Host Recognition Kairomones for Anaphes iole Girault, an Egg Parasitoid of the Western Tarnished Plant Bug☆

Abstract Laboratory experiments were conducted to determine if chemicals derived from host adults or eggs influence the host location/recognition behavior of Anaphes iole Girault (Hymenoptera: Mymaridae) females. Females often probed with their ovipositor, in or near punctures made by Lygus hesperus Knight (Hemiptera:Miridae) females on Gelcarin oviposition packs, in a way that was similar to the probing of protruding host eggs. When the surface Parafilm of the Gelcarin packs that L. hesperus females had oviposited was replaced with clean punctured Parafilm, females also responded to the punctures, suggesting that the internal contents of the Gelcarin packs cause the probing behavior. Females probed punctures on a piece of Parafilm covering the abdominal contents of host females and males, but they did not respond to punctures in Parafilm covering distilled water or Rinaldini solution. Females also probed glass cylinders coated with host hemolymph, contents of host females or males, or seminal depository. These results suggest that A. iole females use chemicals derived from host eggs or adults in host recognition. Because females responded to mature ovarian eggs embedded in Gelcarin packs, a possible source of this stimulant may be the ovaries of the L. hesperus females. Punctured Parafilm removed from Gelcarin packs which host nymphs had probed with their mouthparts stimulated antennation by A. iole females, but not ovipositor probing. Punctures on Gelcarin packs that had never been exposed to hosts sometimes stimulated ovipositor probing by female A. iole . Because the probing response was not elicited from A. iole females by punctured Parafilm covering nothing, distilled water, or liquid from Gelcarin packs, the presence of the gel underneath punctured Parafilm may elicit an ovipositor probing response from A. iole females. Host-derived chemicals play an important role with physical properties of host eggs and the substrate in which host eggs are embedded, on host recognition and acceptance by A. iole females.