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Insect migrations have ecological and economic impacts, particularly in agriculture. However, there is limited knowledge about the migratory movements of pests at the continental scale, which is an important factor influencing the spread of resistance genes. Understanding the migratory patterns of economic pests, like Helicoverpa zea(Boddie), is essential for improving Integrated Pest Management (IPM) and Insect Resistance Management (IRM) strategies. In this study, we used stable hydrogen isotopic ratios in wing tissue as a biogeochemical marker to examine migratory patterns and estimate the native origins of H. zeaindividuals collected across a wide latitudinal gradient in North America. Samples collected at higher latitudes (Ontario, Canada and Minnesota, USA) exhibited a greater proportion (60%–96%) of nonlocal individuals, with an increased probability of origin from the southeastern United States. Populations from mid-latitudes (Florida, North Carolina, and South Carolina) showed a blend of local and nonlocal (40%–60%) individuals. Finally, 15% of the southernmost population individuals (Puerto Rico) were classified as migratory, with some having a probability of origin at higher latitudes (>30°). Overall, our results provide evidence of a northward spring/summer migration of H. zeain North America and underscore the significance of the southeastern United States as a hub for genetic flow. In addition, based on stable hydrogen isotopic ratios, there is strong evidence of reverse (southward) migration of H. zeafrom the continental United States to Puerto Rico. Our study highlights the implications for IPM and IRM programs and the need for management strategies that account for both northward and southward migration patterns.

Exclusion netting in some European and North American apple (Malus domesticaBorkhausen, Rosaceae, Rosales) orchards has been documented to be an effective method of control for multiple insect pest species. By minimizing reliance on insecticides, these orchards have reduced costs, risks to the environment and non-target species, and reduced the risk of insecticide resistance. This study examined the use of commercially available hail netting (DrapeNet®; Prosser, WA) as a pest exclusion strategy under conditions in Minnesota, USA. In 2021 and 2022, we assessed the efficacy of hail netting as a tool for pest suppression in orchards by monitoring pest species in netted and open plots crossed with and without insecticide applications. Our findings show that both of the major pest species in Minnesota, the codling moth (Cydia pomonellaL.; Lepidoptera: Tortricidae) and the apple maggot (Rhagoletis pomonellaWalsh; Diptera: Tephritidae), were significantly reduced inside the netting compared to open plots by 94% and 96%, respectively. For a secondary pest, the red-banded leafroller (Argyrotaenia velutinanaWalker; Lepidoptera: Tortricidae), moth populations were reduced by 56%. We also found that insecticide application alone did not significantly reduce pest pressure in these species. Additionally, we investigated the subsequent effects of hail netting on fruit quality and yield. The use of hail netting and insecticide application resulted in significantly higher proportions of high-quality fruit at harvest. However, netting did not significantly influence yield. These findings suggest that hail netting can be used to control Midwest apple insect pests with limited insecticide applications while maintaining high fruit quality.

Abstract:Background:Microelectrode recordings (MERs) are used during deep brain stimulation surgery (DBS) to optimize patient outcomes and provide a unique method of collecting data regarding neurological conditions. However, MERs can be affected by anesthetics such as dexmedetomidine. Little is known about the effects of dexmedetomidine (DEX) on the globus pallidus interna (GPi), a common target for DBS. The primary aim of this study is to investigate the hypothesis that DEX is associated with alterations in GPi MERs.Methods:We conducted a retrospective analysis comparing MERs from patients with Parkinson’s disease (PD) and dystonia who underwent insertion of DBS of the GPi under DEX sedation with those who went through the same procedure without DEX (No DEX).Results:Firing rates for GPi neurons in the DEX group were lower (57.44 ± 2.04; mean ± SEM, n = 163 cells) than the No DEX group (69.53 ± 2.06, n = 112 cells, P < 0.0001). Overall, DEX was associated with a greater proportion of GPi cells classified as firing in bursty pattern compared to our No DEX group. (29.41%, n = 153 vs 14.81%, n = 108, P = 0.008). This effect was present for both PD and dystonia patients who underwent the procedure. High doses of DEX were associated with lower firing rates than low doses.Conclusions:Our results suggest that DEX is associated with a decrease in GPi firing rates and are associated with an increase in burstiness. Furthermore, these effects are similar between dystonia and PD patients. Lastly, the effects of DEX may differ between high doses and low doses.

Stink bugs represent an increasing risk to soybean production in the Midwest region of the United States. The current sampling protocol for stink bugs in this region is tailored for population density estimation and thus is more relevant to research purposes. A practical decision-making framework with more efficient sampling effort for management of herbivorous stink bugs is needed. Therefore, a binomial sequential sampling plan was developed for herbivorous stink bugs in the Midwest region. A total of 146 soybean fields were sampled across 11 states using sweep nets in 2016, 2017, and 2018. The binomial sequential sampling plans were developed using combinations of five tally thresholds at two proportion infested action thresholds to identify those that provided the best sampling outcomes. Final assessment of the operating characteristic curves for each plan indicated that a tally threshold of 3 stink bugs per 25 sweeps, and proportion infested action thresholds of 0.75 and 0.95 corresponding to the action thresholds of 5 and 10 stink bugs per 25 sweeps, provided the optimal balance between highest probability of correct decisions (≥ 99%) and lowest probability of incorrect decisions (≤ 1%). In addition, the average sample size for both plans (18 and 12 sets of 25 sweeps, respectively) was lower than that for the other proposed plans. The binomial sequential sampling plan can reduce the number of sample units required to achieve a management decision, which is important because it can potentially reduce risk/cost of management for stink bugs in soybean in this region.

Reliable monitoring of the invasive Halyomorpha halysabundance, phenology and geographic distribution is critical for its management. Halyomorpha halysadult and nymphal captures on clear sticky traps and in black pyramid traps were compared in 18 states across the Great Lakes, Mid-Atlantic, Southeast, Pacific Northwest and Western regions of the United States. Traps were baited with commercial lures containing the H. halyspheromone and synergist, and deployed at field sites bordering agricultural or urban locations with H. halyshost plants. Nymphal and adult captures in pyramid traps were greater than those on sticky traps, but captures were positively correlated between the two trap types within each region and during the early-, mid- and late season across all sites. Sites were further classified as having a low, moderate or high relative H. halysdensity and again showed positive correlations between captures for the two trap types for nymphs and adults. Among regions, the greatest adult captures were recorded in the Southeast and Mid-Atlantic on pyramid and sticky traps, respectively, with lowest captures recorded in the West. Nymphal captures, while lower than adult captures, were greatest in the Southeast and lowest in the West. Nymphal and adult captures were, generally, greatest during July–August and September–October, respectively. Trapping data were compared with available phenological models showing comparable population peaks at most locations. Results demonstrated that sticky traps offer a simpler alternative to pyramid traps, but both can be reliable tools to monitor H. halysin different geographical locations with varying population densities throughout the season.

Deep Brain Stimulation (DBS) is an effective treatment for movement disorders, including Parkinson’s disease and essential tremor. However, the underlying mechanisms of DBS remain elusive. Despite the capability of existing models in interpreting experimental data qualitatively, there are very few unified computational models that quantitatively capture the dynamics of the neuronal activity of varying stimulated nuclei—including subthalamic nucleus (STN), substantia nigra pars reticulata (SNr) and ventral intermediate nucleus (Vim)—across different DBS frequencies.

High activity of the default mode network (DMN) has been proposed to be central in processing self-relevant events. Thus far, this hypothesis of DMN function has not been tested directly using neurophysiological techniques. To test for the link between frontal midline DMN activity and self-relevant processing we measured neuronal activity (single-neurons' firing rates) in human subcallosal cingulate cortex (SCC) in the course of Deep Brain Stimulation surgery. We find that firing rates in SCC did not change during the presentation of specifically self-relevant stimuli when compared to the preceding pre-stimulus resting state level. In contrast, we observed significant changes in firing rates during other names in SCC. Such rest-self overlap seems to be specific for SCC since increase in firing rates in response to self-relevant stimuli were observed in another region, the subthalamic nucleus, in a group of Parkinson patients receiving deep brain stimulation surgery. These results suggest specific relationship between resting state and self-related activity, rest-self overlap, in specifically SCC as core region of the default-mode network.

Sweet corn, Zea maysL., transformed to express a novel vegetative insecticidal protein, Vip3A (event MIR162, Syngenta Seeds, Inc..), produced by the bacterium, Bacillus thuringiensis (Bt), was evaluated over four field seasons in Maryland and two field seasons in Minnesota for efficacy against the corn earworm, Helicoverpa zea(Boddie).  Hybrids expressing the Vip3A protein and pyramided in hybrids also expressing the Cry1Ab Bt protein (event Bt11, ATTRIBUTE®, Syngenta Seeds, Inc.) were compared to hybrids expressing only Cry1Ab or to genetically similar non-Bt hybrids each year. In addition to H. zeaefficacy, results for Ostrinia nubilalis(Hübner) and Spodoptera frugiperda(J.E. Smith) are presented. Over all years and locations, the non-Bt hybrids, without insecticide protection, averaged between 43 and 100% ears infested with a range of 0.24 to 1.74 H. zea larvae per ear. By comparison, in the pyramided Vip3A x Cry1Ab hybrids, no larvae were found and only minimal kernel damage (likely due to other insect pests) was recorded. Hybrids expressing only Cry1Ab incurred a moderate level of H. zeafeeding damage, with surviving larvae mostly limited to the first or second instar as a result of previously documented growth inhibition from Cry1Ab. These results suggest that the Vip3A protein, pyramided with Cry1Ab, appears to provide the first “high-dose” under field conditions and will be valuable for ongoing resistance management.

Objectives. The clinical efficacy of subthalamic nucleus (STN) deep brain stimulation (DBS) for major motor symptoms of Parkinson's disease (PD) is well established, but its effects on visually guided vs. internally generated eye movements in the medication off state need to be studied further. Since the basal ganglia are thought to be involved in the generation of voluntary movements under internal control, we hypothesized that voluntary saccades would show improvements with STN DBS. Materials and Methods. Seven PD patients with STN DBS performed visually guided and internally generated (anti- and memory-guided) saccades with STN DBS on and off following 12 hours of levodopa withdrawal. The change in saccade reaction time, first saccade gain, and final saccade gain with STN DBS were measured. Results. STN DBS improved the reaction time of visually guided saccades but not of anti- or memory-guided saccades. STN DBS also improved the first saccade gain of the anti- and memory-guided saccades, but not of the visually guided saccades. Conclusions. These results demonstrate that STN DBS has differential effects on the parameters of visually guided and internally generated saccades. These effects may be mediated by the influence of STN DBS on cortical ocular motor areas, the basal ganglia, ocular motor loop, or downstream structures such as the brainstem saccade generating circuits.

In recent years there has been great interest in oscillatory activity in the brain and in the role of pathological oscillations in the basal ganglia in mediating some of the symptoms of Parkinson's disease (PD). In this study, thalamic and subthalamic nucleus local field potentials were intraoperatively recorded from pairs of closely separated microelectrodes in six PD patients ON and OFF dopaminergic medication. Using correlation and coherence analyses, we found high-frequency oscillatory activity in the 110–170 Hz band in thalamus in patients OFF dopamine. These oscillations were significantly reduced after administration of dopamine-replacement therapy. In contrast, activity in the lower frequencies (the and ranges) was increased. However, in subthalamic nucleus, we observed an increase in high-frequency oscillatory activity (150–200 Hz), and a reduction of the activity in the low-frequency range after levodopa administration. These findings confirm and extend earlier findings suggesting that in PD there are marked changes in basal ganglia oscillatory activity and that these can be reversed after dopaminergic therapy.

Ponto-geniculo-occipital (PGO) waves are phasic pontine, lateral geniculate, and cortical field potentials occurring during and before REM sleep that are proposed to mediate a wide variety of sleep related neural processes. We sought to identify and characterize human PGO waves.

Bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) was performed in a patient with Huntington's disease (HD) with severe chorea. Stimulation at 40 and 130Hz improved chorea. Stimulation at 130Hz slightly worsened bradykinesia overall, whereas 40Hz had little effect. A [15O] H2O positron emission tomography showed increased regional cerebral blood flow in motor decision making and execution areas more evident at 40Hz. Adjustment of stimulation parameters in GPi DBS may have the potential to optimize the motor response in HD, improving chorea without aggravating bradykinesia. Ann Neurol 2004

Dystonia is a neurological syndrome involving sustained contractions of opposing muscles leading to abnormal movements and postures. Recent studies report abnormally low pallidal neuronal activity in patients with generalized dystonia, suggesting hyperkinetic disorders result from underactive basal ganglia output. We examined this hypothesis in 11 patients with segmental and generalized dystonia undergoing microelectrode exploration of the internal globus pallidus (GPi) before pallidotomy or deep brain stimulation (DBS) implantation. The mean firing rates and firing patterns were compared with those in six patients with Parkinson's disease (PD). In seven patients who underwent surgery under local anesthesia, the mean GPi firing rate was 77Hz, similar to the 74Hz observed in the PD patients. However, in three dystonic patients under propofol anesthesia, GPi mean firing rate was much reduced (31Hz), and the firing pattern was distinguished by long pauses in activity, as reported by others. Low‐dose propofol in one other dystonia patient also seemed to suppress GPi firing. These results indicate that an abnormally low basal ganglia output is not the sine qua non of dystonia. The widely accepted pathophysiological models of dystonia that propose global decreases in basal ganglia output need to be viewed with caution in light of these findings. Ann Neurol 2003

Dystonia is a neurological syndrome involving sustained contractions of opposing muscles leading to abnormal movements and postures. Recent studies report abnormally low pallidal neuronal activity in patients with generalized dystonia, suggesting hyperkinetic disorders result from underactive basal ganglia output. We examined this hypothesis in 11 patients with segmental and generalized dystonia undergoing microelectrode exploration of the internal globus pallidus (GPi) before pallidotomy or deep brain stimulation (DBS) implantation. The mean firing rates and firing patterns were compared with those in six patients with Parkinson's disease (PD). In seven patients who underwent surgery under local anesthesia, the mean GPi firing rate was 77Hz, similar to the 74Hz observed in the PD patients. However, in three dystonic patients under propofol anesthesia, GPi mean firing rate was much reduced (31Hz), and the firing pattern was distinguished by long pauses in activity, as reported by others. Low-dose propofol in one other dystonia patient also seemed to suppress GPi firing. These results indicate that an abnormally low basal ganglia output is not the sine qua non of dystonia. The widely accepted pathophysiological models of dystonia that propose global decreases in basal ganglia output need to be viewed with caution in light of these findings. Ann Neurol 2003

Local field potentials and pairs of neurones in the subthalamic nucleus (STN) of patients with Parkinson’s disease show high‐frequency oscillations (HFOs) at 15–30 Hz. This study explores how these HFOs are modulated by voluntary movements and by dopaminergic medication. We examined 15 patients undergoing implantation of bilateral deep brain stimulating electrodes using microelectrode recordings of pairs of STN neurones (eight patients) and macroelectrode recordings of local field potentials from the STN (14 patients). Synchronized HFOs between STN neurones were observed in 28 out of 37 pairs in five patients who had tremor in the operating room and none of 45 pairs in three patients who did not. In two of the three non‐tremulous patients, HFOs in the frequency spectra of local field potentials were detected but were weaker than in those patients with tremor. Active movement suppressed synchronized HFOs in three out of five pairs of neurones, independent of changes in firing rate. HFOs observed in the local field potentials in nine out of 14 patients were reduced with voluntary movement in six of the eight patients tested. Dopaminergic medication decreased the incidence of synchronized HFOs in STN neurone pairs, reduced HFO synchrony in a pair of tremor cells concurrent with a reduction in firing rate and limb tremor, and decreased HFOs of local field potentials in the STN. These results demonstrate that HFO synchronization in the STN is reduced by voluntary movements and by exogenous dopaminergic medication. A mechanism for neuronal oscillatory synchronization in basal ganglia is proposed. It is suggested that the firing of STN neurones can be synchronized by 15–30 Hz cortical beta oscillatory activity, particularly when dopamine deficiency results in a higher background firing rate of STN neurones, and that this synchronization contributes to parkinsonian pathophysiology.

Local field potentials and pairs of neurones in the subthalamic nucleus (STN) of patients with Parkinson's disease show high-frequency oscillations (HFOs) at 15-30 Hz. This study explores how these HFOs are modulated by voluntary movements and by dopaminergic medication. We examined 15 patients undergoing implantation of bilateral deep brain stimulating electrodes using microelectrode recordings of pairs of STN neurones (eight patients) and macroelectrode recordings of local field potentials from the STN (14 patients). Synchronized HFOs between STN neurones were observed in 28 out of 37 pairs in five patients who had tremor in the operating room and none of 45 pairs in three patients who did not. In two of the three non-tremulous patients, HFOs in the frequency spectra of local field potentials were detected but were weaker than in those patients with tremor. Active movement suppressed synchronized HFOs in three out of five pairs of neurones, independent of changes in firing rate. HFOs observed in the local field potentials in nine out of 14 patients were reduced with voluntary movement in six of the eight patients tested. Dopaminergic medication decreased the incidence of synchronized HFOs in STN neurone pairs, reduced HFO synchrony in a pair of tremor cells concurrent with a reduction in firing rate and limb tremor, and decreased HFOs of local field potentials in the STN. These results demonstrate that HFO synchronization in the STN is reduced by voluntary movements and by exogenous dopaminergic medication. A mechanism for neuronal oscillatory synchronization in basal ganglia is proposed. It is suggested that the firing of STN neurones can be synchronized by 15-30 Hz cortical beta oscillatory activity, particularly when dopamine deficiency results in a higher background firing rate of STN neurones, and that this synchronization contributes to parkinsonian pathophysiology.

The internal segment of the globus pallidus (GPi) is being targeted in neurosurgical procedures to treat Parkinson's disease and dystonia. Precise targeting of the pallidal complex is important in determining the efficacy of the surgical intervention and for the avoidance of adverse effects. Intraoperative microelectrode recording can be used to characterize the patterns of activity and receptive field properties of single pallidal neurons and to identify important bordering structures, including the optic tract and internal capsule. Because the clinical features of movement disorders can be differentially affected as a function of location within the pallidal complex, further refinements in intraoperative targeting may become important. © 2002 Movement Disorder Society

The internal segment of the globus pallidus (GPi) is being targeted in neurosurgical procedures to treat Parkinson's disease and dystonia. Precise targeting of the pallidal complex is important in determining the efficacy of the surgical intervention and for the avoidance of adverse effects. Intraoperative microelectrode recording can be used to characterize the patterns of activity and receptive field properties of single pallidal neurons and to identify important bordering structures, including the optic tract and internal capsule. Because the clinical features of movement disorders can be differentially affected as a function of location within the pallidal complex, further refinements in intraoperative targeting may become important. © 2002 Movement Disorder Society

European corn borer (ECB), Ostrinia nubilalis(Hübner), larvae develop resistance to management protocols in laboratory and field environments. Laboratory bioassays, tissue elemental analyses, and field resistance evaluations were conducted on ear tissues of maize, Zea maysL., to (i) identify genotypes and tissues which affect ECB development, (ii) isolate tissue extracts detrimentally affecting larvae, (iii) determine if high performance liquid chromatography (HPLC) absorption peaks are associated with biological activity, (iv) determine if ferulic acid and p‐coumaric acid affect ECB larvae, and (v) determine if laboratory and field resistance are related. Tissue and genotype did not affect larval survival. Silk tissue from W182E, ‘Apache’, MN 3153, and MN 276 reduced 10‐d larval weight, increased time to pupation, reduced pupal weight, and increased time to moth emergence compared with kernel tissue, which did not differ from the cellulose control. Methanol fractions of silks reduced 10‐d larval weight, but not larval survival, compared with the cellulose control. No methanol fraction of silks, except from MG 15, reduced 10‐d larval weight as much as nonextracted Apache silk, suggesting that some allelochemicals were not captured or were lost during extraction. HPLC analysis detected three to four large peaks only found in active methanol fractions. Ear tissue element levels, except for manganese (r= −0.70), were not associated with decreased 10‐d larval weight. Larvae reared on diet containing ferulic acid (2.61 and 1.67 mg/g) or p‐coumaric acid (<0.20 mg/g) had 10‐d weights similar to the control. Laboratory and field resistance were not correlated, suggesting that multiple resistance mechanisms exist in maize. The identification of allelochemicals affecting ECB larvae will allow breeding programs to select resistant maize genotypes.

Inactivation of neurones in the subthalamic nucleus (STN) of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treated monkey model of Parkinson's disease has been shown to relieve parkinsonian motor symptoms. In patients with Parkinson's disease, neurones in the STN display hyperactive firing rates and rhythmic discharge activity such as tremor-related oscillations (3–8 Hz) and synchronous high-frequency oscillations (15–30 Hz). In this study, microinjections of lidocaine (n = 4) and muscimol, a GABAA receptor agonist (n = 2), were performed in the STN of six patients with Parkinson's disease to determine whether the focal suppression of STN neuronal activity can lead to an improvement in tremor, bradykinesia and rigidity. We also report the first use of microelectrode recording of the effects of microinjections on neuronal activity in the human brain (n = 2). Microinjections of 10–23 μl of lidocaine produced striking improvements in bradykinesia, limb tremor and rigidity in three out of three patients. These improvements were correlated with good therapeutic effects of subsequent STN deep brain stimulation performed in the same microelectrode trajectories as these injections. The most dramatic observation following lidocaine injections was the appearance of dyskinetic limb movements. In one patient, simultaneous microelectrode recording during an injection of 3.5 μl of lidocaine demonstrated a suppression of neuronal activity at distances of <0.9 mm from the injection site, but no suppression was observed at ≥1.2 mm from the injection site. Microinjections of 5–10 μl of muscimol in a region with tremor-related activity resulted in suppression of limb tremor in two out of two patients. Interestingly, in one of these patients, 4 Hz oscillatory activity was diminished in a neurone recorded 1.3 mm from the injection site, but there was no reduction in the mean firing rate or 20 Hz oscillatory activity. These results demonstrate that inactivation of neuronal activity in the STN of patients with Parkinson's disease improves motor symptoms. These findings also suggest that a focal block of the STN might alter the oscillatory activity of neurones located beyond the inhibited region.

Abstract Field studies were conducted in 1995 to compare the photosynthesis response between simulated striped cucumber beetle, Acalymma vittatum(F.), defoliation and actual A. vittatumdefoliation in ‘Carolina’ cucumber. Six simulated defoliation levels (0%–100%)were used over 5 timings of defoliation (first true leaf to harvest). Plots were defoliated with scissors twice each week throughout each timing interval, and defined as continuous defoliation. In addition to continuous defoliation, one‐time simulated defoliation treatments were imposed using the same timing treatments but only 4 defoliation levels (0, 25, 50, and 100%). Two cage studies, with A. vittatumadults, were used to provide estimates of actual insect defoliation injury. Beetles were placed in cages for 2 weeks at densities of 0, 1, 3, 5, and 10/plant and net photosynthetic rates were measured. No significant differences (P<0. 05were detected in pho‐tosynthetic rates between simulated and actual insect defoliation treatments. Also, few significant differences in photosynthetic rates were detected between damaged and undamaged leaves in the simulated insect defoliation study. Results indicated that the simulated insect defoliation procedure appeared to accurately reflect the growth response of ‘Carolina’ cucumber subjected to actual A. vittatumdefoliation, and that simulated defoliation results should be appropriate for developing economic injury levels for A. vittatumon cucumber.

AbstractA reliable method for rearing the subterranean summer morph of the sugarbeet root aphid, Pemphigus betaeDoane, is described. Field-collected aphids were reared using hydroponic growth pouches that allowed exposed root tissue to be fed on by P. betae. The aphid has been maintained in continuous culture for over 3 years. Open pouches were subsequently modified with cages to provide more successful mass rearing. Cages placed on the pouch were devised to provide an arena that concentrated aphids on one area of the pouch, minimized wandering behavior, and ensured a more vigorous colony. During a 10-week mass rearing experiment, caged pouches consistently averaged 120.8 ± 9.6(se) aphids per cage (fourth instars and adults) following 2-week incubation periods. Caged pouches also were used to isolate individual aphids for development and fecundity studies. Age-specific life tables were developed for P. betaeusing both open pouches at 20°C, and caged pouches at 24°C. Although the intrinsic rate of increase (rm) was lower at 20°C on a daily time scale (rm= 0.2314 versus 0.2591), rmwas significantly greater at 20°C on a degree-day (DD > 7.6°C) time scale (rm= 0.0187 versus 0.0158). The difference on a DD basis resulted primarily from a longer time interval from birth to first reproduction (TFR) at 24°C(TFR= 158.5 versus 147.1 DD at 20°C). These results corroborate previous experience with P. betae, indicating that 20°C appeared to be an optimum temperature for mass rearing. Stable age distributions for P. betaecohorts were only slightly affected by temperature; on average approximately 55, 22, 11, 7, and 5% of the aphids were first, second, third, and fourth instars, and adults, respectively. Though similar studies have not been reported for other Pemphigusspp., all demographic statistics were characteristic of many foliar-feeding aphids held under similar constant temperature conditions.

We studied tremor‐related activity in globus pallidus internus (GPi) neurons and the effects of pallidotomy on tremor in patients with Parkinson's disease. By using micro‐electrode recording, we identified GPi neurons with rhythmic firing at the frequency of contralateral tremor. There was a strong correlation between the tremor‐related neuronal activity and limb tremor (r = 0.73). The majority of tremor‐related neurons were located in the ventral one half of the caudal GPi, the area that is the target for pallidotomy. We found that pallidotomy produced striking improvements in off‐period contralateral tremor. These effects were immediate and were maintained for ≥ 2 years. This benefit is obtained despite the progressive nature of the illness and the often reduced dose of medications after surgery.

Time-specific life tables were constructed for three pea aphid, Acyrthosiphon pisum(Harris) (Homoptera: Aphididae), populations using a modification ofHughes'analytical procedure. All populations were studied on second-growth alfalfa (mid-June to mid-July) in south central Wisconsin; data for two populations were collected during 1980, and data for the third population were collected during 1982. The intrinsic rate of increase (rm) estimated on a physiological time (day-degree) scale under field conditions but in the absence of natural enemies, provided a reliable estimate of potential population growth rate and was used in preference toHughes'approach of estimating potential population growth rates directly from stage structure data. Emigration by adult alatae and fungal disease were the major sources of A. pisummortality in each of the three populations studied. These factors were most important because of their impact on reducing birth rates within the local population. Parasitism was never greater than 9 percent. Mortality attributable to predation ranged from 0.0 to about 30.0%; however, even at the highest predator densities A. pisumpopulations increased exponentially.

MICROSTIMULATION within and below the ventrocaudal nucleus (Vc) in the human thalamus typically evokes non-painful, paraesthetic cutaneous sensations. We now describe cases in which thalamic microstimulation evoked visceral pains. Data were obtained during stereotactic thalamotomy procedures. Patient 211 had a history of essential tremor. At a site 0.5 mm ventroposterior to Vc, microstimulation elicited pain described as deep, internal, in a straight line like my appendix pain years ago'. Patient 153 had a history of post-stroke hemibody pain. In each of two trajectories, at sites approximately 2 mm ventroposterior to Vc, microstimulation evoked pain in the groin. At one of these sites, the pain was described as like having a baby'. These and additional observations suggest that stimulation ventroposterior to Vc can evoke visceral pain and may trigger pain memories'.

AbstractCornicle length measuremetns of Acyrthosiphon pisum(Harris) nymphs reared in the laboratory were instar-specific and unaffected by rearing temperature. A multimodal analysis of cornicle lengths of field-collected aphids clearly detected four distribution peaks (i.e., instars) in five different field populations, and there was generaaly little overlap between successive instar distributions. However, third and fourth instars in the spring field sample could not be separated accurately due to the shorter cornicle length of nymphs that developed from overwintered eggs. Cornicle length proved to be a useful criterion for separating virginoparous A. pisuminstars in samples collected in southern Wisconsin.

The benefits of stereotactic ventral posteromedial pallidotomy in the treatment of Parkinson’s disease have been recently rediscovered. Optimal lesion location and lesion volume, however, have yet to be determined. Micro-electrode recording and microstimulation are carried out to determine an appropriate site for the placement of electrocoagulation lesions in the medial pallidum. The cellular activity of the globus pallidus is examined for characteristic firing patterns, mean firing rates, movement-evoked activity, and presence of tremor cells, laminae, and border zones. Microstimulation allows the identification of the adjacent optic tract by reports of visual sensation and of the internal capsule by sensorimotor responses. Lesions are centred at sites in the internal segment of the globus pallidus at least 3 mm from these structures, to avoid injury to them during pallidotomy.

Recent imaging studies have implicated the anterior cingulate cortex (ACC) in various cognitive functions, including attention. However, until now, there was no evidence for changes in neuronal activity of individual ACC neurons during performance of tasks that require attention and effortful thought. We hypothesized these neurons must exist in the human ACC. In this study, we present electrophysiological data from microelectrode single neuron recordings in the human ACC of neuronal modulation during attention-demanding tasks in 19% of 36 neurons tested. These findings provide the first direct evidence of an influence of a cognitive state on the spontaneous neuronal activity of human ACC neurons.

The European corn borer, Ostrinia nubilalisHübner, continues to be a consistent economic pest of field and sweet corn (Zea maysL.) in the upper midwestem United States. In Minnesota alone, O. nubilaliscontrol costs and losses to sweet corn (ca. 50 630 ha) exceed $5,000,000 annually (Noetzel et al. 1985). Despite recent efforts to implement alternatives (Lewis and Bing 1991; Prokrym et al. 1992; Bartels and Hutchison 1993; Bolin et al. 1993), insecticide control continues to play a central role in O. nubilalismanagement programs.