MASS-PRIMING APHYTIS - BEHAVIORAL IMPROVEMENT OF INSECTARY-REARED BIOLOGICAL-CONTROL AGENTS

The introduced parasitoid, Aphytis melinus DeBach (Hymenoptera: Apheli nidae), is used for augmentative biological control of California red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae). Commerc ially reared wasps are reared on oleander scale, Aspidiotus nerii Bouc he (Homoptera: Diaspididae). Oleander scale covers lack the chemical, O-caffeoyltyrosine, a kairomone mediating host selection by A. melinus . Wasps reared on oleander scale but individually exposed, or primed, to O-caffeoyltyrosine more readily accepted California red scale for p robing in laboratory bioassays and parasitized a greater proportion of available California red scale in the field than wasps reared similar ly but not exposed to O-caffeoyltyrosine. Thus, it may be possible to improve host recognition of commercial, insectary-reared A. melinus by exposing them to O-caffeoyltyrosine prior to release, The goal of thi s study was to develop an inexpensive but effective means of priming t housands of wasps simultaneously to O-caffeoyltyrosine. The most effec tive method, but potentially the most expensive, was simply to spray p arasitized oleander scale on their host plant with dilute O-caffeoylty rosine prior to wasp emergence. In additional experiments, using contr olled doses of synthetic O-caffeoyltyrosine applied to scale covers, w e showed that primed wasps require both a lower minimum dose of O-caff eoyltyrosine for recognition and also respond to measured O-caffeoylty rosine doses more consistently than unprimed wasps. The ability to mas s-prime thousands of wasps prior to release is a crucial step toward r ealizing the concept of behavioral improvement of host selection of pa rasitoids on a commercial scale. (C) 1997 Academic Press.