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Papers by Andrea Werneburg
Journal of Chemical Ecology, 2011
Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and sim... more Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and similarly, insect oviposition might elicit the release of plant volatiles functioning as host finding cues for egg parasitoids. We hypothesized that egg parasitoids also might utilize HIPVs of emerging larvae to locate plants with host eggs. We, therefore, assessed the olfactory response of two egg parasitoids, a generalist, Trichogramma pretiosum (Tricogrammatidae), and a specialist, Telenomus remus (Scelionidae) to HIPVs. We used a Y-tube olfactometer to tests the wasps' responses to volatiles released by young maize plants that were treated with regurgitant from caterpillars of the moth Spodoptera frugiperda (Noctuidae) or were directly attacked by the caterpillars. The results show that the generalist egg parasitoid Tr. pretiosum is innately attracted by volatiles from freshly-damaged plants 0-1 and 2-3 h after regurgitant treatment. During this interval, the volatile blend consisted of green leaf volatiles (GLVs) and a blend of aromatic compounds, monoand homoterpenes, respectively. Behavioral assays with synthetic GLVs confirmed their attractiveness to Tr. pretiosum. The generalist learned the more complex volatile blends released 6-7 h after induction, which consisted mainly of sesquiterpenes. The specialist T. remus on the other hand was attracted only to volatiles emitted from fresh and old damage after associating these volatiles with oviposition. Taken together, these results strengthen the emerging pattern that egg and larval parasitoids behave in a similar way in that generalists can respond innately to HIPVs, while specialists seems to rely more on associative learning.
European Journal of Entomology, 2012
Age of host eggs can be a limiting factor for egg parasitoids. It is expected that old eggs are l... more Age of host eggs can be a limiting factor for egg parasitoids. It is expected that old eggs are less preferred by egg parasitoids, which can discriminate between eggs of different ages by using chemical cues. The objective of this study was to determine the preference, development and arrestment of Telenomus remus Nixon (Hymenoptera: Scelionidae) parasitizing Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) eggs of different ages. This egg parasitoid preferred to parasitize 1-and 2-day-old eggs rather than 3-day-old eggs in choice and no-choice assays. However, although the percentage emergence of parasitoids is significantly lower from 2-and 3-day-old eggs, the sex ratio and developmental time are unaffected. Parasitoids spent longer searching substrates impregnated with extracts of 1-and 2-day old eggs than 3-day-old eggs. Our results reveal that T. remus is able to distinguish the most suitable (1-day-old) from the least suitable (3-day-old) host eggs, but unable to recognize the unsuitability of intermediate aged eggs. Egg arrestants may be responsible for the preference of T. remus for ovipositing in 1-and 2-day old eggs.
Journal of Chemical Ecology, 2011
Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and sim... more Herbivore-induced plant volatiles are important host finding cues for larval parasitoids, and similarly, insect oviposition might elicit the release of plant volatiles functioning as host finding cues for egg parasitoids. We hypothesized that egg parasitoids also might utilize HIPVs of emerging larvae to locate plants with host eggs. We, therefore, assessed the olfactory response of two egg parasitoids, a generalist, Trichogramma pretiosum (Tricogrammatidae), and a specialist, Telenomus remus (Scelionidae) to HIPVs. We used a Y-tube olfactometer to tests the wasps' responses to volatiles released by young maize plants that were treated with regurgitant from caterpillars of the moth Spodoptera frugiperda (Noctuidae) or were directly attacked by the caterpillars. The results show that the generalist egg parasitoid Tr. pretiosum is innately attracted by volatiles from freshly-damaged plants 0-1 and 2-3 h after regurgitant treatment. During this interval, the volatile blend consisted of green leaf volatiles (GLVs) and a blend of aromatic compounds, monoand homoterpenes, respectively. Behavioral assays with synthetic GLVs confirmed their attractiveness to Tr. pretiosum. The generalist learned the more complex volatile blends released 6-7 h after induction, which consisted mainly of sesquiterpenes. The specialist T. remus on the other hand was attracted only to volatiles emitted from fresh and old damage after associating these volatiles with oviposition. Taken together, these results strengthen the emerging pattern that egg and larval parasitoids behave in a similar way in that generalists can respond innately to HIPVs, while specialists seems to rely more on associative learning.
European Journal of Entomology, 2012
Age of host eggs can be a limiting factor for egg parasitoids. It is expected that old eggs are l... more Age of host eggs can be a limiting factor for egg parasitoids. It is expected that old eggs are less preferred by egg parasitoids, which can discriminate between eggs of different ages by using chemical cues. The objective of this study was to determine the preference, development and arrestment of Telenomus remus Nixon (Hymenoptera: Scelionidae) parasitizing Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) eggs of different ages. This egg parasitoid preferred to parasitize 1-and 2-day-old eggs rather than 3-day-old eggs in choice and no-choice assays. However, although the percentage emergence of parasitoids is significantly lower from 2-and 3-day-old eggs, the sex ratio and developmental time are unaffected. Parasitoids spent longer searching substrates impregnated with extracts of 1-and 2-day old eggs than 3-day-old eggs. Our results reveal that T. remus is able to distinguish the most suitable (1-day-old) from the least suitable (3-day-old) host eggs, but unable to recognize the unsuitability of intermediate aged eggs. Egg arrestants may be responsible for the preference of T. remus for ovipositing in 1-and 2-day old eggs.