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Three species of orchard mites and their predators on apple trees in the southern Okanagan valley of British Columbia, and the effect of three insecticides on this complexChant, Donald Alfred January 1952 (has links)
The behaviour of the orchard mites Bryobia pretiosa (Koch) and Metatetranychus ulmi (Koch) and four species of predators was investigated both on unsprayed and on sprayed apple trees. On unsprayed trees the host mites were found to be most abundant on the east sides; no consistent directional preference was found for the predacious species. Small apple leaves supported the same number of M. ulmi per unit area as large leaves, but more mites of the genus Tetranychus. On unsprayed trees a negative correlation between the total number of predators and the number of host mites was recorded. In abandoned orchards the predators were capable of controlling the host mites and maintaining them at a level below that of economic significance. Each of the insecticides DDT, Parathion, and lead arsenate, was found to be very toxic to all species of predators recorded, and thus hindered or entirely prevented natural control of the host mites. In every instance lead arsenate and DDT produced an increase in the population of B. pretiosa, this effect being partially chemical and partially due to a lack of predators on the sprayed trees. Lead arsenate caused an increase in the population of M. ulmi whereas DDT reduced it to a slight extent. Under arid conditions Parathion caused an increase in the population of B.pretiosa; under less arid conditions the mite was eliminated. Parathion had no effect on M. ulmi in a commercial orchard while, in the same orchard, it caused a great increase in Tetranychus spp. The latter species were reduced by DDT in the commercial orchard. / Science, Faculty of / Zoology, Department of / Graduate
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Microbial interactions with Diazinon.Ralston, Walter Jay 01 January 1967 (has links) (PDF)
No description available.
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Laboratory tests with insecticides dispersed from the American Aerovap.Spear, Philip J. 01 January 1950 (has links) (PDF)
No description available.
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Characterization of the action of pyrethroids on the ciliary calcium channel of Paramecium tetraurelia.Symington, Steven B. 01 January 2000 (has links) (PDF)
No description available.
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Determination of toxicity and bioactivity of four organic insecticides recommended for control of pests in vegetable cropsRodriguez Salvatierra, Hugo Humberto 01 January 1996 (has links) (PDF)
This work was done to determine the toxicity and bioactivity of four organic insecticides and ultimately find answers about their toxic potential. Thus, farmers will be able to take the necessary precautions when using them. This investigation was performed in the Laboratory of Biology of the Eastern University Center (Chiquimula) at the University of San Carlos, Guatemala. In order to determine the acute toxicity and bioactivity of the organic insecticides ANONAZO, BOX, AJORIN, and NARCISO, five doses were used in albino mice and three concentrations in nauplii of brine shrimp (Artemia salina). The finney basic program was used for calculating the average lethal dose (DL50) and the average lethal concentration (CL50). The results showed that in albino mice, ANONAZO had a DL50=707.10 mg/kg of weight which is classified as slightly toxic according to the Williams table. However, a tendency towards being moderately toxic was also present. CAJA had a DL50=>5000 mg/kg of weight classifying it as practically non-toxic. AJORIN had a DL50=4530 mg/kg of weight corresponding to the slightly toxic classification. In addition, a tendency towards being practically non-toxic was present. NARCISO had a DL50=158.11 mg/kg of weight corresponding to the moderately toxic classification but on the border of highly toxic. In regards to bioactivity in nauplii of brine shrimp: Anonazo, Ajorin, and Narciso had values less than 1000 ppm, which indicates that they have bioactivity. Caja showed no bioactivity.
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The Residual Activity of Aldrin and Chlordane in Sandy SoilIneman, Frederick N. January 1964 (has links)
No description available.
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The cycling of chlorine-36 ring-labeled DDT in a marsh ecosystem /Meeks, Robert Leon January 1966 (has links)
No description available.
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Efficacy of Organic Insecticides and Repellents against Brown Marmorated Stink Bug in VegetablesMorehead, John Adam 19 July 2016 (has links)
The brown marmorated stink bug (BMSB), Halyomorpha halys (Stål), is a major pest of vegetable crops, fruit crops, and even ornamental plants in the Mid-Atlantic States. Organic growers have limited chemical options to manage this pest, and are in need of better management options. Several organically-approved insecticides including pyrethrins (Pyganic), azadirachtin (Aza-Direct), azadirachtin + pyrethrins (Azera), spinosad (Entrust), potassium salts of fatty acids (M-Pede), sabadilla alkaloids (Veratran D), extract from Burkholderia sp. (Venerate), and one experimental product, potassium salts + spinosad (Neudorff 1138), were evaluated for toxicity to BMSB nymphs and adults using lab bioassays and field trials on tomatoes and peppers. Another potential control option is to use natural chemicals to deter BMSB feeding in vegetables. Kaolinite [Al4Si4O10 (OH)8] (Surround WP); a white, plate-shaped, aluminosilicate mineral that is sprayed on plants to alter the appearance, feel, and smell of a plant to an insect. Essential oils (Ecotec) are chemicals produced by plants which are repellent and even toxic to certain insects, and by mimicking octopomine these chemicals disrupt the insect's neurotransmitters. Treatments were evaluated in choice test bioassays and field experiments on peppers using weekly applications of the highest labeled rates of the products. The results showed that, although some organically-approved insecticides demonstrate a high level of activity on BMSB in lab bioassays, none of these products appear to be effective at reducing stink bug damage to fruiting vegetables in the field. However, kaolinite provided significant control of BMSB nymphs (p=0.03) and adults (p=0.01) in both choice test bioassays and in field trials. Essential oils did not provide any significant control of BMSB in choice test bioassays or in field trials. Further research is needed to determine if the efficacy of kaolinite holds up under heavy pest pressure. / Master of Science in Life Sciences
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Influence of vegetation structure and food habits on effects of guthion 2S�� (Azinphos-methyl) on small mammalsSchauber, Eric M. 28 September 1994 (has links)
The Quotient Method (QM), a laboratory-based risk assessment methodology
used by the Environmental Protection Agency to evaluate pesticides for registration and
use, has not been thoroughly field-tested and its performance has not always been
reliable. My objective was to determine if variation in vegetation structure or diet of
exposed animals could result in adverse ecological effects that were not predicted by
the QM. In April and early May 1993, I established populations of herbivorous
gray-tailed voles (Microtus canicaudus) and omnivorous deer mice (Peromyscus
maniculatus) in 24 0.2-ha enclosures planted with alfalfa (Medicago sativa). Alfalfa in
12 enclosures was mowed on 22 June to reduce vegetation height. Small mammal
populations were monitored by live trapping from May through August 1993. On 14
July, an organophosphorus insecticide, azinphos-methyl, was applied at 0, 0.88, and
3.61 kg/ha. Insecticide residues were measured on canopy-level spray cards, soil
samples, and alfalfa. I compared the observed residue concentrations with predictions
based on the nomogram used to estimate exposure for QM risk assessments. I also
compared QM predictions of risk with observed effects on population size and growth,
survival, reproductive activity, recruitment, body growth, movements, and diet of the
small mammals.
Much of the insecticide reached ground level in mowed enclosures, but dense
alfalfa intercepted most of the spray in unmowed enclosures. The mean half-life of
azinphos-methyl on alfalfa was 3.4 days and was not affected by mowing. Mean
residue concentrations on mowed alfalfa and the top 15 cm of unmowed alfalfa were
underestimated by the QM exposure nomogram. Therefore, pesticides may pose greater
risk to organisms inhabiting sparse vegetation or the tops of plants than predicted by the
QM.
Treatment with azinphos-methyl at 3.61 kg/ha caused severe effects in both
mowed and unmowed enclosures on population size and growth, survival, recruitment,
and body growth of voles. Effects of azinphos-methyl on vole recruitment and body
growth and on survival of female voles were greater in mowed than in unmowed
enclosures. However, I did not find that population-level responses of voles to the
chemical differed between mowing treatments. Most effects on voles were of short
duration (<27 days) but vole densities in 3.61 kg/ha enclosures remained depressed >6
weeks after spraying. The 3.61 kg/ha application rate resulted in a 42% decrease in
deer mouse densities in mowed enclosures during the week of spraying, but the
insecticide had no adverse effects on deer mice in unmowed enclosures. In addition,
the insecticide may have reduced recruitment of deer mice in mowed enclosures.
Analysis of deer mouse feces indicated that consumption of arthropods increased in
insecticide-treated enclosures just after spraying occurred. Survival, reproductive
activity, body growth, and movements of deer mice were highly variable and not
significantly affected by azinphos-methyl.
Mowing resulted in greater residue concentrations than predicted and,
consequently, the insecticide adversely affected voles and deer mice in mowed
enclosures at application rates characterized as low risk by the QM. However, food
aversion or selective feeding on alfalfa tops may have resulted in similar exposure of
voles to the 3.61 kg/ha treatment in mowed and unmowed enclosures. I did not find
that insectivorous feeding behavior of deer mice made them more susceptible than
predicted. Although residue concentrations on alfalfa did not follow predictions, the
gross pattern of effects on small mammals was consistent with QM risk
characterization. However, the QM may underestimate exposure and risk when
pesticides are sprayed on sparse vegetation. / Graduation date: 1995
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Exposure and health risk assessment for farmers occupationally exposed to chlorpyrifos in Sri Lanka and drinking water and house dust analysis for chlorpyrifosAponso, G. Lalith M. 30 July 2001 (has links)
Graduation date: 2002
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