Soft-bodied Arthropods Research Articles

Computational aspects of a pseudo-elastic constitutive model for muscle properties in a soft-bodied arthropod

In this paper we discuss the computational implementation of a new constitutive model that describes the muscle properties in a soft-bodied arthropod. Qualitatively, the muscle tissues behave similar to particle-reinforced rubber and are capable of large non-linear elastic deformations, show a hysteretic behavior, and display stress softening during the first few cycles of repeated loading. Such behavior can be described by the framework of pseudo-elastic transversely isotropic hyperelasticity. The computational model assumes compressible overall response, and is based upon a multiplicative split of the deformation gradient tensor into volumetric and isochoric parts. Details regarding the implementation of the computational model in the context of an implicit finite element solution procedure are presented. In particular, an explicit expression is provided for the material tangent stiffness tensor. Results obtained utilizing the new implementation are also presented.

Einige Beobachtungen zur Nahrungsökologie der Wolfspinne Pardosa lugubris (WALCK.) (Araneae, Lycosidae)

Some observations on the feeding ecology of the wolf spider Pardosa lugubris (WALCK.). — In a beechspruce forest near Zurich (Switzerland) studies on the feeding ecology of the wolf spider Pardosa lugubris (WALCK.) were carried out. Only 6% of 513 wolf spiders caught by hand held a prey (strongly deformed) between their chelicerae. The food of P. lugubris exclusively was composed of small, soft-bodied arthropods (Insecta, Arachnida). > 85% of the identified prey animals consisted of Collembola (Genera Orchesella and Tomocerus) and small Diptera.

Using GIS to study palaeobiogeographic and macroevolutionary patterns in soft-bodied Cambrian arthropods

Soft-bodied Cambrian arthropods from Burgess Shale-type deposits are some of the most famous and extensively studied fossil invertebrates, but global species-level assessments of their biogeographic patterns have not previously been explored quantitatively. Here we use a newly developed occurrence database, in conjunction with Geographic Information Systems (GIS) analysis and PaleoGIS—which allows fossil locality positions to be viewed in the context of Cambrian palaeogeography—to quantitatively reconstruct geographic distribution patterns of primarily soft-bodied arthropod species. Further, we compare these patterns with those of co-occurring trilobite taxa. Soft-bodied Cambrian arthropods show both statistically larger geographic ranges and greater stratigraphic longevities than co-occurring trilobites. Many of the most widely distributed soft-bodied arthropods were likely capable of swimming, and this may in part explain their extensive distributions.

A constitutive model for muscle properties in a soft-bodied arthropod

In this paper, we examine the mechanical properties of muscles in a soft-bodied arthropod under both passive and stimulated conditions. In particular, we examine the ventral interior lateral muscle of the tobacco hornworm caterpillar, Manduca sexta, and show that its response is qualitatively similar to the behaviour of particle-reinforced rubber. Both materials are capable of large nonlinear elastic deformations, show a hysteretic behaviour and display stress softening during the first few cycles of repeated loading. The Manduca muscle can therefore be considered as different elastic materials during loading and unloading and is best described using the theory of pseudo-elasticity. We summarize the basic equations for transversely isotropic pseudo-elastic materials, first for general deformations and then for the appropriate uniaxial specialization. The constitutive relation proposed is in good agreement with the experimental data for both the passive and the stimulated conditions.

Synthesis of insecticidal sucrose esters

Some synthetic sucrose esters (SE) are a relatively new class of insecticidal compounds produced by reacting sugars with fatty acids, which are safe for the environment. Especially, sucrose esters composed of C6–C12 fatty acids have desirable insecticidal properties against many soft-bodied arthropod pests. In our study, sucrose octanoate which has the highest activity against a range of arthropod species was synthesized by a trans-esterification method and proved its insecticidal property. Under the condition of a homogeneous liquid, sucrose octanoate was prepared by reacting ethyl octanoate with sucrose at reduced pressure; the yield was 79.11%. Sucrose octanoate synthesized was identified and its property analyzed by IR, TLC and spectrophotometric analysis. It was shown that the ratio of monoester to polyester in sucrose octanoate was 1.48:1. The insecticidal activity of the synthetic sucrose octanoate was evaluated at a concentration of 4 and 8 mg·mL−1. The mortality of first-instar larvae of Lymantria dispar from its contact toxicity was 72.5% after 36 hours, the revision insect reduced rate of Aphis glycines reached above 80% at 4 and 8 mg·mL−1 after being treated for 5 days. Since the SE products are nontoxic to humans and higher animals, fully biodegradable and hydrolyzed to readily metabolizable sucrose and fatty acid, they are not harmful to crops and appear to be good insecticide candidates.

Ecology of Mabuya agilis (Raddi) (Lacertilia, Scincidae) at the restinga of Grumari, Rio de Janeiro, southeastern Brazil

Some aspects of the ecology of the skink Mabuya agilis (Raddi, 1823) at the restinga habitat of Grumari, in Rio de Janeiro, Brazil are studied. Most of the lizards were first sighted on the ground, though a few were using perches (mainly cacti) up to 30 cm high. Mean body temperature in activity was 33.1 ± 2.4ºC and was significantly correlated to air temperature. There was sexual dimorphism in size (snout-vent length - SVL), with females growing larger than males. Frequency of broken tails was high overall (83%) and did not differ between sexes. Females and males are sexually mature at 49 mm and 47 mm SVL, respectively. Brood size averaged 3.2 ± 1.0 (range 1-5) and was positively and significantly related to female SVL (r = 0.65, p = 0.001). Relative clutch mass (RCM) of seven gravid females averaged 0.250 ± 0.042, being relatively low compared to those of other congeners. The diet of M. agilis was composed basically of arthropods, with relatively large and soft-bodied arthropods such as spiders, caterpillars and homopterans being the most important prey. The results of our work confirm and expand the knowledge of ecological tendencies previously observed for M. agilis in other areas.

Plant washing as a pest management technique for control of aphids (Homoptera: Aphididae).

Changes in aphid presence following plant washings were evaluated on hibiscus plants, Hibiscus rosa-sinensis L., that supported natural aphid infestations--primarily melon aphid, Aphis gossypii Clover. Type of plant module (such as stems, tight buds, open flowers, and sepal caps) and percent of module's surface covered by aphids were recorded for each branch tip on every plant. Plant washing was done with tap water, applied for 30 s three times a week for 3 wk. Aphid presence was recorded each week. Aphid presence on plant structures immediately before and after a single 30-s wash treatment was also examined. In the 3-wk study, mean percent coverage of plant parts with aphids was significantly affected by wash treatment, plant module type, and their interactions, as well as by time and the interaction of time with wash treatment. By the third week, unwashed plants had 33.1% of stems and branch tips scoring >5% coverage with aphids, and 17.9% of unwashed stems and branch tips had 20% or more of their surface area covered by aphids. Washing plants prevented aphid coverage from ever exceeding the 5% class on all module types. In the second experiment, buds and stems with high numbers of aphids before washing generally experienced notable declines with a single wash. When the prewash coverage was 10% or greater, reduction in coverage ranged from 50 to 100% of the prewash amount. In 64% of the cases, the reduction in coverage was 75% or more of the prewash amount. Plant washing can provide a viable means of management for small, soft-bodied arthropods such as aphids.

Seasonal changes in the canopy arthropod fauna in Rinorea beniensis in Budongo Forest, Uganda

Arthropods were collected by insecticidal tree fogging on the understorey tree species Rinorea beniensis Engler (Violaceae) in Budongo Forest, a seasonal rain forest in Uganda. Eight trees were fogged in adjacent plots of primary, selectively logged and swamp forest during the wet season and again in the dry season. In all forest types, Psocoptera, parasitoid Hymenoptera, and especially Formicidae and Auchenorrhyncha were more abundant during the dry season, while Ensifera, Heteroptera, Lepidoptera, Diptera, and Coleoptera were more abundant during the wet season. Seasonal change in arthropod composition was very low in the swamp forest located near a stream, where permanent water supply is crucial for the development of the distinct swamp vegetation, with comparatively constant microclimatic conditions all over the year. Seasonal change increased in the primary forest, and shows most significant changes of athropod abundance between dry and wet season in the selectively logged forest which also had the highest heterogeneity in forest structures. Especially small and soft bodied arthropods probably accumulate along a humidity gradient in the dense canopies of Rinorea during the dry season, when the forest floor outside the swamp forest is dry. This effect, which is also strongest in the selectively logged forest, leads to a much higher density of canopy dwelling arthropods during the dry season.

A Modified “Riker Specimen Mount” for Soft-bodied Arthropods

THE RIKER SPECIMEN MOUNT (OR RIKER Mount) is a useful way to display dried specimens for classroom instruction. It also has an interesting history (Bailey 1940). At the turn of the century, Clarence B. Riker of Maplewood, NJ, was engaged in the drug-exporting business and, as a consequence, made frequent trips to South America. Riker also had an interest in butterflies; while on his business trips, he collected specimens and stored them in wooden boxes. Because of damage to specimens during transit, he designed the Riker Mount. Friends who saw his collection displayed in Riker Mounts were enthusiastic and urged him to secure a patent on the device and place it on the market. The patent application was made in 1900, and the patent granted in 1902. Today, Riker Mounts can be either purchased from biological supply companies or constructed in the home or laboratory (Steyskal et al. 1986, Borror et al. 1989). Although the Riker Mount works well for displaying dried specimens, it is not suitable for displaying soft-bodied arthropods, such as insect immatures, that shrivel when allowed to dry. These types of specimens are typically stored in 70-95% ethanol and, when used in the classroom, must be viewed either through the wall of a glass vial or (preferably) in a dish of ethanol. When both the adult (in a Riker Mount) and the immature (in ethanol) of a given species must be observed together, it can be problematic. The transfer of specimens from storage units to observation dishes and back to storage units also is time consuming. With these drawbacks in mind, I developed a modified Riker Mount that enables one to display a soft-bodied arthropod either singly or (in larger units) with a dried specimen (Fig. 1). The material requirements are (1) Riker Specimen Mounts, (2) thick-walled glass bottles with teflon/polyethylene-lined screw caps, (3) a bottle-cutting kit, (4) an abrasive for sanding the surface of cut glass,

Diets of Land Birds from Northeastern Venezuela

We estimate diets of 68 bird species inhabiting dry seasonal habitats and mangroves of northeastern Venezuela, based on 3,419 birds forced to regurgitate using tartar emetic. Most birds were generalist feeders, including a wide variety of both invertebrate and plant taxa in their diet. Coleopterans, ants, and insect larvae were the most frequent invertebrate preys. Hummingbirds had low nectar intakes and differed from other species by feeding extensively on small soft-bodied arthropods. Most species fed on fruits to a variable extent. Actually, several species tended to be more frugivorous at our study sites than in previous reports.

Dissimilar bill shapes in new world tropical versus temperate forest foliage-gleaning birds.

The bill shape of foliage-gleaning birds in temperate and tropical new world forests is dissimilar. Tropical species have longer and narrower bills than their temperate zone counterparts. In addition, their bills are longer for a given body size. These differences cannot be readily explained as phylogenetic artifacts. I suggest that the distinct bill morphology of the two assemblages is determined by the type of insects that comprise the largest size classes of potential prey. These large insects are particularly important since they generally comprise the bulk of the nestling diet for insectivorous birds. In tropical forests Orthoptera are probably the most abundant large soft-bodied arthropods; they form an important resource for foliage-gleaning birds during the breeding (rainy) seasons. Most temperate zone foliage-gleaning birds rely almost entirely upon caterpillars when breeding. Long, narrow bills are thought to close more rapidly than shorter, broader bills. These long, "fast" bills may be required to efficiently harvest active Orthoptera. Migrant warblers may face morphological constraints from breeding successfully in lowland tropical forests. While the short-billed temperate zone birds can survive the tropical dry season by foraging on small arthropods, they may be inefficient at handling large Orthoptera to feed to nestlings.

A TECHNIQUE FOR REARING THE PREDACEOUS MITEBALAUSTIUM PUTMANI(ACARINA: ERYTHRAEIDAE), WITH NOTES ON ITS BIOLOGY AND LIFE HISTORY

AbstractThe predaceous miteBalaustium putmaniSmiley was studied in the laboratory and in apple orchards in southern Ontario. A rearing technique was devised which facilitated the study of the life history and behaviour of individual mites.Temperature and moisture influenced the development and hatching of eggs. In the presence of water, development proceeded more rapidly at the higher temperature of the 10°–25°C range tested. In the absence of water no development occurred. LarvalB.putmaniare free-living predators and although some were observed feeding periodically on pollen grains, they could not survive solely on this diet. All three motile stages are predators of a wide range of small, soft-bodied arthropods, but feed mainly on eriophyids and phytophagous tetranychid mites. The rate of consumption of the eggs and motile stages of the European red mite was determined for each motile stage at 20° and 25°C. Insemination is by externally deposited spermatophores and in the adult females, no facultative parthenogenesis was evident.

Comparative Analysis of the Feeding Habits of Two Species of Arizona Blind Snakes, Leptotyphlops h. humilis and Leptotyphlops d. dulcis

Stomach content analyses of 28 Leptotyphlops humilis humilis and 17 L. dulcis dulcis indicate that these snakes feed extensively on ants and termites which compromise 54-64 per cent of the total diet. L. d. dulcis appears to be more fossorial in its feeding activity than L. h. humilis which preys on a greater percentage of surface-dwelling arthropods. Presumably, this serves to reduce competition for the available food supply in geographical areas of sympatry. Both species show a definite preference for soft-bodied prey-types. In addition, several insect species which live as commensals in ant and termite nests are readily consumed along with their hosts. INTRODUCTION Most of the existing literature on the blind snakes of the genus Leptotyphlops deals specifically with the systematics of the group (Klauber, 1940) and their general ecology and geographical distribution (Banks and Farmer, 1963; Banta, 1965; Brattstrom, 1953; Turner and Wauer, 1963). Previous investigations on the feeding behavior of the Western Blind Snake, Leptotyphlops humilis humilis, and the Texas Blind Snake, L. dulcis dulcis, have demonstrated that these fossorial species feed extensively on ants and termites (Brattstrom and Schwenkmeyer, 1951; Reid and Lott, 1963; Stebbins, 1966). It has been further shown that L. d. dulcis frequently utilizes the pheremone trails of some ant species to locate its prey (Watkins, Gehlbach and Baldridge, 1967). Although it has been suggested that additional softbodied arthropods are also consumed (Stebbins, 1954), quantitative and qualitative information concerning the specific food preferences of these snakes is lacking. The purpose of the present study was to accurately analyze the feeding habits of these two species in an area of sympatry as well as to determine what differences, if any, exist in their food preferences. MATERIALS AND METHODS Twenty-eight L. h. humilis and 17 L. d. dulcis were collected 5 km ESE of Chiricahua, Cochise Co., Arizona during May through August 1971. The area was characterized by sand flats and intermittent boulder-strewn hillsides. Several rocky canyons with dry creek beds were present. There were no apparent micro-habitat differences between the two species. The prevalent vegetation included mesquite (Prosopis juliflora), incense bush (Symphoricarpos sp.), creosote (Covillea) and ocotillo (Fouquieria splendens). Most specimens were collected along paved and dirt roads at night. Several individuals were found within rocky crevices during the day. L. h. humilis specimens ranged in length from 21.4-33.8 mm; L. d. dulcis individuals from *Current Address: Dept. of Zoology & Entomology, Iowa State University, Ames, Iowa 50010, USA.

Life History and Behavior of Balaustium putmani (Acarina: Erythraeidae)1

Balaustium putmani Smiley has been abundant in unsprayed fruit orchards of the Niagara Peninsula, Ontario, since 1959. The larva, like the nymph and adult, is a free-living predator of small soft-bodied arthropods on the trees; it was seen attacking all stages of the European red mite, Panonychus ulmi (Koch); all stages of the San Jose scale, Aspidiotus perniciosus Comstock; and the apple aphid, Aphis pomi De Geer, though aphids were not very suitable prey. B. putmani agrees with other Balaustium spp. in having free-living larvae; otherwise its development is typical of erythraeids in general, with apodous quiescent nymphs alternating with motile feeding stages. It has 2 generations per year.