Uniform shrinking and expansion under isotropic Brownian flows

We study some finite time transport properties of isotropic Brownian flows. Under a certain nondegeneracy condition on the potential spectral measure, we prove that uniform shrinking or expansion of balls under the flow over some bounded time interval can happen with positive probability. We also provide a control theorem for isotropic Brownian flows with drift. Finally, we apply the above results to show that under the nondegeneracy condition the length of a rectifiable curve evolving in an isotropic Brownian flow with strictly negative top Lyapunov exponent converges to zero as $t\to \infty$ with positive probability

Transition from ergodic to explosive behavior in a family of stochastic differential equations

We study a family of quadratic stochastic differential equations in the plane, motivated by applications to turbulent transport of heavy particles. Using Lyapunov functions, we find a critical parameter value $\alpha_{1}=\alpha_{2}$ such that when $\alpha_{2}>\alpha_{1}$ the system is ergodic and when $\alpha_{2}<\alpha_{1}$ solutions are not defined for all times. H\"{o}rmander's hypoellipticity theorem and geometric control theory are also utilized.Comment: 35 pages, 6 figure

Insect Pests and Arthropod Predators Associated with Tree-Turf Landscapes

Sweep-nets and pitfall traps were used to examine the distribution and dynamics of predominant predators and pests in turfgrass foliage in parks, golf courses and suburban/rural landscapes in 1991 and 1992. Araneae, Formicidae, and Coccinellidae were the most abundant predators in the sweeps, while Araneae, Formicidae, and) Carabidae were the most abundant predators in the pitfall traps. In both years, Araneae comprised over 60% of the total predators in the sweep samples. Formicidae (\u3e70%) and Araneae (13-19%) were the most abundant arthropod predators in the pitfall samples. Cicadellidae, Chrysomelidae, and Orthoptera accounted for over 96% of the prey in the sweep samples, while Cicadellidae, Orthoptera (grasshoppers and crickets), and Aphididae comprised over 90% of the prey in the pitfall samples. Abundance of predators and prey, and prey I predator ratios fluctuated with site, date, and distance from the trees. During the season, high prey I predator ratios usually preceded peak prey abundance in the sweep samples. Predators usually were more prevalent in sweep samples closer to tree borders, while prey populations tended to be higher at distances further from the tree borders. These results suggest that tree borders provide food, shelter, and refuge for predators during periods of environmental stress

EC92-1555-C Insect Pest Management Strategies for Yards and Gardens

Extension circular 92-1555-C: This circular discusses how integrated pest management can be applied to insect and mite management in yards and gardens

Thermal Requirements for Emergence of Overwintered Sorghum Midge (Diptera: Cecidomyiidae)

Emergence of overwintered sorghum midges, Contarinia sorghicola (Coquillett), was monitored during 1979, 1980, and 1981. Differences in emergence times and distributions among years was a function of soil temperature and rainfall. A heat unit accumulation model incorporating a rainfall adjustment factor was developed which described adult emergence in the spring. Adult midges initiated emergence after accumulating 431 centigrade heat units (based on mean daily to-cm soil temperatures starting 1 April) above a threshold temperature of 14.8°C, whereas, 679 and 977 heat units were required for 50 and 95% emergence, respectively. Sorghum midges that overwintered in johnsongrass spikelets emerged after similar heat unit accumulations as midges that overwintered in sorghum spikelets. The time that midges initiated diapause one year had little effect on the timing or distribution of emergence the following spring. No midges terminated diapause and emerged as adults during the same season that diapause was initiated. Of the diapausing midges, 23% failed to emerge until the second spring and 2.6% emerged the third spring, but times and distributions of emergence were similar for all years

Insect Pests and Arthropod Predators Associated with Tree-Turf Landscapes

Sweep-nets and pitfall traps were used to examine the distribution and dynamics of predominant predators and pests in turfgrass foliage in parks, golf courses and suburban/rural landscapes in 1991 and 1992. Araneae, Formicidae, and Coccinellidae were the most abundant predators in the sweeps, while Araneae, Formicidae, and) Carabidae were the most abundant predators in the pitfall traps. In both years, Araneae comprised over 60% of the total predators in the sweep samples. Formicidae (\u3e70%) and Araneae (13-19%) were the most abundant arthropod predators in the pitfall samples. Cicadellidae, Chrysomelidae, and Orthoptera accounted for over 96% of the prey in the sweep samples, while Cicadellidae, Orthoptera (grasshoppers and crickets), and Aphididae comprised over 90% of the prey in the pitfall samples. Abundance of predators and prey, and prey I predator ratios fluctuated with site, date, and distance from the trees. During the season, high prey I predator ratios usually preceded peak prey abundance in the sweep samples. Predators usually were more prevalent in sweep samples closer to tree borders, while prey populations tended to be higher at distances further from the tree borders. These results suggest that tree borders provide food, shelter, and refuge for predators during periods of environmental stress

Insect Pests and Arthropod Predators Associated with Tree-Turf Landscapes

Sweep-nets and pitfall traps were used to examine the distribution and dynamics of predominant predators and pests in turfgrass foliage in parks, golf courses and suburban/rural landscapes in 1991 and 1992. Araneae, Formicidae, and Coccinellidae were the most abundant predators in the sweeps, while Araneae, Formicidae, and) Carabidae were the most abundant predators in the pitfall traps. In both years, Araneae comprised over 60% of the total predators in the sweep samples. Formicidae (\u3e70%) and Araneae (13-19%) were the most abundant arthropod predators in the pitfall samples. Cicadellidae, Chrysomelidae, and Orthoptera accounted for over 96% of the prey in the sweep samples, while Cicadellidae, Orthoptera (grasshoppers and crickets), and Aphididae comprised over 90% of the prey in the pitfall samples. Abundance of predators and prey, and prey I predator ratios fluctuated with site, date, and distance from the trees. During the season, high prey I predator ratios usually preceded peak prey abundance in the sweep samples. Predators usually were more prevalent in sweep samples closer to tree borders, while prey populations tended to be higher at distances further from the tree borders. These results suggest that tree borders provide food, shelter, and refuge for predators during periods of environmental stress

Beneficial Arthropods Associated with Buffalograss

Beneficial arthropods collected from buffalograss, Buchloe dactyloides (Nuttall) Engelmann, evaluation plots and vegetatively established buffalograss lawns included predatory ants, spiders, ground beetles, rove beetles, big-eyed.bugs, and several species of hymenopterous parasitoids. Ants and spiders were the most abundant beneficial arthropods collected, representing 84% of the total beneficial arthropods captured. Pitfall traps collected \u3e2.5 times as many (16,094) beneficial arthropods as sod plug samples (6,054), demonstrating that pitfall traps are a more effective technique than sod plugs for capturing highly mobile surface-dwelling arthropods. Families of parasitoids captured on sticky traps during the 2-yr sampling period included Scelionidae, Encyrtidae, Mymaridae, and Trichogrammatidae. Mymarids and trichogrammatids were the most abundant parasitoid families, representing 76.8% of the total parasitoids collected. Total numbers of beneficial arthropods collected from sites maintained at higher and lower management levels were not significantly different, suggesting that beneficial arthropod abundance may not be adversely affected by the 2 management regimes applied in this study

Beneficial Arthropods Associated with Buffalograss

Beneficial arthropods collected from buffalograss, Buchloe dactyloides (Nuttall) Engelmann, evaluation plots and vegetatively established buffalograss lawns included predatory ants, spiders, ground beetles, rove beetles, big-eyed.bugs, and several species of hymenopterous parasitoids. Ants and spiders were the most abundant beneficial arthropods collected, representing 84% of the total beneficial arthropods captured. Pitfall traps collected \u3e2.5 times as many (16,094) beneficial arthropods as sod plug samples (6,054), demonstrating that pitfall traps are a more effective technique than sod plugs for capturing highly mobile surface-dwelling arthropods. Families of parasitoids captured on sticky traps during the 2-yr sampling period included Scelionidae, Encyrtidae, Mymaridae, and Trichogrammatidae. Mymarids and trichogrammatids were the most abundant parasitoid families, representing 76.8% of the total parasitoids collected. Total numbers of beneficial arthropods collected from sites maintained at higher and lower management levels were not significantly different, suggesting that beneficial arthropod abundance may not be adversely affected by the 2 management regimes applied in this study

Evaluation of Warm-season Turfgrasses for Resistance to the Chinch Bug, \u3ci\u3eBlissus occiduus\u3c/i\u3e

The chinch bug, Blissus occiduus Barber, has been documented as a serious pest of buffalograss, Buchloë dactyloides (Nutall) Engelmann, and zoysiagrass, Zoysia japonica Steudel, turf grown in the Midwest. In addition to these two warm-season turfgrasses, several other warm-season grasses, including bermudagrass, Cynodon dactylon (L.) Pers., may also be at risk of B. occiduus infestations. This research evaluated selected bermudagrass and zoysiagrass cultivars for resistance to B. occiduus. Eleven zoysiagrass and four bermudagrass cultivars were evaluated for resistance to B. occiduus using no-choice studies under greenhouse conditions. Based on turfgrass damage ratings, the zoysiagrasses ‘Diamond’, ‘Zoro’, and ‘Emerald’, and bermudagrass ‘Mini Verde’ were identified as moderately resistant to B. occiduus. The zoysiagrasses ‘Zenith’, ‘Meyer’, and ‘Crowne’, and bermudagrasses ‘Tifway 419’ and ‘Tifsport’’ were characterized as highly to moderately susceptible to B. occiduus. These results provide the first report of resistance to B. occiduus in zoysiagrass and bermudagrass germplasm