Djw. Morgan et Jd. Hare, INNATE AND LEARNED CUES - SCALE COVER SELECTION BY APHYTIS-MELINUS (HYMENOPTERA, APHELINIDAE), Journal of insect behavior, 11(4), 1998, pp. 463-479
Aphytis melinus recognizes and accepts covers of its host, California
red scale, Aonidiella aurantii (Maskell) (Homoptera: Diaspididae), bef
ore assessing the size or quality of the scale body beneath. We evalua
ted the role of a non-volatile kairomone, O-caffeoyltyrosine, and prio
r experience with hosts on the recognition (antennal drumming) and acc
eptance (ovipositor probing) of scale covers differing in age and, the
refore, size. We tested several hypotheses concerning the role of expe
rience with hosts on host recognition and acceptance. The first predic
ts that experience with a particular host size leads to increased sele
ction of that host size in the future. The second predicts that the ''
quality'' of the experience with hosts sets a threshold of quality for
future acceptance. We manipulated the quality of wasp experience with
hosts by exposing some wasps to high-quality hosts (large scale insec
ts under large covers) and other wasps to low-quality hosts (small sca
le insects under small covers and small scale insects under large cove
rs). Control (naive) wasps were held without experience with hosts. Wa
sps were then offered five size classes of covers directly after remov
al from the scale insects (unmanipulated) or after removing the kairom
one from the covers (kairomone-free). For covers with natural levels o
f kairomone, no effect of experience with hosts on host recognition wa
s observed. When the kairomone was removed, however, any experience wi
th hosts increased recognition compared to naive wasps. Moreover, expe
rienced wasps preferentially recognized covers of the size to which th
ey had experience. Results for host acceptance differed from those for
host recognition. Wasps given experience with large hosts accepted mo
re covers with kairomone than wasps in other treatments, but the size
preference did not vary among treatments. When the kairomone war; remo
ved, however, wasps given experience with large hosts under large cove
rs preferred larger covers. Host recognition and acceptance are contro
lled by different behavioral mechanisms. Prior experience with hosts d
oes not alter host recognition but does affect the rate of acceptance.
The quality of the experience does not affect the acceptance of cover
s containing natural levels of kairomone but does affect host acceptan
ce when the kairomone is removed. Experience with hosts alters the mot
ivation of wasps to accept covers, and the direction of this effect is
determined by the size (quality) of body the wasps were given during
the experience.