Oviposition and development of the tarnished plant bug (Heteroptera: Miridae) on field maize

Reduced insecticide use in cotton, Gossypium hirsutum L., as a consequence of the Boll Weevil Eradication Program and the broad adoption of Bt cotton, have helped make the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), a consistent pest of cotton each year in the mid-south. Maize, Zea mays L., has been implicated as having a role in the season-long dynamics of tarnished plant bug infestations in cotton. To date, no published information exists describing the quality of maize as a host for tarnished plant bug. No-choice field studies indicated that adult tarnished plant bug females oviposited into maize leaves, tassels, and ears. Laboratory studies showed that first-instar tarnished plant bugs could successfully develop to the adult stage when fed maize silks at the R1 growth stage, tassels before (VT) and during (R1) pollen shed, and milk stage (R3) kernels from the tip and base of the ear. The proportion of nymphs surviving to the adult stage on these tissues was often similar to that of broccoli, Brassica oleracea L. Nymphs did not develop to adults when fed V5 or R1 maize leaves. However, survival of first instars to the adult stage was improved when nymphs fed on tassels with pollen for 6 d and then moved to silks or leaves. Another field study showed that tarnished plant bugs reproduced in maize mainly during the tassel (VE and VT) and the R1-R3 ear growth stages, and a single new generation was produced in maize during these stages. The highest population recorded during the study (24 June 2005) consisted mostly of nymphs and was estimated to be 29,600/ha (12,000/acre). These studies showed that maize is a suitable host for tarnished plant bug reproduction and development, and its production plays a significant role in the population dynamics of the tarnished plant bug in the mid-south.     

Among-sampler variation in sweep net samples of adult Lygus hesperus (Hemiptera: Miridae) in cotton

The sweep net is a standard sampling method for adults of the western tarnished plant bug, Lygus hesperus Knight (Hemiptera: Miridae), in cotton (Gossypium spp.). However, factors that influence the relationship between true population levels and population estimates obtained using the sweep net are poorly documented. Improved understanding of these factors is needed for the development and application of refined treatment thresholds. Recent reports of significant among-sampler differences in sweep net-based population estimates of the adult tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), seem to preclude meaningful comparisons of population estimates collected by different samplers. We used a mark-release-recapture method and the standard sweep net to evaluate among-sampler differences in population estimates of L. hesperus adults. Adult lygus, marked with fingernail polish to facilitate identification and prevent flight, were released into 10-m sample rows on the evening before 10-sweep samples were collected the following morning. The experimental design was a randomized complete block with three replications of three treatments (sampler). Separate experiments were conducted in two plantings each of Pima (Gossypium barbadense L.) and Acala (Gossypium hirsutum L.) cotton. Collections of marked bugs from each study were evaluated for effects of sampler, sample date, and their interaction. Although differences in lygus collections were observed among sample dates in some tests, no differences were detected in the population estimates by different samplers. These results demonstrate that the sweep net technique can be sufficiently standardized to allow direct comparison of population estimates obtained by different samplers.     

Sampling strategies for square and boll-feeding plant bugs (Hemiptera: Miridae) occurring on cotton

Sampling methods for square and boll-feeding plant bugs (Hemiptera: Miridae) occurring on cotton, Gossypium hirsutum L., were compared with the intent to assess if one approach was viable for two species occurring from early-season squaring to late bloom in 25 fields located along the coastal cotton growing region of south Texas. Cotton fleaphopper, Pseudatomoscelis seriatus (Reuter), damages squares early-season and dominated collections using five sampling methods (approximately 99% of insects collected). A major species composition shift occurred beginning at peak bloom in coastal fields, when verde plant bug, Creontiades signatus Distant, represented 55-65% of collections. Significantly more cotton fleahoppers were captured by experienced samplers with the beat bucket and sweep net than with the other methods (30-100% more). There were more than twice as many verde plant bugs captured by experienced and inexperienced samplers with the beat bucket and sweep net than captured with the KISS and visual methods. Using a beat bucket or sweep net reduced sampling time compared with the visual method for the experienced samplers. For both species, comparing regressions of beat bucket-based counts to counts from the traditional visual method across nine cultivar and water regime combinations resulted in only one combination differing from the rest, suggesting broad applicability and ability to translate established visual-based economic thresholds to beat bucket-based thresholds. In a first look at sample size considerations, 40 plants (four 10-plant samples) per field site was no more variable than variation associated with larger sample sizes. Overall, the beat bucket is much more effective in sampling for cotton fleahopper and verde plant bug than the traditional visual method, it is more suited to cotton fleahopper sampling early-season when plants are small, it transitions well to sample for verde plant bug during bloom, and it performs well under a variety of soil moisture conditions and cultivar selections.     

Circadian activity of Lygus lineolaris (Hemiptera: Miridae) and effectiveness of sampling techniques in strawberry fields

Mobility and distribution of adult tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), was studied on a day-neutral strawberry cultivar ('Selva') in 1991 and 1992 at L'Acadie, Quebec, Canada. On cage-covered plants, individuals were located mainly on reproductive parts. Study of the flight activity with sticky posts revealed that most captures were obtained < 1 m from ground level and that the time of the day at which the maximum counts occur varied among seasons. Three pest-sampling methods (white sticky trap, tapping of flower clusters, and D-Vac) were evaluated over continuous 24-h periods. Maximum captures of adults with white sticky traps were made at midday (1000-1400 hours), whereas the two other methods proved more effective at the beginning (0600-0800 hours) or the end of the day (2000-2200 hours) or during night time. For nymphs, maximum catches were obtained during the day with tapping and D-Vac; white sticky traps were ineffective. Because the D-Vac captures individuals present on all parts of the plant, these counts were used to monitor the effectiveness of the two other sampling techniques. The data suggest that tapping flower clusters throughout the day is a very effective sampling method to estimate nymphal tarnished plant bug populations in strawberries. However, sampling of populations with a high proportion of adults should take into account the bias caused by their flight activity, and sampling should be conducted early in the morning or at the end of the day.     

Impact of Nosema (Microsporidia) infection and fumagillin treatment on Lygus lineolaris (Hemiptera: Miridae)

A consistent supply of healthy tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), is necessary for the development of novel management strategies targeting this pest. After being in culture for several years, a substantial portion of a tarnished plant bug colony was found to be infected with a Nosema (Microsporidia) species. Studies were subsequently undertaken to evaluate the impact of Nosema infection on tarnished plant bug productivity and to test the efficacy of fumagillin to treat this infection. Using buffalo black stain, infections could not be reliably detected in adult tarnished plant bugs until adults were 6-8days post eclosion. Nosema infections reduced adult longevity and fecundity. Maximum fecundity was restored using a concentration of 16.8ppm fumagillin while maximum longevity for females was at a concentration of 33.6ppm fumagillin incorporated into the tarnished plant bug diet. Minimum infection scores were obtained at 67.2ppm, the highest concentration tested. A field survey of tarnished plant bugs in Mississippi found Nosema infections in 3% of wild tarnished plant bugs.     

Identification of Lygus hesperus by DNA barcoding reveals insignificant levels of genetic structure among distant and habitat diverse populations

Background

The western tarnished plant bug Lygus hesperus is an economically important pest that belongs to a complex of morphologically similar species that makes identification problematic. The present study provides evidence for the use of DNA barcodes from populations of L. hesperus from the western United States of America for accurate identification.

Methodology/Principal Findings

This study reports DNA barcodes for 134 individuals of the western tarnished plant bug from alfalfa and strawberry agricultural fields in the western United States of America. Sequence divergence estimates of <3% reveal that morphologically variable individuals presumed to be L. hesperus were accurately identified. Paired estimates of F_st and subsequent estimates of gene flow show that geographically distinct populations of L. hesperus are genetically similar. Therefore, our results support and reinforce the relatively recent (<100 years) migration of the western tarnished plant bug into agricultural habitats across the western United States.

Conclusions/Significance

This study reveals that despite wide host plant usage and phenotypically plastic morphological traits, the commonly recognized western tarnished plant bug belongs to a single species, Lygus hesperus. In addition, no significant genetic structure was found for the geographically diverse populations of western tarnished plant bug used in this study.     

棉田绿盲蝽种群密度的调查方法

本文比较研究了棉田绿盲蝽Apolygus lucorum(Meyer-Dür)种群的调查方法。全株调查法中,目测法调查到的绿盲蝽种群密度最高,显著高于扫网法和盆拍法。局部调查法发现,蕾上的绿盲蝽种群数量显著高于叶片和花上;蕾上种群数量与整株密度之间呈显著正相关关系(y=1.18 x+3.69)。间接调查法表明:在苗期和蕾期,叶片受害等级和绿盲蝽种群密度之间呈显著正相关关系(苗期:y=25.28 x+8.20;蕾期:y=43.99 x+27.58)。     

Impact of reflective mulch on yield of strawberry plants and incidence of damage by tarnished plant bug (Heteroptera: Miridae).

The current study investigated the impact of reflective mulch on yield of strawberry plants and incidence of damage by tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), for three strawberry cultivars: 'Honeoye', 'Earliglow', and two sibling Dayneutrals ('Tribute' and 'Tristar', herein considered as one cultivar). Of all cultivars tested, Honeoye was the most productive and least susceptible to tarnished plant bug. For Earliglow and Honeoye, reflective mulch enhanced productivity of strawberry plants and suppressed density of nymphs per flower cluster and proportion of damaged fruits, but did not significantly impact numbers of nymphs or damaged fruits per hectare, Results with Dayneutrals were not consistently significant. Both in the presence or absence of reflective mulch, proportion of damaged fruits increased with increasing density of nymphs per flower cluster and with decreasing number of fruits harvested per row section, suggesting that planting productive strawberry cultivars or maintaining cultural practices that promote high yield may provide an effective line of defense against tarnished plant bug. These results also suggest that reflective mulch may suppress incidence of damage by tarnished plant bug both directly, by reducing number of nymphs per flower cluster, and indirectly, by enhancing productivity of strawberry plants. Economic analyses evaluating costs and benefits of using reflective mulch, as well as studies investigating mechanisms that underlie the impact of reflective mulch on yield and incidence of damage by tarnished plant bug, are still needed before reflective mulch can be implemented as a management strategy in commercial strawberry fields.     

Cotton boll age influences feeding preference by brown stink bug (Heteroptera: Pentatomidae)

Cotton plants were infested with brown stink bug, Euschistus servus (Say), to define cotton boll age classes (based on heat unit accumulation beyond anthesis) that are most frequently injured during each of the initial 5 wk of flowering. Bolls from each week were grouped into discrete age classes and evaluated for the presence of stink bug injury. Brown stink bug injured significantly more bolls of age class B (approximately 165-336 heat units), age class C (approximately 330-504 heat units), and age class D (approximately 495-672 heat units) during the initial 3 wk in both years and in week 5 in 2002 compared with other boll ages. Generally, the frequency of injured bolls was lowest in age class A (< or = 168 heat units) during these periods. The preference by brown stink bug for boll age classes B, C, and D within a week was similar when ages were combined across all 5 wk. Based on these data, bolls that have accumulated 165.2 through 672 heat units beyond anthesis (approximately 7-27-d-old) are more frequently injured by brown stink bug when a range of boll ages are available. The boll ages in our studies corresponded to a boll diameter of 1.161-3.586 cm with a mid-range of 2.375 cm. A general protocol for initiating treatments against stink bugs is to sample bolls for evidence of injury as an indicator of presence of infestations in cotton. Sampling bolls within a defined range, which is most likely to be injured, should improve the precision of this method in detecting economic stink bug infestations in cotton.     

Alfalfa weevil (Coleoptera: Curculionidae) larval sampling: comparison of shake-bucket and sweep-net methods and effect of training

Two field-sampling methods, shake-bucket and sweep-net, were compared for use in monitoring alfalfa weevil, Hypera postica (Gyllenhal), larvae in alfalfa hay of the high plains and intermountain region of North America. In this region, alfalfa grows to sufficient height to use both methods before the more damaging late instars peak in abundance. Both methods also were compared with extracting larvae by using Berlese funnels in the laboratory. The shake-bucket method was more sensitive in detecting small larvae (first and second instars) than large larvae (third and fourth instars), and the sweep-net method detected a lower proportion of small larvae. The number of larvae collected with the shake-bucket method was strongly correlated with number of larvae recovered from Berlese funnels (total larval counts, R2 = 0.85). Correlation of the sweep-net samples with the Berlese extraction was also significant but less strong (R2 = 0.56). In addition, sampler instruction was evaluated to determine whether demonstration training affects performance of inexperienced samplers using the two field-sampling methods. Training did not significantly change sampler performance in using the shake-bucket but did increase the number of large larvae when using the sweep-net. In addition, less variability was associated with the shake-bucket sampling method than with the sweep-net method for samplers who only had access to written sampling instructions. Therefore, when estimation of small larval abundance is desired for economic decision-making and sampling is performed by people with little or infrequent sampling experience, such as growers, the shake-bucket method is the preferred field-sampling method in the high plains and intermountain region of North America Sweep-net sampling is more variable than shake-bucket sampling, although demonstration training improves the usefulness of the sweep-net.     

Control of western tarnished plant bug Lygus hesperus Knight (Hemiptera: Miridae) in California organic strawberries using alfalfa trap crops and tractor-mounted vacuums

A key economic pest of strawberries in California is the western tarnished plant bug, Lygus hesperus Knight (Hemiptera:Miridae). Alfalfa (Medicago sativa L.) is a highly attractive plant host to western tarnished plant bug, and we hypothesized that it can be successfully managed as a trap crop for pest suppression in strawberries. Completely randomized design trap cropping experiments were established on an organic strawberry farm from 2002 to 2004. Western tarnished plant bug adults and nymphs were significantly more abundant in alfalfa trap crops than in comparable edge strawberry rows. Over 3 experimental yr, twice-weekly summer vacuuming of alfalfa trap crops with a tractor-mounted vacuuming device reduced adult and nymph abundance by 72 and 90%, respectively, in trap crops. This summer vacuuming of alfalfa trap crops also significantly reduced damage caused by western tarnished plant bug in associated unvacuumed organic strawberries (June and July 2002, June 2003, and June and July 2004) compared with either an untreated control (2003) or the organic strawberry grower's standard whole field vacuuming treatment. Vacuuming of alfalfa trap crops reduces an organic grower's costs (tractor, tractor fuel, and driver time) by 78% compared with current whole field vacuuming practices. An economic analysis of a whole hectare model indicates that a positive return from the use of vacuumed trap crops could be realized in 2004. The overall potential positive net return for the 3 mo of vacuumed alfalfa trap crop treatments in 2004 was calculated at +$1,829/ha.     

新疆棉区主要害虫的演替及其机理分析

阐述了新疆棉区主要害虫的演替及其机理。1950～1960年主要害虫为黄地老虎、牧草盲蝽象、烟蓟马、苜蓿蚜为主;1970～1980年以棉铃虫、烟蓟马、棉长管蚜、棉红蜘蛛为主;从1990年开始以棉铃虫、棉蚜、棉红蜘蛛为主。导致这一演替的主要原因为作物布局、耕作制度、栽培方法、管理技术的变化和农药化肥的过量施用。     

Efficiency of volatile baited sticky traps for the Tarnished Plant Bug (Lygus lineolaris) in strawberry fields

Insecticides have adverse effects on human health and the environment. Thus, the development of non-chemical replacement to manage insect pests is urgent. An alternative is to bait sticky traps with attractive insect sex pheromones or plant volatiles. In Quebec, the tarnished plant bug (Lygus lineolaris) is a major insect pest. We tested the efficiency of sex pheromones (mixture of hexyl butyrate (HB), (E)-2-hexenyl butyrate (E2HB) and (E)-4-oxo-2-hexenal (KA)) and sunflower (Helianthus annuus) volatiles (pinene, sabinene and phenylacetaldehyde) as sticky trap baits for the tarnished plant bug in strawberry fields of the Laurentians in Southern Québec, Canada. The pheromones decreased the number of tarnished plant bug caught in the traps compared to a control. The sunflower volatile did not have any effect on the number of individuals caught in the traps. Different Lygus species use HB, E2HB and KA in different ratios for sexual signals and alarm signals and for species recognition. GC-MS analysis of the sex pheromone bait revealed that the ratios between the three main compounds did not match the intended ratio for the L. lineolaris species. This mismatch probably explains our results. Individuals were not attracted to sunflower volatiles. Our results point to the difficulty of manufacturing and using sex pheromones as baits. Future work should assess the effect of several pheromone ratios.     

A GIS-based approach for areawide pest management: the scales of Lygus hesperus movements to cotton from alfalfa, weeds, and cotton

Understanding the effect of cropping patterns on population dynamics, dispersal, and habitat selection of insect pests has been an unresolved challenge. Here, we studied the western tarnished plant bug, Lygus hesperus (Knight) (Heteroptera: Miridae), in cotton during early summer in central Arizona. We used a general approach based on global positioning system (GPS) and geographic information system (GIS) technologies combined with spatial statistics to assess the maximum distance at which forage and seed alfalfa, fallow fields with weeds, and cotton affect L. hesperus population density. Using a set of 50 cotton fields as focal fields, we found that forage and seed alfalfa as well as weeds acted as L. hesperus sources for these cotton fields. The source effect did not extend beyond 375, 500, and 1500 m for forage alfalfa, weeds, and seed alfalfa, respectively. Conversely, cotton fields acted as L. hesperus sinks, but this effect did not extend further than 750 m from the focal cotton fields. These findings suggest that specific spatial arrangements of these field types could reduce L. hesperus damage to cotton. The spatially explicit approach used here provides a direct evaluation of the effects of agroecosystem heterogeneity on pest population dynamics, dispersal, and habitat selection, which is a significant asset for the development and improvement of areawide pest management.     

Changes in abundance of native and introduced parasites (Hymenoptera: Braconidae), and of the target and non-target plant bug species (Hemiptera: Miridae), during two classical biological control programs in alfalfa.

High numbers of tarnished plant bugs [Lygus lineolaris (Palisot)], were once common in alfalfa, as was a low level of parasitism (9%) by the native Peristenus pallipes (Curtis). After the bivoltine European parasite Peristenus digoneutis Loan became well established, average parasitism of the first and second generations increased to 64%, and tarnished plant bug numbers dropped by 65%. This reduced host density eventually caused a decline in total parasitism by both parasite species to 22%. A few P. digoneutis also attacked the alfalfa plant bug, Adelphocoris lineolatus (Goeze), but did not reduce this pest or increase its parasitism rate. At another location, where P. digoneutis is not established, parasitism of first generation alfalfa plant bugs, an adventive (accidently introduced) pest, was increased to 21% by the introduced univoltine parasite, Peristenus conradi Marsh, and a slight reduction in the pest may have resulted. P. digoneutis did not parasitize the meadow plant bug, Leptopterna dolabrata (L.), an adventive pest of forage grasses, so did not affect this mirid or its parasite. Neither introduced parasite eliminated the native parasites of the tarnished or alfalfa plant bugs. The narrow host ranges of the braconid parasites of mirid nymphs are contrasted with the broad host range of the native tachinid parasite [Phasia robertsoni (Towns.)] of adult mirids. The major changes in mirid abundance and their mortality by parasites that slowly occurred during this 19-year study demonstrate the need for long-term field research, to adequately document and understand these complex interactions.     

Enhanced esterase gene expression and activity in a malathion-resistant strain of the tarnished plant bug, Lygus lineolaris

Extensive use of insecticides on cotton in the mid-South has prompted resistance development in the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). A field population of tarnished plant bugs in Mississippi with 11-fold higher resistance to malathion was used to examine how gene regulation conferred resistance to this organophosphate insecticide. In laboratory bioassays, synergism by the esterase inhibitors S,S,S,-tributylphosphorotrithioate (DEF) and triphenylphosphate (TPP) effectively abolished resistance and increased malathion toxicity by more than 80%. Esterase activities were compared in vitro between malathion susceptible and resistant (selected) strains. More than 6-, 3- and 10-fold higher activities were obtained with the resistant strain using alpha-naphthyl acetate, beta-naphthyl acetate, and p-nitrophenyl acetate, respectively. Up to 95% and 89% of the esterase activity in the susceptible and resistant strains, respectively, was inhibited by 1 mM DEF. Inhibition of esterase activity up to 75% and 85% in the susceptible and resistant strains, respectively, was obtained with 0.03 mM TPP. Esterase activities in field populations increased by up to 5.4-fold during the fall season. The increase was synchronized with movement of the insect into cotton where exposure to pesticides occurred. Esterase cDNA was cloned and sequenced from both malathion susceptible and resistant strains. The 1818-nucleotide cDNA contained a 1710-bp open reading frame coding a 570 amino acid protein which was similar to many insect esterases conferring organophosphate resistance. No amino acid substitution was observed between susceptible and resistant strains, indicating that esterase gene mutation was not involved in resistance development in the resistant strain in Mississippi. Further examination of esterase gene expression levels using quantitative RT-PCR revealed that the resistant strain had a 5.1-fold higher level of esterase mRNA than the susceptible strain. The results of this study indicated that up-regulation of the esterase gene appeared to be related to the development of resistance in the tarnished plant bug.     

Field evaluation of efficacy and persistence of an insect vacuum device against the tarnished plant bug (Hemiptera: Miridae) in a day-neutral strawberry field

The efficacy of a vacuuming device to reduce Lygus lineolaris (Palisot de Beauvois) populations was evaluated over 3 yr in a day-neutral strawberry field. Immediately after treatments, a significant reduction of population estimates (by tapping of flower clusters) was observed for adults (75% of the time) and nymphs (50% of the time). Under the same conditions, control (i.e., vacuum turbine off) treatments significantly reduced adult population estimates 25% of the time. Lygus lineolaris tapping samples taken from strawberry plants adjacent to the treated zone did not show significant variations over sampling time, suggesting that no escape behavior occurred. This was supported by adult catches on sticky traps located in zones adjacent to the treated one. Our results suggest that vacuuming had inconsistent effect on tarnished plant bug populations and that L. lineolaris mobility plays a marginal role in the use of this control method.     

Influence of cover crops on insect pests and predators in conservation tillage cotton

In fall 2000, an on-farm sustainable agricultural research project was established for cotton, Gossypium hirsutum L., in Tift County, Georgia. The objective of our 2-yr research project was to determine the impact of several cover crops on pest and predator insects in cotton. The five cover crop treatments included 1) cereal rye, Secale cereale L., a standard grass cover crop; 2) crimson clover, Trifolium incarnatum L., a standard legume cover crop; 3) a legume mixture of balansa clover, Trifolium michelianum Savi; crimson clover; and hairy vetch, Vicia villosa Roth; 4) a legume mixture + rye combination; and 5) no cover crop in conventionally tilled fields. Three main groups or species of pests were collected in cover crops and cotton: 1) the heliothines Heliothis virescens (F.) and Helicoverpa zea (Boddie); 2) the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois); and 3) stink bugs. The main stink bugs collected were the southern green stink bug, Nezara viridula (L.); the brown stink bug, Euschistus servus (Say); and the green stink bug, Acrosternum hilare (Say). Cotton aphids, Aphis gossypii Glover, were collected only on cotton. For both years of the study, the heliothines were the only pests that exceeded their economic threshold in cotton, and the number of times this threshold was exceeded in cotton was higher in control cotton than in crimson clover and rye cotton. Heliothine predators and aphidophagous lady beetles occurred in cover crops and cotton during both years of the experiment. Geocoris punctipes (Say), Orius insidiosus (Say), and red imported fire ant, Solenopsis invicta Buren were relatively the most abundant heliothine predators observed. Lady beetles included the convergent lady beetle, Hippodamia convergens Guérin-Méneville; the sevenspotted lady beetle, Coccinella septempunctata L.; spotted lady beetle, Coleomegilla maculata (DeGeer); and the multicolored Asian lady beetle, Harmonia axyridis (Pallas). Density of G. punctipes was higher in cotton fields previously planted in crimson clover compared with control cotton fields for all combined sampling dates in 2001. Intercropping cotton in live strips of cover crop was probably responsible for the relay of G. punctipes onto cotton in these crimson clover fields. Density of O. insidiosus was not significantly different between cover crop and control cotton fields. Lady beetles seemed to relay from cover crops into cotton. Conservation of the habitat of fire ants during planting probably was responsible for the higher density of red imported fire ants observed in all conservation tillage cotton fields relative to control cotton fields. Reduction in the number of times in which economic thresholds for heliothines were exceeded in crimson clover and rye compared with control fields indicated that the buildup of predaceous fire ants and G. punctipes in these cover crops subsequently resulted in reduction in the level of heliothines in conservation tillage cotton with these cover crops compared with conventional tillage cotton without cover crops.     

Evaluation of the Biological Sampling Kit (BiSKit) for large-area surface sampling

Current surface sampling methods for microbial contaminants are designed to sample small areas and utilize culture analysis. The total number of microbes recovered is low because a small area is sampled, making detection of a potential pathogen more difficult. Furthermore, sampling of small areas requires a greater number of samples to be collected, which delays the reporting of results, taxes laboratory resources and staffing, and increases analysis costs. A new biological surface sampling method, the Biological Sampling Kit (BiSKit), designed to sample large areas and to be compatible with testing with a variety of technologies, including PCR and immunoassay, was evaluated and compared to other surface sampling strategies. In experimental room trials, wood laminate and metal surfaces were contaminated by aerosolization of Bacillus atrophaeus spores, a simulant for Bacillus anthracis, into the room, followed by settling of the spores onto the test surfaces. The surfaces were sampled with the BiSKit, a cotton-based swab, and a foam-based swab. Samples were analyzed by culturing, quantitative PCR, and immunological assays. The results showed that the large surface area (1 m2) sampled with the BiSKit resulted in concentrations of B. atrophaeus in samples that were up to 10-fold higher than the concentrations obtained with the other methods tested. A comparison of wet and dry sampling with the BiSKit indicated that dry sampling was more efficient (efficiency, 18.4%) than wet sampling (efficiency, 11.3%). The sensitivities of detection of B. atrophaeus on metal surfaces were 42 +/- 5.8 CFU/m2 for wet sampling and 100.5 +/- 10.2 CFU/m2 for dry sampling. These results demonstrate that the use of a sampling device capable of sampling larger areas results in higher sensitivity than that obtained with currently available methods and has the advantage of sampling larger areas, thus requiring collection of fewer samples per site.