scholarly journals Toxicity of Three Formulations of Bacillus Thuringiensis Against Diamondback Moth, 1996

1998 ◽  
Vol 23 (1) ◽  
pp. 369-369
Author(s):  
P. W. Ivey ◽  
S. J. Johnson ◽  
Richard Story

Abstract A leaf-dip assay was used to test three commercial formulations of B. thuringiensis Berliner: Agree 50 WP, Dipel ES, and XenTari AS, against diamondback moth. Concentrations ([AI]/liter) were based on dilution series using the recommended “field” rates of the three formulations of B. thuringiensis. Dipel and Xen-Tari were tested at concentrations of 2.5, 0.25, 0.025, 0.0025, and 0.00025 [ml (AI)/liter]; Agree was tested at concentrations of 3.0, 0.3, 0.03, 0.003, and 0.0003 [g(AI)/liter]. Disks (20 mm diam) were cut from leaves of the above cabbage cultivar. Each disk was dipped into each test solution and hung vertically to dry at room temperature for about 1 h and then placed in petri dishes (100 X 15 mm) on top of a moistened filter peper (90 mm diameter). Five third instars were placed on each leaf disk in each petri dish and allowed to feed for 96 h, after which mortality was recorded. A larva was considered dead if it did not move when prodded with forceps. Tests with each concentration and the untreated control (distilled water) were replicated five times.

1994 ◽  
Vol 19 (1) ◽  
pp. 369-369
Author(s):  
R. L. Horsburgh ◽  
J. R. Warren

Abstract A large commercial apple grower reported failure in attempts to control TABM with airblast applications of Penncap M (2 pt/acre) combined with methomyl (3 pt/acre). At the time of the grower applications larval hatch had begun and most larvae were in the first or second instar. By the time larvae were entering the third instar (10 days after spray application) it was apparent that commercially acceptable control had not been achieved. In 1992 this grower also had poor control when Penncap M was applied to suppress redbanded leafroller and experiments showed that tolerance of Penncap M was present in the resident RBLR population (Horsburgh et al. 1992). This laboratory bioassay was begun on 3 Sep to determine tolerance of the TABM population to Penncap M and other insecticides. Seven treatments (including a water control) were selected and rates calculated on the basis of 300 gal of spray being applied per acre. The appropriate dosage of pesticide for each treatment was mixed with 1 gallon of 77°F water in clean 1 gallon battery jars. Twenty plastic petri dishes containing moistened filter paper were prepared and served as individual cages for twenty 3rd instars per treatment. The larvae, on single leaves, were immersed in the appropriate solutions for five seconds and the leaf placed on the moist filter paper. The petri dish cover was put in place and the cages held at room temperature (80°F) for the duration of the test. All larvae were examined at 24 hour intervals and mortality was recorded. Death of larvae was assumed when no movement was observed when the larvae were gently prodded with a blunt steel probe.


1999 ◽  
Vol 28 (4) ◽  
pp. 611-616 ◽  
Author(s):  
Marina Castelo Branco ◽  
Alexander G. Gatehouse

The effect of Diamondback Moth (Plutella xylostella L.) population density and plant age on the rate of ovarian development was investigated. In tests carried out in Petri dishes, the density of larvae/leaf disk affected the rate of ovarian development. A high proportion of moths from larvae reared on leak disks from two or four-month-old spring cabbage at a density of seven or 14 larvae/leaf disk were mature at emergence. But moths reared at the same type of plant at a density of 28 larvae/leaf disk were largely immature at emergence. When the larvae were reared at a density of 30 larvae/plant on two or four-month-old spring cabbage plants, a high proportion of females were mature at emergence. Crowding has an important effect on the rate of ovarian development in Diamondback Moth with possible consequences for the migratory potential of moths, as insect migration generally occurs when the ovaries of the females are immature. The density of moths necessary to increase the proportion of immature females in the field is probably higher than 30 larvae/plant.


2012 ◽  
Vol 59 (2) ◽  
pp. 253-262
Author(s):  
Halina Lipińska

Experiments were carried out under laboratory conditions in Department of Grass Science and Greenland Shaping in 2002-2004. Studies included six experiment series on Petri dishes set by means of complete randomization method in four replications. Following species were tested: <i>Festulolium</i>, <i>Festuca pratensis</i>, <i>Lolium perenne</i>, <i>Phleum pratense</i> and <i>Poa pratensis</i> making one or two-species combinations. Fifteen seeds of two species were arranged alternately in 1- centimeter distance on a Petri dish. Objects where seeds germinated with no neighborhood of other species (30 seeds on a dish), were control. The filter's humidity on Petri dishes was maintained by wetting it with distilled water. Achieved results revealed significant influence of blastokolins of tested grass species on seed germination and initial seedling growth. Secretion of germinating <i>Festulolium</i> seeds showed the highest activity. Reaction of tested grass species to allelochemicals varied. In reference to control objects, <i>Phleum pratense</i> among tested species was distinguished with the highest susceptibility to allelochemicals released during seed germination.


Author(s):  
А.С. ДАНИЛЬЧЕНКО ◽  
Т.Г. КОРОТКОВА ◽  
С.Ю. КСАНДОПУЛО

Приведены результаты исследований кинетики испарения воды при сушке смеси вода–белок при 60°С в изотермических условиях. Смесь готовили из дистиллированной воды, предварительно доведенной до кипения при атмосферном давлении, которую заливали в две чашки Петри по 20 мл в каждую, и яичного белка, добавленного в количестве 0,2 и 0,6 мл соответственно. Чашки Петри помещали в сушильный шкаф Memmert, оснащенный принудительной конвекцией и устройством контроля температуры. Навеску с чашкой Петри взвешивали через каждые 5 мин на аналитических весах Discovery. Установлено, что увеличение количества белка снижает скорость испарения воды в периоде постоянной скорости сушки, скорость испарения зависит от природы растворенного вещества. По окончании процесса испарения на дне чашки Петри обнаружена полупрозрачная высохшая пленка белка, что свидетельствует о конформационных перестройках белка в процессе убыли влаги и частичном растворении белка в воде в процессе испарения. The results of studies of the kinetics of evaporation of water during drying of the water–protein mixture at 60°C in isothermal conditions are given. The mixture was prepared from distilled water, pre-boiled at atmospheric pressure, which was poured into two Petri dishes of 20 ml each, and egg white added in an amount of 0,2 and 0,6 ml, respectively. Petri dishes were placed in a Memmert drying Cabinet equipped with forced convection and a temperature control equipment. The overhang with a Petri dish was weighed every 5 min on the analytical scales of Discovery. It was found that an increase in the amount of egg protein reduces the rate of evaporation of water in a period of constant drying rate and the rate of evaporation depends on the nature of the dissolved substance. At the end of the evaporation process, a translucent dried protein film is found at the bottom of the Petri dish, which indicates the conformational rearrangements of the protein in the process of moisture loss and partial dissolution of the protein in the water during evaporation.


1941 ◽  
Vol 41 (2) ◽  
pp. 197-224 ◽  
Author(s):  
R. B. Bourdillon ◽  
O. M. Lidwell ◽  
John C. Thomas

1. A slit sampler for air-borne bacteria is described, in which air is sucked through a narrow slit on to the surface of agar in an ordinary Petri dish.2. This method has proved very rapid and simple in use, and has appeared more efficient than other methods against which it has been tested.3. The collection efficiency for an aerosol consisting of Staph. albus, sprayed from distilled water as single cocci, is about 96%. The method thus collects the finest bacteria-carrying, particles almost as efficiently as coarser ones.4. In contrast to this, the exposure of plain open Petri dishes appears to collect the larger particles in the air of crowded rooms at least 200 times as efficiently as it does single washed bacteria. This highly selective effect renders it advisable to use great caution in evaluating tests made in plain open dishes.5. The methods of determining sampling efficiency, and their errors are discussed in detail.


2000 ◽  
Vol 132 (1) ◽  
pp. 69-80 ◽  
Author(s):  
D.J. Pree ◽  
L.A. Bittner ◽  
K.J. Whitty

AbstractThe toxicity of dicofol, pyridaben, formetanate HCl, and abamectin to European red mite, Panonychus ulmi (Koch), was determined using either a Petri dish or leaf dip bioassay (as potential field assay procedures) and was compared with results from a standard laboratory procedure that requires a Potter spray tower to treat leaf disks. Abamectin and pyridaben were the most toxic acaricides tested, and dicofol and pyridaben were more toxic when applied to Petri dishes than to leaf disks. Formetanate HCl was the least toxic acaricide tested by either leaf disk or leaf dip procedures. Diagnostic concentrations of pyridaben were determined as 5 mg active ingredient per litre (a.i./L) with the Petri dish assay and 15 mg a.i./L with the leaf disk assay. Mortality of European red mites to pyridaben at diagnostic concentrations was consistently 100% with the leaf disk assay and > 90% with the Petri dish assay. Residues of pyridaben on Petri dishes stored at 4 °C in a refrigerator were stable for at least 21 d. For dicofol, both leaf disk and Petri dish assays gave similar results, and 25 mg a.i./L, previously used as the diagnostic concentration in the Petri dish assay, resulted in > 99% mortality of the standard susceptible strain. This technique identified resistant individuals in all of the field populations tested. Abamectin applied at 2 mg a.i./L to leaf disks consistently gave 98–100% mortality, but results at 2 mg a.i./L with the Petri dish assay gave variable results and this was not a reliable technique for monitoring resistance. Concentrations of formetanate HCl required for the leaf dip assay were too high to be useful in field assays; however, all populations of European red mite tested using the leaf disk assay appeared susceptible. For the ovicide, clofentezine, mortality of eggs tested by the leaf disk assay at 100 or 500 mg a.i./L ranged from 89 to 100%. Results with the leaf dip procedure, using a 350 mg a.i./L suspension consistently resulted in > 96% mortality of eggs from susceptible field populations. These procedures are a useful tool in the development of resistance management programs for acaricides used in integrated pest management (IPM) systems for tree fruits.


2011 ◽  
Vol 4 (3) ◽  
pp. 130-134 ◽  
Author(s):  
João Antonio Zequi ◽  
Jose Lopes ◽  
Fernando Pereira Santos

Aedes (Stegomyia) aegypti (Linnaeus) e Culex (Culex) quinquefasciatus Say são importantes vetores de patógenos em áreas urbanas. Este trabalho teve como objetivo avaliar diferentes formulados comerciais contendo Bacillus thuringiensis israelensis de Barjac, no controle de Ae. aegypti e Cx. quinquefasciatus, verificando sua eficiência perante a potencia declarada. Testou-se os produtos Aquabac® XT 1200 UTI/mg, Teknar® 3000AAU/mg e Vectobac® AS 1200 UTI/mg, formulados líquidos, e os sólidos Vectobac® WDG 3000 UTI/mg, Vectobac® T 2200 UTI/mg e o formulado experimental Biouel 500 UTI/mg. Todos os produtos foram testados a temperatura de 25±2°C e os líquidos também a 15±2°C, 35±2°C e temperatura ambiente (25,37 a 28,73ºC). Os testes foram realizados utilizando-se 25 larvas no início do 4º estádio, em 150 mL de água destilada, com leitura de mortalidade 24 horas após exposição. Resultados foram analisados através de Probit calculando-se a CL50. A 25±2°C, os produtos Vectobac WDG e Vectobac T foram os mais eficientes para Ae. aegypti, com CL50 respectivamente de 0,10 (0,08 – 0,11) mg/L e 0,10 (0,09 – 0,11 mg/L). Para Cx. quinquefasciatus, os mais eficientes foram Vectobac WDG, Vectobac AS, Biouel e Vectobac T. Tomando como referência a potencia declarada dos produtos, o Biouel teve, proporcionalmente, melhor desempenho para as duas espécies. Nas temperaturas de 15±2°C, 35±2°C e na temperatura ambiente (25,37 a 28,37°C), Vectobac AS foi o mais eficiente para as duas espécies de Culicidae testadas. Na temperatura ambiente a 35±2°C, necessitou-se de menor concentração dos produtos para controle de Cx. quinquefasciatus em relação à Ae. aegypti. Control of Aedes (Stegomyia) aegypti and Culex (Culex) quinquefasciatus Through Formulated Containing Bacillus thuringiensis israelensis at Controlled Temperatures Abstract. Aedes (Stegomyia) aegypti (Linnaeus) and Culex (Culex) quinquefasciatus Say are important pathogen vectors in urban environments. This study was designed to evaluate commercial formulations containing Bacillus thuringiensis israelensis de Barjac for the control of Ae. aegypti and Cx. quinquefasciatus and to assess their efficiency as compared to manufacturers´ claims. The tested products were the liquid formulation of Aquabac® XT 1200 ITU/mg, Teknar® 3000AAU/mg, and Vectobac® AS 1200 ITU/mg, and the solid products Vectobac® WDG 3000 ITU/mg, Vectobac® Tablet 2200 ITU/mg, and the trial formulation of Biouel 500 ITU/mg. All products were tested at 25±2°C temperature and the liquid formulations were also tested at 15±2°C, 35±2°C, and at room temperature (25.37 to 28.73ºC). The experiments were conducted with 25 larvae at the early 4th stage, in 150 mL of distilled water; the dead larvae were counted 24 hours after product application. Results were analyzed using Probit to calculate CL50. The 25±2°C temperature, Vectobac WDG, and Vectobac Tablet were the most efficient in controlling Ae. aegypti, with CL50 of 0.10 (0.08 – 0.11) mg/L and 0.10 (0.09 – 0.11 mg/L), respectively. The most efficient products for Cx. quinquefasciatus were Vectobac WDG, Vectobac AS, Biouel, and Vectobac T. When the potency claimed by manufacturers was compared to our laboratory results, Biouel had the best performance for both species. Vectobac AS was the most efficient for both species of Culicidae tested at 15±2°C, 35±2°C and at room temperature (25.37 to 28.37°C). Lower product concentrations were required at 35±2°C room temperature to control Cx. quinquefasciatus than for Ae. aegypti.


Author(s):  
P. A. Madden ◽  
W. R. Anderson

The intestinal roundworm of swine is pinkish in color and about the diameter of a lead pencil. Adult worms, taken from parasitized swine, frequently were observed with macroscopic lesions on their cuticule. Those possessing such lesions were rinsed in distilled water, and cylindrical segments of the affected areas were removed. Some of the segments were fixed in buffered formalin before freeze-drying; others were freeze-dried immediately. Initially, specimens were quenched in liquid freon followed by immersion in liquid nitrogen. They were then placed in ampuoles in a freezer at −45C and sublimated by vacuum until dry. After the specimens appeared dry, the freezer was allowed to come to room temperature slowly while the vacuum was maintained. The dried specimens were attached to metal pegs with conductive silver paint and placed in a vacuum evaporator on a rotating tilting stage. They were then coated by evaporating an alloy of 20% palladium and 80% gold to a thickness of approximately 300 A°. The specimens were examined by secondary electron emmission in a scanning electron microscope.


1995 ◽  
Vol 20 (1) ◽  
pp. 329-329
Author(s):  
E. Guerrero-Rodriguez ◽  
S. Davalos-Luna ◽  
J. Corrales-Reynaga

Abstract Populations of MCR of commercial field corn from Arenal, Jalisco were exposed to nine insecticides of organophosphorous (OP), cabamate, organo chlorinated and pyrethroid groups. Larvae were collected from the roots of corn plants daily, and confined in polyethylene black bags of two kg capacity with humidity and germinated corn as food for larvae. Insects were taken to the laboratory of Sanidad Vegetal in Guadalajara, Jalisco. Dilutions of the insecticides tested were prepared using acetone from 500 to 5000 ppm (6 to 9 dosage/product). For this study 20 larvae of last instar were selected and 1 u, liter of the solution was placed topically on the thorax, after this, each larva was placed in a petri dish with a moistened paper towel and the petri dishes confined in a cardboard box to eliminate light. Mortality counts were carried out at 24 hours. Percent mortality was corrected by Abbott’s formula. The mortality data were analyzed by probit to obtain LC50 and LC,5 values for each insecticide.


1985 ◽  
Vol 25 (06) ◽  
pp. 945-953 ◽  
Author(s):  
Mark A. Miller ◽  
H.J. Ramey

Abstract Over the past 20 years, a number of studies have reported temperature effects on two-phase relative permeabilities in porous media. Some of the reported results, however, have been contradictory. Also, observed effects have not been explained in terms of fundamental properties known to govern two-phase flow. The purpose of this study was to attempt to isolate the fundamental properties affecting two-phase relative permeabilities at elevated temperatures. Laboratory dynamic-displacement relative permeability measurements were made on unconsolidated and consolidated sand cores with water and a refined white mineral oil. Experiments were run on 2-in. [5.1-cm] -diameter, 20-in. [52.-cm] -long cores from room temperature to 300F [149C]. Unlike previous researchers, we observed essentially no changes with temperature in either residual saturations or relative permeability relationships. We concluded that previous results may have been affected by viscous previous results may have been affected by viscous instabilities, capillary end effects, and/or difficulties in maintaining material balances. Introduction Interest in measuring relative permeabilities at elevated temperatures began in the 1960's with petroleum industry interest in thermal oil recovery. Early thermal oil recovery field operations (well heaters, steam injection, in-situ combustion) indicated oil flow rate increases far in excess of what was predicted by viscosity reductions resulting from heating. This suggested that temperature affects relative permeabilities. One of the early studies of temperature effects on relative permeabilities was presented by Edmondson, who performed dynamic displacement measurements with crude performed dynamic displacement measurements with crude and white oils and distilled water in Berea sandstone cores. Edmondson reported that residual oil saturations (ROS's) (at the end of 10 PV's of water injected) decreased with increasing temperature. Relative permeability ratios decreased with temperature at high water saturations but increased with temperature at low water saturations. A series of elevated-temperature, dynamic-displacement relative permeability measurements on clean quartz and "natural" unconsolidated sands were reported by Poston et al. Like Edmondson, Poston et al. reported a decrease in the "practical" ROS (at less than 1 % oil cut) as temperature increased. Poston et al. also reported an increase in irreducible water saturation. Although irreducible water saturations decreased with decreasing temperature, they did not revert to the original room temperature values. It was assumed that the cores became increasingly water-wet with an increase in both temperature and time; measured changes of the IFT and the contact angle with temperature increase, however, were not sufficient to explain observed effects. Davidson measured dynamic-displacement relative permeability ratios on a coarse sand and gravel core with permeability ratios on a coarse sand and gravel core with white oil displaced by distilled water, nitrogen, and superheated steam at temperatures up to 540F [282C]. Starting from irreducible water saturation, relative permeability ratio curves were similar to Edmondson's. permeability ratio curves were similar to Edmondson's. Starting from 100% oil saturation, however, the curves changed significantly only at low water saturations. A troublesome aspect of Davidson's work was that he used a hydrocarbon solvent to clean the core between experiments. No mention was made of any consideration of wettability changes, which could explain large increases in irreducible water saturations observed in some runs. Sinnokrot et al. followed Poston et al.'s suggestion of increasing water-wetness and performed water/oil capillary pressure measurements on consolidated sandstone and limestone cores from room temperature up to 325F [163C]. Sinnokrot et al confirmed that, for sandstones, irreducible water saturation appeared to increase with temperature. Capillary pressures increased with temperature, and the hysteresis between drainage and imbibition curves reduced to essentially zero at 300F [149C]. With limestone cores, however, irreducible water saturations remained constant with increase in temperature, as did capillary pressure curves. Weinbrandt et al. performed dynamic displacement experiments on small (0.24 to 0.49 cu in. [4 to 8 cm3] PV) consolidated Boise sandstone cores to 175F [75C] PV) consolidated Boise sandstone cores to 175F [75C] with distilled water and white oil. Oil relative permeabilities shifted toward high water saturations with permeabilities shifted toward high water saturations with increasing temperature, while water relative permeabilities exhibited little change. Weinbrandt et al. confirmed the findings of previous studies that irreducible water saturation increases and ROS decreases with increasing temperature. SPEJ P. 945


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