Sweep Net Sampling Research Articles

The genus Processa in the vicinity of Carrie Bow Cay (Belize) with description of a new species (Crustacea: Decapoda: Processidae)

Three species of the genus Processa are reported from shallow waters of Belize. Processa manningi, sp. nov., a newmember of the burrow-dwelling group, was most commonly found in burrows of the callianassid Neocallichirusgrandimana on a lower intertidal unvegetated sand flat. Both sexes of the new species, sometimes as mated pairs, wereobtained along with the host during sampling of burrows with yabby pumps. Processa bermudensis (Rankin) and Processafimbriata Manning & Chace occurred frequently in sweep net samples taken nocturnally in seagrass beds, but were alsotaken occasionally from interstices of eroded conch shells and other shallow rubble collected in daylight. Coloration is documented, and its utility as a character discussed. The genus has not been previously reported from Belize.

Effect of trap color and height on captures of blunt-nosed and sharp-nosed leafhoppers (Hemiptera: Cicadellidae) and non-target arthropods in cranberry bogs

A series of field experiments was conducted in cranberry bogs in 2006–2010 to determine adult attraction of the two most economically important leafhopper pests of cultivated Vaccinium spp. in the northeast USA, the blunt-nosed leafhopper, Limotettix vaccinii (Van Duzee), and the sharp-nosed leafhopper, Scaphytopius magdalensis (Provancher), to colored (yellow, green, red, blue, white, and clear) sticky traps. We also determined the effects of trap height on insect captures, evaluated trap color characteristics (i.e., reflectance spectra, and red, green, and blue RGB values) for maximizing leafhopper capture while minimizing beneficial arthropod capture, and correlated within-season adult leafhopper captures from traps with nymphal captures from sweep nets. Leafhopper species exhibited distinct preferences to particular colors differing in intensities along a spectrum of wavelengths and RGB values: green was the most attractive color to blunt-nosed leafhoppers, followed by red and yellow; while yellow was most attractive to sharp-nosed leafhoppers, followed by green and red. Attraction of leafhoppers to other colors was similar to clear. Most insect predators (e.g. lady beetles, hoverflies, and minute pirate bugs), parasitic wasps, and honey bees also exhibited preferences to particular trap color characteristics, whereas green lacewings and spiders did not. An effective attraction radius was calculated for each color of trap and species. Additionally, we measured mean ± SD of flight heights of several species and showed that more leafhoppers and hoverflies were captured on red and yellow traps placed 0.1 m above the canopy; while captures of lady beetles were highest on traps placed 0.5 m above the canopy. Numbers of adult leafhoppers on traps were largely uncorrelated with numbers of nymphs in sweep net samples, except for blunt-nosed leafhoppers captured on red traps which were positively correlated with sweep net counts. We discuss the potential of using colored sticky traps to monitor leafhopper populations in the context of their non-target species effects in cranberries.

Seasonal Abundance and Population Structure of Chinavia hilaris and Nezara viridula (Hemiptera: Pentatomidae) in Georgia Farmscapes Containing Corn, Cotton, Peanut, and Soybean

Abstract Stink bugs are economically important pests that damage a wide range of crops in the southeastern United States. Stink bug feeding on developing cotton (Gossypium hirsutum L. ) bolls may result in reduced yield and loss of fiber quality; similarly, feeding on developing soybean [Glycine max (L.) Merr.] pods can reduce yield and seed quality. During 2009 and 2010, the seasonal abundance and reproductive biology of Chinavia hilaris (Say) and Nezara viridula (L.) were investigated in replicated 1.62–2.83-ha farmscapes containing equal proportions of corn (Zea mays L.), cotton, peanut (Arachis hypogaea L.), and soybean. Crops were sampled weekly by using whole plant examinations in corn and sweep net sampling in cotton, peanut, and soybean. In 2010 only, adults were dissected to rate their reproductive development, and nymphs were classified to instar. No C. hilaris adults or nymphs ever were observed in corn; however, nymphs were observed in cotton and soybean during late September with peak abundance occurring just after the autumnal equinox. The peak of late-instar nymphs was followed within 2 wk by a peak of nonreproductive adults. More adults were observed in soybean than cotton. In contrast, N. viridula nymphs and adults were found across all crops and had multiple generations throughout the growing season. Results from this study indicate that C. hilaris and N. viridula are different in voltinism, phenology, and use of hosts. These data provide knowledge of stink bug biology and population ecology at the landscape level and are useful for designing and implementing stink bug management programs.

Gafanhotos (Orthoptera, Acridoidea) em áreas de cerrados e lavouras na Chapada dos Parecis, Estado de Mato Grosso, Brasil

Grasshoppers (Orthoptera, Acridoidea) in native savanna and crop areas in Chapada dos Parecis, Mato Grosso State, Brazil. We determined the composition and abundance of grasshoppers using sweep net sampling during three years at the Parecis Plateau, State of Mato Grosso, Brazil. The survey was done in areas with crops and native vegetation (savanna) with, respectively, 56 and 59 sites available in each environment. 3.031 individuals of grasshoppers were collected from 64 species distributed among the following families and subfamilies: Acrididae (49): Gomphocerinae (21), Ommatolampinae (10), Melanoplinae (6), Acridinae (4) Leptysminae (3), Copiocerinae (3), Proctolabinae (1) and Cyrtacanthacridinae (1); Romaleidae (1): Romaleinae (13) and Ommexechidae (1): Ommexechinae (2) and 1550 nymphs. The differences were significant between the number of species found in the savannas (61) and in cultived areas (16). However, the abundance of Acridoidea was significantly higher in crops than in savannas areas which was influenced mainly by two Acrididae's species: Baeacris punctulatus (Thunberg, 1824) and Orphulella punctata (De Geer, 1773) which accounted for 49.5% of the total individuals collected across the Parecis Plateau and, together, they account for 78.8% of recorded abundance in the cultived areas, both species being potential pests.

Variable host phenology does not pose a barrier to invasive weevils in a northern hardwood forest

1 A suite of invasive weevils has established in hardwood forests of the North American Great Lakes Region. We quantified patterns of host availability and the capacity of adults to succeed in a system with high host variability both within and between seasons in Michigan, U.S.A. 2 We quantified phenological development of foliage on three host species [sugar maple, Acer saccharum Marshall; ironwood, Ostrya virginiana (Mill.) K. Koch; and raspberry, Rubus spp.]. We estimated adult abundance using emergence traps and sweep net sampling over 3 years, and compared field host associations with laboratory choice assays. 3 Host plant phenology varied among species, between years, and in their interactions. The four most common weevils, Phyllobius oblongus (L.), Polydrusus sericeus (Schaller), Barypeithes pellucidus (Boheman) and Sciaphilus asperatus (Bonsdorff), emerged in early to mid-June, in approximately that order. After emergence, each species showed evidence of host preference based on their abundances on foliage. Overall, P. oblongus and B. pellucidus were most prevalent on sugar maple, P. sericeus was most prevalent on ironwood, and S. asperatus was relatively evenly distributed. Laboratory choice tests with P. oblongus and P. sericeus confirmed these preferences. 4 These four invasive species comprised over 99% of all 12 845 weevils obtained, suggesting displacement of native species. The optimal sampling methods varied among weevil species. 5 These invasive weevils contend with the highly variable conditions of their environment, and also potential phenological asynchrony, via relatively late emergence, even at the cost of lower host quality. Annual variation is greater for numbers of adults than larvae, suggesting that mortality of late instars or pupae is particularly important.

자운영답에서 알팔파바구미 유충 및 성충 조사방법

자운영포장에서 알팔파바구미 유충 및 성충의 조사방법에 따른 효율을 평가하기 위하여 본 실험을 수행하였다. 알팔파바구미 유충 밀도를 Shake-bucket, Shake-picking, Sweeping net 방법을 사용한 결과 조사지역 3곳에서 조사방법과 조사시기에 따라 유의하게 차이가 있었다. 포충망을 이용하여 유충밀도를 조사한 결과 4월초까지 유충을 조사할 수 없어 초기에 발생하는 유충을 조사하는데 적합하지 않았다. Shake-bucket과 Shake-picking을 이용한 조사에서 유충발생이 3월 중순부터 확인되었으며, 두 방법간에 차이는 없었다. 미끼를 넣은 Pitfall trap을 이용하여 알팔파바구미 성충 밀도를 조사한 결과 유인조건에 따라 유의하게 차이가 있었다(p<0.018). 각 처리간 성충 유인수를 조사한 결과 싹 틔운 강남콩 92마리, 강낭콩 종자 42마리, 트랩만 설치한 것에서 39마리로 싹 틔운 콩을 넣은 트랩에서 밀도유인 효과가 가장 좋았다. 자운영답에서 알팔파 바구미를 조사할 때 초기 발생하는 유충은 Shake-bucket법을 성충은 싹 틔운 강남콩을 미끼로 하는 pitfall trap을 이용하는 것이 좋다. This study was conducted to evaluate the scouting methods for larva and adults of the alfalfa weevil, <TEX>$Hypera$</TEX> <TEX>$postica$</TEX> Gyllenhal on Chinese milkvetch, <TEX>$Astragalus$</TEX> <TEX>$sinicus$</TEX> L. in the field. Three sampling methods, shake-bucket, shake-picking, and a sweeping net were evaluated for collecting alfalfa weevil larvae. We found significant differences among scouting methods and date in all survey fields. Sweep-net sampling was less able to detect small larvae than large larvae, which were not detected until early April whereas the shake-bucket, and shake-picking methods efficiently collected larvae from middle March. A Pitfall trap with three different baits - no bait, kidney bean seeds and sprouting kidney beans were compared for collection efficiency of alfalfa weevil adults. Collection efficiencies were significantly different by bait(p<0.018). Traps baited with sprouting kidney beans were the most efficient for collecting the alfalfa weevil. The number of alfalfa weevil caught was not significantly different between kidney bean seed and no bait in the pitfall trap. Therefore, the shake-bucket method for larvae and a pitfall trap baited with sprouting kidney beans for adults are recommended for scouting of the alfalfa weevil in a Chinese milkvetch field.

Grazing impacts on Auchenorrhyncha diversity and abundance on a Scottish upland estate

Abstract. 1. Livestock grazing impacts on insect populations in a variety of ways. For phytophagous insects the impact is primarily a result of altering the structure and species assemblage of vegetation. However not all species react in similar ways and even within an order there may be winners and losers from different grazing regimes.2. A long‐term, replicated, controlled experiment, comprising four grazing treatments, was established within an upland acid grassland area in Scotland. Auchenorrhyncha were sampled by suction sampling and sweep‐netting in the fifth year following the start of the treatments.3. A significant treatment effect was apparent in the suction samples with Auchenorrhyncha abundance being three to four times higher in the ungrazed plots compared to the other treatments. Abundance was also highest from the ungrazed plots in the sweep net samples, but this effect was not statistically significant. Redundancy analysis (RDA) showed that a suite of species which are typical of shaded positions responded with increased abundance in the ungrazed plots.4. The findings demonstrate that the assemblages found in ungrazed areas can be vastly different to those found in even lightly grazed areas and therefore, underline the benefits of varied grazing regimes in maximising diversity. Furthermore, the work underlines the benefit of employing multiple sampling methods.

Seasonal Abundance and Population Structure of Brown Stink Bug (Hemiptera: Pentatomidae) in Farmscapes Containing Corn, Cotton, Peanut, and Soybean

Abstract Stink bugs are economically important pests of food and fiber production throughout the southeastern United States. In cotton, stink bugs feed on developing bolls thereby decreasing yield and fiber quality. The brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae), is a common species that is found throughout the southeast and feeds on a variety of wild and agronomic hosts. In this study, the population dynamics and reproductive biology of E. servus were assessed in 1.62–2.83-ha farmscapes planted with corn (Zea mays L.), cotton (Gossypium hirsutum L.), peanut (Arachis hypogaea L.), and soybean [Glycine max (L.) Merr.]. Farmscapes were sampled weekly using whole plant sampling for corn and sweep net sampling in cotton, peanut, and soybean. In 2010, but not 2009, nymphs were classified by instar, and adults were dissected to rate gonads as nonrepro-ductive, intermediate, or reproductive. Regardless of year, stink bugs observed in corn during the spring and early summer and were a mixture of all three reproductive stages. The number of E. servus nymphs and adults was low in all crops during the summer (July, August, and early September). In late September, the number of fifth instars rose sharply followed by an increase in the number of nonreproductive adults, which implies that these adults resulted from reproduction as opposed to immigration. Incidence of late instars and nonreproductive adults was extremely low for corn, cotton, and peanut, and these host plants did not seem to be highly suitable reproductive hosts. Results from this study are useful for pest management programs that focus on reducing stink bug populations on a landscape scale.

Assessment of grasshopper abundance in cereal crops using pan traps

Grasshoppers and locusts frequently invade cereal crops from adjacent source habitats. The lack of a simple, reliable sampling method for grasshoppers in cereal crops has hindered both the study of grasshopper dispersal into crops and the evaluation of various management alternatives. Water-filled pan traps were tested as a means of assessing grasshopper abundance. In comparisons of species proportions in sweep net and pan trap samples in fallow fields, there was a good correlation between the two methods, but some differences were noted. In particular, proportions of Chorthippus curtipennis tended to be greater in sweep samples than in pan traps. As a demonstration of the potential of pan traps for study of spatiotemporal dynamics of grasshopper and locust invasion of crops, a grid of pan traps was placed within a field of barley. Geostatistical methods were used to produce maps of grasshopper abundance within the barley field on five occasions during the growing season. Overall, pan traps show promise as a means of studying grasshopper dispersal into field crops.

Seasonal Phenology and Monitoring of the Non-Native &lt;I&gt;Halyomorpha halys&lt;/I&gt; (Hemiptera: Pentatomidae) in Soybean

The introduction of an invasive species into an agroecosystem can alter both the interspecies dynamics and existing management practices. In the area of introduction, seasonality of Halyomorpha halys (Stål) in soybean fields was investigated by comparing monitoring efficiency of sweep net sampling and two sizes of pyramid traps baited with aggregation compound methyl (E,E,Z) 2,4,6-decatrienoate in 2006-2007. The large pyramid trap caught significantly higher densities of H. halys than the small pyramid trap and the sweep net samples each year. Adult males and females were detected in significantly higher densities in the large pyramid trap than other life stages. The pyramid traps caught H. halys adults and nymphs earlier than sweep net samples, during the R3 and R4 phenological stages of soybean growth. Peak abundances in the pyramid traps occurred during the R5-R6 stages, while the sweep samples were highest during the R6 stage. Soybean is sensitive to stink bug feeding damage from the R3-R6 stages. The occurrence of H. halys in soybean coincides with soybean's critical growth stage. H. halys has become the dominant stink bug species in the crop, indicating that damage thresholds need to be determined.

Aerial Insecticide Treatments for Management of Dectes Stem Borer,Dectes texanus, in Soybean

The Dectes stem borer, Dectes texanus LeConte (Coleoptera: Cerambycidae), is an increasingly important pest of soybean and sunflower in central North America. Nine large-scale field trials were conducted over a 3-year period to determine if Dectes stem borer could be managed with insecticide treatments. Aerial applications of lambda on July 6, 12 and 15 were successful in significantly reducing adults, but applications on July 1, 20 and 24 were less successful. These data suggest that for central Kansas two aerial applications may be required to control Dectes stem borers in soybean. Based on our experience the first application should be made at the peak of adult flight about July 5th and the second application 10 days later. The local treatment schedule should be developed to follow the local Dectes stem borer adult emergence pattern. Treated aerial strips 59 m (195 ft) wide were not large enough to prevent reinfestation, but treated half-circles (24 ha or 60 acres) were successful in reducing in Dectes stem borer infestation of soybean. Sweep net samples of adults were not successful in identifying a treatment threshold, so treatment decisions will need to be based on field history of infestation. Further studies are needed to identify better sampling methods that can be used to establish treatment thresholds and to refine the best timing for treatments.

Comparison of two methods for sampling invertebrates: vacuum and sweep-net sampling

ABSTRACT With numerous invertebrate sampling techniques available, deciding which technique to use under certain circumstances may be difficult. Many researchers interested in invertebrate abundance and availability relative to the foraging ecology of birds may use a technique (e.g., vacuum sampling or sweep-netting) without understanding the impacts their choice may have on the samples collected and the ability of the method to meet research objectives. We compared the characteristics, including overall biomass, morphospecies richness, average size, diversity, and body length categories, of invertebrates collected using a sweep-net and a Dietrick vacuum sampler along paired transects in Woodward County, Oklahoma, from May to July 2007 and 2008. These sampling techniques differed in the taxa collected, with the orders Diptera, Homoptera, and Hymenoptera dominating vacuum samples and the orders Homoptera, Orthoptera, and Araneae dominating sweep-net samples. Although morphospecies richness was similar for the two techniques, the mean size of invertebrates collected and overall invertebrate biomass were greater for sweep-netting than vacuum sampling. Vacuum sampling was more effective at collecting small (e.g., 5 cm) Orthopteran and Lepidopteran larvae at higher rates. Thus, our results indicate that neither sampling method effectively sampled all invertebrate families and investigators should be aware of the potential biases of different sampling techniques and be certain that the technique selected will allow study objectives to be met.

VERY HIGH POPULATION ESTIMATES AND LIMITED MOVEMENT OF SNAIL-KILLING FLIES (DIPTERA: SCIOMYZIDAE) ON AN IRISH TURLOUGH (TEMPORARY LAKE)

Sciomyzid flies (Diptera) have potential as biological control agents of intermediate hosts of snail-borne trematode diseases and as bioindicators of habitat condition and quality (particularly hydrology and vegetation structure). Standard area sweep net sampling of these flies in a single vegetation zone across ten turloughs in summer 2004 highlighted the importance of vegetation structure (standing height and outstretched length) on the abundance and species richness of Sciomyzidae. A mark-recapture study was initiated in the summer of 2005 with the aim of quantifying absolute populations at one site where sciomyzid abundance was particularly high (Cregaclare South, Co. Galway). The total abundance of Sciomyzidae at the site was estimated at 3512 flies over an area of 600 square metres. This density (6.08 flies per square metre) is consider ably higher than densities previously reported in two studies of a sciomyzid species in the USA, but is in line with estimates from the 2004 wider study. Specific markings were used in the 2005 mark-recapture study to monitor any adult fly movements within the habitat. Females in two out of the three univoltine species showed a positive correlation in the proportion of gravid individ uals caught over time. Multivoltine species showed no such relationship. Additionally, multivariate procedures were used to investigate the effect of date of sampling and spatial position on sciomyzid assemblage composition.

Evaluation of microcrustacean (Cladocera, Chydoridae) biodiversity based on sweep net and surface sediment samples

Biodiversity (species richness and species diversity) of chydorid Cladocera were examined by weekly sweep net sampling during the ice-free period and through surface sediment assemblages in 9 limnologically different lakes in southern Finland. Species richness in the sweep net samples was low in 2 lakes with recent ecological perturbations and the highest in one oligotrophic lake. Species diversity was the lowest in 2 eutrophicated lakes and generally higher in the oligotrophic lakes. The biodiversity values in sediment assemblages showed trends similar to those in the sweep net samples; the lowest values were observed in one of the eutrophic lakes and the highest in the oligotrophic lakes. It is likely that the observed differences were due to the impact of nutrients on the development of littoral vegetation and consequently chydorid habitats and resources. The role of nutrients as a forcing mechanism on chydorid biodiversity was indicated by high and significant negative correlations between species diversity in both total phosphorus and sweep net and sediment samples. The comparison between biodiversity in the 2 sample types showed that the biodiversity values were almost consistently higher in the surface sediment assemblages than in the sweep net samples, suggesting that surface sediment analysis provides an effective alternative method to living material examination for biodiversity evaluations.

Response of Terrestrial Invertebrates to High‐ and Low‐Diversity Grassland Restorations in South‐Central Nebraska

Successful grassland restorations are influenced by the diversity of seed mixes initially sowed in the restoration. Two common seed mixes used in grassland restorations are high‐ and low‐diversity mixes. The type of seed mixture used in restorations may affect invertebrate diversity and abundances that occur in restorations. We compared terrestrial invertebrate diversity and abundances between high‐ and low‐diversity restorations in south‐central Nebraska. Pitfall trap and sweep net sampling were used to assess invertebrate communities from six low‐ and six high‐diversity plantings. Our results did not clearly demonstrate that terrestrial invertebrate assemblages respond better to high‐diversity plantings than low‐diversity plantings. There was no difference in total abundance, family richness, or diversity of invertebrates between the plantings. Composition of invertebrate communities was similar between plantings. Araneae and Acrididae were the only major taxa that differed in abundances between plantings. Similarity of invertebrate communities in plantings is likely attributed to lack of plant architectural complexity, absence of host‐plants, and time‐lag effects in high‐diversity plantings. Because recovery time of high‐diversity plantings lagged considerably behind low‐diversity plantings, invertebrate communities in high‐diversity plantings were likely to be in early stages of development, but will likely become more diverse and abundant as the planting matures. Consequently, our results emphasize the need for long‐term monitoring of invertebrate and plant communities in grassland restorations. Additionally, discrepancies in types and abundances of captured invertebrates between pitfall trapping and sweep netting emphasizes the need to use more than one sampling method when using invertebrates to monitor and assess restoration success.

Status of non-indigenous benthic invertebrates in the Duluth–Superior Harbor and the role of sampling methods in their detection

As part of a study to develop recommendations for non-indigenous species (NIS) monitoring in Great Lakes areas at risk of invasion, we conducted intensive sampling in the Duluth–Superior Harbor and lower St. Louis River in 2005 and 2006. Of the ~240 benthic invertebrate taxa identified, 19 were non-indigenous, including 8 first detection records for this system: New Zealand mud snail Potamopyrgus antipodarum; African/Asian-origin cladoceran Daphnia lumholtzi; Eurasian-origin amphipod Echinogammarus ischnus; Eurasian-origin bivalves Dreissena bugensis, Pisidium henslowanum and Pisidium supinum; and possibly range expanding oligochaetes Paranais frici and Pristina acuminata. Dreissenids were by far the most abundant NIS. Several other NIS were also common, but others were detected in only a few of the >200 samples taken. Non-indigenous amphipods and Dreissena were most frequently detected in sweep net and colonization plate samples of littoral vegetation, while NIS oligochaetes, gastropods, and non-dreissenid bivalves were most frequently detected in ponar and bottom sled samples of sediments. Our findings confirm that this major shipping port remains a NIS “hotspot” and emphasize that regular surveys covering a range of habitats with multiple sampling gears and thorough taxonomic effort are needed to detect and monitor non-indigenous species.

Disturbance, species loss and compensation: Wildfire and grazing effects on the avian community and its food supply in the Serengeti Ecosystem, Tanzania

AbstractAn important question in biodiversity studies is whether disturbances in ecosystems will cause a net loss of species or whether such losses can be compensated by replacement of other species. We use two natural disturbances, fire and grazing, to examine the response of bird and arthropod communities in grasslands of Serengeti, Tanzania. Both burning and grazing by migrant ungulates take place at the end of the rains in June–July. We documented the communities before disturbance, then 1, 4 and 20 weeks after disturbance on three replicate plots and compared them with three undisturbed plots. Birds were recorded by observation, arthropods from pitfall, tray trap and sweepnet samples. We expected that as the grass biomass was reduced by either disturbance, bird communities would change with concomitant change in arthropod food abundance. Alternatively, bird communities would change not with the absolute amount of food but with the greater accessibility of food as the grass structure changed from long to short grass. Results showed first that both bird species richness and abundance increased after both types of disturbance, but burnt sites showed a greater increase than that for grazed sites. Second, there was a change in bird species composition with disturbance. The functionally equivalent athi short‐toed lark (Calandrella athensis) was replaced by the red‐capped lark (Calandrella cinerea). Third, the abundance of most groups of arthropods was lower on disturbed sites than those on undisturbed sites, and the reduction of arthropod numbers was greatest on burnt sites. These results imply that bird abundance did not occur through an increase in arthropod abundance but rather through a change in the grass structure making food more accessible; and the higher predation could have caused the lower arthropod abundance. In addition, some bird species replaced others thus functionally compensating for their loss.

Utilization of Early Soybeans for Food and Reproduction by the Tarnished Plant Bug (Hemiptera: Miridae) in the Delta of Mississippi

Commercially produced maturity group (MG) IV soybeans, Glycine max L., were sampled during bloom for tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), during May and June 1999 (3 fields) and 2001 (18 fields). The adults and nymphs were found primarily in single population peaks in both years, indicating a single new generation was produced during each year. The peak mean numbers of nymphs were 0.61 and 0.84 per drop cloth sample in 1999 and 2001, respectively. Adults peaked at 3.96 (1999) and 3.76 (2001) per sweep net sample (25 sweeps). Tests using laboratory-reared and field-collected tarnished plant bugs resulted in very poor survival of nymphs on 16 different soybean varieties (MG III, one; IV, four; V, nine; VI, two). A large cage (0.06 ha) field test found that the number of nymphs produced on eight soybean varieties after mated adults were released into the cages was lower than could be expected on a suitable host. These results indicated that soybean was a marginal host for tarnished plant bugs. However, the numbers of adults and nymphs found in the commercially produced fields sampled in the study may have been high enough to cause feeding damage to the flowering soybeans. The nature of the damage and its possible economic importance were not determined. Reproduction of tarnished plant bugs in the commercially produced early soybean fields showed that the early soybeans provided tarnished plant bugs with a very abundant host at a time when only wild hosts were previously available.

Does Bird Predation Enhance the Impact of Green Muscle® (Metarhizium acridum) used for Grasshopper Control?*

A study at Khelcom, Central Senegal, from September 2008 till June 2009 tested two different dose rates (25 and 50 g conidia/ha) of the mycoinsecticide Green Muscle® (Metarhizium acridum) and an untreated control, against grasshoppers in a field trial on nine 400-ha plots in three blocks. The study area was a deforested sylvo-pastoral reserve, 12.5% cultivated, whereas the remainder was fallow or grassland in succession. Grasshopper densities were calculated by executing transect and quadrat counts on plots. The grasshopper community structure was assessed by systematic sweep-net sampling on plots. From these data grasshopper biomass on plots was calculated for each sampling date. Bird numbers were counted on the same transects by the Distance Sampling technique and their densities calculated from Effective Strip Widths (ESW). Energetic requirements of individual bird species were calculated from digestibility-corrected Field Metabolic Rates (FMRs) and for acridivorous species their daily intake of grasshoppers was calculated. Grasshopper densities were very high, with up to 90 ind./m2 in September and 30–35 ind./m2 in October. Numbers and biomass decreased on treated plots as grasshoppers became infected, and remained significantly different from control plots for three months (until January). The relative importance of grasshopper consumption by birds increased between October (high grasshopper densities) and December (medium densities) from an initial 0.06 (±0.03) %/day to a ceiling of 1.6 (±0.9)% per day. Total grasshopper removal during the dry season was 70 %, whereas during the rainy season this was < 1%. Birds specifically captured large and medium-bodied grasshoppers, but rarely small-bodied species, whose numbers initially increased. These findings were corroborated by field observations and by analysis of regurgitated pellet contents of Montagu's Harriers, i.e., small-bodied grasshoppers were only 1.4 – 2.6% of all grasshoppers taken, whereas they constituted 61 – 68% of random samples from the field. Densities of acridivorous Palaearctic migratory birds, in particular White Stork, Ciconia ciconia, Montagu's Harrier, Circus pygargus and Lesser Kestrel, Falco naumanni, were very high and unprecedented elsewhere. Their numbers largely exceeded the 1% criterion for international importance.

Sweep Sampling Capture Rates for Rangeland Grasshoppers (Orthoptera: Acrididae) Vary During Morning Hours

Abstract Rangeland grasshoppers have long been considered pests of serious economic importance and are key components of grassland food webs. Sampling protocols inform decisions to control grasshoppers. Preliminary observations while sampling rangeland grasshoppers indicated differences in species diversity and numbers captured, depending upon time of day. To test these differences, we used USDA-APHIS sweep-net sampling protocols at various times at four rangeland sites during 2006–2007 and compared mean numbers collected. Sweep sampling every hour from 06: 00 to 12:00 revealed that adult and nymphal grasshopper numbers were significantly higher at 06:00 than either 07:00 or 08:00. Captures were similar throughout the afternoon. These patterns were also observed for adults of the most common species, Melanoplus femurrubrum (DeGeer). The results of this study have important implications for rangeland pest management decisions and ecological studies that estimate insect biomass as an indicator of food avail...