Responses of
Metaphycussp. nr. flavus to semiochemicals
released from a scale host, Coccus hesperidum |
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Authors: | Paolo Lo Bue Stefano Colazza Lisa D Forster Jocelyn G Millar Robert F Luck |
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Institution: | (1) University of Palermo S. En. Fi. Mi. Zo. Department, Entomology, Acarology and Zoology, Viale delle Scienze, 90128 Palermo, Italy;(2) University of California, Department of Entomology, Riverside, CA 92521, USA |
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Abstract: | Summary. Metaphycus sp. nr.
flavus (Encyrtidae: Hymenoptera)
is a parasitoid species collected from the Mediterranean
region which lays its eggs in the immature stages of several
economically important soft scale insects (Hemiptera:
Coccidae), including brown soft scale, Coccus hesperidum
L. (= host insect). Preliminary tests suggested that the parasitoid
is most successful in producing offspring when it
oviposits in the younger stages of brown soft scale. In
Y-olfactometer bioassays measuring wasp choices and residence
times, naïve parasitoids were significantly more
attracted to yucca leaves infested with 26, 27, or 28 d-old
scale than to uninfested leaves, whereas leaves with older
(29-30 d-old) scale were no more attractive than uninfested
leaves. Parasitoids also spent significantly more time in the
arm with yucca leaves infested with 26 d-old scale than in
the arm with uninfested leaves. These results are consistent
with observations of the parasitoids reproductive success on
scale of different ages, whereby older scale are more likely
to encapsulate the developing eggs of M.
sp. nr. flavusfemales than are younger scale. Further bioassays determined
that yucca leaves that had been infested with 26 d-old
scale but from which the scale had been removed were as
attractive as infested leaves. In contrast, infested yucca
leaves from which scale had been removed and the leaves
subsequently washed with distilled water were less attractive
than infested leaves. Furthermore, the wash water
containing scale residues was attractive to female wasps. In
total, these results suggest that Metaphycussp. nr. flavus
females utilize volatile, water soluble compounds produced
by brown soft scale as cues to locate suitable hosts. |
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Keywords: | Parasitoid Y-olfactometer Semiochemicals Kairomone Coccus hesperidum Metaphycus sp nr flavus Yucca |
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