Pill-millipedes Research Articles

A method of obtaining dietary data for slow worms (Anguis fragilis) by means of non‐harmful cooling and results from a Danish population

Diet composition of slow worms (Anguis fragilis) from a Danish population was recorded from May to September 2006. Slow worms were maintained in cool conditions (at 8°C) for a maximum of 126 h, which made approximately half of the animals regurgitate. The method worked equally well on juveniles and adults. The regurgitations revealed that the slow worms preyed on small snails, slugs, pill millipedes (Glomeris marginata), earthworms and Lepidoptera larvae. There were seasonal changes in taxon composition of the diet but no ontogenetic or sex‐related differences. The food quality of selected prey types was tested on juveniles in a laboratory experiment. Mealworms gave a significantly lower gain in mass and snout–vent length than slugs, earthworms and a mix of all three prey types. A supplementary experiment revealed that slow worms from the present population completely rejected mealworms as prey. Earthworms seemed to be nutritionally inferior to molluscs.

Distribution of Pill Millipedes ( Arthrosphaera) and Associated Soil Fauna in the Western Ghats and West Coast of India

Seven sampling sites in each of three biomes (Western Ghats, foothills of Western Ghats and west coast) of south-western India were investigated to study the distribution, abundance and ecology of pill millipedes ( Arthrosphaera)and associated fauna in relation to edaphic features. Abundance and biomass of Arthrosphaera and other millipedes were the highest in Western Ghats, while earthworms were in foothills. Arthrosphaera magna and Arthrosphaera spp. were common in Western Ghats and foothills respectively, while no Arthrosphaera were found in the west coast. None of the sampling sites consisted of more than one species of Arthrosphaera. Biomass of Arthrosphaera, other millipedes and earthworms significantly differed in Western Ghats ( P =9.48 × 10 −7) and foothills ( P =1.35 × 10 −8), as did the biomass of species of Arthrosphaera ( P =2.76 × 10 −7) between Western Ghats and foothills. Correlation analysis revealed that biomass of Arthrosphaera was significantly ( P =0.01, r =0.45) correlated with soil organic carbon rather than other edaphic features (pH, phosphate, calcium and magnesium). Distribution pattern, abundance, biomass and ecology of Arthrosphaera of Western Ghats in relation to soil qualities were compared with millipedes of other regions of the world.

Stabilisation of soil organic matter in invertebrate faecal pellets through leaf litter grazing

Soils were amended with either leaf litter or faeces from pill millipedes fed on the leaf litter, then incubated at 20 °C for 130 days whilst monitoring the respiration rates. Significantly more CO 2 was respired from soil containing leaf litter than that amended with an equivalent weight of faecal matter, whilst the unamended soil exhibited a respiration rate similar to soil amended with faecal material. Consideration of these findings with recently observed differences in biochemical compositions of litter and faeces suggests that processing of plant litter by detritivores leads to more stabilised forms of organic matter by removal of biochemical components essential to the nutrient requirements of the invertebrate and the soil microbial biomass.

The biochemical transformation of oak ( Quercus robur) leaf litter consumed by the pill millipede ( Glomeris marginata)

Soil macrofauna play an essential role in the initial comminution and degradation of organic matter entering the soil environment and yet the chemical effects of digestion on leaf litter are poorly understood at the molecular level. This study was undertaken to assess the selective chemical transformations that saprophagous soil invertebrates mediate in consumed leaf litter. A number of pill millipedes ( Glomeris marginata) were fed oak leaves ( Quercus robur) after which the biomolecular compositions (lipids and macromolecular components) of the leaves and millipede faeces were compared using a series of wet chemical techniques and subsequent analysis by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS). It was found that the concentrations of short chain (<C 20) n-alkanoic acids, sterols and triacylglycerols reduced dramatically in the millipede faeces relative to the leaf litter. Hydrolysable carbohydrates and proteins both decreased in concentration in the faeces, whereas similar yields of phenolic components were observed for the cupric oxidation products of lignin, although the oxygenated functionalities were affected by passage through the millipede gut, yielding a more highly condensed state for lignin. This shows that the chemical composition of fresh organic matter entering the soil is directly controlled by invertebrates feeding upon the leaf litter and as such that they are key contributors to the early stages of diagenesis in terrestrial soils.

Seasonal abundance and activity of pill millipedes (Arthrosphaera magna) in mixed plantation and semi-evergreen forest of southern India

Seasonal occurrence and activity of endemic pill millipedes (Arthrosphaera magna) were examined in organically managed mixed plantation and semi-evergreen forest reserve in southwest India between November 1996 and September 1998.Abundance and biomass of millipedes were highest in both habitats during monsoon season. Soil moisture, conductivity, organic carbon, phosphate, potassium, calcium and magnesium were higher in plantation than in forest. Millipede abundance and biomass were about 12 and 7 times higher in plantation than in forest, respectively (P 0.05). Millipede abundance and biomass were positively correlated with rainfall (P = 0.01). Besides rainfall, millipedes in plantation were positively correlated with soil moisture as well as temperature (P = 0.001). Among the associated fauna with pill millipedes, earthworms rank first followed by soil bugs in both habitats. Since pill millipedes are sensitive to narrow ecological changes, the organic farming strategies followed in mixed plantation and commonly practiced in South India seem not deleterious for the endangered pill millipedes Arthrosphaera and reduce the risk of local extinctions. © 2005 Elsevier SAS. All rights reserved.

AN UNUSUAL CASE OF MIMICRY

Numerous spiders mimic ants, and considerable descriptive literature is available (Bonnet, 1945); other spiders are supposed to resemble bird droppings or certain insects. On the other hand, literature on animals that mimic spiders is scant and no references could readily be found. Spiders, however, are poisonous to various groups of animals and should present evolutionary opportunities to potential mimics. Spider beetles (Ptinidae) at times are brought in, mistaken by collectors for spiders; their relationship to spiders is obscure. On a trip to Dalmatia, in the vicinity of Dubrovnik, I found the pill bug, Armadillidium klugii Brandt 1833 (Crustacea: Isopoda), to be so similar to Latrodectus mactans tredecimguttatus (Rossi, 1790), the malmignatte or European form of the black widow, as to be easily mistaken for it. The northern Mediterranean widows have bright red spots on a glistening black body (Fig. la), coloration resembling that of juvenile American forms. The spots are usually absent in adults in other parts of the range of L. mactans. The spiders are found among piles of stones, roadbanks, and deep plow furrows. Among stones in the Dubrovnik area we found Armadillidium klugii, a pill bug endemic in this area of Dalmatia and on adjacent islands, that rolls up when disturbed, showing bright red spots on a shiny black background (Fig. lc), strikingly like the abdomen of Latrodectus. The isopod is found commonly in crevices and between rocks. It was described from alcoholic specimens (Strouhal, 1928) in which the red color had washed out leaving yellow spots instead of red. Bright colors are not commonly found among pill bugs, and the coloration thus is most unusual. According to Strouhal, the species is variable in color, black to brown-black, with spots whitish to yellow and telson yellow to dark in alcohol. No black widows were collected with the isopod but this was perhaps due to the extremely low population of L. mactans in summer of 1962, the lowest in at least 10 years both in Italy and Yugoslavia (personal communication, Z. Maretic and M. Alessandrini), possibly due to unusually cold weather late in spring. The area probably normally supports a large black-widow population. There also occurs on the ground between stones in the Dubrovnik area, a pill millipede Glomeris pulchra C. L. Koch 1847 (Diplopoda: Glomerida), a black species with a series of bright red spots. When disturbed the millipede rolls up like a pill bug (Fig. lb), also strikingly resembling the malmignatte abdomen. Dr. P. Tongiorgi made me aware that pill millipedes of the genus Glomeris in northern Italy may have a similar color pattern. Live animals of a different species from Pisa, Italy, were also all black with two series of spots varying in color from yellowish to reddish; none had bright red spots, but no specimens were obtained from areas where Latrodectus is common.' Mimicry depends upon a characteristic of a model that makes it of selective advantage to be confused with the model. Latrodectus is known to be extremely poisonous to some vertebrates-guinea pigs, horses, camels, and man. Its poison must be effective on some invertebrates as under its webs were found scarabid beetles several times the volume of Latrodectus. The nocturnal habit of mammals and their sensitivity to the poisons would preclude any advantage of mimicry as a means of avoiding predation by them. Superficial acquaintance with the habitat suggests that lizards, abundant everywhere, might be the most important predators of isopods, glomerid millipedes, and ground-dwelling spiders. The only reference that could be found (Vellard, 1936) indicates that Latrodectus is poisonous, but not lethal, to lizards. If the spider should succeed in biting a lizard attempting predation, the lizard would have an opportunity to learn not to attack Latrodectus again, and mimicry might very well give a selective advantage against lizard predation. As far as is known (Mertens, personal communication), Mediterranean lizards of the genus Lacerta feed on isopods, and it is believed that the rolling up of Armadillidium would not serve as complete protection. Another possibility is that the mimics display similar aposematic coloration. However, isopods are not known to be distasteful and the defensive secretions of most millipedes are not well-developed in the glomerids; a pair of glands is present but the secretions are odorless and tasteless (Attems, 1926).