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.

Boll injury and yield losses in cotton associated with brown stink bug (Heteroptera: Pentatomidae) during flowering.

Brown stink bug, Euschistus servus (Say), was infested on cotton, Gossypium hirsutum L., plants during reproductive stages to determine the effects on boll injury and seedcotton yield. During each week in 2002 and 2003, significantly more bolls with > or = 1 injured locule, bolls with > or = 2 injured locules, and bolls with discolored lint were recorded on stink bug-infested plants compared with that on noninfested plants. Significantly fewer bolls displayed external injury on the boll exocarp compared with bolls with only internal locule injury. Boll injury was significantly underestimated by the presence of external symptomology. The boll population increased 6.6- and 5.1-fold from weeks 1-5 in 2002 and 2003, respectively. There was a corresponding 6.2- and 4.6-fold increase in 2002 and 2003, respectively, for total bolls injured from weeks 1-5. Percentage of boll injury ranged from 10.7 (week 4) to 27.4 (week 2) in 2002 and from 9.2 (week 3) to 16.0 (week 2) in 2003. Percentage of injury was greatest during weeks 1 and 2 in both years and also in week 5 in 2002. Brown stink bug significantly reduced seedcotton yield of bolls present on cotton plants during weeks 1, 2, and 5 in 2002 and in weeks 4 and 5 in 2003. However, total seedcotton yield, as a function of bolls exposed to brown stink bug and subsequent bolls produced on plant in the absence of stink bugs, was not significantly different for plots infested during weeks 1-4 in 2002 and weeks 1-3 in 2003. Flowering period and boll population influence the severity of stink bug injury on seedcotton yield. Infestation timing and number of bolls should be considered, in addition to insect densities, when initiating treatments against brown stink bug.

Distribution of bollworm, Helicoverpa zea (Boddie), injured reproductive structures on genetically engineered Bacillus thuringiensis var. kurstaki Berliner cotton.

Bollworm, Helicoverpa zea (Boddie), larvae are commonly observed feeding in genetically engineered Bollgard cotton. Although no information is currently available characterizing the levels of injury bollworms cause, aproximately 25% of the Bollgard acreage in the United States receives at least one insecticide application annually targeting bollworm populations. Studies were conducted to determine the levels of fruiting form injury that can occur from bollworm larvae feeding on white flowers of two types of genetically engineered cotton. The two types of genetically engineered cotton included the original Bollgard that produces one protein (Cry1Ac) from Bacillus thuringiensis variety kurstaki Berliner and Bollgard II that produces two proteins (Cry1Ac + Cry2Ab) from B. thuringiensis kurstaki. In one study, individual larvae (24 +/- 6 h old) were placed in first position white flowers of Deltapine 5415 (non-Bollgard) and Deltapine NuCOTN 33B (Bollgard). Larval infestations were made on 50 plants for each of 5 d during 2000 and 2001. Each plant was visually examined at 3 d and every 2 d thereafter, until larvae were no longer recovered. Larvae injured a total of 46.6 fruiting forms per 50 plants on non-Bollgard cotton, compared with only 18.9 fruiting forms per 50 plants on Bollgard cotton. Mean larval injury per insect was 4.3 fruiting forms on non-Bollgard cotton compared with 2.7 fruiting forms on Bollgard cotton. In a second study, individual larvae (24 +/- 6 h old) were placed in first position white flowers of Deltapine 50 (non-Bollgard), Deltapine 50B (Bollgard), and an experimental Bollgard II line. Larval infestations were made on 10 plants per day for each of six consecutive days during 2001. Larvae injured a total of 25.0 fruiting forms per 10 plants on non-Bollgard, 11.5 on Bollgard, and 6.4 on Bollgard II cottons. Mean larval injury per insect was 6.6 fruiting forms on non-Bollgard, 3.5 on Bollgard, and 0.8 on Bollgard II cottons. These data indicate that supplemental insecticide applications may be necessary to prevent yield losses on Bollgard cotton. In contrast, injury to Bollgard II cotton was minimal and may not require additional insecticide applications for bollworms.

Acute effects of smoking on digital artery blood flow in humans.

Smoking induces several immediate physiologic changes in the distal arteries of the human upper extremity. We examined the hemodynamic effects of cigarette smoking on blood flow in normal human digital arteries using 20 MHz pulsed ultrasonic Doppler velocimeter methods. In each of nine subjects, two presmoke measurements and six postsmoke measurements were collected over a 30-minute period. Maximum velocity and volumetric flow data were averaged. Although no statistical differences were present between presmoke and postsmoke variables, maximum velocity decreased 14% and volumetric flow decreased 60% in the first postsmoke measurement interval. These observations suggest that smoking produces increased vascular resistance in the fingers and an overall reduction in both volumetric blood flow through arteries and tissue perfusion.

Flow field mapping in the anesthetized rat.

This study measured the hemodynamics of peripheral arterial sites in the rat, using 20 MHz pulsed ultrasonic Doppler velocimeter (PUDVM) methods. The lower extremities of 14 male Sprague-Dawley rats were studied. The targeted sites included the abdominal aorta, external iliac, proximal femoral, mid-femoral, and saphenous arteries. The hemodynamic variables of pulse period, maximum centerline velocity, lumen diameter, and mean volumetric flow were calculated interactively from temporal-spatial plots of local velocity distributions. An analysis of variance revealed significant differences between right and left sides for lumen diameter (P = 0.028) and mean volumetric flow (P less than 0.0001). The analysis showed no statistical difference for pulse period (P = 0.0836) among sites. However, three distinct groupings of sites: 1) abdominal aorta, 2) external iliac, proximal femoral, and mid-femoral arteries, and 3) saphenous artery were noted for the remaining hemodynamic variables (P less than 0.05). These results indicate that three hemodynamically distinct regions are available for microvascular research in the rat lower extremity arterial tree.

A microvascular anastomotic device: part I. A hemodynamic evaluation in rabbit femoral arteries and veins.

This study quantitatively assesses the hemodynamic consequences of inserting a 1.5-mm polyethylene anastomotic device in both small arteries and veins. The device was placed in 20 rabbit femoral arteries and 20 femoral veins. Using 20-MHz pulsed ultrasonic Doppler velocimetry techniques, blood flow was measured in 5 immediate postoperative intervals and at the 24-hour and 3-week postoperative intervals. In arteries, volumetric flow (Q) was not statistically different in any postoperative interval; maximum spatial velocity (Vmax) was significantly increased in the immediate postoperative intervals but was not different at 24 hours or 3 weeks. In veins, significant decreases in Q and increases in Vmax occurred in the immediate postoperative intervals, but differences were not noted at the 24-hour or 3-week intervals. The results of this study indicate that the hemodynamic consequences of anastomosing small vessels with a polyethylene device are minimal and that this mechanical technique is an effective method for experimental microvascular repairs.