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21.
Marcela K. Castelo Muriel Ney-Nifle Juan C. Corley Carlos Bernstein 《Behavioral ecology and sociobiology》2006,61(2):231-243
For parasitoids, host finding is a central problem that has been solved through a variety of behavioural mechanisms. Among species in which females do not make direct contact with hosts, as is the case for many dipteran parasitoids, eggs must be laid in an appropriate part of the host habitat. The asilid fly Mallophora ruficauda lays eggs in clusters on tall vegetation. Upon eclosion, pollen-sized larvae fall and parasitize soil-dwelling scarab beetle larvae. We hypothesized that wind dissemination of M. ruficauda larvae is important in the host-finding process and that females lay eggs at heights that maximize parasitism of its concealed host. Through numerical and analytical models resembling those used to describe seed and pollen wind dispersal, we estimated an optimal oviposition height in the 1.25- to 1.50-m range above the ground. Our models take into account host distribution, plant availability and the range over which parasitic larvae search for hosts. Supporting our findings, we found that the results of the models match heights at which egg clusters of M. ruficauda are found in the field. Generally, work on facilitation of host finding using plants focuses on plants as indicators of host presence. We present a case where plants are used in a different way, as a means of offspring dispersal. For parasitoids that carry out host searching at immature stages rather than as adults, plants are part of a dissemination mechanism of larvae that, as with minute seeds, uses wind and a set of simple rules of physics to increase offspring success. 相似文献
22.
Paolo Lo Bue Stefano Colazza Lisa D. Forster Jocelyn G. Millar Robert F. Luck 《Chemoecology》2004,14(3-4):151-156
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. 相似文献