Evaluation of Plants Containing Rotenone

Abstract

(1) Eleven samples, consisting of six Derris elliptica (of four different types), two D. malaccen~is, one D. polyantha, and two Mundulea suberosa, have been examined chemically and biologically. (2) No correlation could be found between toxicity and ether extract or rotenone contents. (3) When, however, the" dehydro-compounds," determined by an optical rotation method, were calculated as percentages of the ether extractive matter, instead of as percentages of the whole sample, then a direct correlation was found. (4) A straight regression line was obtained for probitsplotted against log concentrations of,. optical dehydrocompounds" in the ether extract, the equation being P = 5·176 + 2'63(0 -1·546). (5) The value of P for 0·1 % root concentrations of spray has been called the " coefficient of toxicity" or CT value. (6) The figure obtained by dividing the ether extract value of a sample by the percentage of " optical dehydrocompounds" has been called the "toxicity ratio" or TR value. (7) The T" values of the samples were directly proportional to the weights of each required to give equal toxic effects: i.e., twice the T R value required twice as much root to give the same kill. (8) These results have been based on toxicities to one insect only; they should hold for other similar insects but may not do so for paraffin and oil sprays against flies, cockroaches, etc., but in these cases the correlation is likely to be better than for rotenone or ether extract contents.