Host-searching by Goniozus natalensis females elicited by a short- range kairomone in the frass of its natural host Eldana Saccharina.
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Date
1990
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Abstract
Petri dish and olfactometer tests demonstrated that Goniozus natalensis (Gordh)
females exhibit a host-searching response upon contact and at a short distance by
olfaction, to a kairomone in the frass of its natural host Eldana saccharina (Walker).
The host-searching response was found to be elicited by E. saccharina frass from a
range of substrates, namely: two host plants of E. saccharina, papyrus and sugarcane,
and four media: sugarcane, papyrus, and cellulose based media and a synthetic
medium containing no plant material. The host-searching response was not elicited
by Sesamia calamistis (Hamps) sugarcane medium frass. The sexual state and age of
G. natalensis females were found to influence the host-searching behaviour. Mated
females showed the behaviour in the petri dish bioassays only after completing their
preoviposition time of two to three days, whilst virgin females took longer, even
though their preoviposition time was found to be the same. The response to male or
female produced E. saccharina sugarcane frass was not statistically different, nor was
there a statistically significant preference for either frass type, given the choice. Four
way olfactometer tests showed that an E. saccharina sugarcane frass odour elicited a
host-searching behaviour in mated two to three day old G. natalensis females. Various
solvents were tested for their ability to isolate the kairomone from E. saccharina
sugarcane frass. Chloroform proved to be the best solvent when tested in petri dish
and olfactometer bioassays. The preliminary results of the GC/MS analysis of the
chloroform extract of E. saccharina sugarcane frass are presented. The chemicals
identified are compared with chemicals identified as host location kairomones for
other insect parasitoid-host studies.
Description
Thesis (M.Sc.)-University of Natal, 1990.
Keywords
Chemoreceptors., Insects--host plants., Insects-plant relationships., Lepidoptera--host plants.