Food was not provided during testing because of the very small size of the beetles

(1 mm and 2.5 mm in length). The beetles could have conceivably perched on the food

source for long periods of time, never coming into contact with the walls of the treated

vial. Preliminary studies indicated that a 24-hour period without food would not unduly

stress the beetles. On average, untreated C. nipponicus survived for 8-9 days (n=30) and

untreated R. lophanthae lived for 5-6 days (n=30) before dying of starvation. Cotton used

to stopper the vials was soaked in water to prevent dehydration.

Bioassays Using Coated Glass Vial Method

 A coated glass vial method (Plapp 1971; Amalin et al. 2000; Snodgrass 1996;

Snodgrass et al. 2005) was used to determine the chemical susceptibility of adult R.

lophanthae and C. nipponicus to six pesticides used to control CAS (Howard et al. 1997;

Howard and Weissling 1999; Weissling et al. 1999; Hodges et al. 2003; Emshousen and

Mannion 2004). This is a very effective method for testing the chemical susceptibility of

small arthropods (Amalin et al. 2000) such as R. lophanthae and especially C. nipponicus

because of its extremely small size. The six pesticides tested were fish oil emulsion

(Organocide), insecticidal soap (Garden Safe, Inc.), imidacloprid (Provado),

malathion (Spectracide, Inc.), methidathion (Supracide), and dimethoate (Cygon).

The fish oil and insecticidal soap were purchased at commercial grade, while the

imidacloprid (99% purity), malathion (98% purity), methidathion (98.6% purity), and

dimethoate (98.7% purity) were purchased in the technical grade from Chem Service

(West Chester, PA).

 All pesticides were dissolved in acetone, except the insecticidal soap which does

not dissolve in acetone. Instead, the insecticidal soap was dissolved in 95% ethanol. The

fish oil was shaken in a paint shaker after being placed in acetone in order to break up the