Attraction of Astylus variegatus (Germ.) (Coleoptera: Melyridae) by volatile floral attractants

Abstract

The beetle Astylus variegatus (Germ.) (Coleoptera: Melyridae) is frequently found in flowers feeding on pollen. Responses of A. variegatus to volatile floral attractants were studied in common beans (Phaseolus vulgaris L.) fields. Traps originally designed to capture Diabrotica speciosa (Germ.) (Coleoptera: Chrysomelidae), consisted of plastic bottles (2 L) with 150 holes (5-mm diameter) yellow gold painted and containing inside a plastic strip (3.5 <FONT FACE=Symbol>´</FONT> 25 cm) with Lagenaria vulgaris (L.) powder (0.28% B cucurbitacin - feeding stimulant and arrestant for diabroticites) sprayed with carbaril insecticide. Treatments consisted of 1,4-dimethoxybenzene (one or two dispensers per trap), 1,4-dimethoxybenze + indole, 1,4-dimethoxybenzene + cinnameldehyde and control. Volatile average release rates (over ten days) was approximately 32 mg day-1 per dispenser under laboratory conditions. 1,4-dimethoxybenzene-lured traps caught significantly more beetles than the control, three and seven days after trap setting. Ten days after the onset of the experiment, there were no differences in number of beetles caught by treatments. Captures were higher in the 1,4-dimethoxybenzene + cinnamaldehyde treatment than in 1,4-dimethoxybenzene only in the first assessment. Adding indole to 1,4-dimethoxybenzene did not improve beetle captures.