Lo Bue, P., Forster, L.D., Millar, J.G., Colazza, S., & Luck, R.F. 2004a Metaphycus species near flavus responses to semiochemicals released.. California Conference on Biological Control IV. Center for Biological Control, College of Natural Resources Berkeley

Notes: [Conference held in Berkeley, California, U.S., 13-15 July, 2004.] Metaphycus sp. nr. flavus (Encyrtidae: Hymenoptera) is a Mediterranean parasitoid which oviposits in the immature stages of several economically important soft scale insects (Hemiptera: Coccidae), including brown soft scale Coccus hesperidum and C. pseudomagnolium. In Y-olfactometer bioassays measuring wasp choices and residency times, naive parasitoids were significantly more attracted to yucca (Yucca sp.) leaves infested with 26-, 27-, 28-, and 29-day-old scale than to uninfested leaves, whereas leaves with 30-day-old scale were no more attractive than uninfested leaves. Parasitoids also spent significantly more time in the arm with yucca leaves infested with 26-, 27-, 28-, and 29-day-old scale than in the arm with uninfested leaves, but they spent substantially more time in the arm with a yucca leaf infested 26-day-old scale than in the arm of any other age class of scale. Further, yucca leaves that had been infested with 26-day-old scale but from which the scales had been removed were as attractive as infested leaves. However, yucca leaves that had been infested with 26-day-old scales but from which the scales had been removed and the leaves washed with distilled water were less attractive than infested leaves. When the wash water containing scale residues was used to impregnate a filter paper disc, the impregnated disc was more attractive than a control disc impregnated with distilled water. In sum, these results suggest that Metaphycus sp. nr. flavus females utilize volatile, water-soluble compounds produced by brown soft scale as cues to locate suitable hosts. These results also suggest that 26- to 28-day-old scales are more attractive than older scales. Significantly, these are the scale ages on which M. sp. nr. flavus develops most successfully and suffers the least mortality from encapsulation.