I suggest that you base you LT50 experiment on the LD50, which is a standard value.

Thank you for your answer Sir

Dear Doctor, normally you have to calculate the LTi for each dose.

Best regards

Can you calculate the LT50 of each concentration, this times is variable with any concentration, so each concentration have it own LT50

Merabti Brahim but, we can calculate them that just at the concentrations which give a mortality higher than 50%?

Effectively,but you can calculate it with another technic (probit)....

Merabti Brahim Thank you for your answer Sir. Yes, I'm talking about when i use probit analysis

The probit analysis maked when you want calculate any toxicological parameters like LT or LC and the higher and lower limits of those parameters

Greetings

you could take an idea about it in this article:

https://www.researchgate.net/publication/365782592_Chemical_composition_of_Artemesia_herba-alba_essential_oil_and_its_larvicidal_and_pupicidal_effects_against_Culex_pipiens_Diptera_Culicidae