Toxicology of Cupric Salts in Honeybees : I. Hormesis Effects of Organic Derivatives on Lethality Parameters

Feeding bees with organic cupric salts provides long-term control of the parasite Varroa jacobsoni. A set of new algebraic parameters (M. Bounias C.R. Acad. Sci. 310(3), 65-70, 1990) completely describing the population lethality function has been calculated following chronic administration of cupric gluconate, aspartate, and isoleucinate, with or without dietary pollen. Mortality curves allowed the calculation of LT50 (time for 50% lethality) as well as Hill coefficients (h) of the curves and the LD50 as a function of time. The tangent at the inflexion point of the sigmoidal time/mortality curves (Δi) gave the maximum mortality acceleration as an additional parameter. No toxicity (i.e., no decrease of TL50 vs doses and no LD50 values) was found for cupric gluconate and isoleucinate with pollen, whereas increases in LT50 and decreases in Δ indicated hormesis effects. Doses decreasing by half-time LT50, h, or Δ were used as objective lethality indexes for comparisons of toxicity in the other cases. Routine acute toxicity at high dosage was also compared with phosalone and lindane effects 24 hr after treatment.