THE BIOLOGY OF LAEMOPHLOEUS FERRUGINEUS (STEPH.)

1949 ◽  
Vol 27d (3) ◽  
pp. 112-148 ◽  
Author(s):  
R. Omar Rilett
Keyword(s):  
Relative Humidity ◽  
Larval Feeding ◽  
Stored Grain ◽  
Whole Wheat ◽  
Morphological Studies ◽  
First Instar ◽  
Significant Acceleration ◽  
Wheat Kernels ◽  
Very High ◽  
Gain Access

Life history and morphological studies were made on Laemophloeus ferrugineus (Steph.), a coleopterous pest of stored grain and other products.Temperature greatly affected the rate of development of L. ferrugineus. At a relative humidity of 75%, eggs at 80° F. hatched in four to five days, at 90° F. in three to four days, and at 100° F. in two to three days. Similarly, the period from hatching of the egg to the emergence of the imago at 70° F. was from 69 to 103 days, at 80° F. from 26 to 38 days, at 90°F. from 19 to 33 days, and at 100° F. from 17 to 26 days. First instar larvae did not survive at a temperature of 110° F.An increase in relative humidity within the range from 50 to 75% accelerated development during the larval feeding period. Above 75% relative humidity there was no significant acceleration of development. Mortality was very high at relative humidities below 50%—all larvae failing to develop at a relative humidity of 25%. At 90° F. the period from the hatching of the egg to the emergence of the imago at 50% relative humidity was from 28 to 42 days, at 65% relative humidity from 23 to 33 days, at 75% from 19 to 25 days, at 90% relative humidity from 18 to 25 days, and at 100% relative humidity from 18 to 27 days. The optimum environmental condition for the development of L. ferrugineus was from 90° F. to 100° F. at a relative humidity of 75% or higher.L. ferrugineus populations increased more rapidly in whole rye and wheat grain than in the same materials when they were coarsely ground. Just the opposite was true in the case of oats, barley, corn, sunflower, flax, and soybeans. Whole kernels of rye, wheat, corn, and rice were decreasingly susceptible to injury in the order named, while whole kernels of oats and barley, and the seeds of sunflower, flax, and soybeans were practically free from injury by L. ferrugineus at humidity levels normally occurring in stored grains and seeds. Although first instar larvae did gain access to the wheat germ of grain described commercially as being "whole, sound, and undamaged", they were unable to successfully attack whole wheat kernels that had no breaks in their bran layers. The breaks need only to be microscopic in size to allow penetration by the larvae.

Numerical investigation of low relative humidity aeration impact on the moisture content of stored wheat

2016 ◽  
Vol 08 (02) ◽  
pp. 1740002
Author(s):  
Faten Hammami ◽  
Salah Ben Mabrouk ◽  
Abdelkhader Mami
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Numerical Investigation ◽  
Stored Grain ◽  
High Moisture ◽  
Insect Management ◽  
Moisture Management ◽  
Respiration Rates ◽  
Sufficient Energy ◽  
Wheat Kernels

High moisture content wheat kernels are subject to elevated respiration rates due to enzyme activity and mould growth that reduce the dry grain and may produce sufficient energy which may be harmful to wheat quality. Grain aeration provides a powerful nonchemical stored grain insect management. Currently, aeration is a suitable and economical device to overcome this problem. The moisture management is vital to prevent spoilage in stored grain. The objective of this study is to investigate the influence of using low relative humidity (RH) aeration on the wheat moisture content. The numerical investigation based on heat and mass balances is developed and used to simulate the evolution of grain temperature and moisture under various air RH in a wheat storage silo. Results show that the dehumidification of blown air had greater potential for decreasing RH of interstitial air and wheat moisture at [Formula: see text]C temperature and RH of 40%, 50% and 60%.

Factors influencing the Action of Dust Insecticides

1950 ◽  
Vol 41 (1) ◽  
pp. 1-61 ◽  
Author(s):  
W. A. L. David ◽  
B. O. C. Gardiner
Keyword(s):  
Relative Humidity ◽  
Soft Materials ◽  
Experimental Procedure ◽  
Hard Materials ◽  
Dust Clouds ◽  
Factors Influencing ◽  
Before And After ◽  
Sudan Iii ◽  
Insecticidal Action ◽  
Gain Access

The methods used to investigate the properties of dusts are described and, in a theoretical section, the relevance of the various physical properties to insecticidal action are considered.In order to investigate the effect of toxic and non-toxic dusts on insects the experimental procedure was simplified to eliminate all difficulties associated with the formation of uniform dust clouds and deposits. In problems relating to the adherence of the dusts to insects the actual quantity of dust was measured either by weighing the insects before and after dusting or by dyeing the dust with Sudan III and determining the quantity colorimetrically. The experiments were all conducted under known conditions of temperature and humidity.Non-toxic dusts killed insects by causing them to lose water. Not all non-toxic powders were equally effective when conditioned to the same relative humidity. All were without effect at saturated humidity and became progressively more rapid in action as the humidity at which the test was carried out was decreased (p. 32).The non-toxic dusts caused the insects to lose water by abrading certain areas of the cuticle ; the more extensive the abrasion the more quickly the insects died (p. 27).To be effective as an abrasive the dust must be hard and finely ground and, perhaps also, sharply angular. Thus materials which ranked high in Moh's scale of hardness were in general more effective than soft materials and hard materials became quite ineffective unless they contained material below about 10 μ, diameter. Presumably the coarser materials could not gain access to the articulations, etc., where abrasion usually occurred. This effect can be seen clearly with carborundum powders. Sharply angular glass was more effective than the same powder converted into rounded spheres (pp. 25–31).

scholarly journals Water Vapor Pressure Deficit in Portugal and Implications for the Development of the Invasive African Citrus Psyllid Trioza erytreae

Insects ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 229 ◽  
Author(s):  
Paulo Eduardo Branco Paiva ◽  
Tânia Cota ◽  
Luís Neto ◽  
Celestino Soares ◽  
José Carlos Tomás ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Vapor Pressure ◽  
Vapor Pressure Deficit ◽  
Water Vapor Pressure ◽  
Control Measures ◽  
Effective Control ◽  
First Instar ◽  
Trioza Erytreae ◽  
Water Vapor Pressure Deficit

African citrus psyllid (Trioza erytreae (Del Guercio)) is a vector insect of the bacterium Candidatus Liberibacter africanus, the putative causal agent of Huanglongbing, the most devastating citrus disease in the world. The insect was found on the island of Madeira in 1994 and in mainland Portugal in 2015. Present in the north and center of the country, it is a threat to Algarve, the main citrus-producing region. Trioza erytreae eggs and first instar nymphs are sensitive to the combination of high temperatures and low relative humidity. Daily maximum air temperature and minimum relative humidity data from 18 weather stations were used to calculate the water vapor pressure deficit (vpd) from 2004 to 2018 at various locations. Based on the mean vpd and the number of unfavorable days (vpd < 34.5 and vpd < 56 mbar) of two time periods (February to May and June to September), less favorable zones for T. erytreae were identified. The zones with thermal and water conditions like those observed in the Castelo Branco and Portalegre (Center), Beja (Alentejo), Alte, and Norinha (Algarve) stations showed climatic restrictions to the development of eggs and first instar nymphs of African citrus psyllid. Effective control measures, such as the introduction and mass release of Tamarixia dryi (Waterson), a specific parasitoid, and chemical control are necessary in favorable periods for T. erytreae development, such as in spring and in areas with limited or no climate restrictions.

scholarly journals Evaluation of Microbial and Conventional Insecticides for Control of Larval European Corn Borer on Whorl Stage Corn, Clay Center, Ne, 1995

1996 ◽  
Vol 21 (1) ◽  
pp. 218-218
Author(s):  
Terry A. DeVries ◽  
Robert J. Wright
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Wind Direction ◽  
Growth Stage ◽  
Crop Growth ◽  
Larval Feeding ◽  
Egg Masses ◽  
Crop Growth Stage ◽  
Over The Top

Abstract Bacillus thuringiensis formulations and conventional insecticides were evaluated for efficacy against larval ECB in whorl stage field corn. All plots were planted without soil insecticide on 16 May. The experimental design was a RCB with 4 replicates. Each plot consisted of a single row, 40 ft long with a 30-inch row spacing. Plots were artificially infested with black-head stage ECB egg masses. The egg masses were deposited on wax paper discs, precounted in the laboratory and placed in the whorl of the infested plants on 30 Jun and 9 Jul. Crop growth stage was 37 and 57 inches extended leaf height, respectively. The same 5 plants in each treatment replicate were infested with 10 egg masses per infestation date. All granular insecticides were applied on 13 Jul. Environmental conditions were: air temperature, 81°F; wind direction and speed, west (250°) at 7 mph; relative humidity, 53%; and crop growth stage, 63 inches extended leaf height. A 10-inch Almaco smooth belt cone rear mounted on a Hahn Hi-Boy was used to apply preweighed amounts of the granular insecticides over the top of the plant whorls (G). Liquid insecticides were applied on 15 Jul. Environmental conditions were: air temperature, 74°F; wind direction and speed, east (80°) at 5 mph; relative humidity, 76%; and crop growth stage, 67 inches extended leaf height. A CO2 pressurized backpack sprayer at 30 psi was used to apply a band application over the top of the whorl (total spray volume = 1050 ml/plot) of premeasured amounts of the liquid insecticides (L). All infested plants were evaluated for ECB larval feeding damage on 14-15 Aug. The stalks of the infested plants were split lengthwise and the accumulated length and number of cavities in the 5 plants per treatment replicate were used to evaluate ECB larval damage. The percent infestation at evaluation was determined by the plants with a minimum of 1 cavity per treatment replicate. Data were analyzed by ANOVA for RCB with mean separation using DMRT.

Diffusion of water vapor through human skin in hot environment and with application of atropine

1959 ◽  
Vol 14 (2) ◽  
pp. 276-278 ◽  
Author(s):  
Konrad J. K. Buettner ◽  
Frederick F. Holmes
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Human Skin ◽  
Liquid Water ◽  
Water Loss ◽  
Diffusion Resistance ◽  
Vapor Transfer ◽  
Hot Environment ◽  
Human Forearm ◽  
Very High

At room temperatures between 20° and 40°C, vapor transfer through skin of human forearm was tested with four small heated bottles containing air of humidities ranging from 2 to 100% relative humidity. Exposure times ranging from 30 to 120 minutes had no influence on results. Water loss or gain of skin were observed for the different bottles. At very high humidities, liquid water deposit on the skin was measured by weighing a blotter. Skin vapor loss decreases systematically when bottle moisture increases. This increase is enhanced at room temperatures above 24℃, where total loss into a dry bottle increases more than fivefold. This increase seems only partially caused by sweat and partially by a decrease of the skin diffusion resistance. Tourniquet and locally applied atropine did not affect vapor transfer in a cool room. In a hot room, the tourniquet lowered the vapor loss by only 20%, whereas atropine drastically curtailed vapor loss. Submitted on August 25, 1958

Studies on the biology of the palm aphid, Cerataphis variabilis (Homoptera: Pemphigidae), on Raphia hookeri–1: Developmental period of the immatures, fecundity and longevity of the apterous adults

1985 ◽  
Vol 6 (2) ◽  
pp. 177-181 ◽  
Author(s):  
D. A. Enobakhare
Keyword(s):  
Relative Humidity ◽  
Developmental Period ◽  
Fourth Instar ◽  
First Instar ◽  
Raphia Hookeri

AbstractThe biology of the aphid, Cerataphis variabilis H.R.L., on Raphia hookeri Mann & Wendl., was studied in the laboratory and the field using a ‘clip-on’ cage and a sleeve cage. The first instar lasted 5.1 days. The second and third instars each lasted 2.45 days, while the fourth instar lasted 2.4 days. The total developmental period of the nymphs was 11.3 days at 26.4 ± 1.43°C and r.h. 83 ± 1.46%; 11.6 days at 26.4 ± 1.63°C and r.h. 85 ± 1.19%; 12.9 days at 27.9 ± 1.04°C and r.h. 75.5 ± 1.64%; 12.95 days at 27.8 ± 0.33°C and r.h. 69 ± 1.23%; 15 days at 21.4 ± 0.58°C and r.h. 45 ± 1.77%. These periods were significantly different at 5% level (LSD = 0.59 days). The higher the temperature and relative humidity the shorter the developmental period (with temperature: r = −0.69, 20.8–28.9°C; r.h.: r = −0.97, 43.2–86.2%). The number of progeny per adult ranged from 54 to 60 in a period of 28–31 days. The longevity ranged from 31 to 34 days.

A Water-Trap for Detecting Insects in Stored Grain

1957 ◽  
Vol 89 (4) ◽  
pp. 188-192 ◽  
Author(s):  
F. L. Waiters ◽  
G. A. Cox
Keyword(s):  
Relative Humidity ◽  
Laboratory Experiments ◽  
Stored Grain ◽  
Water Trap ◽  
Insect Infestations ◽  
Sensitive Method

Much of the losses due to insects in stored grain occur when infestations remain unnoticed because of infrequent or inadequate sampling, There is clearly a need for a simple, sensitive method of indicating the presence of insects in stored grain before they become sufficiently numerous to occur in grain samples.At the Winnipeg laboratory, jars of water are sometimes used to increase the relative humidity above wheat containing cultures of rhe rusty grain beetle, Laemophloeus ferrugineus Steph. The fact that adults were often trapped in the water suggested a method of detecting insect infestations in stored grain. This paper reports field and laboratory experiments on the general usefulness of a water-trap to detect insects in stored grain.

Fire and explosive properties of plant materials used in the production of compound feed

2019 ◽  
Vol 570 (3) ◽  
pp. 11-14
Author(s):  
Maciej Celiński ◽  
Agnieszka Gajek ◽  
Michał Gloc
Keyword(s):  
Large Scale ◽  
Dust Explosion ◽  
Grain Production ◽  
Stored Grain ◽  
Rescue Operation ◽  
Plant Materials ◽  
Grain Processing ◽  
Materials Used ◽  
Explosive Properties ◽  
Very High

Extremely large scale of grain processing leads to a very high risk of incidents related to fire or dust explosion. Only in 2018 there were several outbreaks associated with the storage and transport of grain materials, the largest of which took place in May in South Sioux City, Nebraska. Poland is one of the largest grain producers in Europe and in the world. The annual grain production in Poland is about 35 million tons, including about 10 million tons of wheat, 5 million tons of triticale, 4 million tons of barley and 1.5 million tons of oats. Such an amount of grain material means that there is a high probability of failure during the storage processes (i.e. drying, pouring), transport and processing. Current research shows that of all dust explosions, those related to the food-agricultural and fodder industry account for nearly 25%. The most vulnerable are silos, dedusting and ventilation systems (including dryers and warehouses for drying grains). In October 2013, in the BulkTerminal in Gdańsk, there was an explosion and fire in a grain silo. The rescue operation lasted nearly 4 hours and about 10 tons of grain have burned (20% of the total stored grain material). The purpose of this article is to describe the results of research on the phenomenon of flammability and explosibility of industrial dusts on the four most popular grains in Poland.

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