Behavioral responses of Ixodiphagus hookeri (Hymenoptera; Encyrtidae) to Rhipicephalus sanguineus nymphs (Ixodida: Ixodidae) and dog hair volatiles

Abstract

Abstract The wasp Ixodiphagus hookeri (Howard; Hymenoptera: Encyrtidae) parasitizes the larvae and nymphs of several tick species worldwide. In this study, we investigated whether I. hookeri females are attracted to Rhipicephalus sanguineus Latreille (Ixodida: Ixodidae) nymphs, hair samples from non-infested and infested Schnauzer dog volatiles, and a synthetic blend of compounds isolated from dog hair in a Y-tube glass olfactometer. We also studied the acceptance of fed and unfed R. sanguineus nymphs by female wasps. Our results showed that I. hookeri females were not attracted to R. sanguineus nymphs. In contrast, they were attracted to dog hair samples and extracts from non-infested and R. sanguineus-infested Schnauzer dog hair. Wasps were more attracted to hair samples from R. sanguineus-infested dogs than to those from non-infested dogs. In addition, I. hookeri females were attracted to a synthetic blend composed of hexanal, heptanal, and isovaleric acid, compounds previously isolated from dog hair. In contrast, I. hookeri females were not attracted to binary blends or individual compounds. Female wasps showed a higher acceptance of live-fed and live-unfed R. sanguineus nymphs than of dead fed nymphs washed with dichloromethane. Our results suggests that the host seeking behavior of I. hookeri females is attributable to a blend of volatiles from infested and non-infested schnauzer dogs, used to attack R. sanguineus nymphs.