Host Location Behavior by the Tachinid, Lixophaga diatraeae12

Abstract

Frass and methanol extracts of frass from sugarcane borer (SCB), Diatraea saccharalis (F.), larvae consistently stimulated larviposition by the tachinid Lixophaga diatraeae (Townsend). However, frass or frass extracts from larvae fed a soybean-flour wheat germ diet did not stimulate larviposition. Bioassays with frass from SCB, bollworm, Heliothis zea (Boddie), and southwestern corn borer, Diatraea grandiosella (Dyar), larvae fed several plant materials or artificial diet demonstrated that while larviposition was not entirely host specific, preference was influenced by host species and its food source. When extracts of different parts of SCB larvae were submitted to L. diatraeae , the flies larviposited on extracts of all sections of the alimentary canal, but extracts of silk or mandibular glands and hemolymph elicited only weak responses. The release of locomotor activity by volatiles from the host's frass or sugarcane could not be demonstrated. Tests and videotape observations revealed that the primary stimulus for larviposition by L. diatraeae was detected when the fly's fore-tarsi contacted the host frass. Under laboratory conditions once contact had been made parasites tended to aggregate in the area near the frass.