The rhabditid nematode Phasmarhabditis hermaphrodita as a potential biological control agent for slugs

A nematode, Phasmarhabditis hermaphrodita, known to be associated with slugs but not previously thought to be parasitic, was shown to be a parasite capable of killing the pest slug Deroceras reticulatum. The parasite infects slugs in the area beneath the mantle surrounding the shell, causing a disease with characteristic symptoms, particularly swelling of the mantle. Infection leads to death of the slug, usually between seven and 21 days afterwards. The nematode then spreads and multiplies in the cadaver. In an experiment where individual D. reticulatum were exposed to different numbers of P. hermaphrodita, a significant positive relationship was found between nematode dose and slug mortality. In two experiments on host range, the nematode was found to infect and kill all pest slug species tested: Deroceras caruanae, Arion distinctus, Arion silvaticus, Arion intermedius, Arion ater, Tandonia sowerbyi and T. budapestensis, in addition to D. reticulatum.     

CONCENTRATIONS OF METALS (Cu, Pb, Cd, Zn, Ca) IN SIX SPECIES OF BRITISH TERRESTRIAL GASTROPODS NEAR A DISUSED LEAD AND ZINC MINE

Heavy metal concentrations in 6 terrestrial slug species inhabitinga disused Pb/Zn mine site were measured by atomic absorptionspectrophotometry. Differences in metal accumulation patternswere such that the species could be ranked in order of overallmetal accumulation capability: Arion hortensis < Deocerasreticulatum < Milax budapestensis < Arion ater < Derocerascaruanac < Arion subfuscus. Species belonging to the samegenus were widely separated by this simple ranking scheme. Theresults are discussed in the context of inter-species competitionand resource partitioning, and cautionary comments are madeconcerning the utility of slugs as biomonitors of terrestrialheavy metal pollution. (Received 25 November 1987; accepted 2 January 1988)     

Anatomical Description of Anctus angiostomus (Wagner, 1827) from Northeastern Bahia,Brazil (Gastropoda,Pulmonata, Bulimulidae)

Anctus angiostomus (Wagner, 1827) is herein described anatomically, based on material collected at Queimadas, BA, caatinga habitat. This species is characterized by closed primary and secondary ureters; salivary glands distant from the buccal bulb; a poorly developed stomac h; a characteristic mode of emergence of the gonad duct from the annexe glandular sac; very long spermoviduct; a short oviduct and vagina; very long and slender penis and epiphallus and a long flagellum with retractor muscle in the tip.     

TRANSMISSION OF LIQUORICE ROT OF CARROTS BY SLUGS

Three slug species (Arion hortensis, Deroceras reticulationand Milax budapestensis) have been shown to transmit liquoricerot of carrots (Mycocentrospora acerina) in the laboratory.The transmission was not consistent, and the association notlong-term, so that the importance of slugs as vectors in thefield is likely to be minimal. (Received 12 December 1983;     

DISTRIBUTION OF ARION HORTENSIS S.S. AND ARION DISTINCTUS IN NORTHERN SWITZERLAND

The distribution of the sibling slug species Arion hortensiss.s. and Arion distinctus in Northern Switzerland is described.In the sampled area, both species were almost equally abundantand their distributions overlapped. Most of the sampled sitescontained both species. Arion hortensis s.s. is more commonin Switzerland than previously known, and its range extendsmore towards the east of Switzerland. Arion hortensis s.s. wasmore abundant in gardens than in the other habitats sampled.At sites where only A. distinctus occurred, the form with abipartite oviduct prevailed. At sites where both species werepresent, the form of A. distinctus with a tripartite oviductwas more common than the form with a bipartite oviduct. In captivity,one specimen of A. distinctus mated with one A. hortensis s.s.,as indicated by a spermatophore of A. distinctus that was found withinthe atrium of one A. hortensis s.s. A majority of the specimens couldby assigned to the correct species by their colouration, buta safe distinction between A. hortensis s.s. and A. distinctusis only possible using characters of the reproductive system. (Received 4 July 2000; accepted 19 September 2000)     

How can two soft bodied animals be precisely connected? a miniature quick‐connect system in the slugs,Arion lusitanicus and Arion rufus

Among stylommatophoran gastropods, many species have simplified or reduced their copulatory organs, for example, within the Arionidae, many species lack penes. In this study, I ask two questions 1) How are soft bodied slugs which do not possess a penis connected during copulation? and 2) Is there a mechanical isolating barrier between related sympatric slug species? Observations on the mating behavior and the functional morphology of the distal genital apparatus were made in a mixed population of Arion lusitanicus and Arion rufus. The investigated Arion species exhibit an elaborate copulation process with a quick genital coupling. Prior to full eversion of the distal genitalia, the genital coupling proceeds inside the atrium cavity of one of the partners. This is in contrast to the symmetrical mutual eversion in penis‐bearing species. The donor–recipient channels are tightly connected to one after another and fit precisely. During copulation, the jelly‐coated spermatophore of the donor is pressed out into the connected channel of the partner, where it is implanted only with its frontal part. In the field, successful interspecific matings in terms of spermatophore transfer were rarely observed. The observations presented indicate a mechanical barrier which may profoundly influence the intraspecific and interspecific mating success. J. Morphol. 276:631–648, 2015. © 2014 Wiley Periodicals, Inc.     

The Use of Metaldehyde Against Slugs

One part of metaldehyde in thirty parts of bran by volume is the minimum effective concentration for obtaining an economic kill of slugs under average weather conditions. For use against Milax gracilis Leydig. heaps of bait should not be normally more than 2 yd. apart and against Arion hortensis Fer. not more than 3 ft. apart. The mortality of slugs attracted to metaldehyde-bran baits is dependent on the drying property of the soil and atmosphere around the baits. D.D.T. flea-beetle dust and powdered pyrethrum flowers are sufficiently distasteful to slugs to prevent their consuming a lethal dose of the poison mixed with bran. The addition of 10%, by volume, of dried blood to metaldehyde-bran bait increases the catch of some slugs under certain conditions but does not increase the mortality. The addition of 10%, by volume, of dextrose increases the mortality produced by metaldehyde but does not increase the numbers attracted to the bait. A metaldehyde-bran bait compacted into 'biscuit' form with anhydrous calcium sulphate catches more slugs than an ordinary metaldehyde-bran bait, but almost completely counteracts the effect of the metaldehyde. A metal-dehyde-bran-casein glue bait in 'biscuit' form increases the catch and kill of Milax gracilis and Agriolimax reticulatus Müll., but not of Arion hortensis . Metaldehyde-bran-casein glue bait broadcast in 'broken biscuit' form is effective over a longer period, thus producing a greater kill of slugs, than a broadcast metaldehyde-bran bait.     

The fumigant effect of metaldehyde on slugs

The fumigant effect of metaldehyde on slugs is confirmed and shown almost certainly to be caused by impure metaldehyde breaking down to the volatile parent monomer, acetaldehyde. Acetaldehyde was slightly more toxic to Agriolimax reticulatus than to Arion hortensis.     

Variation in the genitalia of the land snail Heterostoma paupercula (Lowe, 1831) (Helicidae) in Madeira

The small helicid snail Heterostoma paupercula occurs in the Azores and Madeira. Previously regarded as a single species, it was split into two genera on the basis of variation in shell morphology and genital anatomy: Heterostoma having a toothed shell and being hemiphallic, while Steenbergia had a toothless shell and was euphallic. This division was first questioned when toothed shells {Heterostoma) in the Azores were found not to be hemiphallic. In this study the genitalia of 361 specimens from islands in the Madeira archipelago were examined. Four components of the genitalia were measured (penis/epiphallus, flagellum, bursa stalk and bursa) for 158 individuals. Hemiphally was found to be rare, occurring in only a proportion of the populations at two localities and it did not correspond with the expected shell morphology–the shells were untoothed (= Steenbergia) , which is the opposite of that previously described.
Variation in the genitalia was geographically based: Madeira and its nearest neighbour islands forming one group and the Porto Santo islands another. There is no evidence to suggest that the hemiphallic animals are more than an intraspecific form. It is suggested that the variation between the two island groups is reflective of allopatric differentiation. Without für ther evidence of divergence, H. paupercula should be regarded as the sole species throughout the range and the genus Steenbergia should be suppressed.     

云南管螺属一新种记述(肺螺亚纲,柄眼目,烟管螺科)

记述采自云南省石林县陆生贝类1新种,即石林管螺Phaedusa shilinensis sp.nov.,文中对新种形态特征、栖息环境进行了描述,并对其相似种进行了分析和讨论。     

CALCIUM PHOSPHATE GRANULES IN THE REPRODUCTIVE SYSTEM OF OXYCHILUS ATLANTICUS (GASTROPODA: PULMONATA)

The presence of connective interstitial cells in the wall ofseveral organs of the distal reproductive system in Oxychilus atlanticusis described by means of scanning electron microscopy (SEM).Connective interstitial cells extend from the distal part of thevas deferens to the penis, being the dominant cell type of large portionsof the epiphallus as well as in the whole penial caecum (=flagellum).These cells are highly mineralized and are characterized bythe presence of large amounts of solid spherules (up to 4 mmin diameter) in their cytoplasm. A semi-quantitative evaluationby X-ray microanalysis demonstrates that calcium and phosphorusare the main elements of the spherules. Their function is unknown,but they could aid in copulation or they could assist the survivalof the transferred spermatozoa. (Received 7 June 1999; accepted 8 September 1999)     

Cold tolerance and freeze-induced glucose accumulation in three terrestrial slugs

Cold tolerance and metabolic responses to freezing of three slug species common in Scandinavia (Arion ater, Arion rufus and Arion lusitanicus) are reported. Autumn collected slugs were cold acclimated in the laboratory and subjected to freezing conditions simulating likely winter temperatures in their habitat. Slugs spontaneously froze at about -4 °C when cooled under dry conditions, but freezing of body fluids was readily induced at -1 °C when in contact with external ice crystals. All three species survived freezing for 2 days at -1 °C, and some A. rufus and A. lusitanicus also survived freezing at -2 °C. (1)H NMR spectroscopy revealed that freezing of body fluids resulted in accumulation of lactate, succinate and glucose. Accumulation of lactate and succinate indicates that ATP production occurred via fermentative pathways, which is likely a result of oxygen depletion in frozen tissues. Glucose increased from about 6 to 22 μg/mg dry tissue upon freezing in A. rufus, but less so in A. ater and A. lusitanicus. Glucose may thus act as a cryoprotectant in these slugs, although the concentrations are not as high as reported for other freeze tolerant invertebrates.     

Four New Species of Symphypleona (Collembola) from Korea

ABSTRACT Four new species of Symphypleona, Ptenothrix plumiseta, Deuterosminthurus serratus, Sminthurus annulatus, Smithurinus distinctus , are described from Korea. Especially two genera, Deuterosminthurus and Sminthurinus are new record to Korea. Korean Collembola Symphypleona add up to 18 species, 11 genera in 6 family.     

Slug activity in relation to weather

Multiple regression analysis was carried out on the effect of certain meteorological factors on the numbers of slugs attracted by metaldehyde and bran biscuits at Cardiff in the autumn months. By far the greatest reduction in the variance in numbers of slugs attracted each morning was achieved by taking out the effects of two factors: (1) the length of time the biscuits had been exposed, and (2) the average night air temperature. The percentage relative humidity considered alone had little effect on the variance. Regression coefficients, at each site, for factors (I) and (2) on slug numbers appeared to be in close agreement and it is suggested that these figures would serve as a measure of slug activity. Arion hortensis behaved differently from the other species studied, its day-to-day variation in numbers not being tied so closely to the meteorological factors examined.
Methods of assessing slug numbers in the field usually rely on the animals' activity. Barnes & Weil (1944) made direct counts on the slugs observable in half-hourly periods, and Thomas (1944) based estimates of the number attracted to metaldehyde and bran biscuits overnight; Duthoit (1961) used baits of wheat seed in making weekly estimates. Measures of activity, however, may be less directly related to the actual population present than to day-to-day climatological variations. The aim of the work described below was to find if it was possible to arrive at more reproducible population estimates by using standard slug biscuits, and allowing for the effect of some of the meteorological variables.     

Litter decomposition by slugs in mixed deciduous woodland

For the one year period considered, it is calculated that 683.5 g m^-2 plant litter entered the study area site. Of the six slugs studied, Arion intermedius Normand, the smallest species, had the highest overall consumption rate on the nine test foods (29.1 ± 0.9 mg dry wt g live wt^-1 d^-1) and the highest overall mean assimilation efficiency (72.0 + 0.9%). The mean faecal production for each of the six slug species was very similar, ranging from 8.4 to 9.9 mg dry wt g live wt^-1 d^-1. Using regression equations of food consumed on faeces produced, it is estimated that the slug fauna each year consumes 8.4% of the leaf litter input and 6.5% of the total available plant litter. Of the plant material consumed, 13.8 g dry wt m^-2 are deposited annually as faeces. The role of slugs in decomposition processes is discussed and compared with that of other soil organisms.     

Description of Longidorus fagi n. sp. (Nematoda, Dorylaimida) with an identification key to the species of the genus occurring in Bulgaria

Longidorus fagi n. sp. is described from Vitosha Mountain, Bulgaria, where it was found in soil around roots of Fagus sylvatica L. The new species is characterised by its medium size, narrow anteriorly rounded lip region which is offset from the body by a very slight depression, large amphidial pouches which are distinctly bilobed at the base, and a conoid-elongate tail which is ventrally curved with a narrow, rounded terminus. L. fagi resembles L. nirulai, L. distinctus, L. curvatus and L. fragilis, An identification key for species of the genus Longidorus present in Bulgaria is provided.     

SOME OBSERVATIONS ON DAMAGE TO POTATOES BY SLUGS

The garden slug, Arion hortensis Fér., and the keeled slugs, Milax spp., are the slugs mainly responsible for primary damage to potato tubers in the south-west of England. A variety trial clearly demonstrated the existence of significant differences in susceptibility to slug attack between the three varieties tested. Arran Banner was the most damaged variety, Arran Peak the least, while Majestic occupied an intermediate position. Varietal differences in the amount and time of damage to tubers were associated with differences in the dates of maturity, and little damage occurred prior to the maturing of the tuber. The results confirm the need for prompt lifting of the potato crop on maturity, in order to avoid damage by slugs.