Table of Contents
- Introduction 3
- Methods 3
- Results 4
- Discussion 6
- Conclusion 7
- Bibliography 8
- Appendix 9
- Introduction
American cockroaches are one of the most common pests found in Australia as well as many other countries. It has been well stated by Dahlgren (2014) that along with American cockroach, oriental cockroach and German cockroach are also found in Australia. However, among them, the American cockroach is the largest in its species. The average body length of the American cockroach is 35-40 mm. Through commerce, American cockroaches have spread all over the world and can be found in large and commercial buildings. Specifically, it can be found in many places where food is stored or being prepared. As identified by Mbowane (2014), American cockroaches spread a large number of diseases to human beings as it carries around 50 types of micro-organisms and pathogens. The diseases caused due to such nymph cockroaches include food poisoning, typhoid, diarrhoea, and dysentery. Other than that, Nodez et al. (2018) also stated that long term health problems and asthma are also generated due to the allergen generated by the pests.
Carbamates are insecticide composed of methyl carbamate and carbamic acid. The activities of such organic compound are it acts as a pesticide for the garden, home and indoor due to its lower dermal toxicities towards cockroaches. On the other hand, propoxur also termed as Baygon is a non-systemic insecticide that targets cockroaches by jamming the activity of acetylcholinesterase. In addition, it has a long residual effect. However, the limited dose must be used to kill cockroaches or else it can create difficulties for humans. Hence, the acute toxicity of insecticide should be analysed by examining the LD50 of propoxur. It has been well stated by Qian et al. (2010) that individual dose of propoxur insecticide can kill fifty percent of cockroaches. The aim of this experiment is to analyse the concentration of the carbamate insecticide propoxur that will kill between 15 % and 85 % of the test population through the comparison of class 2017 and class 2019. - Methods
In relation to the method for this experiment, the 91707 Subject Manual of Pharmacology has been considered from page 29-35 where the illustrated experiment has been done from page LD-LD2. Other than that, 0.2562g of technical grade material has been weighted out as this experiment is based on the use of 97.6% purity of Propoxur. - Results
Probit log graph
(Figure 1: Probit log graph of Class 2017 and Class 2019 of American cockroach mortality (%) against different propoxur dose concentration.)
In relation to Figure 1, the Probit Log graph highlights the percentage of death response of American cockroaches based on different concentration dose of Propoxur for the Class of 2017 and 2019. This graph has been plotted through the use of calculated data illustrated in Table 3 and Table 4 (Appendix). The dot highlights class 2019 data and cross represents 2017 data in the graph. Furthermore, the line of best has been also indicated for both the class of 2017 and 2019. It has been observed that the increase in the concentration of Propoxur, increases the death of American cockroaches. On the other hand, the graph also highlights the value of LD50 for class 2017 which is 0.04 (%w/v) and for class 2019 is 0.004 (%w/v), in Table 5 (Appendix). The control on Class 2019 is 40% death response and the class 2019 is an outlier.
The data attained through the experiment were gathered after 24 hours application of different dose of concentration of propoxur on the American cockroaches. The death was recorded accordingly.
Linear-log graph
(Figure 2: Linear log graph of Class 2017 and Class 2019 of American cockroach mortality (%) against different propoxur dose concentration.)
In relation to Figure 2, the Linear Log graph highlights a number of death response of American cockroaches in percentage for both Class 2017 and 2019 against different propoxur dose concentration. In addition, trend lines for both the class of 2017 and 2019 have been drawn. The orange dot represents class 2019 and blue dots represent class 2017. Furthermore, the LD50 has been converted for both the class 2017 and 2019 to mg/kg as illustrated in Table 2 (Appendix). Other than that, the average mass of cockroaches of class 2019 is 0.579g after working out. On the other hand, the average mass of cockroaches of class 2017 is 0.431g which was given. It has been observed that the death response of 2017 class is 40 % whereas for the 2019 class it was highly limited. The LD50 for class 2017 is 0.038 (%w/v) and class 2019 is 0.010 (%w/v), as illustrated in Table 6 (Appendix) along with entire calculation.
The data attained through the experiment were gathered after 24 hours application of a different dose of concentration of propoxur on the American cockroaches. The death was recorded accordingly.
LD50 Linear-log graph Probit-log graph
LD50 of class 2017 0.882 mg/kg 0.928 mg/kg
LD50 of class 2019 0.173 mg/kg 0.069 mg/kg
Table- 1 (Comparison of LD50 (mg/kg) for Class 2017 and 2019 based on Probit log graph and Liner long graph)
In relation to Table 1, it has been analysed that both Linear Log graph and Probit Log graph for LD50 of class 2017 is relatively higher form LD50 of class 2019. Hence, it can be stated that the death response of class 2019 is an outlier compared to class 2017.
- Discussion
As put forward by Rahimian et al. (2018), the female American nymph cockroaches have more tolerance levels of propoxur compared to adult males. In relation to Table 1, it has been analysed that the method utilised in the class of 2017 have been valid and significant compared to the class of 2019 for killing the cockroaches. Other than that, the results attained through the experiment highlights that the increase of carbamate Propoxur insecticide doses certainly increases the mortality rate of American cockroaches. It has been clearly illustrated in Table 4 which depicts 40% mortality at 0.1 w/v concentration. This reveals that the increase in doses of propoxur leads to death of the cockroach population. On the other hand, Saenmanot (2016) highlighted that the fat of female cockroaches is relatively high compared to the male cockroaches; hence, the need for higher concentration of propoxur dose is significant for killing the population.
In relation to such context, Table 4, highlights that 0.02% concentration of propoxur leads to 50% of mortality rate for class 2019. On the other hand, in Table 3, 0.1 concentration of propoxur for class 2017 highlights 73% of a mortality rate within the cockroach population. Hence, it has been observed that increasing the dose of concentration of propoxur can certainly lead to the death of American cockroaches. Other than that, the experiment conducted by Salehi et al. (2016) revealed that the thickness of cuticles critically impacts the concentration of propoxur. Based on such context, it has been found that LD50 for 2017 class is relatively higher than in 2019 indicating the need for the increasing concentration of propoxur. The variability in the results identified through the experiment can be caused due to human errors as well due to change in appropriate dilution. However, the entire method used for this experiment revealed significant findings of the study based on the analysis of LD50 of carbamate propoxur upon American nymph cockroaches in order to kill the population. - Conclusion
In conclusion, it can be stated that there were significant challenges for conducting the experiment as the gender of the cockroach population were different which affected the appropriate concentration dose of propoxur. However, the appropriateness in one general trend has been identified which is an increase in propoxur concentration can certainly lead to an increase in mortality of cockroaches. The concentration of LD50 has been significant for gaining 40% death of American cockroaches in the Class 2017 whereas Class 2019 results were an outlier.
- Bibliography
Dahlgren, L., 2014. Mechanisms of differential toxicity between honey bee (Apis mellifera L.) castes with an emphasis on coumaphos.
Mbowane, C., 2014. Efficacy evaluation of Mohlolo Insecticide Bait on German Cockroach, Blattella Germanica L (Doctoral dissertation).
Nodez, S.M.M., Rafatpanah, A., Khosravani, M., Hakak, F.S. and Paksa, A., 2018. Susceptibility status of German cockroaches, Blattella germanica (L.) to carbamate and pyrethroid insecticides within surface contact method in Shiraz city, Iran. Journal of Entomology and Zoology Studies, 6(2), pp.1043-1046.
Qian, K., Wei, X.Q., Zeng, X.P., Liu, T. and Gao, X.W., 2010. Stage-dependent tolerance of the German cockroach, Blattella germanica for dichlorvos and propoxur. Journal of Insect Science, 10(1).
Rahimian, A.A., Hanafi-Bojd, A.A., Vatandoost, H. and Zaim, M., 2018. A Review on the Insecticide Resistance of Three Species of Cockroaches (Blattodea: Blattidae) in Iran. Journal of economic entomology, 112(1), pp.1-10.
Saenmanot, S., 2016. Insecticidal activity of Thai botanical extracts against German cockroach, Blattella germanica (l.)(Orthoptera: Blattellidae) (Doctoral dissertation, Chulalongkorn University).
Salehi, A., Vatandoost, H., Hazratian, T., Sanei-Dehkordi, A., Hooshyar, H., Arbabi, M., Salim-Abadi, Y., Sharafati-Chaleshtori, R., Gorouhi, M.A. and Paksa, A., 2016. Detection of bendiocarb and carbaryl resistance mechanisms among German cockroach Blattella germanica (Blattaria: Blattellidae) collected from Tabriz Hospitals, East Azerbaijan Province, Iran in 2013. Journal of arthropod-borne diseases, 10(3), p.403. - Appendix
Table 2: Number of American Cockroaches dead by the application of different concentration of Propoxur and average mass of cockroaches in each group (in Class 2019)
Class 2019
Group Control 0.01% 0.02% 0.05% 0.1% Average mass of Cockroaches
Group 1 0 0.5 5 5 5 0.602g
Group 2 4 2 5 5 5 0.969g
Group 3 2 5 5 5 5 0.167g
Class Average Weight 0.579g
The average mass of cockroaches of class 2019 is 0.579g after working out.
The average mass of cockroaches of class 2017 is 0.431g which was given
Table 3: result of mortality rate of American cockroaches in different concentration propoxur between class 2017
Class 2017
Concentration of Propoxur Average Mortality Rate (%) of Class 2017 Standard Deviation
Control (0%) 0 0
0.01% 18 3.5
0.02% 30.7 7
0.05% 58 15
0.1% 73 20
Table 4: result of mortality rate of American cockroaches in different concentration propoxur between class 2019
Class 2019
Concentration of Propoxur Average Mortality Rate (%) of Class 2019 Standard Deviation
Control (0%) 40 40
0.01% 50 45.83
0.02% 100 0
0.05% 100 0
0.1% 100 0
Calculation: from log-probit graph to mg/kg
Table 5: LD50 from Log-Probit graph converting to mg/kg for class 2017 and class 2019 average
LD50 for 2017 class LD50 for 2019 class
0.040% w/v
=0.04% / 100mL
=0.0004 mg/uL (per cockroach)
Then dividing by class 2017 average 0.431g
0.0004 / 0.431g
= 9.28X10-4 mg/g
=9.28X10-4 mg/g X 1000
=0.928 mg/kg
0.004 w/v
=0.004% / 100mL
=0.00004 mg/uL (per cockroach)
Then dividing by class 2019 average 0.579g
0.00004 / 0.579g
= 6.90X10-5 mg/g
=6.90X10-5 mg/g X 1000
=0.069 mg/kg
Table 6: LD50 from the log – linear graph converting to mg/kg for class 2017 and class 2019 average
LD50 for 2017 class LD50 for 2019 class
0.038% w/v
=0.038% / 100mL
=0.00038 mg/uL (per cockroach)
Then dividing by class 2017 average 0.431g
0.00038 / 0.431g
= 8.82X10-4 mg/g
=8.82X10-4 mg/g X 1000
=0.882 mg/kg 0.010% w/v
=0.010% / 100mL
=0.0001 mg/uL (per cockroach)
Then dividing by class 2019 average 0.579g
0.0001 / 0.579g
= 1.73X10-4 mg/g
=1.73X10-4 mg/g X 1000
=0.173 mg/kg