There is another link on this topic: https://www.researchgate.net/post/What_exactly_is_the_sublethal_dose_of_a_drug_and_how_i_measure_it

Found this information:

1. Sublethal effects are defined as biological, physiological, demographic or behavioral effects on individuals or populations that survive exposure to a toxicant at lethal or sublethal dose/concentration. A sublethal dose/concentration is defined as inducing no apparent mortality in the experimental population. Ref.: Chapter The Sublethal Effects of Insecticides in Insects

2. EC50 (median effective concentration): The concentration of chemical in water to which test organisms are exposed that is estimated to be effective in producing some sublethal response in 50% of the test organisms. The EC50 is usually expressed as a time-dependent value (e.g., 24 h or 96 h EC50). The sublethal response elicited from the test organisms as a result of exposure to the chemical must be clearly defined (e.g., test organisms may be immobilized, lose equilibrium, or undergo physiological or behavioral changes). (Ref. Book: Handbook of Toxicology, page 948. Editors, Derelanko & Hollinger, 3rd Edn., CRC Press).

3. EC50 (effective concentration–50%): A statistically or graphically determined concentration of a chemical that reduces a sublethal response parameter of interest by 50%. (Ref. Book: Haye's Principles & Methods of Toxicology, 6th Edition, page 2084).

4. Most toxic effects in polluted ecosystems are sublethal and so sublethal tests should be used in order to assess the likely effects of pollutants. This can be done by determining the median effective concentration (EC50). This is the concentration of added toxicant that in a given time under given conditions brings about a specified sublethal effect in 50% of the test population. Such an effect might be a 20% reduction in growth rate relative to a control with no added toxicant. It could also be a 20% change in any physiological process, such as a 20% reduction in photosynthetic or respiratory rate relative to a control, or a 20% change in a developmental process such as the formation of reproductive bodies in an alga. (Ref. Book: Fundamental Toxicology, 2006, Editors: Duffus & Worth, page 268, RSC publishing).

There is another link on this topic: https://www.researchgate.net/post/What_exactly_is_the_sublethal_dose_of_a_drug_and_how_i_measure_it

Found this information:

1. Sublethal effects are defined as biological, physiological, demographic or behavioral effects on individuals or populations that survive exposure to a toxicant at lethal or sublethal dose/concentration. A sublethal dose/concentration is defined as inducing no apparent mortality in the experimental population. Ref.: Chapter The Sublethal Effects of Insecticides in Insects

2. EC50 (median effective concentration): The concentration of chemical in water to which test organisms are exposed that is estimated to be effective in producing some sublethal response in 50% of the test organisms. The EC50 is usually expressed as a time-dependent value (e.g., 24 h or 96 h EC50). The sublethal response elicited from the test organisms as a result of exposure to the chemical must be clearly defined (e.g., test organisms may be immobilized, lose equilibrium, or undergo physiological or behavioral changes). (Ref. Book: Handbook of Toxicology, page 948. Editors, Derelanko & Hollinger, 3rd Edn., CRC Press).

3. EC50 (effective concentration–50%): A statistically or graphically determined concentration of a chemical that reduces a sublethal response parameter of interest by 50%. (Ref. Book: Haye's Principles & Methods of Toxicology, 6th Edition, page 2084).

4. Most toxic effects in polluted ecosystems are sublethal and so sublethal tests should be used in order to assess the likely effects of pollutants. This can be done by determining the median effective concentration (EC50). This is the concentration of added toxicant that in a given time under given conditions brings about a specified sublethal effect in 50% of the test population. Such an effect might be a 20% reduction in growth rate relative to a control with no added toxicant. It could also be a 20% change in any physiological process, such as a 20% reduction in photosynthetic or respiratory rate relative to a control, or a 20% change in a developmental process such as the formation of reproductive bodies in an alga. (Ref. Book: Fundamental Toxicology, 2006, Editors: Duffus & Worth, page 268, RSC publishing).

Sublethal effects are by definition effects that do not necessarily cause mortality, but which do have measurable and quantifiable effects on the (reproductive) fitness of an organism. As such, LD50, LD95 or other LD's are not appropriate to measure sublethal effects. Instead one can assess various lifetable parameters, such as development speed, longevity, or reproductive success.

Behavioral modifications, as seen, for instance, by exposure to some pesticides, can also be quantified. This can be done directly, or indirectly through behavioral bioassays, or through impacts on the lifetable parameters mentioned above.

I agree with Felix L Wäckers reply, and you can see:

Article A comparison of the lethal and sublethal toxicity of organic...

Sublethal effects are adverse impacts of chemicals on the biological performance of an individual and don't actually cause mortality. while LD50/LD100 are related with mortality of organisms i.e., 50%/100%, respectively. thus the two terms describe different level of effects of the toxic substance on the organism.

Felix has covered the essentials of this question well. However, sublethal effects refer to concentration levels that do not result in mortality but induce physiological or other notable effects on a given proportion of the experimental subjects.

As a PhD student in 1983 I showed the LD01 of pyrethroids reduced feeding by 50%

LD01 = LD 1%?