Epiphytic ant-plant obtains nitrogen from both native and invasive ant inhabitants

Ant-plants have been extensively used as model systems in the study of the evolution and ecology of mutualisms. Using a 15N isotope labeling experiment, we found that both a native ant mutualist (Philidris cordata) and an invasive ant (Pheidole megacephala) provide nitrogen to the Australian ant-plant Myrmecodia beccarii

Epiphytic ant-plant obtains nitrogen from both native and invasive ant inhabitants

Ant-plants have been extensively used as model systems in the study of the evolution and ecology of mutualisms. Using a 15N isotope labeling experiment, we found that both a native ant mutualist (Philidris cordata) and an invasive ant (Pheidole megacephala) provide nitrogen to the Australian ant-plant Myrmecodia beccarii

What Defines a Host? Oviposition Behavior and Larval Performance of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Five Putative Host Plants

When an invasive species first breaches quarantine and establishes in yet another country, it invariably causes consternation for growers, in part because of incomplete understanding of the plants that are at risk. The Fall Armyworm, Spodoptera frugiperda (J.E. Smith) is the most recent example in Australia. The number of plants that this polyphagous noctuid is reported to attack is vast, including many crop species. Consequently, initial reactions from grower industry groups that perceived themselves at risk were to demand emergency use of insecticides. Yet the field evidence suggests that many crops might not be at risk and since S. frugiperda arrived in Australia, maize crops have suffered most damage, followed by sorghum. We question the accuracy of some of the claims of reported host plants of S. frugiperda and report experiments that compared oviposition behavior, neonate silking behavior, and larval performance on five crops: the known hosts maize and sorghum, and the putative hosts cotton, peanut, and pigeon pea. Maize ranked highest in all preference and performance measures, followed by sorghum and peanut, with pigeon pea and cotton ranking lowest. Although S. frugiperda can survive, develop, and pupate on the crop species we examined, cotton and pigeon pea are not preferred by the pest in either the larval or adult stages. We suggest that before a plant is listed as a host for a given insect that the evidence should be fully reported and carefully evaluated. Collecting an immature insect from a plant does not make that plant a host

Melomys cervinipes (Rodentia: Muridae)

Melomys cervinipes (Gould, 1852) is a murid rodent commonly called the fawn-footed mosaic-tailed rat. A small, russet brown rodent with light fawn-colored feet, it is 1 of 21 currently recognized species in the genus Melomys. The species is endemic to Australia, occurring in the rainforests and forests along the eastern coast. M. cervinipes is listed as "Least Concern" by the International Union for the Conservation of Nature and Natural Resources

Previous diet affects the amount but not the type of bait consumed by an invasive ant

BACKGROUND Recent research on multiple invasive ant species has revealed the importance of carbohydrates for achieving high activity levels and outcompeting native ants. However, comparatively little is known about the role of diet and macronutrient preferences for uptake of insecticidal baits used to control invasive ants. We tested whether diet affected yellow crazy ant (Anoplolepis gracilipes Fr Smith) survival, behavior, and whether bait preference would be complementary to past diet. RESULTS We found that colonies fed only crickets for 28 days had fewer live workers and queens and less brood per live queen than colonies fed crickets + honeydew but did not differ significantly from colonies fed only honeydew. Colonies that had been fed only crickets were more active (as assessed by interaction with a novel object), retrieved 16-17 times more bait per worker overall, and consumed more of the six bait types than cricket + honeydew and honeydew-only fed colonies. However, prior diet did not affect bait choice. The two highest sugar bait formulations combined accounted for most of the bait consumed across all treatments (cricket-only: 74.8% ± 28.1; cricket + honeydew: 69.2% ± 12.4; honeydew-only: 62.5% ± 30.4). CONCLUSION Yellow crazy ant colonies fare better without protein than without carbohydrates. Yellow crazy ants ate the most bait when fed only crickets but did not choose baits complementary to their previous diet. Baits in a sugar-rich carrier may be most effective for the control of yellow crazy ants, regardless of the relative availability of macronutrients. This article is protected by copyright. All rights reserved

Ontogenetic Changes in the Feeding Behaviour of Helicoverpa armigera Larvae on Pigeonpea (Cajanus cajan) Flowers and Pods

Despite substantial research examining caterpillar–plant interactions, changes in the feeding behaviour of lepidopteran larvae as they develop are poorly understood. In this study, we investigated ontogenetic changes in the behaviour of Helicoverpa armigera larvae feeding on reproductive structures of pigeonpea (Cajanus cajan). Specifically, we examined the preference for and avoidance of pigeonpea flowers and pods of first, second, third, and fourth instar H. armigera larvae. We also conducted a no-choice assay to compare the ability of third and fourth instar larvae to penetrate pigeonpea pod walls, which act as a physical defence against herbivory. When presented with a choice between pigeonpea pods and flowers, different instars behaved differently. First and second instar larvae largely avoided pigeonpea pods, instead feeding on flowers; third instar larvae initially avoided pods, but by 24 h, did not strongly discriminate between the structures; and fourth instars demonstrated a preference for pods. When initially placed on pods, first instars were slower than other instars to leave these structures, despite pods being suboptimal feeding sites for small caterpillars. We identified a clear instar-specific ability to penetrate through the pod wall to reach the seeds. Most third instar larvae were unable to penetrate the pod wall, whereas most fourth instars succeeded. Third instars suffered a physiological cost (measured by relative growth rate) when boring through the pod wall, which was not observed in fourth instars. Our study further illuminates the insect–plant interactions of the H. armigera–pigeonpea system and provides evidence for the significant changes in feeding behaviour that may occur during lepidopteran larval development

High invasive ant activity drives predation of a native butterfly larva

Yellow crazy ants (Anoplolepis gracilipes) threaten invertebrates on many tropical islands, but little work has been done in continental ecosystems. We found 4.4–16.0 times more cruiser butterfly caterpillars were attacked in Australian rain forest sites with A. gracilipes than in native ant sites, and extrafloral nectar had little influence