The navel orangeworm Amyelois transitella (Walker, 1863, Lepidoptera: Pyralidae), a pest of California tree nuts, is associated with the fungus Aspergillus flavus, and previous research suggests these species are facultative mutualists. Because navel orangeworm larvae exhibit improved performance on diets containing this fungus, orientation toward hostplants infected with A. flavus may be adaptive. We conducted behavioral assays to determine if larvae respond to chemical cues produced by almond hull split and fungal infection. In petri dish arenas, larvae showed a preference for 1-octen-3-ol and 2-phenylethanol, volatiles characteristic of damaged plants, as well as methanolic extracts of almond meal with 1-octen-3-ol and the fungal volatile conophthorin. In contrast, larvae displayed aversion to ethyl benzoate, an inhibitor of fungal growth. When we assessed oviposition behavior relative to substrates with and without A. flavus, females laid almost twice as many eggs near inoculated surfaces. Moreover, an average of 63% of eggs laid near inoculated substrates were fertilized, compared with 24% of eggs near uninoculated sites. We also tested the hypothesis that unfertilized eggs are laid on nutrient-poor substrates to provide supplemental nutrition for larvae in an assay comparing larval survivorship in the presence and absence of unfertilized eggs. Neonates given eggs survived 2.5 times longer on an average than unprovisioned neonates (208.8 h vs. 85.2 h), indicating that this species may compensate with cannibalism for oviposition on lower-quality food sources. We conclude that larvae orient to probable host plant and fungal volatiles associated with hull split and document a possible strategy for larvae to establish on low-quality hosts.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 46 • No. 3