I am going to start an experiment with some essential oil to check their effect in a group of mesquite. I am wondering if anyone can explain me how should I check the LC50 and LC90 value of those some essential oil?
The type of regression you may use to calculate LC50 would depend on your data: the definition of LC50 does not contain information on the specific model to be used.
The most frequently used is probit analysis, but Hill equation, log-logistics (and their modifications), or even linear regression can be fitted.
You may review your data distribution, fit several models, and evaluate them to choose the best model.
Try to carry out some biological activities such as cytotoxic, free radical scavenging e.t.c. with the essential oil and through it LC50 can be determined.
I am not sure our colleagues have followed your meaning entirely. There is a problem for measuring LC50 and LC95 with essential oils because nearly all of them show volatility. So you have potentially two questions to answer:
1. is any mortality observed due to vapour and 2. is any mortality observed due to physical contact.
Most essential oils exhibit some level of neurotoxic activity and some/many also exhibit enzyme decoupling and other similar effects at a sub-cellular level. However, for measuring characteristics of lethal concentration you do not need to know the exact mechanism before you start.
I suggest you design two sets of experiments. One set will expose your insects to vapour in a closed container but where the insects cannot come into physical contact with the treated substrate, i.e. the essential oil treated substrate is enclosed in some kind of "cage" that excludes the insects but allows free vapour movement. The other set uses an "open space" container with free movement of air in an out but has a treated substrate that the insects must stand on at some point during the test so they acquire chemical by contact. Those insects are left in contact for a fixed time and then removed to a clean cage to recover or die.
Once you have those data you can use the analytical methods suggested and show the differences between vapour toxicity and contact toxicity.
Article In vitro study of anti-coccidial activity of essential oils ...
This article may be helpful. Mansour Abdulnabi H. Mehdi
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