LOGARITHMIC TRANSFORMATION OF MAGNITUDE ESTIMATION DATA AND COMPARISONS OF SCALING METHODS

Recent studies comparing magnitude estimation to other scaling methods have been criticized for failure to submit the data to logarithmic transformation before statistical analysis, a procedure which can improve the ability of magnitude estimation scaling to differentiate among products. Data from one of these studies was available for re-analysis, which was conducted both with and without logarithmic transformation of magnitude estimation, category scales and line scales. The ability of magnitude estimation to differentiate among products was improved by log transformation, while the other methods were not. Improvements were associated in pan with reductions in positive skew and improved approximation of the normal distribution. In spite of this improvement, magnitude estimation remained slightly inferior to the other methods especially in the hands of an untrained consumer sample.     

Effects of Selected Chemical Pesticides on Agamermis unka (Nematoda: Mermithidae), a Parasite of the Brown Plant Hopper,Nilaparvata lugens

Selected commercial and technical grade pesticides were tested against the egg, preparasite and adult stages of Agamermis unka , a nematode parasite of the brown planthopper, Nilaparvata lugens . The commercial insecticide, diazinon (LC = 0.37 ppm), was most toxic to the 50 preparasites, followed by phenthoate (LC = 0.43 ppm), BPMC (LC = 0.44 ppm), IBP 50 50 (LC = 0.46 ppm), cartap hydrochloride (LC = 0.82 ppm) and buprofezin + isoprocarb 50 50 (LC = 1.11 ppm). The least toxic commercial pesticide tested was the fungicide, pencycuron 50 (LC = 2.19 ppm). Out of 12 technical grade insecticides tested, phenthoate, monocrotophos, 50 diazinon and carbofuran (LC = 0.37-0.46 ppm) were highly toxic to the preparasites, followed by 50 buprofezin, BPMC and fenitrothion (LC = 0.74-0.86 ppm). Fenthion, etofenprox, chlorpyrifos, 50 imidacloprid and MIPC (LC = 1.11-2.19 ppm) were the technical grade insecticides least toxic 50 to the preparasites. Most preparasites survived for up to 24 h at the low insecticide concentrations (0.63 and 0.31 ppm). Preparasites that were exposed to BPMC for 24 h at concentrations as high as 5.0 ppm and survived the treatments infected brown planthopper nymphs. Four selected insecticides-chlorpyrifos, BPMC, imidacloprid and carbofuran-had significant adverse effects on A. unka egg hatching. Eggs that were in the insecticide solution for 168 h fared poorly with imidacloprid having the best survival ( > 2% of the eggs hatching at 0.04 ppm). No eggs hatched from the other insecticide treatments. Three selected insecticides, BPMC, imidacloprid and chlorpyrifos, tested against adult A. unka showed that most adults survived the exposure to the insecticides between 0.31 and 2.5 ppm. At 5.0 ppm of BPMC or chlorpyrifos none of the adults survived, whereas with imidacloprid 70% of the adults survived. Egg deposition by the surviving adults was greatly reduced in those treated with the insecticides compared with those in the controls. Imidacloprid had some negative impact on the preparasites' ability to infect BPH nymphs, but it had the least detrimental effect of the insecticides tested on preparasite survival and on the eggs and adults of A. unka .     

Novel fungal disease in complex leaf‐cutting ant societies

Abstract 1. The leaf‐cutting ants practise an advanced system of mycophagy where they grow a fungus as a food source. As a consequence of parasite threats to their crops, they have evolved a system of morphological, behavioural, and chemical defences, particularly against fungal pathogens (mycopathogens). 2. Specific fungal diseases of the leaf‐cutting ants themselves have not been described, possibly because broad spectrum anti‐fungal defences against mycopathogens have reduced their susceptibility to entomopathogens. 3. Using morphological and molecular tools, the present study documents three rare infection events of Acromyrmex and Atta leaf‐cutting ants by Ophiocordyceps fungi, agenus of entomopathogens that is normally highly specific in its host choice. 4. As leaf‐cutting ants have been intensively studied, the absence of prior records of Ophiocordyceps suggests that these infections may be a novel event and that switching from one host to another is possible. To test the likelihood of this hypothesis, host switching was experimentally induced, and successfully achieved, among five distinct genera of ants, one of which was in a different sub‐family than the leaf‐cutter ants. 5. Given the substantial differences among the five host ants, the ability of Ophiocordyceps to shift between such distant hosts is remarkable; the results are discussed in the context of ant ecological immunology and fungal invasion strategies.     

AN INTEGRATING RECORDER FOR PHOTOSYNTHETICALLY ACTIVE RADIANT ENERGY WITH IMPROVED RESOLUTION

A device counting fixed amount of parcels of radiant energyefficient in photosynthesis (wavelength region 400 to 720 mµand recording their total as a digital reading on a counteris described. Radiant energy is transformed by means of a phototubeto electrical current which becomes divided into individualparcels by cycles of charging .and discharge of a condenserbetween two fixed values of potential, and the number of thesecycles is counted. From instruments of similar design published earlier the onepresented here is distinguished mainly (1) by improved linearityof response in the integrating circuit down to slow countingrates and (2) by the design of a nonselective detector (in thelimited range of wavelengths indicated) based on a vacuum emissionphototube, which may be combined with the simple integratingcircuit used. Thus totals of irradiance (throughout the rangeof intensities of solar radiation) may be obtained directlyin units of energy or in the number of quanta. A very reliable and stable receiver with energy proportionalresponse in the region of wavelength 400–720 mµ(with possible extension up to 1,000 mµ) was realizedusing a vacuum emission photocell with photosensitive surfaceof the double-peak emission type (covering the range from nearUV to near IR) and precisely counterbalancing its spectral sensitivitycurve by selective absorption glass filters. The RENTSCHLER's type integrating circuit with a cold cathodedischarge tube was improved by increasing the maximum countingrate on one side (damping germanium diodes across the coilsof relay and counter) and by minimization of leakage in parallelto spare condenser (the contact which shortcircuits the condensersimultaneously with ignition of the discharge tube). ¹ Dedicated to Prof. H. TAMIYA on his 60th birthday. (Received November 24, 1962; )     

Comparison of adult mosquito community structure on various habitats

The community structure of adult mosquitoes was compared from New Jersey light trap collections in six different types of habitats in Citrus County, Florida, USA. From October 1998 to December 2000, mosquitoes were collected three times a week from the following habitats (swamps, swamps and freshwater marshes, pine fiat-woods, pine fiat-woods and scrub, salt marshes, and salt marshes and mangroves). Mosquito density was highest in the swamps and freshwater marshes habitat, with an average of 95.65 specimens per trap.Density was lowest in the flatwoods and scrub habitat, with an average of 14.38 specimens per trap. Species dominance differed among habitats. Salt marshes produced the greatest aggregation index, while pine flatwoods produced the lowest. Conversely, diversity analysis showed that pine flatwoods had the greatest diversity, while salt marshes the lowest diversity. Similarity indices indicated that the adult mosquito communities from pine flatwoods and pine flatwoods and scrub were very similar (0.8583). The adult mosquito community of salt marshes was different from that of swamps and freshwater marshes (the similar index was 0.0217).     

Phytochrome control of the growth and development of Rumex obtusifolius under simulated canopy light environments*

Abstract Studies on the growth and development of Rumex obtusifolius seedlings under simulated shade conditions show that both light quantity and quality contribute to the observed responses. In the shade situation the plants have lower dry matter, lower leaf area and lower net assimilation rates. Petiole elongation occurs under shade conditions only after transfer of the plants from non-shade environments. The effects of light quality are related to phytochrome photoequilibria set up by the increased relative photon flux in the far-red found under vegetation canopies.     

Capture and Ingestion of Paramecium by Didinium nasutum

SYNOPSIS. This study attempts to analyze how a number of specialized organelles are coordinated in a rapid but complex sequence of events during the capture and ingestion of prey by Didinium . Accidental contact between a Paramecium and the proboscis of a hungry Didinium causes instantaneous discharge of 2 kinds of extrusive organelles from the latter. The short pexicysts attach to the surface of Paramecium but do not penerate. The long toxicysts penetrate the victim, altho their proximal end s remain embedded in the proboscis of Didinium . Cytoplasmic streaming pulls the discharged toxicysts inward, and since they are firmly attached to the prey, the latter is drawn steadily into the cytostome. As the prey is being swallowed, it is compressed, and its volume is reduced by elimination of fluid. When the prey is completely inside the predator, the temporary cytostome closes, and the proboscis is reformed.