Toxicological studies on a beetle, Alphitobius Zaevigatus (F.)

Abstract

SUMMARYA series of joint action experiments was done using 4,6‐dinitro‐2‐n‐butylphenol and 4,6‐dinitro‐2‐sec‐butylphenol in solution in Risella 17 oil. The following were tested: (1) the joint action of doses of the n‐butyl compound on two sites of application on the beetle, the mesoscutellum and the hind coxae; (2) the joint action of doses of the sec‐butyl compound on the two sites; (3) the joint action of the two compounds applied to the mesoscutellum; and (4) the joint action of the two compounds applied to the hind coxae.The data obtained were interpretable on the assumption that the joint action of the doses (whether of one compound on the two sites, or of the two on one site) was simply similar, with complete positive correlation of tolerances, and that the amount of toxicant reaching the site of action was proportional to the dose (volume of solution) raised to the power of η, where η < 1. This meant that the joint applications were more toxic than was predicted by an equation for similar joint action given by Finney (1952), which in effect makes the assumption that η= 1. In the portion of the present work in which the results can be so expressed, the joint applications ranged from 1·11 to 1·51 times as toxic as the predictions by Finney's equation. The estimates of 7 ranged from 0·62 to 0·87, with a mean of 0·755 ± 0·037. The finding that the joint toxicities were higher than predicted by Finney's equation agrees with predictions made by Plackett & Hewlett (1952) and by Hewlett & Plackett (1959, 1961). Experiments with the see‐butyl compound indicated that values of η < 1 were not interpretable on the hypothesis that the coefficient of regression of probits on log‐concentration was greater than that on log‐volume, for estimates of the two coefficients were not significantly different.