Two mineral oils and 12 linear primary alcohols were studied, alone and in combination, to determine their contact toxicity to adult German cockroaches, Blattella germanica (L.) (Dictyoptera: Blattellidae). The more toxic oil, PD23 (LD50 = 1.45 mg per cockroach) was used
for combination studies. Alcohols with carbon chain lengths of C3 and C8 through C12 were the most toxic, with LD50 values ranging from 0.3 to 0.6 mg. C1 (methanol) and C14 (1-tetradecanol) were least toxic, with LD50 values of 2.35 and 1.75 mg, respectively. Eight of
the 12 combinations of a nonlethal dose of PD23 oil with an LD10 dose of alcohol produced significantly greater mortality than predicted under the assumption of additive effects. A sample of five synergistic oil + alcohol combinations, covering most of the alcohol carbon chain length
range over which synergy occurred, was further studied by calculating LD50 values for three fixed mixture ratios (80:20, 50:50, and 20:80) of each combination. Results were analyzed using both graphical techniques (isobole analysis) and by nonlinear regression. At least one, but
not necessarily all, of the three fixed ratio combinations of each oil + alcohol pairing indicated synergy. The conclusions drawn from the isobole and regression analyses were consistent.
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.