Report Ld 50 of Cockroaches

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Pharmacology Report 1: Determination of an insecticide in cockroaches

Introduction
Pesticides are toxic and go through many different testings and procedures before they are put on the shelf in various industries. One general method that is used to asses toxicity of pesticides before released for sale is the LD50 (Lethal Dose 50) method. This method is conducted by calculating the most accurate dose of toxin that will kill animals 50% of the time. Before determining an accurate LD50 of a chemical however, a range finding analysis of the chemical will be performed in order to calculate the most accurate LD50. Undergoing this procedure includes using a wide-spread range of concentrations which are mostly preformed at log dose intervals. (H.P. Rang, M.M. Dale, J.M. Ritter and R.J. Flower, 2007).

Carbamate Propoxur is an insecticide that can inhibit the action of cholinesterase and disrupt nervous system function (Extension Toxicology network, Pesticide Information Profiles; http://extoxnet.orst.edu/pips/propoxur.htm). In this experiment propoxur was used to investigate the effects on the American cockroach nymphs.

The LD50 for one species is very different from another. In each LD50 test there is considerations that need to be understood such as age, weight, sex, health and diet (David Rall, Ph.D., former Director, National Toxicology Program “Inadequacy of the LD50 test” Found at http://www.pcrm.org/resch/anexp/LD50.htm). Each individual factor cannot be accurately monitored for each individual animal if randomly acquired. This is only one of the reasons why the LD50 test is not quite useful as it does not maintain a biological constant and that value therefore has little significance in testing toxicity.

Methodology
Refer to practical manual; however note change in purity of propoxur to 99.5% hence 0.2513g was used and also the use of 12 cups of 5 cockroaches making total number of nymphs used 60

Results

Table 1.1
This table shows the procedure used in order to create the suitable diluted solutions needed (Not including the EMK control)

| | Starting solution| | Volume of diluents|
Tube| Dilution required| Concentration| Vol. (mL)| Vol.| 1| 0.005%| 0.01%| 1 mL| 1 mL|
2| 0.01%| 0.1%| 1 mL| 9 mL|
3| 0.02%| 0.1%| 0.25 mL| 1 mL|
4| 0.05%| 0.1%| 1 mL| 1 mL|
5| 0.1%| 1.0%| 1 mL| 9 mL|

As you can see each tube has different means of measures weather it was in volume, concentration or the dilution percentage. This was done in order to achieve a variety of concentrations in calculating the LD50.

Table 1.2
This table shows the average weight of cockroaches in each group Group Name| Average Weight of Cockroaches (g)|
Group Anything| 0.534|
JAAMNL| 0.484|
#2| 0.515|
TA| value not provided|
SEX| 0.583|
Ebony| 0.590|
Class Average | 0.521 (includes unknown value for TA)|
As you can see from table 1.2 there were different results when weighing out the cockroaches as you can see the range of the results was 0.106g.

Table 1.3
This table shows the LD50 determination results of individual group. Cockroaches dead| Control| 0.005%| 0.01%| 0.02%| 0.05%| 0.1%| Cup 1| 0| 1| 1| 2| 3| 3|
Cup 2| 0| 0| 0| 2| 4| 5|
Average per cup| 0| 0.5| 0.5| 2| 3.5| 4|
Average % per cup| 0%| 10%| 10%| 40%| 70%| 80%|
Our group (group anything) showed some reliable results and from this table it is obvious to see that the LD50 lies between 0.2% and 0.5% note the trend as concentration increases so does fatality.

Table 1.4
This table shows the LD50 determination results by class groups | Control| 0.005%| 0.01%| 0.02%| 0.05%| 0.1%|
Group Anything| 00| 10| 10| 22| 34| 35|
JAAMNL| 00| 10| 13| 14| 44| 54|
#2| 10| 00| 11| 22| 55| 55|
TA| 00| 00| 01| 21| 43| 45|
SEX| 00| 10| 21| 22| 33| 55|
Ebony| 00| 10| 31| 42| 52| 45|
Average| 0.083| 0.33| 1.25|...
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