Management of the Rice Tungro Virus Vector \u3ci\u3eNephotettix virescens\u3c/i\u3e (Homoptera: Cicadellidae) with Controlled-Release Formulations of Carbofuran

Field trials were conducted in lowland flooded rice in the Philippines to evaluate a number of carbofuran controlled-release formulations in comparison with commercial formulations. The test formulations were based on a biodegradable matrix of pine kraft lignin and were used as granules of different sizes and also in the form of small strips. The release rates were assessed under field conditions by bioassaying rice plants in the field, using adult rice green leafhopper, Nephotettix virescens Distant. The lignin formulations with a high level of active ingredient (15–45% by weight) gave as good or better control than the commercial 3% granules in tests based on three application techniques: broadcast into the floodwater, soil incorporation, and root zone injection. The improvements in control levels of green leafhoppers were most marked with soil incorporation and root zone application. The best lignin-based formulation reduced levels of tungro virus infection from 23% for a conventional flowable carbofuran formulation to 1.0% at an application rate of 0.5 kg (AI)/ha. At the same rate, the grain yield was increased from 3.56 t/ha to 5.5 t/ha, using the controlled-released formulation

Hatching of Sod Webworm Eggs in Relation to Low Temperatures

Eggs of Chrysoteuchia topiaria (Zeller), Crambus pascuellus floridus (Zeller), and Pediasia trisecta (Walker) were exposed to temperatures of 25, 15, 10, 4, and –10°C. Only those of P. trisecta hatched after exposure to 4°C for 30 days, while none hatched after exposure to –10°C. Eggs of none of the species hatched after exposure to 4 and 10°C for 60 days. Pre-exposure and post-exposure conditioning had no significant effect on percent hatch of P. trisecta eggs, while length of exposure period had a significant effect

Seasonal Abundance and Distribution of Benthic Fauna within a Pond

A Tennessee pond was sampled weekly from June 18 to August 20, 1968, to determine quantitative differences among benthic organisms in sampling depths and dates. Annelids (Oligochaeta), Chironomidae larvae, and Chaoboridae larvae were the dominant organisms collected. Preferred depths existed for each group of organisms. Chaoboridae and Chironomidae exhibited distinct seasonal variations in numbers, with the population decreasing throughout the summer. Chaoboridae were the most and Chironomidae the least numerous of the 3 groups

Hatching of Sod Webworm Eggs in Relation to Low and High Temperatures

Eggs of 12 species of sod webworm were exposed for various periods to temperatures of 0, 10, and 45°C. Hatchability was compared with control eggs kept at 25°C. Short exposures to any temperature did not significantly affect percent hatch. Prolonged exposure resulted in a significant decrease in hatchability for several species at 0° and for all species at 45°C. There was a significant difference in hatchability between the 3 generations of Crambus teterrellus (Zincken) and of Pediasia trisecta (Walker) at extreme temperatures. Populations of Agriphila ruricolella (Zeller), collected at 2 elevations, differed significantly in hatching percentage and developmental rate

Enhanced Transmission Through Disordered Potential Barrier

Effect of weak disorder on tunneling through a potential barrier is studied analytically. A diagrammatic approach based on the specific behavior of subbarrier wave functions is developed. The problem is shown to be equivalent to that of tunneling through rectangular barriers with Gaussian distributed heights. The distribution function for the transmission coefficient $T$ is derived, and statistical moments \left are calculated. The surprising result is that in average disorder increases both tunneling conductance and resistance.Comment: 10 pages, REVTeX 3.0, 2 figures available upon reques

Chorion Characteristics of Sod Webworm Eggs

The egg chorion was investigated for 15 species of sod webworm moths (Lepidoptera: Pyralidae: Crambinae) collected in Tennessee. Liquid plastic was used for surface printing of chorion sculpturing. Scanning electron micrographs were utilized in construction of a taxonomic key to eggs of the Crambinae species studied and the characteristics illustrated

Exact transmission moments in one-dimensional weak localization and single-parameter scaling

We obtain for the first time the expressions for the mean and the variance of the transmission coefficient for an Anderson chain in the weak localization regime, using exact expansions of the complex transmission- and reflection coefficients to fourth order in the weakly disordered site energies. These results confirm the validity of single-parameter scaling theory in a domain where the higher transmission cumulants may be neglected. We compare our results with earlier results for transmission cumulants in the weak localization domain based on the phase randomization hypothesis

Getting the User’s Attention

CAN WE DELIVER INFORMATION the way our users want it--cheap, fast, and good? According to Stewart Bodner, associate chief librarian of the New York Public Library, that\u27s what users desire and what librarians and vendors must provide. But at least in the public library world, convenience trumps quality every time, Bodner went on to tell the audience at the annual meeting of NFAIS (National Federation of Abstracting and Information Services) in Philadelphia this February. NFAIS brought together company representatives and librarians to brainstorm ways to redirect users away from Internet search engines and the open web and toward high-quality information