (Dendy), and evidence for passive dispersal in Northern Ireland

Genetic variation in 12 populations of the terrestrial planarian Artioposthia triangulata from Northern Ireland and one in the Republic of Ireland were assessed using starch-gel electrophoresis. Seven enzymes - adenylate kinase, aspartate aminotransferase, enolase, malate dehydrogenase, phosphoglucose isomerase, phosphomannose isomerase and superoxide dismutase - provided consistent, resolved stains. Coefficients of genetic identity were similar for all comparisons suggesting that the populations did not belong to distinct taxa. There was no relationship between genetic distance and geographic distance for populations, thus confirming the role of passive dispersal in the spread of A. triangulata. Average percentage polymorphic loci and mean heterozygosities were higher in the east of the Province (41.4% and 0.240), than the west (37.5% and 0.185) suggesting that the planarian had spread westwards after an initial colonisation in the east.     

Surface movement rates of the New Zealand flatworm Artioposthia triangulata: potential for spread by active migration

Movement rates for the surface activity of the New Zealand flatworm Artioposthia triangulata (Dendy) (Tricladida: Terricola) were estimated under semi-field conditions in the Faroe Islands. The distance travelled during 10 consecutive 1-minute periods per individual was measured from mucus trails left behind as the flatworms moved over black plastic sheeting sprayed with fine droplets of water. Adult specimens were found to crawl at rates of up to 28 cm min^-1 (almost 17m h^-1), whereas juveniles crawled at rates of between 3 and 4cm min^-1 (approximately 2m h^-1). This study provides the first data concerning the potential for species spread by active migration.     

Long-term effects of prey-availability, partnering and temperature on overall egg capsule output of 'New Zealand flatworms', Arthurdendyus triangulates

Arthurdendyus triangulatus is an invasive terrestrial flatworm that preys on earthworms. To assess A. triangulatus egg capsule production, flatworms were maintained in ventilated polypropylene tubs (7.5 L) kept in controlled environment (CE) chambers or outdoors in the ground. Controlled environment chambers were maintained at 8°C or 14°C, flatworms kept singly or paired within tubs and offered Eisenia fetida according to a weight equalling one‐eighth or one‐half of the mean flatworm weight, or left unfed. The tubs were a successful method for keeping flatworms, with some surviving for over one year. The greatest number of egg capsules produced by an individual A. triangulatus was nine over a 16 week period for a flatworm kept at 14°C and fed at the one‐half regime (0.56 egg capsules flatworm^‐1 week^‐1). Although the effects of treatments varied with CE chambers, there was some evidence from flatworms kept outdoors, that feeding affected egg capsule output, with those flatworms fed at the one‐half regime tending to produce more egg capsules (P= 0.057). Flatworms at the one‐eighth regime or that were unfed produced progressively lighter egg capsules and substantially declined in weight themselves. Nevertheless, even unfed flatworms continued to produce egg capsules for 18 weeks. The lightest egg capsule weighed 8 mg, whilst the heaviest was 180 mg. In the CE chambers at 14°C, there was evidence for two different reproductive/survival strategies. Some flatworms produced cumulatively more egg capsules the longer they survived, whereas others lived longer but produced fewer egg capsules. Flatworms kept without a partner still produced egg capsules up to 35 weeks later. Egg capsules contained a mean of 4.14 (CE chambers) or 4.62 (outdoors) juveniles, with a maximum of 11. Overall, juveniles were 45% of the weight of egg capsules, although larger egg capsules had more juveniles, which comprised a greater proportion of the egg capsule. The conversion of earthworm prey to egg capsule production was estimated at 13%.     

Studies on the local dispersal of the New Zealand flatworm, a predator of earthworms, in Edinburgh between 1993 and 1999

The flatworm Artioposthia triangulata was found, from studies using weighted down plastic sheeting, to move predominantly through the soil rather than over it and to use earthworm burrows. Under compost‐filled plastic sacks the flatworm was most active at night although its numbers were similar to those during the day. The transfer of specimens into an area covered with weighted plastic sheeting had no lasting effect on their numbers. The flatworm was regularly removed over 6 years from under paving stones, sheets of newspaper and cardboard placed on the ground in a garden. The rise and fall of the numbers of the flatworm under this debris suggest a predator‐prey periodicity between the flatworm and earthworms of 3 years.     

Density of the New Zealand flatworm, a predator of earthworms, in allotments in Edinburgh between 1993 and 1995

The density of the New Zealand flatworm, Artioposthia triangulata, found between 1993 and 1995 on the surface of the soil under various types of debris scattered in four allotments, was 1–2 m^?2. The type of debris did not markedly affect the density of the flatworm and the distribution of the flatworm within the allotment studied was significantly clustered. Fluctuation in numbers of specimens under different sets of compost‐filled plastic sacks varied in a similar manner to one another. The flatworm was most abundant in the upper 100 mm of soil and its egg capsules were most numerous between 100 and 200 mm below the surface. The flatworm was as abundant under the soil surface shelters as it was beneath shelters buried below the soil surface.     

Observations on feeding and population structure of five New Zealand terrestrial planarians which prey on lumbricid earthworms

The feeding of five terrestrial planarians found in New Zealand on European lumbricid earthworms was studied. Under laboratory conditions between 60–83% of Artioposthia spp. fed in the first 24 h compared with 21–40% of Australoplana spp. The mean percentage weight gain varied from 31% for Australoplana sanguinea var. alba to 113% for Artioposthia sp. 1. Analysis of the weights of the planarian species showed a mean 11-fold difference between Australoplana sanguinea and Artioposthia triangulata and that these body weights were not related to mean percentage weight gains after feeding. The relationship between the weights of egg capsules and pregnant female planarians was similar for Australoplana sanguinea var. alba (11%), Artioposthia triangulata (12%) and Artioposthia testacea (13%). This study confirms that there are terrestrial planarians in New Zealand which have the potential to prey upon European lumbricid earthworms but which have not been detected in Europe. Greater knowledge of their biology is necessary to control the spread and impact of these organisms around the world.     

Quinic acid derivatives from Saussurea triangulata attenuates glutamate-induced neurotoxicity in primary cultured rat cortical cells

The leaves of Saussurea triangulata (Compositae) have been eaten with rice as a wrapping vegetable for preventing neuro-aging. However, the components responsible for the neuroprotective effects of S. triangulata still remain unidentified. In the process of investigating the neuroprotective activity of S. triangulata, we found that a methanol extract of S. triangulata exhibited significant protection against glutamate-induced toxicity in primary cultured rat cortical cells. Three quinic acid derivatives were isolated from the n-BuOH fraction of S. triangulata. Among these three quinic acid derivatives, methyl 5-caffeoylquinic acid (3) exhibited significant neuroprotective activities against glutamate-induced toxicity exhibiting cell viability of about 50%, at concentrations ranging from 0.1 μM to 10 μM. Therefore, the neuroprotective effect of S. triangulata might be due to the inhibition of glutamate-induced toxicity by the quinic acid derivatives from S. triangulata.