Arthropod Samples Research Articles

A new inexpensive suction apparatus for sampling arthropods in grassland

Abstract. We describe a new technique for sampling arthropods from grassland and other vegetation, using a modified petrol‐driven suction apparatus called a‘Blow & Vac’. The new apparatus was tested by comparing its efficiency in extracting arthropods from vegetation with that of a conventional Dietrick, or‘D‐Vac’, suction sampler. Unimpeded air velocity inside the suction tube was approximately 4 times that of the D‐Vac. In field trials on semi‐natural grasslands, the Blow & Vac caught more individuals of most spider and certain beetle species compared to the D‐Vac and approximately equal numbers of Auchenorrhyncha. We conclude that the‘Blow & Vac’has considerable potential for sampling arthropod populations. Its low cost and weight make it a suitable alternative to the conventional D‐Vac apparatus.

Comparison of Three Methods for Sampling Arthropod Pests and Their Natural Enemies in Peanut Fields

We compared the use of beat sheets, pitfall traps, and sweep nets for sampling common arthropods in peanut fields by taking weekly samples in the 1987 to 1989 growing seasons. We used σ 2/ x ratios and number of samples needed as the criteria for comparing sampling techniques. Pitfall trap samples had the largest means for soil surface-dwelling arthropods such as Labidura riparia (Pallas) (Dermaptera: Labiduridae), Oxyopes salticus Hentz (Arachnida: Araneae: Oxyopidae), ground beetles, rove beetles, and wolf spiders. Beat sheet samples had the smallest σ 2/ x ratios for Solenopsis invicta (Buren) (Hymenoptera: Formicidae) and Peucetia viridans Hentz (Arachnida: Araneae: Oxyopidae). Samples from sweep nets had the smallest σ 2/ x ratios for Geocoris spp. (Hemiptera: Lygaeidae). All three techniques had similar σ 2/ x ratios for Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) and the Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). Sweep net samples had the smallest σ 2/ x ratios for Spissistilus festinus (Say) (Homoptera: Membracidae). None of the techniques adequately sampled all common pest and beneficial arthropods in peanuts.

Diet of Nestling Winter Wrens in Relationship to Food Availability

We identified major arthropod taxa in the feces of nestling Winter Wrens (Troglodytes troglodytes) and quantified their number, size, and biomass. These data were compared with samples of arthropods obtained from habitats and microhabitats that were typical of breeding territories. Larval Lepidoptera on shrubs in the clearcut were more numerous and had a higher biomass than those on shrubs in forested areas. Total arthropod biomass, the biomass of Coleoptera, and numbers of Araneae on Vaccinium shrubs were higher in the forest. On the ground, numbers and biomass of most taxa were higher in the clearcut than in the forest. Coleoptera and Araneae were fed to nestlings in high proportions relative to their proportionate numbers and biomass in the environmental samples.

Ecology and Management of Arthropod Pests of Poultry

The worldwide spread of modern, high-density confined poultry production systems under the direction of integrators has intensified the importance of a select number of arthropod ectoparasites and habitat pests. This concentrated production of poultry provides artificial ecosystems that are sometimes ideal for the development of large populations of arthropod pests. At the same time the systems are amenable to integrated pest management involving a multipest and multimethod approach to reducing or eliminating arthropod pests. Since rodents are major pests, they should be included in an integrated pest management program to make the program most cost-effective and attractive to the integrators and producers (5). Quantitative data are scarce on economic effects, and the concept of economic thresholds is difficult to apply either to ectoparasites or to habitat pests. The risk of transporting ectoparasites among flocks is difficult to evaluate and necessitates treatment after early detection of the arthropods. Flies and litter beetles present a threat of disease transmission and the potential for lawsuits from neighbors or public health agencies that are factors not subject to easy cost estimates. The monetary losses of a flock devastated by disease or a farm forced to close are so great that the risks are unacceptable. Production losses from lowered feed conversion ratios and insulation damage are likely to be detected by the sophisticated record-keeping of the integrators. Minimal use of pesticides and other chemicals on poultry and in poultry housing is an objective of the integrators and, consequently, an integrated pest management (IPM) approach that reduces the need for pesticides is attractive. The key to further development of effective arthropod management programs for poultry is the implementation of pest and disease monitoring programs for the complete system. Improvements in arthropod sampling methods and more attention to monitoring the biosecurity systems to minimize ectoparasite dispersal are needed. The integrators have servicemen who regularly visit the production facilities and can be trained to perform monitoring functions and to instigate and supervise integrated pest management measures. With the increasing use of computers by the integrators, the prospects for utilizing the monitoring data in predictive computer simulation models for pest management decision-making justify more efforts to develop such tools (64, 102, 168). Future poultry pest management programs must be based on sound data, which presently is too limited, and must be flexible enough to adjust rapidly to evolving pest problems in rapidly changing production systems.

Species number, species abundance and body length relationships of arboreal beetles in Bornean lowland rain forest trees

ABSTRACT. The relationships between number of species, abundance per species, and body length are examined for 859 species of beetles in samples of arthropods collected from ten Bornean lowland forest trees by insecticide fogging. Similar relationships are examined for different feeding guilds of these beetles, and for those beetles from different species of trees. The data are used to construct four interrelated graphs, namely species: abundance, species: body length, population abundance: body length and total number of individuals: body length distributions. In contrast to a number of previous studies, no consistent linear relationship between population density and body length was found for the Bornean beetles and it is suggested that, as in birds, the added dispersal ability of flight reduces critical population densities necessary for persistence in small species. Previous relationships between body weight and population abundance may also be artefacts of the way in which data were gathered. Despite large samples, we failed to locate the mode in plots of the number of species in each abundance category (species: abundance distribution). Species: body length and total number of individuals: body length plots were similar to those found in previous studies, although using data for Coleoptera alone may have produced a steeper decline in the total number of individuals as body size increases than is apparent in samples of all arthropods. We present the first three‐dimensional graph relating numbers of species, body lengths and population abundances. The surface of this three‐dimensional relationship is relatively simple.

Arthropod faunal similarity of Bornean rain forest trees

ABSTRACT. 1. Arthropod samples, collected by insecticide fogging ten Bornean lowland rain forest trees, were sorted to species and used to study some of the determinants of faunal similarity of these trees.2. Similarity indices were calculated between pairs of trees for guilds of beetles, beetle families and for different orders and other families of insects.3. Multiple regression analyses of five independent variables of the trees (taxonomic similarity, distance apart, vertical canopy overlap, similarity in tree height, epiphytic load) were carried out against these similarity indices.4. In eight of the eighteen insect groups analysed, taxonomic similarity of the trees is the most important variable affecting their species composition, accounting for a maximum of 29.4% of the variation.5. For the Homoptera, Gryllidae, Anthicidae, Chrysomeloidea and scavengers, distance between the trees and the similarity of the trees’epiphyte load have a greater effect on their faunal similarities than taxonomic similarity of the trees.6. The maximum variation accounted for by variables with significant T ratios was 38.6% in the Anthicidae. In four groups, the Formicidae, Heteroptera, Galerucinae and Corylophidae, none of the variables was significant.7. These data may support the view that for many insect groups there is less host‐specificity in the tropics than in temperate regions.

Guild structure of arthropods from Bornean rain forest trees

ABSTRACT. 1. 23275 arthropods collected by insecticide fogging from ten Bornean lowland rain forest trees were sorted to approximately 3000 species and assigned to guilds using two sets of criteria.2. The rank order for proportions of guilds of species but not individuals is similar in tropical and temperate canopy samples.3. Misplacement in the guild assignments of a few species can cause important differences in the proportions of certain guilds. This can seriously affect the results of comparisons of different samples, and views on proportional constancy of guilds of species on different trees.4. Guilds of arthropod species such as chewers, suckers, all phytophages, predators, ants and tourists, occur in constant proportions in samples from different tropical trees and this constancy of proportion is similar in samples from groups of‘closely related’and‘distantly related’trees.5. The guild concept of community structure and problems in assigning species to guilds are considered with respect to arthropod samples. The conclusions on constancy of proportion for guilds of species are tempered by remarks on the problems of guild composition.

Immigration and colonization of portable apple trees by arthropod pests and their natural enemies

Levels of immigration/colonization by selected arthropod pests and natural enemy species into portable apple orchards were estimated in eight combined treatments of two orchard-density groups or regions, three distance classes from orchard source pools and two orchard-species pool types (i.e. abandoned vs commercial). Eighteen to 24 trees comprised each portable orchard and ground cover, cultural management, spraying, etc. were standardized at each site. Arthropod sampling included both extensive and intensive timed samples through the growing season in each site. Species immigration rates were compared for each portable orchard site. Pest species immigration was similar between regions, but decreased with distance from source pool. Generalist predator immigration was similar between regions and across sites. Specific observations of immigration and colonization were made on 96 species in 11 orders and 46 families.

Seasonal variation and the effects of drought on the abundance of arthropods in savanna woodland on the Northern Tablelands of New South Wales

AbstractMonthly samples of arthropods were collected for 3 years in savanna woodland at Wollomombi, New South Wales, from the foliage of eucalypts, bipinnate acacias, Olearia viscidula Jacksonia scoparia, Exocarpos cupressiformis and Cassinia spp., and from the ground‐layer. The second and third years of the study coincided with the worst drought recorded for the area. Biomass of arthropods matched primary productivity and decreased greatly during the drought. In the first year there was a pronounced summer peak and winter low. Some species of plants showed peaks that did not conform to the overall pattern. Most arthropod groups were greatly reduced in number during the drought and some groups virtually disappeared, although coleopterans were not significantly affected. Arthropods were less severely reduced in shrubs than they were in the tree‐layer of eucalypts. Arthropods were on average smaller during winter.

Comparison of Sweep-net and Ground-cloth Sampling Methods for Estimating Arthropod Densities in Different Soybean Cropping Systems

Methods involving a sweep net, ground cloth, and ground cloth plus visual observation were evaluated for sampling arthropod pests and predators in three soybean cropping systems. The ground-cloth technique provided a good estimate of absolute density for most of the species sampled. In conventionally planted soybeans with rows spaced 81 cm apart, the ground cloth alone sampled from 82 to 97% of the true arthropod density as measured by the ground cloth plus visual observation method. In drill-planted soybeans and soybeans planted in small grain stubble, these ranges in efficiency were 75 to 96% and 73 to 90%, respectively. The lower percentages in ground-cloth sampling were primarily due to individuals remaining on the soybean foliage after the plants had been shaken. A power model was used to transform sweep-net counts to equivalent ground-cloth counts using regression analyses on mean densities of nine arthropod species encountered in 150 fields. In 11 of the 27 species/cropping system combinations, a linear model adequately described the relationship between the two methods. In those regressions that showed nonlinear relationships, the sweep net was more efficient than the ground cloth at high pest densities. Our equations provide estimates of absolute densities of arthropods in different cropping systems using different sampling methods and can be used to convert action thresholds between systems and methods.

A Collapsible Tow Net Used for Sampling Arthropods by Airplane

A cost-efficient, easy-to-use tow net for use on a high-wing monoplane was developed. Nets are deployed and retrieved while in flight. A 0.37-m2 net can be used by virtue of a rigging system that allows the net to collapse upon retrieval. Net design and sampling efficiency of the net are described.

Arthropod Communities in a Maritime Antarctic Moss-Turf Habitat: Effects of the Physical and Chemical Environment

SUMMARY (1) 384 samples of moss and peat were cut from a moss-turf habitat on Signy Island in the maritime Antarctic. For each sample, the arthropods were extracted and counted, and the following environmental variables were measured: dry weight, percentage water content, Polytrichum cover, pH, and the concentrations of sodium, potassium, calcium, phosphorus and nitrogen. (2) Sample dry weight, percentage water content and calcium were most regularly correlated with the number of arthropods in samples. Nitrogen, phosphorus and pH were least important. (3) In step-wise multiple regression analyses, calcium, potassium and percentage water content were consistently important, whereas sodium and Polytrichum cover were only sometimes important. (4) The three largest principal components of the environmental data were related to the physical, chemical and biological-chemical characteristics of the habitat. Relationships between these components and the arthropod data were weak in the green moss zone, but were stronger in the dead moss zone. (5) Canonical correlation analysis showed that only sodium, potassium, calcium and phosphorus amongst the environmental variables contributed to the correlations, whereas all arthropod species were included. (6) A weak relationship between Polytrichum cover and the arthropods was suggested in the green moss zone, but this relationship was not found in the dead moss zone. (7) A study of the correlation coefficients suggested that there is an optimum water content for Cryptopygus and Eupodes and an optimum calcium concentration for Eupodes and Ereynetes. (8) Although some physical environmental variables affected the arthropod distribution in the green moss zone, overall it was the chemical characteristics of the environment which most influenced the distribution of the arthropods.

Soybean row-spacing: Effects on arthropod population patterns and sampling considerations

Two soybean field experiments were conducted during 1979 to investigate the effects of different row-spacing patterns (1.0 m vs 0.5 m, and 1.0 m vs broadcast) on population levels of selected herbivorous and beneficial arthropods. Sweepnet sampling was used in both experiments, and the ground-cloth shake method was also used in the 1.0-m vs 0.5-m study. Sweepnet results suggested that both herbivorous and beneficial arthropods tended to be more abundant in narrow row-spacings. However, there were exceptions among both groups, with some species (for example, bean leaf beetle) being more abundant in the conventional row-spacing in one experiment, and with several other species (for example, bigeyed bugs) showing no significant differences. Also, ground-cloth data for lepidopteran larvae showed trends opposite to those from sweepnet data in the 1,0-m vs 0.5-m experiment. Results clearly illustrate the importance of sampling methodology in the interpretation of soybean row-spacing research.

New Suction Device for Sampling Arthropod Populations

A new suction sampler was constructed by equipping an Echo Power Blower with a special venturi attachment. The venturi uses energy of the blower exhaust to create suction in separate piping, similar to a flowing water aspirator. The external piping was modified by adding a cannister to hold the collecting net. The mechanical characteristics of this unit were compared to a standard Model lA backpack “D-vac.” The Echo was superior to the D-vac in suction, lighter in weight, had a more comfortable center of gravity, produced much less vibration, and was quieter. Comparative sampling studies in alfalfa showed the Echo to be equal or significantly superior to the D-vac in capturing a diverse complex of arthropods. Detailed plans are presented for the construction of the Echo sampling machine. Total cost for the base unit and modifications required is ca. $350.00.

Arthropods from the canopy of inundated and terra firme forests near Manaus, Brazil, with critical considerations on the pyrethrum‐fogging technique*

Samples of arthropods in canopies of selected trees were collected by pyrethrum‐fogging during the early part of the 1977 dry season from three types of neotropical forest: varzea and igapo forest which are inundated seasonally by white‐water and black‐water rivers respectively, and terra firme forest which is not subject to inundation. Sampling areas were within 30 km of Manaus, Brazil. Number and biomass of arthropods sampled was highest in terra firme, intermediate in igapo and lowest in varzea. Ants were dominant on all sites and a high percentage of their species were found only in one type of forest. It is considered that many taxa are incompletely sampled with the fogging technique. Further statements on the canopy fauna of Central Amazonian forest types should be based on fogging data gathered from all seasons and compared with material sampled with other methods at the same time and locality.

Arthropods in no-tillage soybean agroecosystems: Community composition and ecosystem interactions

Sampling data are provided and concepts discussed regarding soil and foliage arthropod communities in conventional and no-tillage soybean agroecosystems Soil arthropod communities from the two cropping systems were also compared with that from an adjacent old field. Biweekly arthropod samples were collected from conventional, no-tillage, and old-field systems Soil arthropods were sampled by quadrat and pitfall trap methods, foliage arthropods were collected by sweep net Quadrat sampling revealed that ground beetle number, species diversity, and biomass were significantly higher (P<0.05) in no-tillage than in conventional tillage systems. Pitfall trap data indicated higher densities and species diversity for most major soil macro-arthropod guilds Foliage arthropod guilds from no-tillage treatments showed higher species diversity throughout the growing season than those of conventional tillage, possibly because of greater structural diversity provided by weeds and litter in notillage systems No-tillage systems supported a larger and more diverse arthropod community than conventionally grown soybeans, suggesting a need for pest management strategies that simultaneously consider many variables. Both foliar grazing and leaf nitrogen content were higher in conventional than in no-tillage systems, indicating a possible causal connection between soil tillage and insect herbivory rates

Three Methods for Sampling Arthropod Numbers on California Cotton

Three collection methods were compared as measures of pest and beneficial arthropod numbers in cotton: a visual examination of plants, a modified berlese-funnel method, and whole-plant collection in cloth bags. Numbers of arthropods collected by the three methods were compared, with developmental stages separated where possible. No significant differences in the numbers collected by the three methods were detected when arthropod populations were at low densities. No single method was most effective for estimating all life stages of two or more particular arthropod species. A combination of the bag and berlese-funnel methods provided a better estimate for some arthropod populations than the use of bags alone. Some of these methods are suitable for research purposes, but none are feasible for use by commercial pest control advisors.

Foraging Strategies, Diversity, and Seasonality in Bird Communities of Appalachian Spruce‐Fir Forests

Breeding bird communities in spruce—fir forests of the southern Appalachian mountains are considerably less diverse than those of similar northern forests. Censuses also show more widespread coexistence of congeneric and confamilial species in the north. Long—distance migrants dominate the northern forests while resident species dominate in the south. In a 4—yr study of these bird communities, I used observations of foraging strategies and resource partitioning to test hypotheses that might explain this probematic latitudinal gradient in species diversity. I conducted quantitative studies of foraging behavior of arboreal insectivorous birds at sites with very similar plant communities in the Great Smoky Mountains of North Carolina and in northwestern Maine. Six species that breed in both north and south had consistently more generalized foraging in the south, as measured by spatial distribution of foraging, variety of techniques used, directionality in probing and flights, and patchiness of habitat use. These north—south differences in foraging behavior result in part from greater behavioral diversity of each individual. Five exclusively northern species showed greater foraging generalization at the northern site than their sympatric congeners that breed in the south as well. The 11 species in the north occupied a smaller total foraging niche volume than the 6 species in the south. Each species overlapped more broadly with others in the north, and maximum overlap was greater. The southern avifauna is a nearly totally included subset of the northern. Northern diversity is produced by the addition of very similar (congeneric), widely overlapping generalists. This "stacking" of generalists differs considerably from tropical patterns of community diversification. Ecological, biogeographic, and evolutionary hypotheses explaining tropical diversity and island diversity are inadequate to account for the reversal of this latitudinal gradient and the species—packing characteristics of northern diversification. Populations in the depauperate south apparently released from competition with exclusively northern congeners did not show stronger generalization than populations of species that are the sole representatives of their families north and south, contrary to expectation. This is better explained by a common response, predicted by foraging optimization theory, to lower food levels in the south than by ecological release. Seasonal compression of productivity in northern spruce—fir forests, suggested by geophysical and climatological data, produces stronger pulses of food production than in the south, as shown by arthropod sampling. Compressed productivity and winter limitation of both northern residents and migrants probably produce higher food levels relative to consumer biomass in the north. Seasonal diversity is probably enhanced in northern forests by strong, predictable resource oscillations that are difficult for consumers to track Cyclic relaxation of limits to ecological similarity through seasonally abundant resources creates a higher diversity peak than under weaker seasonality. In the more seasonally constant south, residents are probably better able to track resources, and dominance by these groups is enhanced. Predictable seasonal peaks of production have probably promoted the evolution of opportunistic migrants and reduced their competition with winter—limited residents. I discuss this hypothesis in light of a theory proposing that variable conditions may often lead to greater diversity than more stable conditions. This study and others indicate the importance of seasonal species and temporal complexity in natural communities.

DEHP in the vicinity of an industrial area in Finland

Samples of fish, net plankton, freshwater and soil arthropods and soil obtained in the vicinity of an industrial area were analysed for di-(2-ethyl hexyl) phthalate (DEHP) content. The highest concentration was found in soil arthropods (2·8 mg/kg). No contamination was discovered in plankton, but the levels of contamination in other organisms were as follows: 0·1 mg/kg in small fish (fry and sticklebacks), freshwater arthropods, molluscs and perch ( Perca fluviatilis); 0·5 mg/kg in bream ( Abramis brama) and 1·1 mg/kg in roach ( Rutilus rutilus). The muscle and kidney of pike ( Esox lucius) were free from contamination but the contamination of pike's liver was equivalent to 2·3 mg/kg.

A Comparison of Vacuum and Whole-Plant Methods for Sampling Predaceous Arthropods on Cotton

A survey of predaceous arthropods in California cotton ( Gossypium hirsutum L.) fields was conducted over a 3-year period as part of an evolving pest management program. The primary objective of the survey was to develop an efficient method for sampling arthropods in relation to larval populations of the bollworm, Heliothis zea (Boddie). Samples were taken with a whole plant extraction method, and at 2 times of day and by 2 methods with the D-VAC® vacuum machine. Vacuum sample data were highly erratic. Data from whole plants had a high man-hours requirement. None of the methods tested is suitable for use in pest management programs. Data from whole plant samples were used to estimate seasonal occurrence of the more abundant predator species. These were the minute pirate bug, Orius tristicolor (White); big-eyed bugs, Geocoris spp. ( G. punctipes (Say) and G. pallens (Stal)); damsel bugs, Nabis spp. mainly americoferus Carayan; green lacewings, Chrysopa spp., mainly carnea Stephens; the notoxus beetle, Notoxus calcaratus Horn; and a complex of spiders. Estimates of their seasonal abundance are given on a per hectare basis. Comparisons were made between the numbers of each predaceous species and numbers of bollworms and cabbage loopers, Trichoplusia ni (Hubner). None of the predaceous species related numerically to bollworms, or to cabbage loopers, the only abundant lepidoptera pest species found in the study areas. The numbers of Geocoris appear to correlate with the abundance of cotton blossoms. The data suggest this species may be feeding principally either on the cotton plant and/or on insect(s) of minor economic importance whose availability as prey depends on the occurrence of a suitable substance in the cotton plant.