Biomedical subjects

D K Weaver

Publications and source records attributed to D K Weaver.

At least 19 recordsLinked to original sources

PubMed2002

Parasitism of the wheat stem sawfly (Hymenoptera: Cephidae) by Bracon cephi and B. lissogaster (Hymenoptera: Braconidae) in wheat fields bordering tilled and untilled fallow in Montana.

We evaluated wheat stem sawfly, Cephus cinctus Norton, parasitism, infestation, and sawfly-cut stems in wheat fields bordering intensely tilled (no visible stubble residue), minimally tilled (>75% stubble residue visible), and untilled (chemical fallow, herbicide fallow management) summer fallow fields in north-central and south-central Montana. No difference in sawfly parasitism or sawfly-cut stems was found between fields bordering minimally tilled and fields bordering untilled summer fallow. Sawfly parasitism in fields bordering untilled summer fallow was greater than in fields bordering intensely tilled summer fallow at six of the eight sites examined. Sawfly-cut stems were greater in the field bordering intensely tilled fallow at four sites, with no difference in sawfly-cut stems between the intensely tilled and untilled field at the other four sites. Although it has never been reported, we have observed that many sawfly stubs are completely buried. Therefore, we measured the depth of sawfly stubs in four untilled fields in Broadwater County, MT. Two-thirds of the stubs were completely buried (206 of 300) with an average depth of 6 mm. Intensive tillage, which results in soil-covered stubble, is not an effective sawfly control practice, because sawflies typically overwinter below ground and upon emergence must dig to reach the soil surface. However, Bracon cephi (Gahan) and Bracon lissogaster Muesebeck overwinter above ground in stems and might be unable to dig to the soil surface if buried. The elimination of intensive tillage in favor of chemical fallow should result in greater sawfly parasitism over time. Producers replacing minimal tillage with chemical fallow should see no effect on sawfly parasitism.

Agriculture↗

PubMed2000

Phenology and spatial pattern of Typhaea stercorea (Coleoptera: Mycetophagidae) infesting stored grain: estimation by pitfall trapping.

The hairy fungus beetle, Typhaea stercorea (L.), occurs frequently in stored grain, often in large numbers. Populations infesting stored barley in Minnesota, corn in South Carolina, and wheat in Florida were sampled by means of grain probe traps. Spatial distribution of the species was examined by contour analysis of trap catch. In South Carolina, corn was sampled at 2 locations over 2 storage seasons, and temperature, moisture content, and malathion residues were measured. These data were used to examine phenology as well as spatial distribution, and showed peak trap catch shortly after harvest in the fall, and in the spring. This pattern followed seasonal changes in grain temperature, but there was no apparent relationship of trap catch to either grain moisture content or malathion residue. The populations of T. stercorea were not distributed randomly, but were largely concentrated in 1 or very few aggregations associated with the "spoutline," a region high in foreign material and broken grain that forms near the center of a bin as it is loaded. However, the spatial patterns were dynamic, even on a very small time scale (week to week). Numbers of insects in aggregations rose and fell, the areas involved expanded and contracted, the centers shifted, and secondary centers appeared and disappeared. These changes were apparently in response to changing patterns of grain temperature and moisture content. Secondary centers of aggregation often formed in warmer grain along bin walls.

Animals↗

PubMed2000

Insect infestation of stored oats in Florida and field evaluation of a device for counting insects electronically.

Automated methods of monitoring stored grain for insect pests will contribute to early detection and aid in management of pest problems. An insect population infesting stored oats at a seed processing plant in north-central Florida was studied to test a device for counting insects electronically (Electronic Grain Probe Insect Counter, EGPIC), and to characterize the storage environment. The device counts insects as they fall through an infrared beam incorporated into a modified grain probe (pitfall) trap and transmits the counts to a computer for accumulation and storage. Eight traps were inserted into the surface of the grain bulk, and the insects trapped were identified and counted manually at weekly intervals. Grain temperature and moisture content also were recorded for each trap location. Manual and automatic counts were compared to estimate error in the EGPIC system. Both over- and undercounting occurred, and errors ranged from -79.4 to 82.4%. The mean absolute value of error (+/- SE) was 31.7% (+/- 4.3). At least 31 species, or higher taxa, were detected, but the psocid Liposcelis entomophila (Enderlein) and the foreign grain beetle, Ahasverus advena (Waltl), accounted for 88% of the captured insects. Species diversity, phenology, and spatial distribution are presented, as well as temporal and spatial distribution of grain temperature and moisture content. The data sets generated will find application in population modeling and development of integrated pest management systems for stored grain.

Animals↗

PubMed2000

Eavesdropping on insects hidden in soil and interior structures of plants.

Accelerometer, electret microphone, and piezoelectric disk acoustic systems were evaluated for their potential to detect hidden insect infestations in soil and interior structures of plants. Coleopteran grubs (the scarabaeids Phyllophaga spp. and Cyclocephala spp.) and the curculionids Diaprepes abbreviatus (L.) and Otiorhynchus sulcatus (F.) weighing 50-300 mg were detected easily in the laboratory and in the field except under extremely windy or noisy conditions. Cephus cinctus Norton (Hymenoptera: Cephidae) larvae weighing 1-12 mg could be detected in small pots of wheat in the laboratory by taking moderate precautions to eliminate background noise. Insect sounds could be distinguished from background noises by differences in frequency and temporal patterns, but insects of similarly sized species could not be distinguished easily from each other. Insect activity was highly variable among individuals and species, although D. abbreviatus grubs tended to be more active than those of O. sulcatus. Tests were done to compare acoustically predicted infestations with the contents of soil samples taken at recording sites. Under laboratory or ideal field conditions, active insects within approximately 30 cm were identified with nearly 100% reliability. In field tests under adverse conditions, the reliability decreased to approximately 75%. These results indicate that acoustic systems with vibration sensors have considerable potential as activity monitors in the laboratory and as field tools for rapid, nondestructive scouting and mapping of soil insect populations.

Acoustics↗

PubMed1999

Thermal treatments to increase acoustic detectability of Sitophilus oryzae (Coleoptera: Curculionidae) in stored grain.

Hidden infestations of stored-product insect larvae are detected most rapidly by acoustic techniques when the larvae are highly active. Larval activity is periodic, however, and it tends to decrease after the larvae are disturbed or cooled. Because of the practical need for rapid inspection of grain at commercial elevators, several heat treatments were tested as potential methods of increasing larval activity and improving the speed and reliability of acoustic detection under adverse conditions. Samples of grain infested with 4th instars of Sitophilus oryzae (L.) were exposed to different radiant and convective heat treatments after they had been conditioned at 11 degrees C, 17 degrees C, or room temperature for 12-24 h. Relative activity levels were evaluated over periods of 0-12 h based on the mean levels in a 15-min interval, 2 h after the beginning of a trial. In comparisons among treatments with precooled larvae, relative activity levels 5-10 min after brief heat pulses were 2-30 times higher than activity levels in precooled controls exposed only to ambient temperatures (25 degrees C). After 15-25 min, the relative activity levels of these heated larvae remained 2-5 times higher than those of the ambient controls. Brief movement disturbances inhibited activity for approximately 20 min at any temperature. These results suggest that, in general, larval detectability is enhanced if cool grain samples are warmed and all samples are left undisturbed for 15-20 min before inspection.

Animals↗

PubMed1989

The urine chemistry survey--series 2. 5 years' experience with an interlaboratory comparison program.

We have reviewed 5 years' experience with the College of American Pathologists Urine Chemistry Survey--Series 2. Analytes studied include aldosterone, total free catecholamines, the fractionated catecholamines norepinephrine, epinephrine, and dopamine, total catecholamines, estriol, 5-hydroxyindoleacetic acid, 17-ketogenic steroids, 17-ketosteroids, vanillylmandelic acid, cortisol, metanephrines, coproporphyrin, and uroporphyrin. Interlaboratory precision achieved by participants did not reach levels reported by various investigators, but their studies do not reflect actual clinical laboratory conditions. The intralaboratory analytical precision may be adequate for clinical diagnosis but better interlaboratory agreement must await the preparation of standards verified by definitive analyses. Biases introduced by the use of many different standards probably are the origin of mediocre interlaboratory proficiency testing performance.

17-Ketosteroids↗

PubMed1981

Atypical lymphadenopathies of the head and neck.

Atypical lymphadenopathies fail to achieve the morphologic criteria of a malignant neoplasm, but exceed the usual concepts of follicular, lymphoid, or sinus histiocytic hyperplasias. Rich cellular proliferations usually composed of prominent histiocytes, or immunoblasts, or both with or without a vascular scaffolding obscure the nodal architecture. Toxoplasmosis, infectious mononucleosis, zoster, and vaccination-induced lymphadenopathies are caused by infectious agents, dermatopathic lymphadenitis is associated with cutaneous disease, anticonvulsant pseudolymphoma occurs in individuals hypersensitive to anticonvulsants (usually phenytoin), and Chediak-Higashi syndrome is an inherited abnormality of lysosomal microtubule function; the causes of sinus histiocytosis with massive lymphadenopathy, giant lymph node hyperplasia, angioimmunoblastic lymphadenopathy, mucocutaneous lymph node syndrome, and this histiocytoses remain unknown. The clinical course of these abnormalities varies from self-limited acute diseases (viral lymphadenopathies, toxoplasmosis, dermatopathic lymphadenitis, and usually anticonvulsive lymphadenopathy) to protracted, but benign abnormalities (sinus histiocytes with massive lymphadenopathy, giant lymph node hyperplasia, and multifocal eosinophilic granuloma). The diagnosis of angioimmunoblastic lymphadenopathy, Chediak-Higashi syndrome, and mucocutaneous lymph node syndrome necessitates a guarded prognosis, for death or the advent of a malignant lymphoma may interrupt their clinical course. Acute disseminated histiocytosis, even though the proliferated cell lacks the cytologic criteria of malignancy, should be regarded and treated as a malignant neoplasm.

Anticonvulsants↗

PubMed1978

Evaluation of a computer-directed pneumatic-tube system for pneumatic transport of blood specimens.

The results of sending specimens through a computerized pneumatic airtransport system and manually delivering specimens were compared for 15 chemical tests and six hematologic procedures. All specimens were collected from inpatients and outpatients into evacuated glass containers. The specimens traversed a maximum of 829 feet (253 meters) involving 16 bends and eight transfer units at 25 feet/second (7.6 meters/second). Only the activity of lactate dehydrogenase exceeded the precision of the test in pneumatically transported specimens. Ruptured erythrocytes in incompletely filled vacuum tubes were the likely source of the increased lactate dehydrogenase activity. Neither the serum sodium, potassium, chloride, carbon dioxide, total protein, albumin, calcium, glucose, creatinine, total bilirubin, alkaline phosphatase, aspartate transaminase, acid phosphatase, uric acid, leukocyte count, erythrocyte count, hemoglobin, hematocrit, nor the prothrombin time and partial thromboplastin time were affected by pneumatic transport. It is concluded that the pneumatic system tested provides a safe, efficient method of transporting the blood specimens tested.

Blood Specimen Collection↗

PubMed1973