Polyethylene Glycol Film Method: A Test for Feeding Stimulants of the German Cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae)

Abstract

A polyethylene glycol (PEG) film method was developed to evaluate the activity of cockroach feeding stimulants. A droplet of aqueous methanol or methanol solution of test material containing PEG was placed on a glass plate to form a spot of PEG film. After exposure to a test insect, mandibular scratches on the film were examined under microscopic observation. The response was recorded as the percentage of marked films. A probit analysis of the concentration/response relation evaluated the EC50 and relative potency of each compound. Assays were conducted on adults of the German cockroach, Blattella germanica (L.), satiated with food and water. For compounds showing little or no activity, starved insects were subjected to assays as well. Sugars and related compounds were active, whereas aliphatic alcohols, fatty acids and esters showed less activities. The active compounds were classified into five groups according to the regression coefficients. Maltose was the most active, showing an EC50 at 7.5 and 4.7 μmol/g PEG to female and male adults, respectively.